Wednesday, February 20, 2019

Arianespace to orbit the first six satellites of the OneWeb constellation

For its second mission of the year - and the initial flight in 2019 with the Soyuz medium launcher - Arianespace will perform the first launch for the OneWeb constellation. By operating this maiden flight, out of 21 launches on behalf of the global satellite operator, Arianespace participates in the fulfilment of its customer's ultimate ambition: providing Internet access for everyone, everywhere. This mission will bring the number of constellation satellites orbited by Arianespace to 109, which shows a remarkable ability to deploy any type of constellation with its current and future family of launchers. The Launch Readiness Review (LRR) will take place on Monday, February 25, 2019 in Kourou to authorize the start of operations for the final countdown. Flight VS21, the 21st Soyuz mission from the Guiana Space Center, will put six OneWeb F6 satellites for U.S operator OneWeb into a circular low Earth orbit at 1,000 km. (close to their operational orbit), along with four Mass Flight Simulators (MFS) that will not be separated from the launcher's dispenser system. OneWeb's mission is to deliver global communications through a next-generation satellite constellation that will bring seamless connectivity to everyone, everywhere. With its system deployed, the OneWeb constellation will enable user terminals capable of offering 3G, LTE, 5G and Wi-Fi coverage, giving high-speed access around the world - by air, sea and land.

Composed of approximately 650 satellites, OneWeb initial constellation will be orbited by Arianespace using 21 Soyuz launchers operated through 2020 from Kourou in French Guiana, Baikonur in Kazakhstan, and Vostochy in Russia.

OneWeb Satellites - a joint-venture between OneWeb and Airbus Defence and Space - is the prime contractor of the constellation. RUAG Space AB, on the other hand, is in charge of the development and production of the innovative dispenser system that will carry the six satellites and the four Mass Flight Simulators aboard Flight VS21. As for APCO Technologies, it is responsible for designing and building the four Mass Flight Simulators.

Sunday, February 17, 2019

Merging neutron stars

The option to measure the gravitational waves of two merging neutron stars has offered the chance to answer some of the fundamental questions about the structure of matter. At the extremely high temperatures and densities in the merger scientists conjecture a phase-transition where neutrons dissolve into their constituents: quarks and gluons. In the current issue of Physical Review Letters, two international research groups report on their calculations of what the signature of such a phase transition in a gravitational wave would look like. Quarks, the smallest building-blocks of matter, never appear alone in nature. They are always tightly bound inside the protons and neutrons. However, neutron stars, weighing as much as the Sun, but being just the size of a city like Frankfurt, possess a core so dense that a transition from neutron matter to quark matter may occur. Physicists refer to this process as a phase transition, similar to the liquid-vapor transition in water. In particular, such a phase transition is in principle possible when merging neutron stars form a very massive meta-stable object with densities exceeding that of atomic nuclei and with temperatures 10,000 times higher than in the Sun's core.The measurement of gravitational waves emitted by merging neutron stars could serve as a messenger of possible phase transitions in outer space. The phase transition should leave a characteristic signature in the gravitational-wave signal.

The research groups from Frankfurt, Darmstadt and Ohio as well as from Darmstadt and Wroclaw (used modern supercomputers to calculate what this signature could look like. For this purpose, they used different theoretical models of the phase transition.

In case a phase transition takes place more after the actual merger, small amounts of quarks will gradually appear throughout the merged object.

"With aid of the Einstein equations, we were able to show for the first time that this subtle change in the structure will produce a deviation in the gravitational-wave signal until the newly formed massive neutron star collapses under its own weight to form a black hole," explains Luciano Rezzolla, who is a professor for theoretical astrophysics at the Goethe University.

In the computer models of Dr. Andreas Bauswein from GSI Helmholtzzentrum fur Schwerionenforschung in Darmstadt a phase transition already happens directly after the merger - a core of quark matter forms in the interior of the central object. "We succeeded to show that in this case there will be a distinct shift in the frequency of the gravitational wave signal," says Bauswein.

"Thus, we identified a measurable criterion for a phase transition in gravitational waves of neutron star mergers in the future."

Not all of the details of the gravitational-wave signal are measurable with current detectors yet. However, they will become observable both with the next generation of detectors, as well as with a merger event relatively close to us.

A complementary approach to answer the questions about quark matter is offered by two experiments: By colliding heavy ions at the existing HADES setup at GSI and at the future CBM detector at the Facility for Antiproton and Ion Research (FAIR), which is currently under construction at GSI, compressed nuclear matter will be produced.

In the collisions, it might be possible to create temperatures and densities that are similar to those in a neutron-star merger. Both methods give new insights into the occurrence of phase transitions in nuclear matter and thus into its fundamental properties.

Friday, February 15, 2019

New study suggests possibility of recent underground volcanism on Mars

A study published last year in the journal Science suggested liquid water is present beneath the south polar ice cap of Mars. Now, a new study in the AGU journal Geophysical Research Letters argues there needs to be an underground source of heat for liquid water to exist underneath the polar ice cap. The new research does not take sides as to whether the liquid water exists. Instead, the authors suggest recent magmatic activity - the formation of a magma chamber within the past few hundred thousand years - must have occurred underneath the surface of Mars for there to be enough heat to produce liquid water underneath the kilometer-and-a-half thick ice cap. On the flip side, the study's authors argue that if there was not recent magmatic activity underneath the surface of Mars, then there is not likely liquid water underneath the ice cap. "Different people may go different ways with this, and we're really interested to see how the community reacts to it," said Michael Sori, an associate staff scientist in the Lunar and Planetary Laboratory at the University of Arizona and a co-lead author of the new paper. The potential presence of recent underground magmatic activity on Mars lends weight to the idea that Mars is an active planet, geologically speaking. That fact could give scientists a better understanding of how planets evolve over time. The new study is intended to further the debate around the possibility of liquid water on Mars. The presence of liquid water on the Red Planet has implications for potentially finding life outside of Earth and could also serve as a resource for future human exploration of our neighboring planet.

"We think that if there is any life, it likely has to be protected in the subsurface from the radiation," said Ali Bramson, a postdoctoral research associate at the Lunar and Planetary Laboratory at the University of Arizona and a co-lead author of the new paper. "If there are still magmatic processes active today, maybe they were more common in the recent past, and could supply more widespread basal melting. This could provide a more favorable environment for liquid water and thus, perhaps, life."

Examining the environment

Mars has two giant ice sheets at its poles, both a couple of kilometers thick. On Earth, it is common for liquid water to be present underneath thick ice sheets, with the planet's heat causing the ice to melt where it meets the Earth's crust.

In a paper published last year in Science, scientists said they detected a similar phenomenon on Mars. They claimed radar observations detected evidence of liquid water at the base of Mars's south polar ice cap. However, the Science study did not address how the liquid water could have gotten there.

Mars is much cooler than Earth so it was unclear what type of environment would be needed to melt the ice at the base of the ice cap. Although previous research has examined if liquid water could exist at the base of Mars's ice caps, no one had yet looked at the specific location where the Science study claimed to have detected water.

"We thought there was a lot of room to figure out if [the liquid water] is real, what sort of environment would you need to melt the ice in the first place, what sort of temperatures would you need, what sort of geological process would you need? Because under normal conditions, it should be too cold," Sori said.

Looking for the heat

The new study's authors first assumed the detection of liquid water underneath the ice cap was correct and then worked to figure out what parameters were needed for the water to exist. They performed physical modeling of Mars to understand how much heat is coming out of the interior of the planet and if there could be enough salt at the base of the ice cap to melt the ice. Salt lowers the melting point of ice significantly so it was thought that salt could have led to melting at the base of the ice cap.

The model showed salt alone would not raise the temperature high enough to melt the ice. Instead, the authors propose there needs to be additional heat coming from Mars's interior.

One plausible heat source would be volcanic activity in the planet's subsurface. The study's authors argue that magma from the deep interior of Mars rose towards the planet's surface about 300,000 years ago. It did not break the surface, like a volcanic eruption, but pooled in a magma chamber below the surface. As the magma chamber cooled, it released heat that melted the ice at the base of the ice sheet. The magma chamber is still providing heat to the ice sheet to generate liquid water today.

The idea of volcanic activity on Mars is not new - there is a lot of evidence of volcanism on the planet's surface. But most of the volcanic features on Mars are from millions of years ago, leading scientists to believe volcanic activity below and above the planet's surface stopped long ago.

The new study, however, proposes that there could have been more recent underground volcanic activity. And, if there was volcanic activity happening hundreds of thousands of years ago, there's a possibility it could be happening today, according to the study's authors.

"This would imply that there is still active magma chamber formation going on in the interior of Mars today and it is not just a cold, sort of dead place, internally," Bramson said.

Jack Holt, a professor at the at the Lunar and Planetary Laboratory at the University of Arizona, said the question of how water could exist underneath the south polar ice cap immediately came to his mind after the Science paper was published, and the new paper adds an important constraint on the possibility of water being there. He said it will likely add to the debate in the planetary science community about the finding and point out that more research needs to be done to evaluate it.

"I think it was a great idea to do this type of modeling and analysis because you have to explain the water, if it's there, and so it's really a critical piece of the puzzle," said Holt, who was not involved in the new research but did talk to the study's authors before they submitted the paper. "The original paper just left it hanging. There could be water there, but you have to explain it, and these guys did a really nice job of saying what is required and that salt is not sufficient."

Wednesday, February 13, 2019

Arianespace to launch satellite deployment solution from Open Cosmos

Arianespace and Open Cosmos report that they have signed a contract for the launch of an innovative CubeSat deployment solution. Launched from the Guiana Space Center in French Guiana using a Soyuz rocket, the CubeSat deployment platform is a key to the commercial offering from Open Cosmos. The first mission comprises an array of CubeSats with a total capacity of 12 units (12U). It will weigh about 30 kg. at liftoff, and the CubeSats will be injected into Sun-synchronous orbit at an altitude over 500 km. Open Cosmos delivers effective satellite-based solutions with the goal of enabling companies to use space technologies for tackling global challenge. It specializes in the development and implementation of missions for small, low-cost satellites (up to 50 kg.), with short lead times (typically less than a year). One of the primary advantages of Open Cosmos is that it gives customers access to a wide range of launchers and orbits. The first Open Cosmos payload will be an auxiliary passenger on the COSMO-SkyMed Second Generation (CSG 1) satellite mission, along with the CHEOPS satellite for the European Space Agency ESA as well as the ANGELS and EyeSat's French CNES space agency missions. Launch is scheduled for the last quarter of 2019. Following the contract signature, Rafael Jorda Siquier, Chief Executive Officer of Open Cosmos, said, "Customers always ask us how they can get their payloads into orbit quickly and surely.

"Our partnership with Arianespace to launch a 12U (units) deployment platform will get them into their targeted orbit less than ten months after signing the contract. This mission will use one of the world's most reliable and highest performance launchers, with a proven track record - and that's exactly the kind of agility that the space industry needs right now."

Stephane Israel, Chief Executive Officer of Arianespace, added, "This contract clearly reflects Arianespace's unwavering commitment to new players like Open Cosmos, which drive the dynamic small satellite market. It also reflects our ability to offer available, flexible and competitive solutions for all market segments, thanks to our family of launch vehicles."

Saturday, February 9, 2019

New technology helps address big problems for small satellites

CubeSats have become big players in space exploration. Their small size and relatively low cost have made them popular choices for commercial launches in recent years, but the process to propel such satellites in space comes with a number of problems. Now, Purdue University researchers have developed a technology to address one of those key problems - the uncertainty of the ignition system that initiates the propulsion system of the CubeSats. Current ignition systems are unreliable and can be subject to significant and irreversible damage during the lifespan of the satellite. "We have created a lower energy triggering technology that uses nanosecond-long pulses, that allows the ignition and propulsion systems to function reliably for a very long time," said Alexey Shashurin, an assistant professor of aeronautics and astronautics in Purdue's College of Engineering. "Specifically, we have successfully tested the ignition system for greater than 1.5 million pulses and it remained operational and almost intact after the test. This is a giant leap for extending the lifetime of electric propulsion systems for CubeSats." Their work aligns with Purdue's Giant Leaps celebration, celebrating the university's global advancements in space exploration as part of Purdue's 150th anniversary. This is one of the four themes of the yearlong celebration's Ideas Festival, designed to showcase Purdue as an intellectual center solving real-world issues.

Overall popularity of the CubeSats is heavily driven by the great advancement in miniaturization of electronic components and sensors that allows for new kinds of space missions and measurements using a CubeSat.

"It is exciting to tackle these new challenges presented on spacecraft of a much smaller scale than in previous years," Shashurin said. "The next step for the CubeSats is to have a robust propulsion system for necessary maneuvering and station-keeping duties."

Shashurin and his team worked with the Purdue Office of Technology Commercialization to file a provisional patent on the technology.

The work was published in the Jan. 10 edition of Plasma Research Express. It was also presented during the American Institute of Aeronautics and Astronautics SciTech Forum last month in San Diego.

The team is planning to participate in the National Science Foundation's I-Corps program, which provides support for conducting extensive customer discovery with an ultimate goal to find industrial partners and commercialize the technology.