Friday, November 22, 2019

MEASAT selects Arianespace for launch of MEASAT-3d

Arianespace and MEASAT Global Berhad (MEASAT), the leading Malaysian satellite operator, has announced the signature of a launch services contract for MEASAT-3d. MEASAT-3d, a new multi-mission telecommunications satellite, will be launched into geostationary transfer orbit by an Ariane 5 heavy-lift launch vehicle from the Guiana Space Center, Europe's Spaceport in Kourou, French Guiana (South America) in 2021. MEASAT, the leading Malaysian satellite operator, operates five satellites, providing coverage over Asia, Middle East, Africa, Europe and Australia. MEASAT-3d will serve the growth requirements of 4G and 5G mobile networks in Malaysia while continuing to provide redundancy and additional distribution capacity for video in HD, 4K, and ultimately 8K in the Asia-Pacific region. The satellite will weigh approximately 5,734 kg. at launch, and offers an operational life of 19 years. When positioned at 91.5 degrees East, MEASAT-3d will be co-located with MEASAT-3a and MEASAT-3b satellites to replace and enhance capacity in Malaysia, Asia, Middle East and Africa. The new MEASAT-3d satellite will carry multiple payload types: C- and Ku-band payloads for direct-to-home television broadcasting and other telecom services, as well as a high-throughput Ka-band payload for internet connectivity. MEASAT-3d also will carry an L-band navigation payload for Korean satellite operator Kt sat as part of the Korea Augmentation Satellite System.

Airbus Defence and Space built MEASAT-3d using the Eurostar E3000 satellite platform.

Commenting on this latest contract, Arianespace Chief Executive Officer Stephane Israel said: "We are honoured that MEASAT entrusted the launch of MEASAT-3d to Arianespace, renewing a long standing partnership with this Malaysian operator that dates back to 1996.

With one new commercial success for Ariane 5, the Ariane family reasserts itself as the best-suited solution to reach the geostationary orbit, just a few weeks before the 40 years of Ariane and before the advent of Ariane 6 in 2020!"

Wednesday, November 20, 2019

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."

Sunday, November 17, 2019

Arianespace will orbit TIBA-1 and Inmarsat GX5 with Ariane 5

On its fourth flight with Ariane 5 in 2019, Arianespace will orbit two telecommunications satellites at the service of long-term customers: TIBA-1 for Thales Alenia Space and Airbus Defence and Space, on behalf of the Government of Egypt; and the GX5 satellite for the operator Inmarsat. Through this mission, Arianespace highlights its ability to be at the service of innovative satellite solutions for commercial and institutional needs. VA250 will be the 250th launch of an Ariane rocket, which lifted off for the first time on December 24, 1979. Flight VA250 will be performed from Ariane Launch Complex No. 3 (ELA 3) in Kourou, French Guiana. The Launch Readiness Review (LRR) will take place on Wednesday, November 20, 2019 in Kourou to authorize the start of operations for the final countdown. TIBA-1 is a civil and government telecommunication satellite for Egypt. It was developed by Thales Alenia Space and Airbus Defence and Space as co-prime contractors, with Thales Alenia Space acting as the consortium's lead partner. TIBA-1 will be owned and operated by the government of Egypt. TIBA-1 will be the fourth satellite launched by Arianespace for Egypt. It will be deployed by Arianespace into geostationary transfer orbit (GTO), subsequently transitioning to its operational orbital slot position at 35.5 East. Airbus Defence and Space is Arianespace's direct customer for this mission, continuing a fruitful cooperation between the two companies that extends back to Arianespace's creation in 1980.

GX5 is a mobile communications satellite built by Thales Alenia Space for Inmarsat. Inmarsat's fifth Ka-band Global Xpress (GX) satellite, GX5 will be the most advanced in the GX fleet, which in less than four years has become the gold standard for seamless, globally available, mobile broadband services.

Located in a geostationary orbit at 11 East, GX5 will deliver greater capacity than the entire existing GX fleet (GX1-GX4) combined and will support the rapid growth in customer demand for GX services in Europe and the Middle East, particularly for aviation passenger Wi-Fi and commercial maritime services.

This is the 10th time that Inmarsat has chosen Arianespace's launch services, demonstrating a well-established trust - with the two companies' relationship dating back to 1981.

Saturday, November 16, 2019

NASA sending solar power generator developed at Ben-Gurion to ISS

A new solar power generator prototype developed by Ben-Gurion University of the Negev (BGU) and research teams in the United States, will be deployed on the first 2020 NASA flight launch to the International Space Station. According to research published in Optics Express, the compact, microconcentrator photovoltaic system could provide unprecedented watt per kilogram of power critical to lowering costs for private space flight. As the total costs of a launch are decreasing, solar power systems now represent a larger fraction than ever of total system cost. Optical concentration can improve the efficiency and reduce photovoltaic power costs, but has traditionally been too bulky, massive and unreliable for space use. Together with U.S. colleagues, Prof. (Emer.) Jeffrey Gordon of the BGU Alexandre Yersin Department of Solar Energy and Environmental Physics, Jacob Blaustein Institutes for Desert Research, developed this first-generation prototype (1.7 mm wide) that is slightly thicker than a sheet of paper (.10 mm) and slightly larger than a U.S. quarter. "These results lay the groundwork for future space microconcentrator photovoltaic systems and establish a realistic path to exceed 350 w/kg specific power at more than 33% power conversion efficiency by scaling down to even smaller microcells," the researchers say. "These could serve as a drop-in replacement for existing space solar cells at a substantially lower cost."

A second generation of more efficient solar cells now being fabricated at the U.S. Naval Research Labs is only 0.17 mm per side, 1.0 mm thick and will increase specific power even further. If successful, future arrays will be planned for private space initiatives, as well as space agencies pursuing new missions that require high power for electric propulsion and deep space missions, including to Jupiter and Saturn.

Thursday, November 14, 2019

With Mars methane mystery unsolved, Curiosity serves scientists a new one: oxygen

For the first time in the history of space exploration, scientists have measured the seasonal changes in the gases that fill the air directly above the surface of Gale Crater on Mars. As a result, they noticed something baffling: oxygen, the gas many Earth creatures use to breathe, behaves in a way that so far scientists cannot explain through any known chemical processes. Over the course of three Mars years (or nearly six Earth years) an instrument in the Sample Analysis at Mars (SAM) portable chemistry lab inside the belly of NASA's Curiosity rover inhaled the air of Gale Crater and analyzed its composition. The results SAM spit out confirmed the makeup of the Martian atmosphere at the surface: 95% by volume of carbon dioxide (CO2), 2.6% molecular nitrogen (N2), 1.9% argon (Ar), 0.16% molecular oxygen (O2), and 0.06% carbon monoxide (CO). They also revealed how the molecules in the Martian air mix and circulate with the changes in air pressure throughout the year. These changes are caused when CO2 gas freezes over the poles in the winter, thereby lowering the air pressure across the planet following redistribution of air to maintain pressure equilibrium. When CO2 evaporates in the spring and summer and mixes across Mars, it raises the air pressure. Within this environment, scientists found that nitrogen and argon follow a predictable seasonal pattern, waxing and waning in concentration in Gale Crater throughout the year relative to how much CO2 is in the air. They expected oxygen to do the same. But it didn't. Instead, the amount of the gas in the air rose throughout spring and summer by as much as 30%, and then dropped back to levels predicted by known chemistry in fall. This pattern repeated each spring, though the amount of oxygen added to the atmosphere varied, implying that something was producing it and then taking it away.

"The first time we saw that, it was just mind boggling," said Sushil Atreya, professor of climate and space sciences at the University of Michigan in Ann Arbor. Atreya is a co-author of a paper on this topic published on November 12 in the Journal of Geophysical Research: Planets.

As soon as scientists discovered the oxygen enigma, Mars experts set to work trying to explain it. They first double- and triple-checked the accuracy of the SAM instrument they used to measure the gases: the Quadrupole Mass Spectrometer. The instrument was fine. They considered the possibility that CO2 or water (H2O) molecules could have released oxygen when they broke apart in the atmosphere, leading to the short-lived rise.

But it would take five times more water above Mars to produce the extra oxygen, and CO2 breaks up too slowly to generate it over such a short time. What about the oxygen decrease? Could solar radiation have broken up oxygen molecules into two atoms that blew away into space? No, scientists concluded, since it would take at least 10 years for the oxygen to disappear through this process.

"We're struggling to explain this," said Melissa Trainer, a planetary scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland who led this research. "The fact that the oxygen behavior isn't perfectly repeatable every season makes us think that it's not an issue that has to do with atmospheric dynamics. It has to be some chemical source and sink that we can't yet account for."

To scientists who study Mars, the oxygen story is curiously similar to that of methane. Methane is constantly in the air inside Gale Crater in such small quantities (0.00000004% on average) that it's barely discernable even by the most sensitive instruments on Mars. Still, it's been measured by SAM's Tunable Laser Spectrometer. The instrument revealed that while methane rises and falls seasonally, it increases in abundance by about 60% in summer months for inexplicable reasons. (In fact, methane also spikes randomly and dramatically. Scientists are trying to figure out why.)

With the new oxygen findings in hand, Trainer's team is wondering if chemistry similar to what's driving methane's natural seasonal variations may also drive oxygen's. At least occasionally, the two gases appear to fluctuate in tandem.

"We're beginning to see this tantalizing correlation between methane and oxygen for a good part of the Mars year," Atreya said. "I think there's something to it. I just don't have the answers yet. Nobody does."

Oxygen and methane can be produced both biologically (from microbes, for instance) and abiotically (from chemistry related to water and rocks). Scientists are considering all options, although they don't have any convincing evidence of biological activity on Mars.

Curiosity doesn't have instruments that can definitively say whether the source of the methane or oxygen on Mars is biological or geological. Scientists expect that non-biological explanations are more likely and are working diligently to fully understand them.

Trainer's team considered Martian soil as a source of the extra springtime oxygen. After all, it's known to be rich in the element, in the form of compounds such as hydrogen peroxide and perchlorates. One experiment on the Viking landers showed decades ago that heat and humidity could release oxygen from Martian soil.

But that experiment took place in conditions quite different from the Martian spring environment, and it doesn't explain the oxygen drop, among other problems.

Other possible explanations also don't quite add up for now. For example, high-energy radiation of the soil could produce extra O2 in the air, but it would take a million years to accumulate enough oxygen in the soil to account for the boost measured in only one spring, the researchers report in their paper.

"We have not been able to come up with one process yet that produces the amount of oxygen we need, but we think it has to be something in the surface soil that changes seasonally because there aren't enough available oxygen atoms in the atmosphere to create the behavior we see," said Timothy McConnochie, assistant research scientist at the University of Maryland in College Park and another co-author of the paper.

The only previous spacecraft with instruments capable of measuring the composition of the Martian air near the ground were NASA's twin Viking landers, which arrived on the planet in 1976. The Viking experiments covered only a few Martian days, though, so they couldn't reveal seasonal patterns of the different gases.

The new SAM measurements are the first to do so. The SAM team will continue to measure atmospheric gases so scientists can gather more detailed data throughout each season. In the meantime, Trainer and her team hope that other Mars experts will work to solve the oxygen mystery.

"This is the first time where we're seeing this interesting behavior over multiple years. We don't totally understand it," Trainer said. "For me, this is an open call to all the smart people out there who are interested in this: See what you can come up with."