Breathable atmospheres may be more common in the universe than we first thought

The existence of habitable alien worlds has been a mainstay of popular culture for more than a century. In the 19th century, astronomers believed that Martians might be using canal-based transport links to traverse the red planet. Now, despite living in an age when scientists can study planets light years from our own solar system, most new research continues to diminish the chances of finding other worlds on which humans could live. The biggest stumbling block may be oxygen - human settlers would need a high oxygen atmosphere in which to breathe. So how were we so lucky to evolve on a planet with plenty of oxygen? The history of Earth's oceans and atmosphere suggests that the rise to present-day levels of O2 was pretty difficult. The current consensus is that Earth underwent a three-step rise in atmospheric and oceanic oxygen levels, the first being called the "Great Oxidation Event" at around 2.4 billion years ago. After that came the "Neoproterozoic Oxygenation Event" around 800 million years ago, and then finally the "Paleozoic Oxygenation Event" about 400 million years ago, when oxygen levels on Earth reached their modern peak of 21%. What happened during these three periods to increase oxygen levels is a matter for debate. One idea is that new organisms "bioengineered" the planet, restructuring the atmosphere and oceans through either their metabolisms or their lifestyles.

For example, the rise of land plants roughly 400 million years ago could have increased oxygen in the atmosphere through land-based photosynthesis, taking over from photosynthetic bacteria in the ocean which have been the main oxygen producers for most of Earth's history. Alternatively, plate tectonic changes or gigantic volcanic eruptions have also been linked to the Earth's oxygenation events.

This event-based history of how oxygen came to be so plentiful on Earth implies that we're very fortunate to be living on a high-oxygen world. If one volcanic eruption hadn't happened, or a certain type of organism hadn't evolved, then oxygen might have stalled at low levels.

But our latest research suggests that this isn't the case. We created a computer model of the Earth's carbon, oxygen and phosphorus cycles and found that the oxygen transitions can be explained by the inherent dynamics of our planet and likely didn't require any miraculous events.

Phosphorus - University of Leeds
One thing we think is missing from theories about Earth's oxygenation is phosphorus. This nutrient is very important for photosynthetic bacteria and algae in the ocean. How much marine phosphorous there is will ultimately control how much oxygen is produced on Earth. This is still true today - and has been so since the evolution of photosynthetic microbes some three billion years ago.

Photosynthesis in the ocean depends on phosphorus, but high phosphate levels also drive consumption of oxygen in the deep ocean through a process called eutrophication. When photosynthetic microbes die, they decompose, which consumes oxygen from the water. As oxygen levels fall, sediments tend to release even more phosphorus. This feedback loop rapidly removes oxygen. This meant that oxygen levels in the oceans were able to change rapidly, but they were buffered over long timescales by another process involving the Earth's mantle.

Throughout Earth's history, volcanic activity has released gases that react with and remove oxygen from the atmosphere. These gas fluxes have subsided over time due to Earth's mantle cooling, and our computer model suggests this slow reduction along with the initial evolution of photosynthetic life was all that was necessary to produce a series of step-change increases in oxygen levels.

These stepped increases bear a clear resemblance to the three-step rise in oxygen that has occurred throughout Earth's history. The model also supports our current understanding of ocean oxygenation, which appears to have involved numerous cycles of oxygenation and deoxygenation before the oceans became resiliently oxygenated as they are today.

What is really exciting about all of this is that the oxygenation pattern can be created without the need for difficult and complex evolutionary leaps forward, or circumstantial catastrophic volcanic or tectonic events. So it appears that Earth's oxygenation may have been inescapable once photosynthesis had evolved - and the chances of high oxygen worlds existing elsewhere could be much higher.

Boeing CST-100 Starliner takes next step for orbital flight test

The Boeing CST-100 Starliner spacecraft that will launch to the International Space Station on the company's uncrewed Orbital Flight Test for NASA's Commercial Crew Program (CCP) has taken a significant step toward launch. Starliner rolled out of Boeing's Commercial Crew and Cargo Processing Facility at NASA's Kennedy Space Center in Florida on Nov. 21, making the trek on a transport vehicle to Space Launch Complex 41 at Cape Canaveral Air Force Station. "This is critical to our future as a nation," said Kennedy's center director Bob Cabana. "We've got to get astronauts flying on U.S rockets from U.S. soil, and this is just a huge step forward." Cabana was joined by CCP and Boeing leaders in a gathering of employees and families to watch Starliner roll out of the factory. "For the team that has built the first American spacecraft designed to land on land, and to get it rolling out, is absolutely incredible," said John Mulholland, Vice President and Program Manager of Boeing Commercial Crew Programs. "Something this complex takes a huge team." "Look at that amazing sight and what your success looks like," said Kathy Lueders, NASA's Commercial Crew Program Manager. "We're not done yet. We've got to step into the mission carefully, fly this vehicle up to the space station, and bring it home safely." At the pad, Starliner was hoisted up at the Vertical Integration Facility and secured atop a United Launch Alliance Atlas V rocket for the flight test to the space station. The Atlas V rocket that will carry Starliner comprises a booster stage and dual-engine Centaur upper stage, as well as a pair of solid rocket boosters.

NASA astronauts Mike Fincke and Nicole Mann and Boeing astronaut Chris Ferguson were on hand to witness the rollout milestone ahead of the uncrewed flight test.

"This is the dawn of a new era," said Ferguson. "For all of you youngsters out there who came out here early to watch, I'm glad you were a part of this. This is really important because this is your future, too."

"We're looking forward to the day when we're launching people on a regular basis," said Fincke. "As graduates of military test pilot schools, we are really excited to see how Starliner's going to behave; we know it's going to be awesome, and we're going to get all kinds of really great test data from it."

The uncrewed flight test, targeted to launch Dec. 17, will provide valuable data on the end-to-end performance of the Atlas V rocket, Starliner spacecraft and ground systems, as well as in-orbit, docking and landing operations. The data will be used as part of NASA's process of certifying Boeing's crew transportation system for carrying astronauts to and from the space station.

"It comes down to trust," said Mann. "I'm talking about trust in the individuals-our fellow Americans-who are building this spacecraft and making this possible. You walk around the factory and there is this amazing attention to detail, and it gives you this great level of confidence," said Mann.

NASA is working in partnership with Boeing and SpaceX to launch astronauts on American rockets and spacecraft from American soil for the first time since 2011. Safe, reliable and cost-effective human transportation to and from the space station will allow for additional research time and increase the opportunity for discovery aboard humanity's testbed for exploration.

Exoplanet axis study boosts hopes of complex life, just not next door

"They're out there," goes a saying about extraterrestrials. It would seem more likely to be true in light of a new study on planetary axis tilts. Astrophysicists at the Georgia Institute of Technology modeled a theoretical twin of Earth into other star systems called binary systems because they have two stars. They concluded that 87% of exo-Earths one might find in binary systems should have axis tilts similarly steady to Earth's, an important ingredient for climate stability that favors the evolution of complex life. "Multiple-star systems are common, and about 50% of stars have binary companion stars. So, this study can be applied to a large number of solar systems," said Gongjie Li, the study's co-investigator an assistant professor at Georgia Tech's School of Physics. Single-star solar systems like our own with multiple planets appear to be rarer. The researchers started out contrasting how the Earth's axis tilt, also called obliquity, varies over time with the variation of Mars' axis tilt. Whereas our planet's mild obliquity variations have been great for a livable climate and for evolution, the wild variations of Mars' axis tilt may have helped wreck its atmosphere, as explained in the section below. Then the researchers modeled Earth into habitable, or Goldilocks, zones in Alpha Centauri AB - our solar system's nearest neighbor, a binary system with one star called "A" and the other "B." After that, they expanded the model to a more universal scope.

"We simulated what it would be like around other binaries with multiple variations of the stars' masses, orbital qualities, and so on," said Billy Quarles, the study's principal investigator and a research scientist in Li's lab. "The overall message was positive but not for our nearest neighbor."

Alpha Centauri A actually didn't look bad, but the outlook for mild axis dynamics on an exo-Earth modeled around star B was wretched. This may douse some hopes because Alpha Centauri AB is four lightyears away, and a mission named Starshot with big-name backers plans to launch a space probe to look for signs of advanced life there.

The researchers are publishing their study, which was co-led by Jack Lissauer from NASA Ames Research Center, in Astrophysical Journal on November 19, 2019, under the title: "Obliquity Evolution of Circumstellar Planets in Sun-like Stellar Binaries." The research was funded by the NASA Exobiology Program.

No exoplanets have been confirmed around A or B; an exoplanet has been confirmed around the nearby red dwarf star Proxima Centauri, but it is very likely to be uninhabitable.

Earth? Just right
Even with its ice ages and hot phases, Earth's climatological framework has been calm for hundreds of millions of years - in part because of its mild orbital and axis-tilt dynamics - allowing evolution to take big strides. Wildly varying dynamics, and thus climate, like on Mars would stand to regularly kill off advanced life, stunting evolution.

Earth's orbit around the sun is on a slight incline that seesaws gently and very slowly through a slight precession, a kind of oscillation. As Earth revolves, it shifts position relative to the sun, circling it a little like a spirograph drawing. The orbit also precesses in shape between slightly more and slightly less oblong over 100,000-year periods.

Earth's axis tilt precesses between 22.1 and 24.5 degrees over the course of 41,000 years. Our large moon stabilizes our tilt through its gravitational relationship with Earth, otherwise, bouncy gravitational interconnections with Mercury, Venus, Mars, and Jupiter would jolt our tilt with resonances.

"If we didn't have the moon, Earth's tilt could vary by about 60 degrees," Quarles said. "We'd look maybe like Mars, and the precession of its axis appears to have helped deplete its atmosphere."

Mars' axis precesses between 10 degrees and 60 degrees every 2 million years. At the 10-degree tilt, the atmosphere condenses at the poles, creating caps that lock up a lot of the atmosphere in ice. At 60 degrees, Mars could grow an ice belt around its equator.

Universe? Hopeful
In Alpha Centauri AB, star B, about the size of our sun, and the larger star, A, orbit one another at about the distance between Uranus and our sun, which is a very close for two stars in a binary system. The study modeled variations of an exo-Earth orbiting either star but concentrated on a modeled Earth orbit in the habitable zone centered around B, with A being the orbiting star.

A's orbit is very elliptical, passing close by and then moving very far away from B and slinging powerful gravity, which, in the model, overpowered exo-Earth's own dynamics. Its tilt and orbit varied widely; adding our moon to the model didn't help.

"Around Alpha Centauri B, if you don't have a moon, you have a more stable axis than if you do have a moon. If you have a moon, it's pretty much bad news," Quarles said.

Even without a moon and with mild axis variability, complex, Earthlike evolution would seem to have a hard time on the modeled exo-Earth around B.

"The biggest effect you would see is differences in the climate cycles related to how elongated the orbit is. Instead of having ice ages every 100,000 years like on Earth, they may come every 1 million years, be worse, and last much longer," Quarles said.

But a sliver of hope for Earthlike conditions turned up in the model: "Planetary orbit and spin need to precess just right relative to the binary orbit. There is this tiny sweet spot," Quarles said.

When the researchers expanded the model to binary systems in the universe, the probability of gentle obliquity variations ballooned.

"In general, the separation between the stars is larger in binary systems, and then the second star has less of an effect on the model of Earth. The planet's own motion dynamics dominate other influences, and obliquity usually has a smaller variation," Li said. "So, this is quite optimistic."

SpaceX's new ride-sharing launches to boost small-satellite industry

SpaceX's plans for more frequent, regularly scheduled ride-sharing launches will unleash new growth in the small-satellite industry, leading to easier and cheaper rollouts for new communication networks, experts said. SpaceX recently published a schedule of 30 rocket launches for small satellites in 2020 and 2021. Its customers can buy space on the missions for as low as $1 million, a previously unprecedented price to put a satellite into orbit. Reserving an entire launch on the company's Falcon 9 rocket costs $62 million. The small-satellite market is poised to generate $1 billion a year over the next decade, according to Northern Sky Research, which is based in Cambridge, Mass., and specializes in the satellite and space markets. "What SpaceX is doing is great for the satellite industry," Leena Pivovarova, an analyst for Northern Sky, told UPI. "It's definitely going to lead to expansion. It will also make the small-rocket market more competitive," she said. "Things will get a little more difficult for new launch companies trying to enter the market." The new SpaceX schedule for small satellites is in addition to its regular missions to the International Space Station or for large customers like the U.S. military. The first date on the new schedule is in March, when a Falcon 9 rocket is to lift off from Vandenberg Air Force Base in California, but other launches will be in Florida, the company said. One of the first customers for the new program, California-based Momentus, will be launching a satellite specifically designed to move other satellites around once they reach space. That launch is set for late 2020. Momentus said it will provide "last mile" service for other satellites by helping them reach specific orbits. Its satellite shuttle service, or tugboat, is called Vigoride, and also is poised to support more frequent small-satellite deployments.

"We think the cost reduction for SpaceX launches is going to be fantastic, and it will stimulate all kinds of new business in space," said Joel Sercel, the Momentus chief technology officer.

He said the key to success is the regular schedule that businesses can count on.

Plans to launch thousands of new satellites have raised fears of potential problems, though, especially collisions and increased space trash.

SpaceX and the European Space Agency already had a recent close call. The space agency said the United States' collision alert system indicated a European weather satellite was at risk of colliding Monday with a Starlink satellite launched from Florida in May. The risk was 1 in 10,000, which exceeds industry standards, the agency said.

The agency issued a statement saying it had contacted SpaceX, and the space company had indicated it planned to to take no action. Starlink satellites, like many satellites, have the ability to fire thrusters to avoid collisions. Instead, the space agency moved its satellite to avoid the problem.

In a statement afterward, SpaceX acknowledged that it was aware of a problem, but blamed "a bug in our on-call paging system" that prevented a Starlink operator from seeing updates that had raised the probability to the 1 in 10,000 level.

"SpaceX is still investigating the issue and will implement corrective actions. However, had the Starlink operator seen the correspondence, we would have coordinated with ESA to determine best approach," a SpaceX statement said.

On Tuesday, the European agency called for new protocol to communicate and resolve similar problems.

"Today, this negotiation is done through exchanging emails - an archaic process that is no longer viable as increasing numbers of satellites in space mean more space traffic," said Holger Krag, head of space safety at European agency.

Meanwhile, SpaceX is moving forward, noting that dedicated ride-share missions will not be delayed by trouble with another passenger's schedule. "If you are ready to fly during the scheduled launch period, you will fly," the SpaceX announcement said.

Customers who run into delays that prevents them from launching can book another launch with a 10 percent rebooking fee, SpaceX said.

SpaceX's ride-sharing launches and lower cost are partly a result of the company making its rockets reusable, Northern Sky's Pivovarova said.

She said SpaceX simply might launch its own satellites for its Starlink internet network if a scheduled launch doesn't have as many paying customers.

"Personally, I think it may take a while before they can achieve that kind of regular launch rhythm," Pivovarova said. "It could be that they are dropping their prices because they can afford to now, or because they see competition coming up from other rocket companies getting into the business."

Momentus has raised $34 million for its satellite shuttle. The company says its unique new technology uses water plasma as the propellant.

Gwynne Shotwell, the SpaceX president, said Momentus "will offer a strong complement to Falcon 9's capability to reliably and affordably launch payloads for small satellite operators."

China's satellite tests pulsar navigation for future deep space exploration

Chinese scientists have conducted experiments on pulsar navigation with an X-ray space telescope, and the technology could be used in future deep space exploration and interplanetary or interstellar travel. The experiments were conducted on the Hard X-ray Modulation Telescope (HXMT), dubbed Insight, which was sent into space on June 15, 2017, to observe black holes, pulsars and gamma-ray bursts, by scientists from the Institute of High Energy Physics of the Chinese Academy of Sciences. The positioning accuracy in the experiments reached 10 km, further verifying the feasibility of autonomous navigation of spacecraft by using pulsars, which lays a foundation for future practical application in deep space exploration, said scientists. An article about the experiments was published in the Astrophysical Journal Supplement on Wednesday. Insight carries several detectors including a high energy X-ray telescope (HE), a medium energy X-ray telescope (ME) and a low energy X-ray telescope (LE). Through more than two years of operation, Insight has observed many black holes, pulsars and gamma-ray bursts. In addition, the in-orbit demonstration of the X-ray pulsar navigation technique has been carried out, said Zheng Shijie, the principal investigator of the pulsar navigation demonstration. More and more space probes are exploring the solar system and "Voyager 1" and "Voyager 2" are going deeper into space. Being far away from Earth, they cannot use the global navigation satellite systems (GNSS). These spacecraft mainly depend instead on radio technologies which have many limitations.

Pulsar navigation, an autonomous navigation technology, is receiving more and more attention as it is less dependent on the support of ground equipment and meets the continuous navigation requirements for deep space exploration, Zheng said.

"X-ray pulsar navigation is a new type of autonomous navigation method," said Zheng, adding that, "It uses the periodic pulse signals from pulsars, the distant celestial objects in the universe, providing navigation and timing services for spacecraft in space."

Pulsars, a kind of rapidly rotating neutron star, are produced in supernova explosions. They are found to be highly magnetized, emitting two beams of electromagnetic radiation. This radiation can be observed only when the beam of emission is pointing toward Earth. It is much the same as how a lighthouse can be seen only when the light is pointed at an observer. To date, scientists have discovered more than 2,000 pulsars. The Milky Way is thought to have around 100 million of them.

They are also called "cosmic-lighthouses" because of their long-term timing stability comparable to atomic clocks on Earth. By detecting the periodic pulse signals of pulsars, a spacecraft can autonomously determine its orbit parameters, said scientists.

The time interval of two adjacent pulses emitted by the pulsar is constant. If a spacecraft moves toward the pulsar, the received pulse interval will be shortened, and vise versa. Thus the observed pulse profile will change as the spacecraft moves in space. The relative arrival times of pulses also indicate the relative position of the spacecraft with respect to the pulsar. Therefore, by analyzing the characteristics of the pulsar signals received by the spacecraft, the three-dimensional position and velocity of the spacecraft can be determined, Zheng explained.

From Aug. 31 to Sept. 5, 2017, Insight observed the Crab pulsar for about five days to test the feasibility of pulsar navigation. The research team had also proposed an algorithm for X-ray pulsar navigation, according to Zhang Shuangnan, lead scientist of the Insight space telescope.

The research team further improved the algorithm and applied it in the processing of the observation data of the three detectors onboard Insight. The satellite's orbit was determined successfully, with the positioning accuracy within 10 km, comparable to that of a similar experiment conducted on the International Space Station, Zhang said.

To test the feasibility and reliability of the algorithm, the research team has carried out theoretical analysis and simulation verification with various types of pulsars. Their results show that the method works for different pulsars.

The reviewer for the Astrophysical Journal commented that "The flight demonstrations from the Insight-HXMT satellite are important contributions to the development of X-ray navigation."

Insight-HXMT is China's first X-ray astronomical satellite with a designed lifespan of four years.

China has also conducted a pulsar navigation test on the Tiangong-2 space lab and launched a pulsar navigation experiment satellite in 2016.

NASA Marshall to lead Artemis Program's human lunar lander development

NASA Administrator Jim Bridenstine was joined Friday by U.S. Representatives Mo Brooks and Robert Aderholt of Alabama and Scott DesJarlais of Tennessee at the agency's Marshall Space Flight Center in Huntsville, Alabama, to announce the center's new role leading the agency's Human Landing System Program for its return to the Moon by 2024. "Marshall Space Flight Center is the birthplace of America's space program. It was Marshall scientists and engineers who designed, built, tested, and helped launch the giant Saturn V rocket that carried astronauts on the Apollo missions to the Moon," Brooks said. "Marshall has unique capabilities and expertise not found at other NASA centers. I'm pleased NASA has chosen Marshall to spearhead a key component of America's return to the Moon and usher in the Artemis era. Thanks to Administrator Bridenstine for travelling here to share the great news in person." Bridenstine discussed the announcement in front of the 149-foot-tall Space Launch System (SLS) rocket liquid hydrogen tank structural test article currently being tested. "We greatly appreciate the support shown here today by our representatives in Congress for NASA's Artemis program and America's return to the Moon, where we will prepare for our greatest feat for humankind - putting astronauts on Mars," Bridenstine said. "We focus on a 'One NASA' integrated approach that uses the technical capabilities of many centers. Marshall has the right combination of expertise and experience to accomplish this critical piece of the mission." Informed by years of expertise in propulsion systems integration and technology development, engineers at Marshall will work with American companies to rapidly develop, integrate, and demonstrate a human lunar landing system that can launch to the Gateway, pick up astronauts and ferry them between the Gateway and the surface of the Moon.

"Marshall Space Flight Center, and North Alabama, have played a key role in every American human mission to space since the days of Mercury 7. I am proud that Marshall has been selected to be the lead for the landers program," said Aderholt. "I am also very proud that Marshall has designed and built the rocket system, the Space Launch System, which will make missions to the Moon and Mars possible. We look forward to working with our industry partners and our NASA partners from around the country."

NASA's Johnson Space Center in Houston, which manages major NASA human spaceflight programs including the Gateway, Orion, Commercial Crew and International Space Station, will oversee all aspects related to preparing the landers and astronauts to work together. Johnson also will manage all Artemis missions, beginning with Artemis 1, the first integrated test of NASA's deep space exploration systems.

The trip to Marshall came the day after Bridenstine visited NASA's Michoud Assembly Facility in New Orleans, where he viewed progress on the SLS core stage that will power NASA's Artemis 1 lunar mission. With the start of testing in June on the liquid hydrogen tank article, and the recent arrival of the liquid oxygen tank at Marshall, which manages the SLS Program, NASA is more than halfway through SLS structural testing.

"The Tennessee Valley, including Huntsville and stretching across Middle Tennessee, is a dynamic, exciting region, home to thousands of men and women - working at both public and private institutions - who are leading the United States into the next age of space exploration," said DesJarlais.

"As a member of the House Armed Services Committee, I am thrilled to visit one of our country's premier facilities, near Arnold Air Force Base and others, developing the latest spaceflight technology. NASA's Artemis program will help our country to create another American Century. We can be proud of our achievements, especially here at the Marshall Space Flight Center."

NASA recently issued a draft solicitation and requested comments from American companies interested in providing an integrated human landing system - a precursor to the final solicitation targeted for release in the coming months.

The agency's human lunar exploration plans are based on a two-phase approach: the first is focused on speed - landing on the Moon within five years, while the second will establish a sustained human presence on and around the Moon by 2028. The agency will use what we learn on the Moon to prepare for the next giant leap - sending astronauts to Mars.

Beresheet Impact Site Spotted

The photo above shows the landing site of the Israeli Beresheet spacecraft on a region of the Moon called Sea of Serenity, or Mare Serenitatis in Latin. On April 11, 2019, SpaceIL, a non-profit organization, attempted to land its spacecraft in this ancient volcanic field on the nearside of the Moon. After a smooth initial descent, Beresheet made a hard landing on the surface. As soon as its orbit placed NASA's Lunar Reconnaissance Orbiter (LRO) over the landing site on April 22, 2019, LRO imaged Beresheet's impact site. The LRO Camera (LROC) consists of three imagers: a seven-color Wide Angle Camera (WAC) and two black-and-white Narrow Angle Cameras (NAC) mounted on the LRO, which has been studying the Moon from orbit for a decade. NAC captured the Beresheet impact photo. LROC took this image from 56 miles (90 kilometers) above the surface. The cameras captured a dark smudge, about 10 meters wide, that indicates the point of impact. The dark tone suggests a surface roughened by the hard landing, which is less reflective than a clean, smooth surface. From so far away, LROC could not detect whether Beresheet formed a surface crater upon impact. It's possible the crater is just too small to show up in photos. Another possibility is that Beresheet formed a small indent instead of a crater, given its low angle of approach (around 8.4 degrees relative to the surface), light mass (compared to a dense meteoroid of the same size), and low velocity (again, relative to a meteoroid of the same size; Beresheet's speed was still faster than most speeding bullets).

The light halo around the smudge could have formed from gas associated with the impact or from fine soil particles blown outward during Beresheet's descent, which smoothed out the soil around the landing site, making it highly reflective.

There are many clues that we're actually looking at a man-made crater instead of a meteoroid-caused one. This is an important consideration, since the Moon, having no atmosphere, is constantly bombarded by space rocks that leave craters.

Most importantly, we knew the coordinates of the landing site within a few miles thanks to radio tracking of Beresheet, and we have 11 "before" images of the area, spanning a decade, and three "after" images. In all of these images, including one taken 16 days before the landing, we saw only one new feature of the size Beresheet would have created.

Existing mathematical models helped us estimate the size and shape of the crater that would have formed if an object of Beresheet's mass and velocity struck the surface. We also referenced craters created by similar-size spacecraft (GRAIL, LADEE, Ranger) that have struck the Moon at about the same speed, and we saw that the white tail stretching from the landing halo towards the south is a shape that's consistent with Beresheet's southward descent trajectory and angle of approach.

For the before image above, we used a photo from December 16, 2016. This is because the lighting conditions that day, based on the angle at which the Sun would have illuminated the Moon at that particular time in its orbit, were the most similar to the April 22 image.

Because LRO was beyond the horizon during Beresheet's descent and landing, it couldn't capture a photo until its orbit brought it nearby 11 days later. LRO passes over the lunar poles with each revolution. Meanwhile, the Moon rotates on its axis below the spacecraft, allowing LRO to pass over every part of the Moon twice a month (once during lunar night and once during lunar day). LROC may take more images of the landing site when it passes the same area again on May 19.

Efforts are ongoing to bounce laser pulses from the Lunar Orbiter Laser Altimeter, also on board LRO, to measure the return from the Laser Retroreflector Array of small corner cube mirrors. This instrument was provided by NASA's Goddard Space Flight Center and was installed on the top deck of the Beresheet spacecraft. Attempts are ongoing to examine if the retroreflector may have survived the impact.

Water cycle along the northern rim of Hellas Basin throughout Mars' history

The northeastern rim region of Hellas impact basin, located in the southern hemisphere of Mars, contained numerous ephemeral lakes throughout Mars' history, a new study reveals. A new paper published in Astrobiology examines a region where depressions may have been hosted ponding water that originated from different sources, including precipitation, fluvial transportation and ground water. Sediments partially filled the depressions or formed fan shaped deposits within these paleolakes. Some of these paleolakes formed in fresh to degraded impact craters, others were situated in depressions of rolling terrain - paleolakes are lakes that existed at a time when the climate where it was located was different than today. The paper's authors are Henrik I. Hargitai, who conducted the research while at NASA Ames Research Center; Virginia C. Gulick, SETI Institute; and Natalie H. Glines, SETI Institute. The candidate paleolakes are identified along drainage systems that emptied into smaller depressions at the margin of Hellas Planitia, the largest and oldest impact basin on the surface of Mars, terminating in almost the same elevations along a 250 km long line."We have found several groups of paleolakes with different geologic histories along each drainage system", the authors explain. Some paleolake groups served as the source of km-wide, hundreds of km long channel systems, while others formed through-flowing, or terminal lakes. "Some of the inlet channels and their deposits are similar to those produced by flash floods" the lead author, H. Hargitai explains.

"Some of these flood discharges may even have been catastrophic in magnitudes (~ several 105 - 106 m3/s) similar to those that formed the Channeled Scablands in eastern Washington state, while the morphology of other channels and valleys suggest much lower, longer duration discharges more like those of the Mississippi River", co-author Gulick added.

"These hundreds-of-meters wide channels cut across widespread ash-laden volcanic lava and impact debris terrains across the interior slope of Hellas basin".

Through-flowing lakes are identified from two connecting channels, one inlet, and another outlet. Minor inlet channels in these sites suggest that these lakes were filled by ground water and provided only a minor water discharge on the surface. Other lakes may have been filled during occasional floods and several impact crater lakes were identified as fed precipitation, likely in the form of snow.

One terminal impact crater paleolake is nearly filled with smooth sediment, which is similar to that found in the salars (saline lakes) in the Andes mountain region of Patagonia. This similarity suggests that conditions on Mars may have been comparable to those at the high-elevation, cold and arid Andes region at the time when those lakes formed.

The list of 34 new candidate Martian paleolakes were compiled from a detailed hydrogeographic analysis of the Northeast Hellas region, where only one impact crater paleolake had been previously identified.

This suggests that Mars was hydrologically much more active than previously recorded and that some regions hosted numerous lakes periodically throughout Mars' history. The lakes were fed by different hydrological processes, likely related to recurring hydrothermal activity from nearby volcanoes Hadriaca and Tyrrhena Paterae.

Construction of Europe's exoplanet hunter Plato begins

The construction of ESA's Plato mission to find and study planets beyond our Solar System will be led by Germany's OHB System AG as prime contractor, marking the start of the full industrial phase of the project. The announcement was made this week at the 69th International Astronautical Congress in Bremen, Germany, where the contract was formally signed. The contract covers the delivery of the satellite, including the testing phase leading to launch, support during the launch campaign, and the in-orbit commissioning phase. Plato, the PLAnetary Transits and Oscillations of stars mission, will be launched in 2026 to find and study extrasolar planetary systems, with a special emphasis on rocky planets around Sun-like stars and their habitable zone - the distance from a star where liquid water can exist on a planet's surface. "Does a second Earth exist in the Universe? is one of the exciting questions in astrophysics today," says Johann-Dietrich Worner, Director General of ESA. "With our Plato satellite we are focusing on Earth-like planets orbiting up to the habitable zone around other stars which are similar to our Sun. This will be a major step towards finding another Earth." The spacecraft will be built and assembled by OHB together with Thales Alenia Space (France and the UK) and RUAG Space Switzerland; many ESA member States will also be involved in the construction of this European planet hunter.

The German Aerospace Center (DLR) and a consortium of various European research centers and institutes will provide the scientific instrument, consisting of an array of 26 cameras and electronic units, that will observe a large patch of the sky on the lookout for planets.

"Plato is a next-generation exoplanet mission that will monitor thousands of bright stars over a large area of the sky in search of tiny, regular dips in their brightness caused by transiting planets," says Ana Heras, Plato project scientist at ESA.

"Since planets only block a minute portion of the light radiated by their parent star, this quest requires extremely precise, long-term photometric observations."

Plato will not only seek new planets but will also investigate the properties of their host stars, and determine the planetary masses, sizes and ages with unprecedented accuracy. This will help scientists understand the architecture of exoplanet systems and determine whether they might host habitable worlds. In addition, Plato will also perform asteroseismology - the study of seismic activity of stars - providing insight into stellar interiors and evolution.

The mission will expand on the work of Cheops, ESA's upcoming exoplanet watcher, which will be launched next year to perform a first characterisation of known planets. It will be followed by Ariel, scheduled for launch in 2028, which will observe a large and diverse sample of exoplanets to study their atmospheres in great detail.

Plato will operate from the 'L2' virtual point in space 1.5 million km beyond Earth as seen from the Sun. From this vantage point, it will be our outpost to unravel the mysteries of a multitude of extrasolar worlds.

"We are pleased to kick off construction of this exciting mission," says Filippo Marliani, ESA's Plato Project Manager.

"With the prime contractor and the support of European space industry, we are looking forward to building a spacecraft that will tackle some of humankind's most profound questions."

NASA Evaluates Commercial Small-Sat Earth Data for Science

NASA has launched a pilot program to evaluate how Earth science data from commercial small-satellite constellations could supplement observations from the agency's fleet of orbiting Earth science missions. On Sept. 28, the agency awarded sole-source contracts to acquire test data sets from three private sector organizations. NASA's Earth Science Division in Washington issued blanket purchase agreements for the "Private Sector Small Constellation Satellite Data Product Pilot" program. Under these agreements, the agency purchases data sets and related products based on observations derived from Earth-orbiting, small-satellite constellations designed and operated by non-governmental entities. "This pilot program is an innovative and efficient way for us to acquire, examine, and evaluate a wide range of private sector Earth observation data," said Michael Freilich, director of NASA's Earth Science Division. "As our very capable NASA research satellite fleet ages and more small satellites are launched by private industry, there are opportunities to leverage the strengths of each into even more complete climate data sets." NASA will provide the test data products to NASA-funded researchers, who will examine whether the data help advance the agency's science and applications development goals.

The pilot program is designed to determine whether these private sector observations and associated products offer a cost-effective means to augment or complement the suite of Earth observations acquired directly by NASA, other U.S. government agencies, and international partners.

he contracts were awarded to:

DigitalGlobe, a Maxar Technologies company headquartered in Westminster, Colorado, has five very high-resolution Earth imaging satellites (GeoEye-1, WorldView-1, WorldView-2, WorldView-3, WorldView-4) capable of collecting 30-centimeter resolution imagery.

Planet, headquartered in San Francisco, has three satellite constellations (SkySat, Dove, RapidEye) with more than 150 satellites supplying imagery and derived products over the entire Earth at medium and high resolution with high repeat frequencies.

SPIRE, headquartered in San Francisco, operates a constellation of over 60 satellites collecting radio occultation soundings, aircraft location information and ship reports. GPS radio occultation measurements can be used to sound the atmosphere for temperature, water vapor, and atmospheric pressure.

These contracts represent the first time that NASA has engaged with commercial small-satellite constellation operators to purchase their data for scientific evaluation. They establish a way for NASA to acquire and examine the data products during the next 12 months. Each contract includes an option for NASA to extend the agreement for an additional four years, for a total value of up to $7 million for each of the three agreements.

To be considered for participation in this pilot program, companies had to demonstrate they were currently operating a small satellite constellation of no fewer than three satellites in non-geostationary orbit and producing consistent global coverage. Companies also were asked to supply a comprehensive catalog of their data, describing areal coverage, data latency, pricing, and other factors.

NASA uses the vantage point of space to understand and explore our home planet, improve lives and safeguard our future. The agency's observations of Earth's complex natural environment are critical to understanding how our planet's natural resources and climate are changing now and could change in the future.

UB scientists await launch of NASA ice-monitoring satellite

As the Sept. 15 launch date for NASA's new ice-monitoring satellite approaches, University at Buffalo scientists are among many worldwide who are counting down the days. They're excited, but nervous, too. That's what happens when your future research is reliant on equipment that's going to be hurled, atop a flaming rocket, into the harsh environs of outer space. Or when - as in the case of UB climate scientist Beata Csatho - you actually helped to build the thing that's blasting into orbit. "There is so much that goes into these missions. We all want it to succeed," says Csatho, PhD, chair of geology in the UB College of Arts and Sciences. "After the satellite makes it into orbit, there is a commissioning period. This is when people will be checking to make sure that the satellite is making accurate measurements." Csatho - one of hundreds of scientists and engineers who worked on the mission - will be at Vandenberg Air Force Base in California for the September launch of NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2). From 2011-14, she led the Science Definition Team that helped determine the satellite's scientific requirements, such as the precision of the laser-based research instrument on board.

Once in orbit, ICESat-2 is expected to be a vital tool in understanding the impacts of climate change. The satellite will use laser pulses to measure the elevation of the surface of the Earth, covering the Arctic and Antarctica in detail every 91 days - data that will enable scientists to calculate the changing thickness of ice sheets, glaciers and sea ice.

This work will address important questions in a warming world. For example: How much will sea level rise in coming years? How will coastal communities be affected, from remote island nations like Tuvalu to huge metropolises like Shanghai, Rio de Janeiro and New York City?

"In the past few years, there have been changes in ice sheet behavior, especially in elevation, which is connected with sea level rise," says Anton Schenk, PhD, UB research professor of geology, who will be heading to California with Csatho to witness the ICESat-2 launch. "Are these changes temporary or permanent, and where are they happening? Our work is all about trying to find trends in the data."

Chinese private space company to launch first carrier rocket

China will launch its first solid-propellant carrier rocket developed by a Chinese private company late this year. The ZQ-1 rocket was developed by Landspace, a Beijing-based rocket-maker. Its technicians are former state-owned aerospace industry workers. Carrying a small satellite, the rocket will be launched at the Jiuquan Satellite Launch Center in northwest China, the company said Thursday. "If the launch mission can go well, the ZQ-1 will become China's first private carrier rocket that can send satellites into space," said Zhang Changwu, CEO of Landspace. The 19-meter-long rocket has a 1.35-meter diameter, a takeoff weight of 27 tonnes and thrust of 45 tonnes. It is flexible, cost-efficient and has been designed with mature technology and fast response ability. "After nine months of development, the rocket completed the final assembly Monday and entered the launching phase, showing that the company is capable of making rockets," Zhang said. The satellite, Future, carried by the rocket is for space science and remote sensing for a TV show on China Central Television. It will orbit for two years. ZQ is short for Zhuque (Vermilion bird). It is one of the four spirits of ancient Chinese mythology, representing fire and controlling the southerly direction.

The company also plans to launch ZQ-2, a liquid-fueled rocket, in 2020.

China has more than 60 private companies entering the commercial space industry. They are growing fast and competing in market for launches of small satellites and rockets.

Heat shield install brings Orion spacecraft closer to space

During Exploration Mission-1 (EM-1), an uncrewed Orion spacecraft will launch atop NASA's Space Launch System rocket and begin a three-week voyage in space, taking it about 40,000 miles beyond the Moon and back to Earth. On its return, the spacecraft's heat shield will need to withstand temperatures of nearing 5,000 degrees Fahrenheit during its fiery re-entry through the Earth's atmosphere before it splashes down in the Pacific Ocean. Technicians at NASA's Kennedy Space Center (KSC) in Florida recently secured the heat shield to the bottom of the crew module, using 68 bolts. Designed and manufactured by Orion prime contractor, Lockheed Martin, the heat shield is like an intricate puzzle with pieces that all have to fit together perfectly. Before the final installation, a fit check was performed to ensure all of the bolt fittings lined up. "Installation of the EM-1 crew module heat shield is a significant milestone representing the beginning of closing out the crew module assembly," said Jules Schneider, Lockheed Martin Orion senior manager for KSC Operations. "When the heat shield is installed, access to components becomes more difficult, and in some cases there is no more access. So by installing the heat shield you are declaring that a certain percentage of the spacecraft is finished."

Measuring 16.5 feet in diameter, Orion's new heat shield is the largest of its kind developed for missions that will carry astronauts. The heat shield base structure has a titanium truss covered with a composite substrate, or a skin composed of layers of carbon fiber material.

In a new process, several large blocks of an ablative material called Avcoat, licensed from Boston-based Textron Systems, were produced at Michoud Assembly Facility in New Orleans by Lockheed Martin. They were shipped to Kennedy, where Lockheed Martin technicians machined them into more than 180 unique blocks and bonded them to the heat shield's surface.

To fill tiny gaps between the blocks, the seams were filled with a mixture that over time will become solid. Technicians applied a coat of white epoxy paint to the heat shield's surface and then applied aluminized tape after the painted surface dried. The tape provides surface resistivity, and absorbs solar heat and infrared emissions.

"Witnessing assembly, test and installation of the EM-1 crew module heat shield brought an appreciation for its innovative design and assembly techniques," said Amy Marasia, the Crew Module Assembly operations lead in NASA's Orion Production Operations.

While Avcoat isn't new to spacecraft - it was used on the heat shields of Apollo and the Orion Exploration Flight Test-1 - the technique of using blocks instead of injecting the ablative material is proving to be a real production time-saver.

"A benefit of switching from the honeycomb system to the blocks is we now can make the Avcoat blocks at the same time that the Orion structure is being made, and when the module is ready we can secure the blocks, which saves time," said John Kowal, NASA Orion Thermal Protection System manager at Johnson Space Center in Houston.

"Before, with EFT-1, we had to wait for the carrier portion to be done, and then apply the Avcoat directly to the crew module."

During its first mission around the Moon, engineers will monitor how Orion's systems perform in the environment of deep space and its return to Earth. During re-entry the ablative material of the Avcoat blocks will burn away, essentially carrying the heat away from Orion because of the gases created during the ablative process.

Orion is the exploration spacecraft that will carry astronauts to deep-space destinations, including the Moon and on to Mars. Orion will be equipped with power, communications and life support systems to sustain space travelers during their long-duration missions and return them safely to Earth.

China unveils Chang'e-4 rover to explore Moon's far side

China's moon lander and rover for the Chang'e-4 lunar probe, which is expected to land on the far side of the moon this year, was unveiled Wednesday. Images displayed at Wednesday's press conference showed the rover was a rectangular box with two foldable solar panels and six wheels. It is 1.5 meters long, 1 meter wide and 1.1 meters high.Wu Weiren, the chief designer of China's lunar probe program, said the Chang'e-4 rover largely kept the shape and conditions of its predecessor, Yutu (Jade Rabbit), China's first lunar rover for the Chang'e-3 lunar probe in 2013. However, it also has adaptable parts and an adjustable payload configuration to deal with the complex terrain on the far side of the moon, the demand of relay communication, and the actual needs of the scientific objectives, according to space scientists. Like Yutu, the rover will be equipped with four scientific payloads, including a panoramic camera, infrared imaging spectrometer and radar measurement devices, to obtain images of moon's surface and detect lunar soil and structure. It will also endure vacuum, intense radiation and extremes of temperature. The moon has a large temperature difference between day and night, which can reach more than 300 degrees Celsius.

Both the lander and rover will carry international payloads for other countries.

The Chang'e-4 lunar probe will land on the Aitken Basin of the lunar south pole region on the far side of the moon, which is a hot spot for scientific and space exploration.

Direct communication with the far side of the moon, however, is not possible, which is one of the many challenges for the Chang'e-4 lunar probe mission.

China launched a relay satellite, named Queqiao, in May, to set up a communication link between the Earth and Chang'e-4 lunar probe.

The global public will have a chance to name the rover, according to State Administration of Science, Technology and Industry for National Defense.

Participants can submit their proposed names for the rover through the internet from Aug. 15 to Sept. 5, and the official name will be announced in October after several selection rounds.

Winners will be rewarded at most 3,000 yuan and invited to watch the lunar probe launch.

The name Yutu was chosen from 200,000 proposals submitted over two months worldwide.

New launch unit standards announced for smallsats

The Aerospace Corporation (Aerospace) announced details of a new small satellite (smallsat) standard called a Launch Unit (Launch-U) during a briefing at the Small Satellite Conference in Logan, Utah. This standard provides major benefits to the smallsat industry-manufacturers, launch providers, and satellite users-by increasing access to space and decreasing launch costs. It also enables the space community to come together to work innovative solutions for sharing costs, adopting new business models, and adapting to regulatory or statutory changes. "We are proud to partner with industry, government, and academia to develop the first official Launch Unit standard," said Steve Isakowitz, Aerospace president and CEO. "The Launch-U team's efforts will help reduce the complexities on the satellite and launch vehicle sides. It will also lead to shorter integration timelines and increased access to space." The space community was in search of a standard to make launching small satellites more flexible. Given Aerospace's role as an objective technical advisor, the community identified the corporation as the ideal partner to work across all elements of the space enterprise, from satellite and launch manufacturers to service providers and government officials.

"The Launch-U concept was born out of the industry's continuous requests for help, said Dr. Randy Villahermosa, general manager of Aerospace's Innovation Initiatives. "The goal was to create a standard that industry would view as enabling rather than an impediment to growth. Aerospace was a key broker in making this a reality."

Carrie O'Quinn, senior project engineer for Aerospace's Research and Development Department and the Launch-U lead, emphasized that currently there are no industry standards for satellites between the size of a CubeSat (approximately the size of a toaster) and an EELV Secondary Payload Adapter (ESPA) class satellite, which is about the size of a large dorm refrigerator.

"The Launch-U standard seeks to change this through our volume recommendation of 45 cm x 45 cm x 60 cm, said O'Quinn. "That's roughly the size of two carry-on bags strapped together. We also address a mass range, fundamental frequency, and loads in the recommendations."

The space access industry is altering in an exceedingly rapid pace and is driven by smallsat and small launch vehicle development, the increasing popularity of multi-manifest missions, and a widespread interest in reducing launch cost and timelines while deploying even more spacecraft. Currently, industry experts estimate that 6,000 to 20,000 smallsats could be launched over the next 10 years.

O'Quinn explained that the group's vision for the Launch-U standard is the solution the industry is looking for. "This is not envisioned to be a requirement levied on spacecraft developers, but rather a standard that is embraced by all as a game-changer."

For industry, the next step is to develop hardware and other technical solutions needed to support the Launch-U. O'Quinn emphasized that each stakeholder plays a specific role in implementing the Launch-U.

"Launch vehicle providers, integrators, and aggregators can begin considering how Launch-U satellites will affect their business models once implemented," said O'Quinn. "For example, these companies might publish information on Launch-U launch costs, as Spaceflight Industries and other commercial entities currently do for CubeSat launch costs."

Satellite manufacturers could also build to the Launch-U standard and make it available to the community at large.

7,000 small satellites to be launched over coming decade

According to Euroconsult's latest report, Prospects for the Small Satellite Market, a significant expansion is underway in the smallsat market, both in terms of demand and systems' capabilities. About 7,000 smallsats are due to be launched over the next ten years, i.e. a six-fold increase from the 1,200 units launched over the past decade. About 50 constellations, two of which are mega constellations, account for over 80% of the smallsat count. "By 2022, an average of 580 smallsats will be launched every year as a result of initial constellation deployment. This compares to an annual average of 190 satellites launched over the past five years. The average will then jump to 850 satellites per year on subsequent years up to 2027 because of the deployment of one mega constellation," said Maxime Puteaux, Senior Consultant at Euroconsult and editor of the report. "Smallsat demand for constellations is cyclical as it is driven by deployment in batches whereas demand for single satellite missions is more stable. Performance improvements and continuous miniaturization reshape the smallsat market as customers have the choice between lighter satellites with the same capabilities or larger but more capable satellites. In the heaviest mass category, smallsats are now able to perform missions that were only achievable in the past by satellites heavier that 500 kg."

Smallsat applications are multiple. In the past, "technology development" was the dominant application to test future technologies and payloads or for educational purposes. In future years, three applications will dominate the smallsat market:

Broadband Communication is by far the largest application with close to 3,500 satellites expected from 2018 to 2027 (of which 92% for two mega constellations);

Earth Observation will almost triple, from 540 satellites in the past to 1,400 anticipated from 2018 to 2027. Three constellations alone plan to launch more than 800 satellites during this period, of which two are cubesat-based;

Information for data collection and narrowband communications for AIS, ADS-B, Internet of Things, and Machine to Machine communication. It is a growing market with 850 satellites to be launched by 14 constellations that are currently raising funds or launching demonstrators.

The 7,000 smallsats that are due to be launched over 2018-2027 are valued at $38 billion for satellite manufacturing and launch, almost a quintupling decade-to-decade. The smaller growth in market value relative to that in smallsats count reflects the growing penetration of low-cost smallsats for 1) cubesats and nanosats below 50 kg of launch mass and 2) for large scale constellations with satellite unit cost of $1-$1.5 million.

Cubesats alone represent a mere 4% of future total market value. A significant part of that market is already contracted or captive via domestic providers as vertical integration (i.e. in-house manufacturing and/or launch) is more common for smallsats than for larger satellites.

The launch services of smallsats are expected to generate $16 billion in the next ten years i.e. strong growth over that of the past decade. Growth in launch revenues is stronger than that of satellite manufacturing with more diversity in launch services and various quality of services.

Smallsat operators currently launch with medium to heavy launchers that are contracted directly or through launch brokers. Several dedicated smallsat launchers are in development, the most advanced being on the edge to perform maiden flights, in order to be more responsive to market needs (on time, on orbit) but at the expense of a premium in specific price (price per kg into orbit).

Russia Plans to Send Capsule With Microorganisms to Mars

Russian scientists plan to send a capsule containing microorganisms to Mars' natural satellite Phobos and then get it back to Earth in order to study the possible mutations during the space flight, Natalya Novikova, the head of the microbiology laboratory at the Institute of Biomedical Problems of the Russian Academy of Sciences, told Sputnik. The project will be carried out as part of the Bumerang mission, which reproduces Russia's attempted Fobos-Grunt mission. "Now as part of the Bumerang project - a repetition of the Fobos-Grunt mission - it is planned to do a new experiment with sending to Mars and returning back a capsule with microorganisms," Novikova said. In November 2011, Russia attempted to launch Fobos-Grunt mission to Mars, however, after moving into the orbit the spacecraft did not manage to start its engines.

Two months later, it reentered Earth's atmosphere and fell into the Pacific Ocean. The Fobos-Grunt project also provided for sending a capsule with microorganisms to Mars, with the experiment dubbed Biofobos.

Exoplanets where life could develop as on Earth

Scientists have identified a group of planets outside our solar system where the same chemical conditions that may have led to life on Earth exist. The researchers, from the University of Cambridge and the Medical Research Council Laboratory of Molecular Biology (MRC LMB), found that the chances for life to develop on the surface of a rocky planet like Earth are connected to the type and strength of light given off by its host star. Their study, published in the journal Science Advances, proposes that stars which give off sufficient ultraviolet (UV) light could kick-start life on their orbiting planets in the same way it likely developed on Earth, where the UV light powers a series of chemical reactions that produce the building blocks of life. The researchers have identified a range of planets where the UV light from their host star is sufficient to allow these chemical reactions to take place, and that lie within the habitable range where liquid water can exist on the planet's surface. "This work allows us to narrow down the best places to search for life," said Dr. Paul Rimmer, a postdoctoral researcher with a joint affiliation at Cambridge's Cavendish Laboratory and the MRC LMB, and the paper's first author. "It brings us just a little bit closer to addressing the question of whether we are alone in the universe."

The new paper is the result of an ongoing collaboration between the Cavendish Laboratory and the MRC LMB, bringing together organic chemistry and exoplanet research. It builds on the work of Professor John Sutherland, a co-author on the current paper, who studies the chemical origin of life on Earth.

In a paper published in 2015, Professor Sutherland's group at the MRC LMB proposed that cyanide, although a deadly poison, was in fact a key ingredient in the primordial soup from which all life on Earth originated.

In this hypothesis, carbon from meteorites that slammed into the young Earth interacted with nitrogen in the atmosphere to form hydrogen cyanide. The hydrogen cyanide rained to the surface, where it interacted with other elements in various ways, powered by the UV light from the Sun. The chemicals produced from these interactions generated the building blocks of RNA, the close relative of DNA which most biologists believe was the first molecule of life to carry information.

In the laboratory, Sutherland's group recreated these chemical reactions under UV lamps, and generated the precursors to lipids, amino acids and nucleotides, all of which are essential components of living cells.

"I came across these earlier experiments, and as an astronomer, my first question is always what kind of light are you using, which as chemists they hadn't really thought about," said Rimmer. "I started out measuring the number of photons emitted by their lamps, and then realised that comparing this light to the light of different stars was a straightforward next step."

The two groups performed a series of laboratory experiments to measure how quickly the building blocks of life can be formed from hydrogen cyanide and hydrogen sulphite ions in water when exposed to UV light. They then performed the same experiment in the absence of light.

"There is chemistry that happens in the dark: it's slower than the chemistry that happens in the light, but it's there," said senior author Professor Didier Queloz, also from the Cavendish Laboratory. "We wanted to see how much light it would take for the light chemistry to win out over the dark chemistry."

The same experiment run in the dark with the hydrogen cyanide and the hydrogen sulphite resulted in an inert compound which could not be used to form the building blocks of life, while the experiment performed under the lights did result in the necessary building blocks.

The researchers then compared the light chemistry to the dark chemistry against the UV light of different stars. They plotted the amount of UV light available to planets in orbit around these stars to determine where the chemistry could be activated.

They found that stars around the same temperature as our Sun emitted enough light for the building blocks of life to have formed on the surfaces of their planets. Cool stars, on the other hand, do not produce enough light for these building blocks to be formed, except if they have frequent powerful solar flares to jolt the chemistry forward step by step. Planets that both receive enough light to activate the chemistry and could have liquid water on their surfaces reside in what the researchers have called the abiogenesis zone.

Among the known exoplanets which reside in the abiogenesis zone are several planets detected by the Kepler telescope, including Kepler 452b, a planet that has been nicknamed Earth's 'cousin,' although it is too far away to probe with current technology. Next-generation telescopes, such as NASA's TESS and James Webb telescopes, will hopefully be able to identify and potentially characterise many more planets that lie within the abiogenesis zone.

Of course, it is also possible that if there is life on other planets, that it has or will develop in a totally different way than it did on Earth.

"I'm not sure how contingent life is, but given that we only have one example so far, it makes sense to look for places that are most like us," said Rimmer. "There's an important distinction between what is necessary and what is sufficient. The building blocks are necessary, but they may not be sufficient: it's possible you could mix them for billions of years and nothing happens. But you want to at least look at the places where the necessary things exist."

According to recent estimates, there are as many as 700 million trillion terrestrial planets in the observable universe. "Getting some idea of what fraction have been, or might be, primed for life fascinates me," said Sutherland. "Of course, being primed for life is not everything and we still don't know how likely the origin of life is, even given favourable circumstances - if it's really unlikely then we might be alone, but if not, we may have company."

SpaceX launches, lands rocket in challenging conditions

SpaceX's Falcon 9 rocket carried 10 Iridium satellites into orbit on Wednesday. The Iridium-7 mission marked SpaceX's 14th launch of the year and the seventh mission for Iridium Communications, which aims to launch 75 satellites into orbit. After Wednesday's mission, Iridium now has 65 satellites in operation. The rocket blasted-off early Wednesday morning from Vandenberg Air Force Base in California. "All 10 satellites have deployed into an on-target orbit," Spaceflight Now's Stephen Clark reported at 8:53 a.m. ET. As usual, SpaceX safely landed the rocket's reusable first stage. The rocket stage landed on the spaceport drone ship "Just Read the Instructions." Though SpaceX's rocket reusability has become routine, Wednesday's weather conditions made the feat more difficult. "Despite challenging weather conditions, Falcon 9 first stage booster landed on Just Read the Instructions," SpaceX wrote on Twitter. Foggy conditions made visibility a problem. At the outset of the live streaming broadcast, the Falcon 9 rocket was nearly invisible, only coming into clear view after liftoff. Choppy seas added to the challenge of landing the first stage back on Earth.

The 10 Iridium satellites will join the dozens of Iridium satellites already in space. The constellation of communication satellites -- now featuring 75 satellites and scheduled to get 10 more later this summer -- is designed to support the Internet of Things, the technology behind smart devices.

Mars Express Detects Liquid Water Hidden Under Planet's South Pole

Evidence for the Red Planet's watery past is prevalent across its surface in the form of vast dried-out river valley networks and gigantic outflow channels clearly imaged by orbiting spacecraft. Orbiters, together with landers and rovers exploring the Martian surface, also discovered minerals that can only form in the presence of liquid water. But the climate has changed significantly over the course of the planet's 4.6-billion-year history and liquid water cannot exist on the surface today, so scientists are looking underground. Early results from the 15-year-old Mars Express spacecraft already found that water ice exists at the planet's poles and is also buried in layers interspersed with dust. The presence of liquid water at the base of the polar ice caps has long been suspected; after all, from studies on Earth, it is well known that the melting point of water decreases under the pressure of an overlying glacier. Moreover, the presence of salts on Mars could further reduce the melting point of water and keep the water liquid even at below-freezing temperatures. But until now evidence from the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument, MARSIS, the first radar sounder ever to orbit another planet, remained inconclusive. It has taken the persistence of scientists working with this subsurface-probing instrument to develop new techniques in order to collect as much high-resolution data as possible to confirm their exciting conclusion.

Ground-penetrating radar uses the method of sending radar pulses towards the surface and timing how long it takes for them to be reflected back to the spacecraft, and with what strength. The properties of the material that lies between influences the returned signal, which can be used to map the subsurface topography.

The radar investigation shows that south polar region of Mars is made of many layers of ice and dust down to a depth of about 1.5 km in the 200-km-wide area analyzed in this study. A particularly bright radar reflection underneath the layered deposits is identified within a 20-km-wide zone.

Analyzing the properties of the reflected radar signals and considering the composition of the layered deposits and expected temperature profile below the surface, the scientists interpret the bright feature as an interface between the ice and a stable body of liquid water, which could be laden with salty, saturated sediments. For MARSIS to be able to detect such a patch of water, it would need to be at least several tens of centimeters thick.

"This subsurface anomaly on Mars has radar properties matching water or water-rich sediments," says Roberto Orosei, principal investigator of the MARSIS experiment and lead author of the paper published in the journal Science.

"This is just one small study area; it is an exciting prospect to think there could be more of these underground pockets of water elsewhere, yet to be discovered."

"We'd seen hints of interesting subsurface features for years but we couldn't reproduce the result from orbit to orbit, because the sampling rates and resolution of our data was previously too low," adds Andrea Cicchetti, MARSIS operations manager and a co-author on the new paper.

"We had to come up with a new operating mode to bypass some onboard processing and trigger a higher sampling rate and thus improve the resolution of the footprint of our dataset: now we see things that simply were not possible before."

The finding is somewhat reminiscent of Lake Vostok, discovered some 4 km below the ice in Antarctica on Earth. Some forms of microbial life are known to thrive in Earth's subglacial environments, but could underground pockets of salty, sediment-rich liquid water on Mars also provide a suitable habitat, either now or in the past? Whether life has ever existed on Mars remains an open question, and is one that Mars missions, including the current European-Russian ExoMars orbiter and future rover, will continue to explore.

"The long duration of Mars Express, and the exhausting effort made by the radar team to overcome many analytical challenges, enabled this much-awaited result, demonstrating that the mission and its payload still have a great science potential," says Dmitri Titov, ESA's Mars Express project scientist.

"This thrilling discovery is a highlight for planetary science and will contribute to our understanding of the evolution of Mars, the history of water on our neighbor planet and its habitability."

Mars Express launched 2 June 2003 and celebrates 15 years in orbit on 25 December this year.