Posted on by Matt Williams

Underground Liquid Water Found on Mars!

Mars’ south polar ice cap. Credit: ESA / DLR / FU Berlin /

According to evidence gathered by multiple robotic orbiters, rovers, and landers over the course of several decades, scientists understand that Mars was once a warmer, watery place. But between 4.2 and 3.7 billion years ago, this began to change. As Mars magnetic field disappeared, the atmosphere slowly began to be stripped away by solar wind, leaving the surface the cold and dry and making it impossible for water to exist in liquid form.

While much of the planet’s water is now concentrated in the polar ice caps, scientists have speculated some of Mars’ past water could still be located underground. Thanks to a new study by a team of Italian scientists, it has now been confirmed that liquid water still exists beneath Mars’ southern polar region. This discovery has put an end to a fifteen-year mystery and bolstered the potential for future missions to Mars.

The study, titled “Radar evidence of subglacial liquid water on Mars“, recently appeared in the journal Science. The study was led by Roberto Orosei of the National Institute of Astrophysics (INAF) in Italy, and included members from the Italian Space Agency (ASI), the ESA Center for Earth Observation (ESRIN), and multiple observatories, research institutions and universities.

Radar detection of water under the south pole of Mars. Credit: ESA/NASA/JPL/ASI/Univ. Rome

So far, robotic missions have revealed considerable evidence of past water on Mars. These include dried-out river valleys and gigantic outflow channels discovered by orbiters, and evidence of mineral-rich soils that can only form in the presence of liquid water by rovers and landers. Early evidence from the ESA’s Mars Express probe has also showed that water-ice exists at the planet’s poles and is buried in the layers interspersed with dust.

However, scientists have long suspected that liquid water could exist beneath the polar ice caps, much in the same way that liquid water is believed to underlie glaciers here on Earth. In addition, the presence of salts on Mars could further reduce the melting point of subsurface water and keep it in a liquid state, despite the sub-zero temperatures present on both the surface and underground.

For many years, data from the Mars Express’ Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument – which has been used to study the southern polar region – has remained inconclusive. Like all ground-penetrating radar, this instrument relies on radar pulses to map surface topography and determine the properties of the materials that lie beneath the surface.

Luckily, after considerable analysis, the study team was able to develop new techniques that allowed them to collect enough high-resolution data to confirm the presence of liquid water beneath the southern ice cap. As Andrea Cicchetti, the MARSIS operations manager and a co-author on the new paper, indicated:

“We’d seen hints of interesting subsurface features for years but we couldn’t reproduce the result from orbit to orbit, because the sampling rates and resolution of our data was previously too low. We had to come up with a new operating mode to bypass some onboard processing and trigger a higher sampling rate and thus improve the resolution of the footprint of our dataset: now we see things that simply were not possible before.”

Water detection under the south pole of Mars. Credit: Context map: NASA/Viking; THEMIS background: NASA/JPL-Caltech/Arizona State University; MARSIS data: ESA/NASA/JPL/ASI/Univ. Rome; R. Orosei et al 2018

What they found was that the southern polar region is made of many layers of ice and dust down to a depth of about 1.5 km over a 200 km-wide area, and featured an anomalous area measuring 20-km wide. As Roberto Orosei, the principal investigator of the MARSIS experiment and lead author of the paper, explained in a recent ESA press release:

“This subsurface anomaly on Mars has radar properties matching water or water-rich sediments. This is just one small study area; it is an exciting prospect to think there could be more of these underground pockets of water elsewhere, yet to be discovered.”

After analyzing the properties of the reflected radar signals and taking into account the composition of the layered deposits and expected temperature profiles below the surface, the scientists concluded that the 20-km wide feature is an interface between the ice and a stable body of liquid water. For MARSIS to be able to detect such a patch of water, it would need to be at least several tens of centimeters thick.

These findings also raise the possibility of there being life on Mars, both now and in the past. This is based on research that found microbial life in Lake Vostok, which is located some 4 km (2.5 mi) below the ice in Antarctica. If life can thrive in salty, subglacial environments on Earth, then it is possible that they could survive on Mars as well. Determining if this is the case will be the purpose of existing and future missions to Mars.

The MARSIS instrument on the Mars Express is a ground penetrating radar sounder used to look for subsurface water and ice. Credit: ESA

As Dmitri Titov, one of the Mars Express project scientist, explained:

“The long duration of Mars Express, and the exhausting effort made by the radar team to overcome many analytical challenges, enabled this much-awaited result, demonstrating that the mission and its payload still have a great science potential. This thrilling discovery is a highlight for planetary science and will contribute to our understanding of the evolution of Mars, the history of water on our neighbour planet and its habitability.”

The Mars Express launched on June 2nd, 2003, and will celebrate 15 years in orbit of Mars by December 25th this year. In the coming years, it will be joined by the ESA’s ExoMars 2020 mission, NASA’s Mars 2020 Rover, and a number of other scientific experiments. These missions will pave the way for a potential crewed mission, which NASA is planning to mount by the 2030s.

If there is indeed liquid water to be found on Mars, it will go a long way towards facilitating future research and even an ongoing human presence on the surface. And if there is still life on Mars, the careful research of its ecosystems will help address the all-important question of how and when life emerged in the Solar System.

Further Reading: ESA, Science

Posted on by Matt Williams

One Bonus From the Gaia Data Release: the Rotation of the Large Magellanic Cloud

Rotation of the Large Magellanic Cloud, as revealed by the ESA's Gaia spacecraft. Copyright: ESA/Gaia/DPAC

On December 19th, 2013, the European Space Agency’s (ESA) Gaia spacecraft took to space with for a very ambitious mission. Over the course of its planned 5-year mission (which was recently extended), this space observatory would map over a billion stars, planets, comets, asteroids and quasars in order to create the largest and most precise 3D catalog of the Milky Way ever created.

Since that time, the ESA has made two data releases that cover the first three years of the Gaia mission. The second data release, which took on April 25th, 2018, has already proven to be a treasure trove for astronomers. In addition to the positions, distance indicators and motions of over a billion stars and celestial objects in the Milky Way Galaxy, it also contained a hidden gem – the proper motions of stars within the Large Magellanic Cloud (LMC).

Located about 200,000 light-years from Earth, the LMC has dense clouds of dust that results in it experiencing high rates of star formation. In addition, it’s central bar is warped (where the east and west ends are nearer to the Milky Way), suggesting that it was once a barred dwarf spiral galaxy who’s spiral arms were disrupted by interaction with the Small Magellanic Cloud (SMC) and the Milky Way.

The proper motions of the stars in the LMC, as captured by the Gaia spacecraft (without color). Copyright: ESA/Gaia/DPAC

For these reasons, astronomers have been hoping to derive the orbits of dwarf galaxies (and globular clusters) that revolve around the Milky Way. In so doing, they hope to learn more about how our galaxy evolved due to mergers with clusters and other galaxies. By determining the proper motions of the LMC’s stars, the Gaia mission has provided clues as to how the Milky Way and its largest satellite galaxy have interacted over time.

As you can see from the image (at top), the bar of the LMC is outlined in great detail, along with individual star-forming regions like the Tarantula Nebula (aka. 30 Doradus, which is visible just above the center of the galaxy). The image combines the total amount of radiation detected by the observatory in each pixel. The radiation measurements were then taken through different filters on the spacecraft to generate color information.

This allowed Gaia to obtain information about the total density of stars within the LMC as well as their proper motions. As you can see, the image is dominated by the brightest, most massive stars, which greatly outshine their fainter, lower-mass counterparts. The proper motions of the stars observed is represented as the texture of the image – which looks a lot like a fingerprint.

The Large Magellanic Cloud (LMC), one of the nearest galaxies to our Milky Way, as viewed by ESA’s Gaia satellite using information from the mission’s second data release. Copyright ESA/Gaia/DPAC

From this, scientists were able to see an imprint of the stars rotating clockwise around the center of the galaxy. Using this information, astronomers will be able to create new models on how the LMC, SMC, and Milky Way evolved together over time. This, in turn, could shed light on how galaxies like our own, formed and evolved over the course of billions of years.

As with other information contained in the first and second data releases, this latest discovery demonstrates that the Gaia mission is fulfilling its intended purpose. The third release of Gaia data is scheduled to take place in late 2020, with the final catalog being published in the 2020s. Meanwhile, an extension has already been approved for the Gaia mission, which will now remain in operation until the end of 2020 (to be confirmed at the end of this year).

And be sure to enjoy this animated view of the LMC’s rotation, courtesy of the ESA:

Further Reading: ESA

Posted on by Matt Williams

ExoMars Has Sent Back its First Images From Mars

ExoMars images Korolev Crater. Copyright: ESA/Roscosmos/CaSSIS

On October 19th, 2016, the European Space Agency’s Exobiology on Mars (ExoMars) mission established orbit around Mars. Consisting of the ExoMars Trace Gas Orbiter (TGO) and the Schiaparelli lander, the purpose of this mission is to investigate Mars for past signs of life. And whereas the Schiaparelli unfortunately crashed during deployment, the TGO has managed to begin its mission ahead of schedule.

A few weeks ago, the satellite achieved a near circular orbit around Mars after performing a series of braking maneuvers. Since that time, the orbiter’s Color and Stereo Surface Imaging System (CaSSIS) took a stunning image of the surface. This picture was not only the TGO’s first image of Mars, it was also a test to see if the orbiter is ready to being its main mission on April 28th.

The image captured a 40 km- (25 mi) long segment of the Korolev Crater, which is located high in Mars’ northern hemisphere. The image was a composite of three images in different colors that were taken simultaneously on April 15th, 2018, which were then assembled to produce this color image. The bright material that appears at the edge of the crater is water ice.

The ExoMars Colour and Stereo Surface Imaging System, CaSSIS, captured this view of the rim of Korolev crater (73.3ºN/165.9ºE). Copyright ESA/Roscosmos/CaSSIS

As Antoine Pommerol, a member of the CaSSIS science team working on the calibration of the data, explained in a recent ESA press release:

“We were really pleased to see how good this picture was given the lighting conditions. It shows that CaSSIS can make a major contribution to studies of the carbon dioxide and water cycles on Mars.”

Prior to the test phase, the camera team transmitted new software to the TGO, and after a few minor issues, they determined that the instrument was ready to work. The camera is one of four instruments on the TGO, which also carries two spectrometer suites and a neutron detector. The spectrometers began their science mission on April 21st by taking the first sample of the atmosphere to see how its molecules absorb sunlight.

By doing this, the TGO hopes to determine the chemical composition of Mars atmosphere and find evidence of methane and other trace atmospheric gases that could be signatures of active biological or geological processes. Eventually, the camera will help characterize features on the surface that could be related to trace gas sources. Hence the importance of this recent test.

ExoMars’ Trace Gas Orbiter (TGO) and Schiaparelli lander seperating in orbit of Mars. Credit: ESA/ATG medialab

“We aim to fully automate the image production process,” said Nicolas Thomas, the camera’s principal investigator from the University of Bern. “Once we achieve this, we can distribute the data quickly to the science community for analysis.”

A lot of challenges lie ahead, which includes a long period of data collection to bring out the details of rare (or yet to be discovered) trace gases in Mars’ atmosphere. This is necessary since trace gases (as the name would suggest) are present in only very small amounts – i.e. less than 1% of the volume of the planet’s atmosphere. But as Håkan Svedhem – the ESA’s TGO project scientist – indicated, the test image was a good start.

“We are excited to finally be starting collecting data at Mars with this phenomenal spacecraft,” he said. “The test images we have seen so far certainly set the bar high.”

By 2020, the second part of the ExoMars mission is scheduled to launch. This will consist of a Russian surface platform and a European rover landing on the surface in support of a science mission that is expected to last into 2022 or longer. Alongside NASA’s proposed Mars 2020 rover, the Red Planet is due to have several more visitors in the coming years!

Further Reading: ESA

Posted on by Matt Williams

I Can’t Stop Watching This Amazing Animation from Comet 67P

A single frame from the animation created by twitter user landru79. The images were taken by the Rosetta spacecraft of 67P on June 1st, 2016. Credit: Europeans Space Agency -ESAC

The European Space Agency’s Rosetta mission was an ambitious one. As the first-ever space probe to rendezvous with and then orbit a comet, Rosetta and its lander (Philae) revealed a great deal about the comet 67p/Churyumov-Gerasimenko. In addition to the learning things about the comet’s shape, composition and tail, the mission also captured some incredible images of the comet’s surface before it ended.

For instance, Rosetta took a series of images on June 1st, 2016, that showed what looks like a blizzard on the comet’s surface. Using these raw images (which were posted on March 22nd, 2018), twitter user landru79 created an eye-popping video that shows just what it would be like to stand on the comet’s surface. As you can see, its like standing in a blizzard on Earth, though scientists have indicated that it’s a little more complicated than that.

The video, which consists of 25 minutes worth of images taken by Rosetta’s Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS), was posted by landru79 on April 23rd, 2018. It shows the surface of 67p/Churyumov-Gerasimenko on the loop, which lends it the appearance of panning across the surface in the middle of a snowstorm.

However, according to the ESA, the effect is likely caused by three separate phenomena. For instance, the snow-like particles seen in the video are theorized to be a combination of dust from the comet itself as well as high-energy particles striking the camera. Because of OSIRIS’ charge-coupled device (CCD) – a radiation-sensing camera – even invisible particles appear like bright streaks when passing in front of it.

As for the white specks in the background, those are stars belonging to the Canis Major constellation (according to ESA senior advisor Mark McCaughrean). Since originally posting the video, landru79 has posted another GIF on Twitter (see below) that freezes the starfield in place. This makes it clearer that the comet is moving, but the stars are remaining still (at least, relative to the camera’s point of view).

And of course, the entire video has been sped up considerably for dramatic effect. According to a follow-up tweet posted by landru79, the first image was shot on June 1st, 2016 at 3.981 seconds past 17:00 (UTC) while the last one was shot at 170.17 seconds past 17:25.

Still, one cannot deny that it is both captivating and draws attention to what Rosetta the mission accomplished. The mission launched in 2004 and reached 67P/Churyumov-Gerasimenko in 2014. After two years of gathering data, it was deliberately crashed on its surface in 2016. And yet, years later, what it revealed is still captivating people all over the world.

Further Reading: Live Science, Gizmodo

Posted on by Matt Williams

Tiangong-1 Splashes Down in the Pacific Ocean

Radar images acquired of China's Tiangong-1 space station by the Tracking and Imaging Radar system, which is operated by Germany’s Fraunhofer FHR research institute at Wachtberg. Credit: Fraunhofer FHR

Over the weekend, multiple space agencies’ had their instruments fixed on the skies as they waited for the Tiangong-1 space station to reenter our atmosphere. For the sake of tracking the station’s reentry, the ESA hosted the 2018 Inter Agency Space Debris Coordination Committee, an annual exercise that consists of experts from 13 space agencies taking part in a joint tracking exercise.

And on April 2nd, 02:16 CEST (April 1st, 17:16 PST), the US Air Force confirmed the reentry of the Tiangong-1 over the Pacific Ocean. As hoped, the station crashed down close to the South Pacific Ocean Unpopulated Area (SPOUA), otherwise known as the “Spaceship Cemetery”. This region of the Pacific Ocean has long been used by space agencies to dispose of spent spacecraft after a controlled reentry.

The confirmation came from the Joint Force Space Component Command (JFSCC) on April 2nd, 0:400 CEST (April 1st, 19:00 PST). Using the Space Surveillance Network sensors and their orbital analysis system, they were able to refine their predictions and provide more accurate tracking as the station’s reentry time approached. The USAF regularly shares information with the ESA regarding its satellites and debris tracking.

Artist’s illustration of China’s 8-ton Tiangong-1 space station, which is expected to fall to Earth in late 2017. Credit: CMSE

As with the ESA’s coordination with other space agencies and European member states, JFSCC’s efforts include counterparts in Australia, Canada, France, Germany, Italy, Japan, South Korea, and the United Kingdom. As Maj. Gen. Stephen Whiting, the Deputy Commander of the JFSCC and Commander of the 14th Air Force, indicated in a USAF press release:

“The JFSCC used the Space Surveillance Network sensors and their orbital analysis system to confirm Tiangong-1’s reentry, and to refine its prediction and ultimately provide more fidelity as the reentry time approached. This information is publicly-available on USSTRATCOM’s website www.Space-Track.org. The JFSCC also confirmed reentry through coordination with counterparts in Australia, Canada, France, Germany, Italy, Japan, South Korea, and the United Kingdom.”

The information is available on U.S. Strategic Command’s (USSTRATCOM) website – www.Space-Track.org. Holger Krag, the head of ESA’s Space Debris Office, confirmed the reentry of Tiangong-1 shortly thereafter on the ESA’s Rocket Science Blog. As he stated, the reentry was well within ESA’s earlier reentry forecast window – which ran from April 1st 23:00 UTC to 03:00 UTC on April 2nd (April 2nd, 01:00 CEST to 05:00 CEST):

“According to our experience, their assessment is very reliable. This corresponds to a geographic latitude of 13.6 degrees South and 164.3 degrees West – near American Samoa in the Pacific, near the international date Line. Both time and location are well within ESA’s last prediction window.”

 

Artist’s illustration of China’s 8-ton Tiangong-1 space space station. Credit: CMSE.

China’s Manned Space Agency (CMSA) also made a public statement about the station’s reenty:

“According to the announcement of China Manned Space Agency (CMSA), through monitoring and analysis by Beijing Aerospace Control Center (BACC) and related agencies, Tiangong-1 reentered the atmosphere at about 8:15 am, 2 April, Beijing time. The reentry falling area located in the central region of South Pacific. Most of the devices were ablated during the reentry process.”

As Krag noted, the ESA’s monitoring efforts were very much reliant on its campaign partners from around the world. In fact, due to when the station entered the Earth’s atmosphere, it was no longer visible to the Fraunhofer FHR institute’s Tracking and Imaging (TIRA) radar, which provides tracking services for the ESA’s Space Debris Office (SDO).

Had the station still been in orbit by 06:05 CEST (21:00 PST), it would have still been visible to the institute’s TIRA radar. Some unexpected space weather also played a role in the station’s reentry. On March 31st, the Sun’s activity spontaneously dropped, which delayed the Tiangong-1’s entry by about a day.

“This illustrates again the dependence that Europe has on non-European sources of information to properly and accurately manage space traffic, detect reentries such as Tiangong-1 and track space debris that remains in orbit – which routinely threatens ESA, European and other national civil, meteorological, scientific, telecomm and navigation satellites,” said Krag.

While news of the Tiangong-1’s orbital decay caused its share of concern, the reentry happened almost entirely as predicted and resulted in no harm. And once again, it demonstrated how international cooperation and public outreach is the best defense against space-related hazards.

 

 

Further Reading: Vandenburg Air Force Base,

Posted on by Matt Williams

Did You Know That a Satellite Crashes Back to Earth About Once a Week, on Average?

Artist's impression of all the space junk in Earth orbit. Credit: NASA

This past weekend, a lot of attention was focused on the Tiangong-1 space station. For some time, space agencies and satellite trackers from around the world had been predicting when this station would fall to Earth. And now that it has safely landed in the Pacific Ocean, many people are breathing a sigh of relief. While there was very little chance that any debris would fall to Earth, the mere possibility that some might caused its share of anxiety.

Interestingly enough, concerns about how and when Tiangong-1 would fall to Earth has helped to bring the larger issue of orbital debris and reentry into perspective. According to the SDO, on average, about 100 tonnes of space junk burns up in Earth’s atmosphere every year. Monitoring these reentries and warning the public about possible hazards has become routine work for space debris experts.

This junk takes the form of defunct satellites, uncontrolled spacecraft, the upper stages of spent rockets, and various discarded items (like payload covers). Over time, this debris is slowed down by Earth’s upper atmosphere and then succumbs to Earth’s gravitational pull. Where larger objects are concerned, some pieces survive the fiery reentry process and reach the surface.

Radar images acquired by the Tracking and Imaging Radar system – one of the world’s most capable – operated by Germany’s Fraunhofer FHR research institute. Credit: Fraunhofer FHR

In most cases, this debris falls into the ocean or lands somewhere far away from human settlement. While still in orbit, these objects are tracked by a US military radar network, the ESA’s Space Debris Office, and other agencies and independent satellite trackers. This information is shared in order to ensure that margins of error can be minimized and predicted reentry windows can be kept narrow.

For the SDO team, these efforts are based on data and updates provided by ESA member states and civil authorities they are partnered with, while additional information is provided by telescopes and other detectors operated by institutional and private researchers. One example is the Tracking and Imaging Radar (TIRA) operated by the Fraunhofer Institute for High Frequency Physics and Radar Techniques near Bonn, Germany.

This is a challenging task, and often subject to a measure of imprecision and guesswork. As Holger Krag, the head of ESA’s Space Debris Office, explained:

“With our current knowledge and state-of-the-art technology, we are not able to make very precise predictions. There will always be an uncertainty of a few hours in all predictions – even just days before the reentry, the uncertainty window can be very large. The high speeds of returning satellites mean they can travel thousands of kilometres during that time window, and that makes it very hard to predict a precise location of reentry.”

Tiangong-1 as seen in a a composite of three separate exposures taken on May 25, 2013. Credit and copyright: David Murr.

Of the 100 tonnes that enters our atmosphere every year, the vast majority are small pieces of debris that burn up very quickly – and therefore pose no threat to people or infrastructure. The larger descents, of which there are about 50 per year, sometimes result in debris reaching the surface, but these generally land in the ocean or remote areas. In fact, in the history of spaceflight, no casualties have ever been confirmed by falling space debris.

The ESA also takes part in a joint tracking campaign run by the Inter Agency Space Debris Coordination Committee, which consists of experts from 13 space agencies. In addition to the ESA, this committee includes several European space agencies, NASA, Roscosmos, the Canadian Space Agency, the Japanese Aerospace Exploration Agency, the Indian Space Research Organization, the China National Space Agency, and the State Space Agency of Ukraine.

The purpose of these campaigns is for space agencies to pool their respective tracking information from radar and other sources. In so doing, they are able to analyze and verify each other’s data and improve prediction accuracy for all members. The ESA hosted the 2018 campaign, which followed the reentry of China’s Tiangong-1 space station as it entered Earth’s atmosphere this weekend – the details of which are posted on the ESA’s Rocket Science blog.

“Today, everyone in Europe relies on the US military for space debris orbit data – we lack the radar network and other detectors needed to perform independent tracking and monitoring of objects in space,” said Krag. “This is needed to allow meaningful European participation in the global efforts for space safety.”

While predicting when and where space debris will reenter our atmosphere may not yet be an exact science, it does have one thing going for it – its 100% safety record. And as the Tiangong-1 descent showed, early warning and active tracking ensure that potential threats are recognized well in advance.

In the meantime, be sure to enjoy this video on the Space Debris Office’s reentry monitoring, courtesy of the ESA:

Further Reading: ESA

Posted on by Matt Williams

This Bizarre Image is a 3D Scan of a Cave Network in Spain. This Technology Could be Used to Map Out Lava Tubes on the Moon and Mars

The intricate 3D map of the La Cueva de Los Verdes lava tube system in Lanzarote, Spain. Credit: Vigea – Tommaso Santagata

For some time, scientists have known that the Moon and Mars have some fascinating similarities to Earth. In addition to being similar in composition, there is ample evidence that both bodies had active geological pasts. This includes stable lava tubes which are very similar to those that exist here on Earth. And in the future, these tubes could be an ideal location for outposts and colonies.

However, before we can begin choosing where to settle, these locations need to be mapped out to determining which would be suitable for human habitation. Luckily, a team of speleologists (cave specialists), geologists and ESA astronauts recently created the largest 3D image of a lava tube ever created. As part of the ESA’s PANGAEA program, this technology could one day help scientists map out cave systems on the Moon and Mars.

The lava tube in question was the La Cueva de Los Verdes, a famous tourist destination in Lanzarote, Spain. In addition to ESA astronaut Matthias Mauer, the team consisted of Tommaso Santagata (a speleologist from the University of Padova and the co-founder of the Virtual Geographic Agency), Umberto Del Vecchio and Marta Lazzaroni – a geologists and a masters student from the University of Padova, respectively.

Testing out the Leica BLK360 in La Cueva de los Verdes lava tube in Lanzarote, Spain. Credit and Copyright: ESA – Alessio Romeo

Last year, the team mapped the path of this cave system as part of the ESA’s 2017 Pangaea-X campaign. As one of many ESA Spaceflight Analog field campaigns, the purpose of Pangaea-X is to conduct experiments designed to improve the future of the ESA’s Planetary ANalogue Geological and Astrobiological Exercise for Astronauts (PANGAEA) training course.

For five days in November 2017, this campaign mobilized 50 people, four space agencies and 18 organizations in five different locations. The La Cueva de los Verdes lava tube was of particular importance since it is one of the world’s largest volcanic cave complexes, measuring roughly 8 km in length. Some of these caves are even large enough to accommodate residential streets and houses.

During the campaign, Mauer, Santagata, Vecchio and Lazzaroni relied on two instruments to map the lava tube in detail. These included the Pegasus Backpack, a wearable mapping solution that collects geometric data without a satellite ad synchronizes images collected by five cameras and two 3D imaging laser profilers, and the Leica BLK360 – the smallest and lightest imaging scanner on the market.

In less than three hours, the team managed to map all the contours of the lava tube. And while the results of the campaign continue to be analyzed, the team chose to use the data they obtained to produce a 3D visual of all the twists and turns of the lava tube. The scan that resulted covers a 1.3 km section of the cave system with an unprecedented resolution of a few centimeters.

Santagata and the Virtual Geography Agency also turned their 3D visual into a lovely video titled “Lave tube fly-through”, which beautifully illustrates the winding and organic nature of the lava tube system.  This video was posted to the ESA’s twitter feed on Tuesday, March 13th (shown above). This video, like the scans that preceded it, represent a breakthrough in geological mapping and astronaut training.

While lava tubes have been mapped since the 1970s, a clear view of this subterranean passage has remained elusive until now. Beyond being the first, the scans the team conducted could also help scientists to study the origins of the cave system, its peculiar formations, and assist local institutions in protecting the subterranean environment. As intended, the scans could also assist future space exploration and colonization efforts.

Pangaea-X arrives at the entrance to La Cueva de los Verdes lava tube. Credit and Copyright: ESA–Robbie Shone

For instance, the 8 km lava tube has both dry and water-filled sections. In the six-kilometer dry section, the lava tube has natural openings (jameos), that are aligned along the top of the cave pathway. These formations are very similar to “skylights” that have been observed on the Moon and Mars, which are holes in the surface that open into stable lava tubes.

Such structures are considered to be a good place for building outposts and colonies since they are naturally shielded from radiation and micrometeorites. Lava tubes also have a constant temperature, therefore offering protection against environmental extremes, and could provide access to underground sources of water ice. Some sections could also be sealed off and pressurized to create a colony.

As such, exploring such environments here on Earth is a good way to train astronauts to explore them on other bodies. As all astronauts know, mapping an environment is the first step in exploration, especially when you are looking for a place to establish a base camp. And in time, this information can be used to establish more permanent settlements, giving rise to eventual colonization.

Further Reading: ESA, Blogs ESA

Posted on by Matt Williams

Air-Breathing Electric Thruster Could Keep Satellites in Low Earth Orbit for Years

An ESA-led team has built and fired an electric thruster to ingest scarce air molecules from the top of the atmosphere as propellant, opening the way to satellites flying in very low orbits for years on end. Credit: ESA/Sitael

When it comes to the future of space exploration, one of the greatest challenges is coming up with engines that can maximize performance while also ensuring fuel efficiency. This will not only reduce the cost of individual missions, it will ensure that robotic spacecraft (and even crewed spacecraft) can operate for extended periods of time in space without having to refuel.

In recent years, this challenge has led to some truly innovative concepts, one of which was recently build and tested for the very first time by an ESA team. This engine concept consists of an electric thruster that is capable of “scooping” scarce air molecules from the tops of atmospheres and using them as propellant. This development will open the way for all kinds of satellites that can operate in very low orbits around planets for years at a time.

The concept of an air-breathing thruster (aka. Ram-Electric Propulsion) is relatively simple. In short, the engine works on the same principles as a ramscoop (where interstellar hydrogen is collected to provide fuel) and an ion engine – where collected particles are charged and ejected. Such an engine would do away with onboard propellant by taking in atmospheric molecules as it passed through the top of a planet’s atmosphere.

The test set-up for the air-breathing electric propulsion thruster recently developed by Sitael and QuinteScience in conjunction with the ESA. Credit: ESA/Sitael

The concept was the subject of a study titled “RAM Electric Propulsion for Low Earth Orbit Operation: An ESA Study“, which was presented at the 30th International Electric Propulsion Conference in 2007. The study emphasized how “Low Earth orbit satellites are subject to atmospheric drag and thus their lifetimes are limited with current propulsion technologies by the amount of propellant they can carry to compensate for it.”

The study’s authors also indicated how satellites using high specific impulse electric propulsion would be capable of compensating for drag during low altitude operation for an extended period of time. But as they conclude, such a mission would also be limited to the amount of fuel it could carry. This was certainly the case for the ESA’s Gravity field and steady-state Ocean Circulation Explorer (GOCE) gravity-mapper satellite,

While GOCE remained in orbit of Earth for more than four years and operated at altitudes as low as 250 km (155 mi), its mission ended the moment it exhausted its 40 kg (88 lbs) supply of xenon as propellant. As such, the concept of an electric propulsion system that an utilize atmospheric molecules as propellant has also been investigated. As Dr. Louis Walpot of the ESA explained in an ESA press release:

“This project began with a novel design to scoop up air molecules as propellant from the top of Earth’s atmosphere at around 200 km altitude with a typical speed of 7.8 km/s.”

Diagram illustrated how air-breathing electric propulsion works. Credit: ESA–A. Di Giacomo

To develop this concept, the Italian aerospace company Sitael and the Polish aerospace company QuinteScience teamed up to create a novel intake and thruster design. Whereas QuinteScience built an intake that would collect and compress incoming atmospheric particles, Sitael developed a dual-stage thruster that would charge and accelerate these particles to generate thrust.

The team then ran computer simulations to see how particles would behave across a range of intake options. But in the end, they chose to conduct a practice test to see if the combined intake and thruster would work together or not. To do this, the team tested it in a vacuum chamber at one of Sitael’s test facilities. The chamber simulated an environment at 200 km altitude while a “particle flow generator” provided the oncoming high-speed molecules.

To provide a more complete test and make sure the thruster would function in a low-pressure environment, the team began by igniting it with xenon-propellant. As Dr. Walpot explained:

“Instead of simply measuring the resulting density at the collector to check the intake design, we decided to attach an electric thruster. In this way, we proved that we could indeed collect and compress the air molecules to a level where thruster ignition could take place, and measure the actual thrust. At first we checked our thruster could be ignited repeatedly with xenon gathered from the particle beam generator.”

Fired at first using standard xenon propellant, the test thruster was then shifted to atmospheric air, proving the principle of air-breathing electric propulsion. Credit: ESA

As a next step, the team partially replace xenon with a nitrogen-oxygen air mixture to simulate Earth’s upper atmosphere. As hoped, the engine kept firing, and the only thing that changed was the color of the thrust.

“When the xenon-based blue color of the engine plume changed to purple, we knew we’d succeeded,” said Dr. Walpot. “The system was finally ignited repeatedly solely with atmospheric propellant to prove the concept’s feasibility. This result means air-breathing electric propulsion is no longer simply a theory but a tangible, working concept, ready to be developed, to serve one day as the basis of a new class of missions.”

The development of air-breathing electric thrusters could allow for an entirely new class of satellite that could operate with the fringes of Mars’, Titan’s and other bodies atmospheres for years at a time. With this kind of operational lifespan, these satellites could gather volumes of data on these bodies’ meteorological conditions, seasonal changes, and the history of their climates.

Such satellites would also be very useful when it comes to observing Earth. Since they would be able to operate at lower altitudes than previous missions, and would not be limited by the amount of propellant they could carry, satellites equipped with air-breathing thrusters could operate for extended periods of time. As a result, they could offer more in-depth analyses on Climate Change, and monitor meteorological patterns, geological changes, and natural disasters more closely.

Further Reading: ESA

Posted on by Evan Gough

Special Skinsuits Could Help Astronauts Avoid Back Pain When Their Spines Expand In Space

The microgravity in space makes astronauts' spines grow, and causes back pain. A new SkinSuit being developed by the ESA is helping. This image shows student test subjects wearing the suit. Image: Kings College London, Centre for Human Aerospace Physiological Sciences

The microgravity in space causes a number of problems for astronauts, including bone density loss and muscle atrophy. But there’s another problem: weightlessness allows astronauts’ spines to expand, making them taller. The height gain is permanent while they’re in space, and causes back pain.

A new SkinSuit being tested in a study at King’s College in London may bring some relief. The study has not been published yet.

The constant 24 hour microgravity that astronauts live with in space is different from the natural 24 hour cycle that humans go through on Earth. Down here, the spine goes through a natural cycle associated with sleep.

Sleeping in a supine position allows the discs in the spine to expand with fluid. When we wake up in the morning, we’re at our tallest. As we go about our day, gravity compresses the spinal discs and we lose about 1.5 cm (0.6 inches) in height. Then we sleep again, and the spine expands again. But in space, astronauts spines have been known to grow up to 7 cm. (2.75 in.)

Study leader David A. Green explains it: “On Earth your spine is compressed by gravity as you’re on your feet, then you go to bed at night and your spine unloads – it’s a normal cyclic process.”

In microgravity, the spine of an astronaut is never compressed by gravity, and stays unloaded. The resulting expansion causes pain. As Green says, “In space there’s no gravitational loading. Thus the discs in your spine may continue to swell, the natural curves of the spine may be reduced and the supporting ligaments and muscles — no longer required to resist gravity – may become loose and weak.”

The SkinSuit being developed by the Space Medicine Office of ESA’s European Astronaut Centre and the King’s College in London is based on work done by the Massachusetts Institute of Technology (MIT). It’s a spandex-based garment that simulates gravity by squeezing the body from the shoulders to the feet.

ESA astronauts have tested the SkinSuit both in weightless parabolic flights, and on-board the ISS. Image: CNES/Novespace, 2014

The Skinsuits were tested on-board the International Space Station by ESA astronauts Andreas Mogensen and Thomas Pesquet. But they could only be worn for a short period of time. “The first concepts were really uncomfortable, providing some 80% equivalent gravity loading, and so could only be worn for a couple of hours,” said researcher Philip Carvil.

Back on Earth, the researchers worked on the suit to improve it. They used a waterbed half-filled with water rich in magnesium salts. This re-created the microgravity that astronauts face in space. The researchers were inspired by the Dead Sea, where the high salt content allows swimmers to float on the surface.

“During our longer trials we’ve seen similar increases in stature to those experienced in orbit, which suggests it is a valid representation of microgravity in terms of the effects on the spine,” explains researcher Philip Carvil.

The SkinSuit has evolved through several designs to make it more wearable, comfortable, and effective. Image: Kings College London/Philip Carvill

Studies using students as test subjects have helped with the development of the SkinSuit. After lying on the microgravity-simulating waterbed both with and without the SkinSuit, subjects were scanned with MRI’s to test the SkinSuit’s effectiveness. The suit has gone through several design revisions to make it more comfortable, wearable, and effective. It’s now up to the Mark VI design.

“The Mark VI Skinsuit is extremely comfortable, to the point where it can be worn unobtrusively for long periods of normal activity or while sleeping,” say Carvil. “The Mk VI provides around 20% loading – slightly more than lunar gravity, which is enough to bring back forces similar to those that the spine is used to having.”

“The results have yet to be published, but it does look like the Mk VI Skinsuit is effective in mitigating spine lengthening,” says Philip. “In addition we’re learning more about the fundamental physiological processes involved, and the importance of reloading the spine for everyone.”

Posted on by Matt Williams

ESA’s ExoMars has Completed its Aerobraking Maneuvers to Bring it Into a Circular 400 km Orbit Around Mars

Artist’s impression depicting the separation of the ExoMars 2016 entry, descent and landing demonstrator module, named Schiaparelli, from the Trace Gas Orbiter, and heading for Mars. Credit: ESA/D. Ducros

In March of 2016, the European Space Agency (ESA) launched the ExoMars (Exobiology on Mars) mission into space. A joint project between the ESA and Roscosmos, this two-part mission consisted of the Trace Gas Orbiter (TGO) and the Schiaparelli lander, both of which arrived in orbit around Mars in October of 2016. While Schiaparelli crashed while attempting to land, the TGO has gone on to accomplish some impressive feats.

For example, in March of 2017, the orbiter commenced a series of aerobraking maneuvers, where it started to lower its orbit to enter Mars’ thin atmosphere and slow itself down. According to Armelle Hubault, the Spacecraft Operations Engineer on the TGO flight control team, the ExoMars mission has made tremendous progress and is well on its way to establishing its final orbit around the Red Planet.

TGO’s mission has been to study the surface of Mars, characterize the distribution of water and chemicals beneath the surface, study the planet’s geological evolution, identify future landing sites, and to search for possible biosignatures of past Martian life. Once it has established its final orbit around Mars – 400 km (248.5 mi) from the surface – the TGO will be ideally positioned to conduct these studies.

Visualization of the ExoMars mission’s Trace Gas Orbiter conducting aerobraking maneuvers to March of 2018. Credit: ESA

The ESA also released a graphic (shown above) demonstrating the successive orbits the TGO has made since it began aerobraking – and will continue to make until March of 2018. Whereas the red dot indicates the orbiter (and the blue line its current orbit), the grey lines show successive reductions in the TGO’s orbital period. The bold lines denote a reduction of 1 hour while the thin lines denote a reduction of 30 minutes.

Essentially, a single aerobraking maneuver consist of the orbiter passing into Mars’ upper atmosphere and relying on its solar arrays to generate tiny amounts of drag. Over time, this process slows the craft down and gradually lowers its orbit around Mars. As Armelle Hubault recently posted on the ESA’s rocket science blog:

“We started on the biggest orbit with an apocentre (the furthest distance from Mars during each orbit) of 33 200 km and an orbit of 24 hr in March 2017, but had to pause last summer due to Mars being in conjunction. We recommenced aerobraking in August 2017, and are on track to finish up in the final science orbit in mid-March 2018. As of today, 30 Jan 2018, we have slowed ExoMars TGO by 781.5 m/s. For comparison, this speed is more than twice as fast as the speed of a typical long-haul jet aircraft.”

Earlier this week, the orbiter passed through the point where it made its closest approach to the surface in its orbit (the pericenter passage, represented by the red line). During this approach, the craft dipped well into Mars’ uppermost atmosphere, which dragged the aircraft and slowed it down further. In its current elliptical orbit, it reaches a maximum distance of 2700 km (1677 mi) from Mars (it’s apocenter).

Visualization of the ExoMars Trace Gas Orbiter aerobraking at Mars. Credit: ESA/ATG medialab

Despite being a decades-old practice, aerobraking remains a significant technical challenge for mission teams. Every time a spacecraft passes through a planet’s atmosphere, its flight controllers need to make sure that its orientation is just right in order to slow down and ensure that the craft remains stable. If their calculations are off by even a little, the spacecraft could begin to spin out of control and veer off course. As Hubault explained:

“We have to adjust our pericentre height regularly, because on the one hand, the martian atmosphere varies in density (so sometimes we brake more and sometimes we brake less) and on the other hand, martian gravity is not the same everywhere (so sometimes the planet pulls us down and sometimes we drift out a bit). We try to stay at about 110 km altitude for optimum braking effect. To keep the spacecraft on track, we upload a new set of commands every day – so for us, for flight dynamics and for the ground station teams, it’s a very demanding time!”

The next step for the flight control team is to use the spacecraft’s thrusters to maneuver the spacecraft into its final orbit (represented by the green line on the diagram). At this point, the spacecraft will be in its final science and operation data relay orbit, where it will be in a roughly circular orbit about 400 km (248.5 mi) from the surface of Mars. As Hubault wrote, the process of bringing the TGO into its final orbit remains a challenging one.

“The main challenge at the moment is that, since we never know in advance how much the spacecraft is going to be slowed during each pericentre passage, we also never know exactly when it is going to reestablish contact with our ground stations after pointing back to Earth,” she said. “We are working with a 20-min ‘window’ for acquisition of signal (AOS), when the ground station first catches TGO’s signal during any given station visibility, whereas normally for interplanetary missions we have a firm AOS time programmed in advance.”

Artist’s impression of the ESA’s Exomars 2020 rover, which is expected to land on the surface of Mars by the Spring of 2o21. Credit:ESA

With the spacecraft’s orbital period now shortened to less than 3 hours, the flight control team has to go through this exercise 8 times a day now. Once the TGO has reached its final orbit (by March of 2018), the orbiter will remain there until 2022, serving as a telecommunications relay satellite for future missions. One of its tasks will be to relay data from the ESA’s ExoMars 2020 mission, which will consist of a European rover and a Russian surface platform being deployed the surface of Mars in the Spring of 2021.

Along with NASA’s Mars 2020 rover, this rover/lander pair will be the latest in a long line of robotic missions looking to unlock the secrets of Mars past. In addition, these missions will conduct crucial investigations that will pave the way for eventual sample return missions to Earth, not to mention crewed to the surface!

Further Reading: ESA