New estimates of Mercury's thin, dense crust

Mercury is small, fast and close to the sun, making the rocky world challenging to visit. Only one probe has ever orbited the planet and collected enough data to tell scientists about the chemistry and landscape of Mercury's surface. Learning about what is beneath the surface, however, requires careful estimation. After the probe's mission ended in 2015, planetary scientists estimated Mercury's crust was roughly 22 miles thick. One University of Arizona scientist disagrees.Using the most recent mathematical formulas, Lunar and Planetary Laboratory associate staff scientist Michael Sori estimates that the Mercurial crust is just 16 miles thick and is denser than aluminum. His study, "A Thin, Dense Crust for Mercury," will be published May 1 in Earth and Planetary Science Letters and is currently available online. Sori determined the density of Mercury's crust using data collected by the Mercury Surface, Space Environment and Geochemistry Ranging (MESSENGER) spacecraft. He created his estimate using a formula developed by Isamu Matsuyama, a professor in the Lunar and Planetary Laboratory, and University of California Berkeley scientist Douglas Hemingway. Sori's estimate supports the theory that Mercury's crust formed largely through volcanic activity. Understanding how the crust was formed may allow scientists to understand the formation of the entire oddly structured planet.

"Of the terrestrial planets, Mercury has the biggest core relative to its size," Sori said.

Mercury's core is believed to occupy 60 percent of the planet's entire volume. For comparison, Earth's core takes up roughly 15 percent of its volume. Why is Mercury's core so large?

"Maybe it formed closer to a normal planet and maybe a lot of the crust and mantle got stripped away by giant impacts," Sori said. "Another idea is that maybe, when you're forming so close to the sun, the solar winds blow away a lot of the rock and you get a large core size very early on. There's not an answer that everyone agrees to yet."

Sori's work may help point scientists in the right direction. Already, it has solved a problem regarding the rocks in Mercury's crust.

Mercury's Mysterious Rocks

When the planets and Earth's moon formed, their crusts were born from their mantles, the layer between a planet's core and crust that oozes and flows over the course of millions of years. The volume of a planet's crust represents the percentage of mantle that was turned into rocks.

Before Sori's study, estimates of the thickness of Mercury's crust led scientists to believe 11 percent of the planet's original mantle had been turned into rocks in the crust. For the Earth's moon - the celestial body closest in size to Mercury - the number is lower, near 7 percent.

"The two bodies formed their crusts in very different ways, so it wasn't necessarily alarming that they didn't have the exact same percentage of rocks in their crust," Sori said.

The moon's crust formed when less dense minerals floated to the surface of an ocean of liquid rock that became the body's mantle. At the top of the magma ocean, the moon's buoyant minerals cooled and hardened into a "flotation crust." Eons of volcanic eruptions coated Mercury's surface and created its "magmatic crust."

Explaining why Mercury created more rocks than the moon did was a scientific mystery no one had solved. Now, the case can be closed, as Sori's study places the percentage of rocks in Mercury's crust at 7 percent. Mercury is no better than the moon at making rocks.

Sori solved the mystery by estimating the crust's depth and density, which meant he had to find out what kind of isostasy supported Mercury's crust.

Determining Density and Depth

The most natural shape for a planetary body to take is a smooth sphere, where all points on the surface are an equal distance from the planet's core. Isostasy describes how mountains, valleys and hills are supported and kept from flattening into smooth plains.

There are two main types isostasy: Pratt and Airy. Both focus on balancing the masses of equally sized slices of the planet. If the mass in one slice is much greater than the mass in a slice next to it, the planet's mantle will ooze, shifting the crust on top of it until the masses of every slice are equal.

Pratt isostasy states that a planet's crust varies in density. A slice of the planet that contains a mountain has the same mass as a slice that contains flat land, because the crust that makes the mountain is less dense than the crust that makes flat land. In all points of the planet, the bottom of the crust floats evenly on the mantle.

Until Sori completed his study, no scientist had explained why Pratt isostasy would or wouldn't support Mercury's landscape. To test it, Sori needed to relate the planet's density to its topography. Scientists had already constructed a topographic map of Mercury using data from MESSENGER, but a map of density didn't exist. So Sori made his own using MESSENGER's data about the elements found on Mercury's surface.

"We know what minerals usually form rocks, and we know what elements each of these minerals contain. We can intelligently divide all the chemical abundances into a list of minerals," Sori said of the process he used to determine the location and abundance of minerals on the surface. "We know the densities of each of these minerals. We add them all up, and we get a map of density."

Sori then compared his density map with the topographic map. If Pratt isostasy could explain Mercury's landscape, Sori expected to find high-density minerals in craters and low-density minerals in mountains; however, he found no such relationship. On Mercury, minerals of high and low density are found in mountains and craters alike.

With Pratt isostasy disproven, Sori considered Airy isostasy, which has been used to make estimates of Mercury's crustal thickness. Airy isostasy states that the depth of a planet's crust varies depending on the topography.

"If you see a mountain on the surface, it can be supported by a root beneath it," Sori said, likening it to an iceberg floating on water.

The tip of an iceberg is supported by a mass of ice that protrudes deep underwater. The iceberg contains the same mass as the water it displaces. Similarly, a mountain and its root will contain the same mass as the mantle material being displaced. In craters, the crust is thin, and the mantle is closer to the surface. A wedge of the planet containing a mountain would have the same mass as a wedge containing a crater.

"These arguments work in two dimensions, but when you account for spherical geometry, the formula doesn't exactly work out," Sori said.

The formula recently developed by Matsuyama and Hemingway, though, does work for spherical bodies like planets. Instead of balancing the masses of the crust and mantle, the formula balances the pressure the crust exerts on the mantle, providing a more accurate estimate of crustal thickness.

Sori used his estimates of the crust's density and Hemingway and Matsuyama's formula to find the crust's thickness. Sori is confident his estimate of Mercury's crustal thickness in its northern hemisphere will not be disproven, even if new data about Mercury is collected. He does not share this confidence about Mercury's crustal density.

MESSENGER collected much more data on the northern hemisphere than the southern, and Sori predicts the average density of the planet's surface will change when density data is collected over the entire planet. He already sees the need for a follow-up study in the future.

The next mission to Mercury will arrive at the planet in 2025. In the meantime, scientists will continue to use MESSENGER data and mathematical formulas to learn everything they can about the first rock from the sun.

Bernese Mars camera CaSSIS sends first colour images from Mars

The Mars camera CaSSIS on the ExoMars Trace Gas Orbiter has returned its first colour images of the red planet. The camera system, which was developed at the University of Bern, is now ready for the start of its prime mission on April 28, 2018. The Colour and Stereo Surface Imaging System (CaSSIS) has been designed by an international team under guidance of the University of Bern. The Mars camera is on board of the ExoMars Trace Gas Orbiter, a European Space Agency/Roscosmos mission. It has now returned its first colour images from the orbit at Mars. The camera system was switched on 20 March and has been undergoing tests in preparation for the start of its prime mission on April 28, 2018. "We have had a couple of minor software issues in the initial test phase", says Principal Investigator, Nicolas Thomas from the Center of Space and Habitability (CSH), University of Bern in Switzerland, "but the instrument is actually in good health and ready to work." The UniBern team transmitted a completely new software version to the instrument at the start of test phase. "It is amazing that you can totally change the software in an instrument flying around Mars more than 100 million kilometres away and that it works", says Thomas.

Korolev crater (Mars)

Some of the first images have been spectacular. The example image is from the rim of an ice-filled crater called Korolev at high latitude in the northern hemisphere. The bright material is ice that can be seen on the rim of the crater (which is much larger than the image).

The picture has a resolution of just over 5 metres and outperforms the resolution of images from Hubble and other telescopes by far. In the future, CaSSIS should operate from slightly lower altitudes to give resolutions of less than 5 metres.

"We were really pleased to see how good this picture was given the lighting conditions", says Antoine Pommerol, a member of the CaSSIS science team at the CSH working on the calibration of the data. "It shows that CaSSIS can make a major contribution to studies of Mars's carbon dioxide and water cycles."

The image is a composite of three images in different colours that were taken almost simultaneously by CaSSIS on April 15, 2018. They were then assembled to produce this colour view.

"Our aim is to fully automate the image production process", says Thomas. "Once we achieve this, we can distribute the data to the community quickly for analysis."

Observing dynamics on Mars

CaSSIS is designed to complement the data acquired by the other payload on TGO and other Mars orbiters while also enhancing our knowledge of the surface of Mars. It is now known that Mars is more dynamic than previously thought.

Of particular interest to the 25-strong science team from 9 countries (incl. US and Russia) is the chance CaSSIS offers to study changes that occur over the day and over the Martian seasons. Further studies of recently discovered liquid water on the surface will be one of the main aims.

Aerospace explores next steps in space development

The Aerospace Corporation's Center for Space Policy and Strategy (CSPS) released a new policy paper that explores future opportunities in cislunar space-essentially, the space inside the moon's orbit and the orbital area around the moon. Cislunar Development: What to Build- and Why discusses the possible applications for cislunar space-for example, outposts on the moon, extraterrestrial mining operations, interplanetary waystations-and determines the infrastructure that will be needed to realize those ambitious goals. Author Dr. James Vedda, senior policy analyst with CSPS, says that the cislunar region remains a largely underdeveloped resource, and any coherent, long-term strategy for space commerce and exploration will need to make better use of it. "An enduring, multi-purpose space infrastructure means more than just rockets and spacecraft," said Vedda."It needs a wide range of capabilities, such as inter-orbital transportation, on-orbit servicing, standardization, fuel storage, energy distribution, communication and navigation services, resource extraction, and materials processing."

Vedda added that visions for cislunar development have been proposed by public and private stakeholders in spacefaring countries, but no widespread consensus on what to build and how to build it has emerged.

"Most of these concepts have focused on small aspects of the overarching design-but to truly realize the enormous potential of cislunar space, infrastructure projects should strive for broad applicability, beyond a single mission or short-term series of missions for a single agency."

Dr. Jamie Morin, executive director for CSPS, echoed those sentiments, noting, "Investment in cislunar development makes sense as a strategy for boosting U.S. space commerce and expanding the human footprint in the solar system. Building an effective space infrastructure will involve a mix of government agencies and private-sector entrepreneurs from around the world, so collaboration between the public and private sectors and across national lines will be key."

NanoRacks space station airlock "Bishop" completes CDR, moves to fab stage

The NanoRacks Space Station Airlock Module "Bishop" met another major milestone with completion of the Critical Design Review (CDR) on March 20 and 21, 2018 in Houston, Texas. This milestone begins the transition from the engineering design phase to the fabrication phase. Detailed design drawings such as those for the critical pressure shell will be signed and released to NanoRacks fabrication partner, Thales Alenia Space, in order for them to continue their fabrication efforts. In February 2018, NanoRacks announced that Thales Alenia Space, the joint venture between Thales (67%) and Leonardo (33%), was chosen as the latest partner in its commercial airlock program, joining with a number of key partners, including Boeing. Thales Alenia Space is set to produce and test the critical pressure shell for the NanoRacks Airlock Module and will also manufacture various secondary structures, including the Micrometeoroid Orbital Debris (MMOD) shields with Multi-Layer Isolation (MLI) panels, the power and video grapple fixture support structure and other structural components.

Other key features, such as the Passive Common Berthing Mechanism (PCBM), being manufactured by Boeing, require a long lead time and have been in production for over a year now. The PCBM will be delivered to Thales Alenia Space in May 2018 and will then be installed to the pressure shell.

"I'm very proud of the NanoRacks engineering team and our partner, ATA Engineering, who performs the structural and thermal analysis for Bishop," says Airlock Project Manager Brock Howe.

"This is a crucial milestone that required many long hours, and the team has been working together very smoothly. We're also very appreciative of our relationship with NASA and the International Space Station Program Office, as they have provided guidance and expertise in several critical areas. As always, there is plenty of work still to do - and we will continue to push forward."

The next major milestone is the Phase II Safety Review scheduled for June 2018. The project is still on track to meet the SpaceX CRS-19 launch, targeting fourth quarter 2019.

Virtual contact lenses for radar satellites

Radar satellites supply the data used to map sea level and ocean currents. However, up until now the radar's "eyes" have been blind where the oceans are covered by ice. Researchers at the Technical University of Munich (TUM) have now developed a new analysis method to solve this problem.The melting of the polar ice cap would have a drastic effect: Sea level would rise by several meters around the world, impacting hundreds of millions of people who live close to coasts. "This means one of the most important questions of our time is how climate change is affecting the polar regions," explains Dr. Marcello Passaro of the TUM German Geodetic Research Institute. But changes in sea level and ocean currents in the ice-covered regions of the Arctic and Antarctic in particular are very difficult to detect. The reason: The radar signals of the altimeter satellites that have been surveying the surfaces of the earth and oceans for more than two decades are reflected by the ice at the poles. This renders the water underneath the ice invisible.But ocean water also passes through cracks and openings in the permanent ice, reaching the surface. "These patches of water are however very small and the signals are highly distorted by the surrounding ice.

Here standard evaluation methods like those used for measurements made on the open seas are incapable of returning reliable results," Passaro points out. Together with an international team he has now developed a data analysis method which sharpens the focus of the radar's eyes.

An algorithm for all occasions

The core of this virtual "contact lens" is the adaptive algorithm ALES+, (Adaptive Leading Edge Subwaveform). ALES+ automatically identifies the portion of the radar signal which is reflected by water and derives sea level values using this information only.

This makes it possible to precisely measure the altitude of the ocean water which reaches the surface through ice cracks and openings. By comparing several years of measurements, climate researchers and oceanographers can now draw conclusions about changes in sea level and ocean currents.

"The special thing about our method is that it is adaptive," Passaro notes.

"We can use one and the same algorithm to measure sea level in both open and ice-covered ocean areas. ALES+ can also be used for coastal waters, lakes and rivers. Here the signals are highly varied, but always exhibit certain characteristic properties which the system then learns."

The scientists were able to use a test scenario in the Greenland Sea to demonstrate that ALES+ returns water levels for ice-covered and open ocean regions which are significantly more precise than the results of previous evaluation methods.

Moon Colonization: Why do we want it and what technologies do we have?

Scientists are convinced that humankind is capable of turning the Moon into a space outpost: people have cosmodromes, heavy carrier rockets, space modules and lunar rovers. Sputnik reveals what is behind the human desire to conquer space and what challenges colonizers may face on the way. The idea of the Moon's colonization was quite popular during the Cold War era. But in the mid-1970s such projects by the USSR and the US were suspended as travel to the satellite proved very expensive and didn't pursue any concrete goal. But half a century later, the dreams of settling on the Moon have taken over mankind once again. Perhaps, this is due to the high technological level of civilization that needs really ambitious goals as well as the prospects for the development of private space exploration, journalist and scientific observer Tatyana Pichugina wrote for Sputnik. According to her, the arsenal of the world's space industry has everything one needs to conquer the Moon. What is missing, are clearly formulated goals.

How Can We Use the Moon?

Many scientists believe that space expansion is a logical step towards mankind's further development.

Sooner or later, Earth will become too "crowded" and there will be a need for a transshipment base on the Moon, from where one could go to Mars and other planets of the solar system.

Moon colonization would also give people an opportunity to extract valuable minerals. Particular hopes are associated with helium-3, which is used in neutron counters.

There is very little helium-3 available on the Earth, but quite a lot - on the Moon. Therefore, a number of governments have already signaled their readiness to go to the satellite to mine helium-3 as a fuel supply.

The possibility of transferring energy-intensive production to the Moon in order to reduce industrial emissions on Earth in the distant future has also been voiced by a number of researchers.

What Challenges Are We About to Face?

There is no atmosphere and no magnetic field on the Moon. Its surface is continuously bombarded with micrometeorites, while the temperature differences during one day may reach two hundred degrees Celsius.

People can work there only in suits and within sealed lunar rovers, or in a stationary inhabited module with a complete life support system.

Generally, the whole construction process must be also based on completely different and advanced technologies: using inflatable modules, producing many building elements on a 3D printer, creating composite materials from the lunar regolith by means of laser sintering.

Thus, there are many things that scientists still have to think through before any actual colonization efforts will take place.

Concrete Projects

A moon-orbiting space station is considered a logical step on the way to the colonization of the moon.

The United States, Russia and China have already announced the implementation of a corresponding project by 2025-2030.

In particular, the US and Russia have agreed on the establishment of a joint orbital station called the Deep Space Gateway. The project may be joined by China, India and some BRICS countries.

Technical details are expected to be presented this year. Construction works in orbit are set to start in 2024.

NASA's New Space 'Botanist' Arrives at Launch Site

A new instrument that will provide a unique, space-based measurement of how plants respond to changes in water availability has arrived at NASA's Kennedy Space Center in Florida to begin final preparations for launch to the International Space Station this summer aboard a cargo resupply mission. NASA's ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) left NASA's Jet Propulsion Laboratory in Pasadena, California, on April 6 by ground transport and arrived at Kennedy Space Center on April 9. A few days after it reaches the space station, ECOSTRESS will be robotically installed on the exterior of the station's Japanese Experiment Module Exposed Facility Unit. ECOSTRESS will give us new insights into plant health by quantifying the temperature of plants from space as never before, measuring regions as small as 230 feet (70 meters) on a side, or about the size of a small farm. It will do this by estimating how much water plants are releasing to cool themselves (i.e., evapotranspiration - the equivalent of sweating in humans). This will tell us how much water different plants use and need, and how they react to environmental stresses caused by water shortages.

ECOSTRESS will estimate how much water moves through and out of plants by tracking how the temperatures of plants change. The data from its minimum one-year mission will be used by ecologists, hydrologists, agriculturalists, meteorologists and other scientists.

"Most satellite measurements of plant surface temperature are made at a particular time of day, often in the mid-morning, when plants are not stressed," said Simon Hook, the project's principal investigator at JPL.

"ECOSTRESS takes advantage of the space station's orbit to obtain measurements at different times of day, allowing us to see how plants respond to water stress throughout the day."

Until now, scientists addressing this question globally have had to estimate how that same-time-of-day snapshot varies over the course of a day. ECOSTRESS promises to eliminate much of this guesswork.

ECOSTRESS is expected to provide key insights into how plants link Earth's global carbon and water cycles. ECOSTRESS data will be used in conjunction with other satellite and ground measurements, such as those from NASA's Orbiting Carbon Observatory-2 satellite.

By doing this, scientists hope to understand more clearly the total amount of carbon dioxide plants remove from the atmosphere during a typical day. In addition, they hope to better identify which areas on the planet require more or less water for the amount of carbon dioxide they take up.

In practical terms, the year of data gleaned from ECOSTRESS will be useful for agricultural water managers. This data should improve our understanding of how certain regions are affected by drought and help agricultural and water management communities better manage water use for agriculture.

The high ground spatial resolution of ECOSTRESS data will be useful for research on the effects of drought on agriculture at the field-scale.

JPL built and manages the ECOSTRESS mission for NASA's Earth Science Division in the Science Mission Directorate in Washington. ECOSTRESS is sponsored by NASA's Earth System Science Pathfinder program, managed by NASA's Langley Research Center in Hampton, Virginia.

Boeing HorizonX Invests in Reaction Engines, a UK Hypersonic Propulsion Company

Boeing has announced its investment in Reaction Engines Limited, a leader in advanced propulsion systems based in Oxfordshire, United Kingdom. Reaction Engines' technology will contribute to the next generation of hypersonic flight and space access vehicles. Reaction Engines is known for its Synergetic Air-Breathing Rocket Engine (SABRE), a hybrid engine blending jet and rocket technology that is capable of Mach 5 in air-breathing mode and Mach 25 in rocket mode for space flight. As part of the SABRE program, Reaction Engines developed an ultra-lightweight heat exchanger that stops engine components from overheating at high speeds, thus improving access to hypersonic flight and space."As Reaction Engines unlocks advanced propulsion that could change the future of air and space travel, we expect to leverage their revolutionary technology to support Boeing's pursuit of hypersonic flight," said Steve Nordlund, vice president of Boeing HorizonX. Founded by three propulsion engineers in 1989, Reaction Engines produces robust technical designs for advanced heat exchangers, air-breathing engines, and the vehicles they could power. These capabilities may lead to high-speed point-to-point transport that is cost-effective and sustainable.

"Boeing is a world-leader in many fields, bringing invaluable expertise in hypersonic research and space systems. I am thrilled and honored that Boeing HorizonX has chosen Reaction Engines as its first UK investment," said Mark Thomas, CEO of Reaction Engines.

"This is a very exciting step that will contribute to our efforts to develop a commercial technology business and accelerate opportunities to further the future of air and space travel through SABRE technology."

Boeing HorizonX Ventures participated in this $37.3 million Series B funding round alongside Rolls-Royce Plc and BAE Systems.

The Boeing HorizonX Ventures investment portfolio is made up of companies specializing in technologies for aerospace and manufacturing innovations, including autonomous systems, energy storage, advanced materials, augmented reality systems and software, machine learning, hybrid-electric propulsion and Internet of Things connectivity.

Boeing is the world's largest aerospace company and leading manufacturer of commercial jetliners and defense, space and security systems. A top U.S. exporter, the company supports airlines and U.S. and allied government customers in more than 150 countries.

Boeing employs more than 2,200 people across the UK at numerous sites, and in 2018 the company celebrates 80 years of partnership with British customers, suppliers, manufacturing, the Armed Forces and the air transport industry. Today, the UK remains a critically important market, supplier base and a source of some of the world's most innovative technology partners.

Astrophysics CubeSat Demonstrates Big Potential in a Small Package

The ASTERIA satellite, which was deployed into low-Earth orbit in November, is only slightly larger than a box of cereal, but it could be used to help astrophysicists study planets orbiting other stars. Mission managers at NASA's Jet Propulsion Laboratory in Pasadena, California, recently announced that ASTERIA has accomplished all of its primary mission objectives, demonstrating that the miniaturized technologies on board can operate in space as expected. This marks the success of one of the world's first astrophysics CubeSat missions, and shows that small, low-cost satellites could be used to assist in future studies of the universe beyond the solar system. "ASTERIA is small but mighty," said Mission Manager Matthew W. Smith of JPL. "Packing the capabilities of a much larger spacecraft into a small footprint was a challenge, but in the end we demonstrated cutting-edge performance for a system this size." ASTERIA, or the Arcsecond Space Telescope Enabling Research in Astrophysics, weighs only 22 pounds (10 kilograms). It carries a payload for measuring the brightness of stars, which allows researchers to monitor nearby stars for orbiting exoplanets that cause a brief drop in brightness as they block the starlight.

This approach to finding and studying exoplanets is called the transit method. NASA's Kepler Space Telescope has detected more than 2,300 confirmed planets using this method, more than any other planet-hunting observatory. The agency's next large-scale, space-based planet-hunting observatory, the Transiting Exoplanet Survey Satellite (TESS), is anticipated to discover thousands of exoplanets and scheduled to launch from Cape Canaveral Air Force Station in Florida on April 16.

In the future, small satellites like ASTERIA could serve as a low-cost method to identify transiting exoplanets orbiting bright, Sun-like stars. These small satellites could be used to look for planetary transits when larger observatories are not available, and planets of interest could then be studied in more detail by other telescopes.

Small satellites like ASTERIA could also be used to study certain star systems that are not within the field of view of larger observatories, and most significantly, focus on star systems that have planets with long orbits that require long observation campaigns.

The ASTERIA team has now demonstrated that the satellite's payload can point directly and steadily at a bright source for an extended period of time, a key requirement for performing the precision photometry necessary to study exoplanets via the transit method.

Holding steady on a faraway star is difficult because there are many things that subtly push and pull on the satellite, such as Earth's atmosphere and magnetic field. ASTERIA's payload achieved a pointing stability of 0.5 arcseconds RMS, which refers to the degree to which the payload wobbles away from its intended target over a 20-minute observation period. The pointing stability was repeated over multiple orbits, with the stars positioned on the same pixels on each orbit.

"That's like being able to hit a quarter with a laser pointer from about a mile away," said Christopher Pong, the attitude and pointing control engineer for ASTERIA at JPL. "The laser beam has to stay inside the edge of the quarter, and then the satellite has to be able to hit that exact same quarter - or star - over multiple orbits around the Earth. So what we've accomplished is both stability and repeatability."

The payload also employed a control system to reduce "noise" in the data created by temperature fluctuations in the satellite, another major hurdle for an instrument attempting to carefully monitor stellar brightness. During observations, the temperature of the controlled section of the detector fluctuates by less than 0.02 Fahrenheit (0.01 Kelvin, or 0.01 degree Celsius).

Small satellites

ASTERIA is a CubeSat, a type of small satellite consisting of "units" that are 10 centimeters cubed, or about 4 inches on each side. ASTERIA is the size of six CubeSat units, making it roughly 10 centimeters by 20 centimeters by 30 centimeters. With its two solar panels unfolded, the satellite is about as long as a skateboard.

The ASTERIA mission utilized commercially available CubeSat hardware where possible, and is contributing to a general knowledge of how those components operate in space.

"We're continuing to characterize CubeSat components that other missions are using or want to use," said Amanda Donner, mission assurance manager for ASTERIA at JPL.

ASTERIA launched to the International Space Station in August 2017. Having been in space for more than 140 days, the satellite is operating on an extended mission through May.

ASTERIA was developed under the Phaeton Program at JPL. Phaeton provides early-career hires, under the guidance of experienced mentors, with the challenges of a flight project. ASTERIA is a collaboration with the Massachusetts Institute of Technology in Cambridge; where Sara Seager is the principal investigator.

Mars Express to get major software update

Every so often, your smartphone or tablet receives new software to improve its functionality and extend its life. Now, ESA's Mars Express is getting a fresh install, delivered across over 150 million km of space. With nearly 15 years in orbit, Mars Express - one of the most successful interplanetary missions ever - is on track to keep gathering critical science data for many more years thanks to a fresh software installation developed by the mission teams at ESA. The new software is designed to fix a problem that anyone still using a five-year-old laptop knows well: after years of intense usage, some components simply start to wear out. The spacecraft arrived at Mars in December 2003, on what was planned to be a two-year mission. It has gone on to spend more than 14 years gathering a wealth of data from the Red Planet, taking high-resolution images of much of the surface, detecting minerals on the surface that form only in the presence of water, detecting hints of methane in the atmosphere and conducting close flybys of the enigmatic moon, Phobos. Today, Mars Express is in good shape, with only some minor degradation in performance, but its gyroscopes are close to failing.

Gyros gone bad

These six gyros measure how much Mars Express rotates about any of its three axes. Together with the spacecraft's two startrackers, they determine its orientation in space.

This is critical for pointing its large parabolic radio antenna towards Earth and to aim its instruments - like the high-resolution stereo camera - at Mars.

Startrackers are simple, point-and-shoot cameras that capture images of the background star field and, with some clever processing, are used to determine the craft's orientation in space every few seconds.

The rotation information from the gyros fills in the information between these snapshots and also when the trackers lose track of the stars - which can last for minutes or even hours.

"After looking at variations in the intensity of the gyros' internal lasers, we realised last year that, with our current usage, four of the six gyros were trending towards failure," says spacecraft operations manager James Godfrey.

"Mars Express was never designed to fly without its gyros continuously available, so we could foresee a certain end to the mission sometime between January and June 2019."

Engineers knew, however, from long experience with similar gyros on previous missions, including Rosetta and ERS-2, that it might be possible to fly the mission primarily using its startrackers, with the gyros only being switched on occasionally, to extend their lives.

Hacking 15 year-old code

"Flying on startrackers with the gyros mostly switched off meant that a significant portion of the 15 year-old software on Mars Express would have to be rewritten, and this would be a major challenge," says operations engineer Simon Wood.

While the spacecraft's builder provided great assistance, it was mostly up to the teams at ESA to open the code, rewrite the software, test it and prepare it for upload as soon as possible.

"We were also helped by being able to take code flown on Rosetta and transplant it into the Mars Express guidance software," adds Simon.

A massive, multi-month effort followed, involving teams from across the Agency working to develop the new software that would enable Mars Express to keep flying. This also meant significant changes in instrument science planning.

"We didn't know if such a massive revision was possible - it hadn't been done before, especially as we would be in a race against time to complete it. But faced with the almost-certain end of mission, what began as wild speculation during a tea break one afternoon last summer has led to the full rewrite now being ready to send up."

The new software was finalised earlier this year, and has undergone meticulous testing to ensure it will work as intended.

Go/No-Go

The effort came to fruition yesterday, when the mission team met for a critical go/no-go meeting with the ESA managers to get final approval to activate the new software.

The new code was actually uploaded to an area of spare memory on Sunday, but just like when your phone or tablet gets a software upgrade, mission controllers will have to shut Mars Express down and trigger a reboot to start running the new code, a critical step set for 16 April.

If all goes as expected, the mission teams will then spend about two weeks testing and reconfiguring the spacecraft to ensure everything is working as it should before resuming normal science operations.

"Similar, but much smaller fixes, have been developed in the past for other missions with old gyros, such as Rosetta, but this is certainly the most complex and extensive software rewrite we've done in recent memory," says mission manager Patrick Martin.

"Thanks to the skill of ESA's teams, Mars Express will fly well into the 2020s, depending on fuel supply, and continue delivering excellent science for many years yet.

"I look forward to seeing continued joint science campaigns between Mars Express and other Mars missions like ESA's Trace Gas Orbiter and incoming rover missions."

NASA's Mission to Touch the Sun Arrives in the Sunshine State

NASA's Parker Solar Probe has arrived in Florida to begin final preparations for its launch to the Sun, scheduled for July 31, 2018. In the middle of the night on April 2, the spacecraft was driven from NASA's Goddard Space Flight Center in Greenbelt, Maryland, to nearby Joint Base Andrews in Maryland. From there, it was flown by the United States Air Force's 436th Airlift Wing to Space Coast Regional Airport in Titusville, Florida, where it arrived at 10:40 a.m. EDT. It was then transported a short distance to Astrotech Space Operations, also in Titusville, where it will continue testing, and eventually undergo final assembly and mating to the third stage of the Delta IV Heavy launch vehicle. Parker Solar Probe is humanity's first mission to the Sun. After launch, it will orbit directly through the solar atmosphere - the corona - closer to the surface than any human-made object has ever gone. While facing brutal heat and radiation, the mission will reveal fundamental science behind what drives the solar wind, the constant outpouring of material from the Sun that shapes planetary atmospheres and affects space weather near Earth.

"Parker Solar Probe and the team received a smooth ride from the Air Force C-17 crew from the 436th," said Andy Driesman, Parker Solar Probe project manager from the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland.

"This is the second most important flight Parker Solar Probe will make, and we're excited to be safely in Florida and continuing pre-launch work on the spacecraft."

At Astrotech, Parker Solar Probe was taken to a clean room and removed from its protective shipping container on Wednesday, April 4. The spacecraft then began a series of tests to verify that it had safely made the journey to Florida.

For the next several months, the spacecraft will undergo comprehensive testing; just prior to being fueled, one of the most critical elements of the spacecraft, the thermal protection system (TPS), or heat shield, will be installed.

The TPS is the breakthrough technology that will allow Parker Solar Probe to survive the temperatures in the Sun's corona, just 3.8 million miles from the surface of our star.

"There are many milestones to come for Parker Solar Probe and the amazing team of men and women who have worked so diligently to make this mission a reality," said Driesman. "The installation of the TPS will be our final major step before encapsulation and integration onto the launch vehicle."

Parker Solar Probe will be launched from Launch Complex-37 at NASA's Kennedy Space Center, Florida. The two-hour launch window opens at approximately 4 a.m. EDT on July 31, 2018, and is repeated each day (at slightly earlier times) through Aug. 19.

Throughout its seven-year mission, Parker Solar Probe will explore the Sun's outer atmosphere and make critical observations to answer decades-old questions about the physics of stars.

Its data will also be useful in improving forecasts of major eruptions on the Sun and the subsequent space weather events that impact technology on Earth, as well as satellites and astronauts in space.

The mission is named for University of Chicago Professor Emeritus Eugene N. Parker, whose profound insights into solar physics and processes have guided the discipline. It is the first NASA mission named for a living individual.

Parker Solar Probe is part of NASA's Living With a Star Program to explore aspects of the connected Sun-Earth system that directly affect life and society. Living With a Star is managed by the agency's Goddard Space Flight Center in Greenbelt, Maryland, for NASA's Science Mission Directorate in Washington. Johns Hopkins APL designed, built and manages the mission for NASA.

Instrument teams are led by researchers from the University of California, Berkeley; the University of Michigan in Ann Arbor; Naval Research Laboratory in Washington, D.C.; Princeton University in New Jersey; and the Smithsonian Astrophysics Observatory in Cambridge, Massachusetts.

United Launch Alliance of Centennial, Colorado, is the provider of the Delta IV launch service for Parker Solar Probe. NASA's Launch Services Program (LSP), based at Kennedy Space Center in Florida, manages the agency's efforts to commercially provide rockets for specific missions. LSP also directs the overall launch effort including overseeing development and integration of the rocket with the spacecraft.

Giant solar tornadoes put researchers in a spin

Despite their appearance solar tornadoes are not rotating after all, according to a European team of scientists. A new analysis of these gigantic structures, each one several times the size of the Earth, indicates that they may have been misnamed because scientists have so far only been able to observe them using 2-dimensional images. Dr Nicolas Labrosse will present the work, carried out by researchers at the University of Glasgow, Paris Observatory, University of Toulouse, and Czech Academy of Sciences, at the European Week of Astronomy and Space Science (EWASS) in Liverpool on Friday 6 April. Solar tornadoes were first observed in the early 20th century, and the term was re-popularised a few years ago when scientists looked at movies obtained by the AIA instrument on the NASA Solar Dynamics Observatory (SDO). These show hot plasma in extreme ultraviolet light apparently rotating to form a giant structure taking the shape of a tornado (as we know them on Earth). Now, using the Doppler effect to add a third dimension to their data, the scientists have been able to measure the speed of the moving plasma, as well as its direction, temperature and density. Using several years' worth of observations, they were able to build up a more complete picture of the magnetic field structure that supports the plasma, in structures known as prominences.

Dr Nicolas Labrosse, lead scientist in the study, explains: "We found that despite how prominences and tornadoes appear in images, the magnetic field is not vertical, and the plasma mostly moves horizontally along magnetic field lines. However we see tornado-like shapes in the images because of projection effects, where the line of sight information is compressed onto the plane of the sky."

Dr Arturo Lopez Ariste, another member of the team, adds: "The overall effect is similar to the trail of an aeroplane in our skies: the aeroplane travels horizontally at a fixed height, but we see that the trail starts above our heads and ends up on the horizon. This doesn't mean that it has crashed!"

Giant solar tornadoes - formally called tornado prominences - have been observed on the Sun for around a hundred years. They are so called because of their striking shape and apparent resemblance to tornadoes on Earth, but that is where the comparison ends.

Whereas terrestrial tornadoes are formed from intense winds and are very mobile, solar tornadoes are instead magnetized gas. They seem to be rooted somewhere further down the solar surface, and so stay fixed in place.

"They are associated with the legs of solar prominences - these are beautiful concentrations of cool plasma in the very hot solar corona that can easily be seen as pink structures during total solar eclipses," adds Labrosse.

"Perhaps for once the reality is less complicated than what we see!" comments Dr Brigitte Schmieder, another scientist involved in the work.

She continues: "Solar tornadoes sound scary but in fact they normally have no noticeable consequences for us. However, when a tornado prominence erupts, it can cause what's known as space weather, potentially damaging power, satellite and communication networks on Earth."

Deep Space Industries to provide Comet satellite propulsion for BlackSky, LeoStella

Deep Space Industries (DSI) has signed a contract to provide its Comet water-based satellite propulsion systems for the BlackSky Earth observation constellation of smallsats. DSI will provide an initial block of 20 water thrusters for the BlackSky satellites which are scheduled to start launching later this year. This announcement comes on the heels of Spaceflight Industries' recent $150 million funding and the development of LeoStella LLC, a joint venture between Spaceflight Industries and Thales Alenia Space. LeoStella is developing a Seattle-based facility to manufacture the low-cost, high-performance BlackSky satellites and is tasked with building the next 20 spacecraft with the Comet propulsion technology between now and 2020. These smallsats are part of an ultimate constellation of 60 satellites that provide high revisit rate Earth imagery and when combined with other space and terrestrial based sensors, will enable delivery of innovative global monitoring solutions and geospatial activity-based intelligence services. "The launch-safe propulsion features of the Comet system are well aligned with BlackSky's performance needs to enable affordable and flexible satellite systems," said Nick Merski, vice president of space operations, Spaceflight Industries. "We're looking forward to working with the DSI team on this and future projects."

"Customers like LeoStella are exactly why we developed the Comet propulsion system," said William Miller, chief executive officer of Deep Space Industries.

Comet is the first propulsion system in Deep Space Industries' line of green propulsion solutions designed for small satellites. While other propulsion systems use either high-pressure or toxic propellants, DSI propulsion systems are designed to be low-pressure, non-toxic, and therefore launch-safe, while still offering suitable performance for small satellites.

Comet is ride-share compatible, easy to work with, and customizable for many mission types and size. Furthermore, and in the context of DSI's longer-term goals, all its propulsion systems use propellants that can be sourced from space resources.

Virgin Galactic completes first rocket-powered Unity space craft launch

Virgin Galactic successfully launched and landed its Unity spacecraft by rocket power, completing its first powered flight in almost four years. Richard Branson's space company shared a photo of the SpaceShipTwo model spacecraft as it blasted into the air above the Mojave Air and Space Port before going supersonic and landing safely. "VSS Unity completed her first supersonic, rocket-powered flight this morning in Mojave, California. Another great test flight, another step closer to being," Virgin Galactic wrote on Twitter. Unity took off at about 8:02 a.m. as it was propelled to an altitude of 46,500 feet by the WhiteKnightTwo carrier aircraft, VMS Eve. Eve then released Unity from under its wing and the SpaceShipTwo's pilots Mark Stucky and Dave Mackay brought the spacecraft's engines to life and propelled it into an 80 degree climb, accelerating to Mach 1.87 during the 30 seconds of rocket burn. "On rocket shutdown, Unity continued an upwards coast to an apogee of 84,271 feet before readying for the downhill return," Virgin Galactic said.

Once the spacecraft began to descend, the pilots raised its tail booms to a 60 degree angle from the fuselage into the "feathered" configuration, which was adopted after fatal 2014 VSS Enterprise test flight crash.

At 50,000 feet, the tail-booms were lowered again and the Unity glided toward a safe landing on the runway.

"The flight has generated valuable data on flight, motor and vehicle performance which our engineers will be reviewing," Virgin Galactic said. "It also marks a key moment for the test flight program, entering now the exciting phase of powered flight and the expansion to full duration rocket burns."

The newest SpaceShipTwo model was unveiled in February 2016, when the late professor Stephen Hawking gave the ship the name "Unity."

In the future Virgin Galactic's spacecraft will take passengers 68 miles above the Earth's surface for a price of $250,000.

Here, There and Everywhere: Across the Universe with the Beatles

The Beatles are one of the greatest cultural phenomena to come from the 20th Century, yet many people are unaware of their impact on science. In 'Here, There and Everywhere', inspired by the book 'La scienza dei Beatles' ('The science of the Beatles'), Viviana Ambrosi shows how the Fab Four can bring the study of celestial objects and the exploration of the universe closer to a large public audience. This is set out in a presentation on 3rd April at the European Week of Astronomy and Space Science in Liverpool. The Beatles formed at the start of the space race, and have always inspired scientists, whether they knew it or not. The Beatles' record company (EMI) used money from the sale of the White Album to fund scientific research. Some of which went towards Godfrey Hounsfield's research into X-rays, which led to the invention of the CT scanner, for which he shared a Nobel Prize.

'Across the Universe' was transmitted into deep space in 2008, and numerous songs have been played as the wakeup call for astronauts on the International Space Station, including a live musical wake up by Paul McCartney in 2005.

There are five asteroids named: Beatles, Lennon, McCartney, Harrison, and Starr. There is also a crater on Mercury named 'Lennon', and when a diamond star (a white dwarf covered in crystallised carbon) was discovered in 2004, it was nicknamed 'Lucy' after 'Lucy in the Sky with Diamonds'.

This was also the inspiration for 'Lucy', the fossil that rewrote the story of humanity, and this in turn has inspired NASA to name their first mission to Jupiter's Trojan asteroids 'Lucy'.

This mission is due to launch in 2021 and will take 12 years to complete its journey. It is safe to say that the Beatles will be an inspiration for many years to come.

Is there life adrift in the clouds of Venus?

In the search for extraterrestrial life, scientists have turned over all sorts of rocks. Mars, for example, has geological features that suggest it once had - and still has - subsurface liquid water, an almost sure prerequisite for life. Scientists have also eyed Saturn's moons Titan and Enceladus as well as Jupiter's moons Europa, Ganymede and Callisto as possible havens for life in the oceans under their icy crusts. Now, however, scientists are dusting off an old idea that promises a new vista in the hunt for life beyond Earth: the clouds of Venus. In a paper published online in the journal Astrobiology, an international team of researchers led by planetary scientist Sanjay Limaye of the University of Wisconsin-Madison's Space Science and Engineering Center lays out a case for the atmosphere of Venus as a possible niche for extraterrestrial microbial life. "Venus has had plenty of time to evolve life on its own," explains Limaye, noting that some models suggest Venus once had a habitable climate with liquid water on its surface for as long as 2 billion years. "That's much longer than is believed to have occurred on Mars."

On Earth, terrestrial microorganisms - mostly bacteria - are capable of being swept into the atmosphere, where they have been found alive at altitudes as high as 41 kilometers (25 miles) by scientists using specially equipped balloons, according to study co-author David J. Smith of NASA's Ames Research Center.

There is also a growing catalog of microbes known to inhabit incredibly harsh environments on our planet, including the hot springs of Yellowstone, deep ocean hydrothermal vents, the toxic sludge of polluted areas, and in acidic lakes worldwide.

"On Earth, we know that life can thrive in very acidic conditions, can feed on carbon dioxide, and produce sulfuric acid," says Rakesh Mogul, a professor of biological chemistry at California State Polytechnic University, Pomona, and a co-author on the new paper. He notes that the cloudy, highly reflective and acidic atmosphere of Venus is composed mostly of carbon dioxide and water droplets containing sulfuric acid.

The habitability of Venus' clouds was first raised in 1967 by noted biophysicist Harold Morowitz and famed astronomer Carl Sagan. Decades later, the planetary scientists David Grinspoon, Mark Bullock and their colleagues expanded on the idea.

Supporting the notion that Venus' atmosphere could be a plausible niche for life, a series of space probes to the planet launched between 1962 and 1978 showed that the temperature and pressure conditions in the lower and middle portions of the Venusian atmosphere - altitudes between 40 and 60 kilometers (25-27 miles) - would not preclude microbial life. The surface conditions on the planet, however, are known to be inhospitable, with temperatures soaring above 450 degrees Celsius (860 degrees Fahrenheit).

Limaye, who conducts his research as a NASA participating scientist in the Japan Aerospace Exploration Agency's Akatsuki mission to Venus, was eager to revisit the idea of exploring the planet's atmosphere after a chance meeting at a teachers' workshop with paper co-author Grzegorz Slowik of Poland's University of Zielona Gora. Slowik made him aware of bacteria on Earth with light-absorbing properties similar to those of unidentified particles that make up unexplained dark patches observed in the clouds of Venus. Spectroscopic observations, particularly in the ultraviolet, show that the dark patches are composed of concentrated sulfuric acid and other unknown light-absorbing particles.

Those dark patches have been a mystery since they were first observed by ground-based telescopes nearly a century ago, says Limaye. They were studied in more detail by subsequent probes to the planet.

"Venus shows some episodic dark, sulfuric rich patches, with contrasts up to 30-40 percent in the ultraviolet, and muted in longer wavelengths. These patches persist for days, changing their shape and contrasts continuously and appear to be scale dependent," says Limaye.

"Venus has had plenty of time to evolve life on its own," explains Limaye, noting that some models suggest Venus once had a habitable climate with liquid water on its surface for as long as 2 billion years. "That's much longer than is believed to have occurred on Mars."

The particles that make up the dark patches have almost the same dimensions as some bacteria on Earth, although the instruments that have sampled Venus' atmosphere to date are incapable of distinguishing between materials of an organic or inorganic nature.

The patches could be something akin to the algae blooms that occur routinely in the lakes and oceans of Earth, according to Limaye and Mogul - only these would need to be sustained in the Venusian atmosphere.

Limaye, who has spent his career studying planetary atmospheres, was further inspired to revisit the idea of microbial life in the clouds of Venus by a visit to Tso Kar, a high-altitude salt lake in northern India where he observed the powdery residue of sulfur-fixing bacteria concentrated on decaying grass at the edge of the lake being wafted into the atmosphere.

Limaye notes, however, that a part of the equation that isn't known is when Venus' liquid water evaporated - extensive lava flows in the last billion years likely have either destroyed or covered up the planet's earlier terrestrial history.

In the hunt for extraterrestrial life, planetary atmospheres other than Earth's remain largely unexplored.

One possibility for sampling the clouds of Venus, says Limaye, is on the drawing board: VAMP, or Venus Atmospheric Maneuverable Platform, a craft that flies like a plane but floats like a blimp and could stay aloft in the planet's cloud layer for up to a year gathering data and samples.

Such a platform could include instruments like Raman Lidar, meteorological and chemical sensors, and spectrometers, says Limaye. It could also carry a type of microscope capable of identifying living microorganisms.

"To really know, we need to go there and sample the clouds," says Mogul. "Venus could be an exciting new chapter in astrobiology exploration."

The Wisconsin scientist and his colleagues remain hopeful that such a chapter can be opened as there are ongoing discussions about possible NASA participation in Russia's Roscosmos Venera-D mission, now slated for the late 2020s. Current plans for Venera-D might include an orbiter, a lander and a NASA-contributed surface station and maneuverable aerial platform.