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April 30, 2017May 1, 2017 by Bob King

Star-travel 5 Million Years Into The Milky Way’s Future

Two Million Stars on the Move

Gaze into Gaia’s crystal ball and you will see the future. This video shows the motion of 2,057,050 stars in the coming 5 million years from the Tycho-Gaia Astrometric Solution sample, part of the first data release of European Space Agency’s Gaia mission.

Gaia is a space observatory parked at the L2 Lagrange Point, a stable place in space a million miles behind Earth as viewed from the Sun. Its mission is astrometry: measuring the precise positions, distances and motion of 1 billion astronomical objects (primarily stars) to create a three-dimensional map of the Milky Way galaxy. Gaia’s radial velocity measurements — the motion of stars toward or away from us — will provide astronomers with a stereoscopic and moving-parts picture of about 1% of the galaxy’s stars.

Think about how slowly stars move from the human perspective. Generations of people have lived and died since the days of ancient Greece and yet the constellations outlines and naked eye stars appear nearly identical today as they did then. Only a few stars — Arcturus, Sirius, Aldebaran — have moved enough for a sharp-eyed observer of yore to perceive their motion.

Given enough time, stars do change position, distorting the outlines of the their constellations. This view shows the sky looking north in 91,000 A.D. Both Lyra and the Big Dipper are clearly bent out of shape! Created with Stellarium

We know that stars are constantly on the move around the galactic center. The Sun and stars in its vicinity orbit the core at some half-million miles an hour, but nearly all are so far away that their apparent motion has barely moved the needle over the time span of civilization as we know it.

This video shows more than 2 million stars from the TGAS sample, with the addition of 24,320 bright stars from the Hipparcos Catalogue that weren’t included in Gaia’s first data release back in September 2016. The video starts from the positions of stars as measured by Gaia between 2014 and 2015, and shows how these positions are expected to evolve in the future, based on the stars’ proper motions or direction of travel across space.

This frame will help you get your footing as you watch the video. Orion (at right) and the Alpha Persei stellar association and Pleiades (at left) are shown. Credit: ESA/Gaia/DPAC

Watching the show

The frames in the video are separated by 750 years, and the overall sequence covers 5 million years. The dark stripes visible in the early frames reflect the way Gaia scans the sky (in strips) and the early, less complete database. The artifacts are gradually washed out as stars move across the sky.

Using the map above to get oriented, it’s fun to watch Orion change across the millennia. Betelgeuse departs the constellation heading north fairly quickly, but Orion’s Belt hangs in there for nearly 2 million years even if it soon develops sag! The Pleiades drift together to the left and off frame and then reappear at right.

Stars seem to move with a wide range of velocities in the video, with stars in the galactic plane moving quite slow and faster ones speeding across the view. This is a perspective effect: most of the stars we see in the plane are much farther from us, and thus seem to be moving slower than the nearby stars, which are visible across the entire sky.

Artist’s impression of The Milky Way Galaxy to provide context for the video. The Sun and solar system are located in the flat plane of the galaxy, so when we look into the Milky Way (either toward the center or toward the edge), the stars pile up across the light years to form a band in the sky. If we could rise above the disk and see the galaxy from the halo, we’d be able to look down (or up) and see the galaxy as a disk with winding spiral arms. Credit: NASA

Some of the stars that appear to zip in and out of view quickly are passing close to the Sun. But motion of those that trace arcs from one side of the sky to the other while passing close to the galactic poles (top and bottom of the frame) as they speed up and slow down, is spurious. These stars move with a constant velocity through space.

Stars located in the Milky Way’s halo, a roughly spherical structure centered on the galaxy’s spiral disk, also appear to move quite fast because they slice through the galactic plane with respect to the Sun. In reality, halo stars move very slowly with respect to the center of the galaxy.

Early in the the visualization, we see clouds of interstellar gas and dust that occupy vast spaces within the galaxy and block the view of more distant suns. That these dark clouds seem to disappear over time is also a spurious effect.

After a few million years, the plane of the Milky Way appears to have shifted towards the right as a consequence of the motion of the Sun with respect to that of nearby stars in the Milky Way. Regions that are depleted of stars in the video will not appear that way to future stargazers but will instead be replenished by stars not currently sampled by Gaia. So yes, there are a few things to keep in mind while watching these positional data converted into stellar motions, but the overall picture is an accurate one.

I find the video as mesmerizing as watching fireflies on a June night. The stars seem alive. Enjoy your ride in the time machine!

April 25, 2017April 25, 2017 by Bob King

Meet Steve, A Most Peculiar Aurora

STEVE, as imaged by Dave Markel in the skies of northern Canada.. Copyright: https://instagram.com/davemarkelphoto

Nicknamed Steve, this unusual aurora feature is a 15.5-mile-wide (25 km) ribbon of hot gas flowing westward at about 13,300 mph, more than 600 times faster than the surrounding air. The photo was taken last fall. Copyright: **Instagram.com/davemarkelphoto**

This remarkable image was captured last fall by Dave Markel, a photographer based in Kamloops, British Columbia. Later, aurora researcher Eric Donovan of the University of Calgary, discovered Markel’s strange ribbon of light while looking through photos of the northern lights on social media. Knowing he’d found something unusual, Donovan worked sifted through data from the European Space Agency’s Swarm magnetic field mission to try and understand the nature of the phenomenon.

Swarm is ESA’s first constellation of Earth observation satellites designed to measure the magnetic signals from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere, providing data that will allow scientists to study the complexities of our protective magnetic field. Credit: ESA/AOES Medialab

Launched on 22 November 2013, three identical Swarm satellites orbit the Earth measuring the magnetic fields that stem from Earth’s core, mantle, crust and oceans, as well as from the ionosphere and magnetosphere. Speaking at the recent Swarm science meeting in Canada, Donovan explained how this new finding couldn’t have happened 20 years ago when he started to study the aurora.

A beautiful aurora featuring green arcs near the horizon and many parallel rays lights up the northern sky last October. A small meteor appears to the right of center. Credit: Bob King

While the shimmering, eerie, light display of auroras might be beautiful and captivating, they’re also a visual reminder that Earth is connected electrically and magnetically to the Sun. The more we know about the aurora, the greater our understanding of that connection and how it affects everything from satellites to power grids to electrically-induced corrosion of oil pipelines.

“In 1997 we had just one all-sky imager in North America to observe the aurora borealis from the ground,” said Prof. Donovan. “Back then we would be lucky if we got one photograph a night of the aurora taken from the ground that coincides with an observation from a satellite. Now we have many more all-sky imagers and satellite missions like Swarm so we get more than 100 a night.”

The Suomi NPP satellite photographed this view of the aurora on December 22, 2016, when the northern lights stretched across northern Canada. Credit: NASA Earth Observatory image by Jesse Allen / Suomi National Polar-orbiting Partnership. Colorized and labeled by the author

And that’s where sharing photos and observations on social media can play an important role. Sites like the Great Lakes Aurora Hunters and Aurorasaurus serve as clearinghouses for observers to report auroral displays. Aurorasaurus connects citizen scientists to scientists and searches Twitter feeds for instances of the word ‘aurora,’ so skywatchers and scientists alike know the real-time extent of the auroral oval.

At a recent talk, Prof. Donovan met members the popular Facebook group Alberta Aurora Chasers. Looking at their photos, he came across the purple streak Markel and others had photographed which they’d been referring to as a “proton arc.” But such a feature, caused by hydrogen emission in the upper atmosphere, is too faint to be seen with the naked eye. Donovan knew it was something else, but what?Someone suggested “Steve.” Hey, why not?

Aurora researchers now us a network of all-sky cameras and multiple satellites to keep track of the ever-shifting aurora. Click to see the video. Credit: University of Calgary

While the group kept watch for the Steve’s return, Donovan and colleagues looked through data from the Swarm mission and his network of all-sky cameras. Before long he was able to match a ground sighting of streak to an overpass of one of the three Swarm satellites.

“As the satellite flew straight though Steve, data from the electric field instrument showed very clear changes,” said Donovan.

“The temperature 186 miles (300 km) above Earth’s surface jumped by 3000°C and the data revealed a 15.5-mile-wide (25 km) ribbon of gas flowing westwards at about 6 km/second compared to a speed of about 10 meters/second either side of the ribbon. A friend of mine compared it to a fluorescent light without the glass.

Little did I know I’d met Steve back on May 18, 1990 in this remarkable, narrow arc that stretched from the northwestern horizon to the southeastern. To the eye, a “wind” of vague forms pulsed through the arc. The Big Dipper stands vertically at right. Credit: Bob King

It turns out that these high-speed “rivers” of glowing auroral gas are much more common than we’d thought, and that in no small measure because of the efforts of an army of skywatchers and aurora photographers who keep watch for that telltale green glow in the northern sky.

I spoke to Steve’s keeper, Dave Markel, via e-mail yesterday and he described what the arc looked like to his eyes:

“It’s similar to the image just not as intense. It looks like a massive contrail moving rapidly across the sky. This one lasted almost an hour and ran in an arc almost perfectly east to west. I was directly below it but often there are green pickets (parallel streaks of aurora) rising above the streak.”

This is the same May 18, 1990 streak as above but the eastern half. The bright star Arcturus is visible at upper right. Wish I’d had a fisheye! Credit: Bob King

I know whereof Dave speaks because thanks to his photo and Prof. Donovan’s research, I realize I’ve seen and photographed Steve, too! In decades of aurora watching I’ve only seen this rare streak a handful of times. On most of those occasions, there was either no other aurora visible or minor activity in the northern sky. The narrow arc, which lasted for an hour or so, pulsed and flowed with light and occasionally, Markel’s “pickets” were visible. Back in May 1990 I had a camera on hand to get a picture.

Goes to show, you never know what you might see when you poke your head out for a look. Keep a lookout when aurora’s expected and maybe you’ll get to meet Steve, too.

April 22, 2017April 22, 2017 by Ken Kremer

SS John Glenn Arrives at Space Station with Science and Supplies

#Canadarm2 on @Space_Station is positioning #Cygnus for berthing to Unity module on 22 April 2017. Credit: NASA TV

KENNEDY SPACE CENTER, FL – The SS John Glenn commercial Cygnus resupply vessel arrived at the International Space Station early this morning, April 22, carrying nearly four tons of science and supplies crammed inside for the five person multinational Expedition 51 crew.

After reaching the vicinity of the space station overnight Saturday, the commercial Cygnus cargo ship was successfully captured by astronaut crew members Thomas Pesquet of ESA (European Space Agency) and Expedition 51 Station Commander Peggy Whitson of NASA at 6:05 a.m. EDT using the stations Canardarm2.

Working at robotic work consoles inside the domed Cupola module, Pesquet and Whitson deftly maneuvered the space station’s 57.7-foot (17.6-meter) Canadian-built Canadarm2 robotic arm to reach out and flawlessly snare the Cygnus CRS-7 spacecraft at 6:05 a.m. EST at the short and tiny grappling pin located at the base of the vessel.

Now bolted into place on @Space_Station, @OrbitalATK’s #Cygnus will spend ~3 months at the orbiting outpost. Credit NASA TV

Cygnus and the station were soaring some 250 miles (400 km) over Germany as they were joined at Canada’s high tech arm in a perfect demonstration of the peaceful scientific purpose of the massive laboratory complex.

The private supply ship was moved and bolted into place a few hours later at 8:19 a.m. EDT to physically berth and join the station at the Unity module.

Thus begins a three month long sentimental journey ‘bridging history’ to the dawn of America’s human spaceflight with the cylindrically shaped ship named in tribute to John Glenn – the first American to orbit Earth way back in 1962.

The SS John Glenn is a private Cygnus spacecraft manufactured by Orbital ATK under the commercial resupply services (CRS) contact with NASA whose purpose is to deliver many thousands of pounds of cargo and research supplies to the space station to enable the scientific research for which it was built.

Cygnus arrived at the station via a carefully choreographed series on thruster maneuvers after almost four days in orbit following liftoff earlier this week.

The SS John Glenn blasted to orbit on time at 11:11 a.m. EDT Tuesday, April 18 atop a United Launch Alliance Atlas V rocket from Space Launch Complex 41 on Cape Canaveral Air Force Station in Florida.

The Orbital ATK Cygnus cargo craft approaches its 10 meter capture point where the Canadarm2 grapples resupply ship on 22 April 2017. Credit: NASA TV

The SS John Glenn Cygnus vehicle counts as Orbital ATK’s seventh cargo delivery flight to the station.

The vehicle is also known alternatively as the Cygnus OA-7 or CRS-7 mission.

GO for capture of S.S. John Glenn #Cygnus on 22 April 2017 with Canadarm2. Credit: NASA TV

The entire rendezvous and grappling sequence was broadcast live on NASA TV starting at 4:30 a.m. Saturday: http://nasa.gov/nasatv

“Over the pin. Trigger initiated and snares closed,” radioed Pesquat in the final moments of approach as he carefully and ever so slowly moved the arm towards Cygnus this morning.

“Capture confirmed right on time at 6:05 a.m,” replied Houston Mission Control.

“We have a good capture, and are go for safing,” reported Station Commander Whitson.

“The crew of Expedition 51 would like to congratulate all the teams at NASA, Orbital ATK and the contractors for a flawless cargo-delivery mission,” Pesquat elaborated. “We are very proud to welcome onboard the S.S. John Glenn.”

“The more than three tons of pressurized cargo in the Cygnus spacecraft will be put to good use to continue our mission of research, exploration and discovery. Achievements like this, fruit of the hard work by space agencies and private companies and the international cooperation across the world, are what truly makes the ISS such a special endeavor at the service of all mankind.”

“Station, Houston, well said,” replied Mission Control.

After the astronauts finished their work in orbit, mission controllers in Houston took over and commanded the arm to move Cygnus to the Earth facing port on Node 1 where it was remotely bolted in place with 16 hooks and latches and hard mated to the Unity module.

The Orbital ATK Cygnus spacecraft named for Sen. John Glenn, one of NASA’s original seven astronauts, stands inside the Payload Hazardous Servicing Facility at NASA’s Kennedy Space Center in Florida behind a sign commemorating Glenn on March 9, 2017. It launched on April 18, 2017 on a ULA Atlas V. Credit: Ken Kremer/Kenkremer.com

The mission is named the ‘S.S. John Glenn’ in tribute to legendary NASA astronaut John Glenn – the first American to orbit Earth back in February 1962.

Glenn was one of the original Mercury Seven astronauts selected by NASA. At age 77 he later flew a second mission to space aboard Space Shuttle Discovery- further cementing his status as a true American hero.

Glenn passed away in December 2016 at age 95. He also served four terms as a U.S. Senator from Ohio.

A picture of John Glenn in his shuttle flight suit and a few mementos are aboard.

Cygnus OA-7 is loaded with 3459 kg (7626 pounds) of science experiments and hardware, crew supplies, spare parts, gear and station hardware to the orbital laboratory in support over 250 research experiments being conducted on board by the Expedition 51 and 52 crews. The total volumetric capacity of Cygnus exceeds 27 cubic meters.

Science plays a big role in this mission named in tribute to John Glenn. Over one third of the payload loaded aboard Cygnus involves science.

“The new experiments will include an antibody investigation that could increase the effectiveness of chemotherapy drugs for cancer treatment and an advanced plant habitat for studying plant physiology and growth of fresh food in space,” according to NASA.

The astronauts will grow food in space, including Arabidopsis and dwarf wheat, in an experiment that could lead to providing nutrition to astronauts on a deep space journey to Mars.

“Another new investigation bound for the U.S. National Laboratory will look at using magnetized cells and tools to make it easier to handle cells and cultures, and improve the reproducibility of experiments. Cygnus also is carrying 38 CubeSats, including many built by university students from around the world as part of the QB50 program. The CubeSats are scheduled to deploy from either the spacecraft or space station in the coming months.”

Also aboard is the ‘Genes in Space-2’ experiment. A high school student experiment from Julian Rubinfien of Stuyvescent High School, New York City, to examine accelerated aging during space travel. This first experiment will test if telomere-like DNA can be amplified in space with a small box sized experiment that will be activated by station astronauts.

The Saffire III payload experiment will follow up on earlier missions to study the development and spread of fire and flames in the microgravity environment of space. The yard long experiment is located in the back of the Cygnus vehicle. It will be activated after Cygnus departs the station roughly 80 days after berthing. It will take a few hours to collect the data for transmission to Earth.

Four spacecraft are parked at the station including the Orbital ATK Cygnus resupply ship, the Progress 66 cargo craft and the Soyuz MS-03 and MS-04 crew vehicles as of 22 April 2017. Credit: NASA

Watch for Ken’s onsite launch reports direct from the Kennedy Space Center and Cape Canaveral Air Force Station in Florida.

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer

Orbital ATK’s seventh cargo delivery flight to the International Space Station -in tribute to John Glenn- launched at 11:11 a.m. EDT April 18, 2017, on a United Launch Alliance Atlas V rocket from Space Launch Complex 41 on Cape Canaveral Air Force Station in Florida. Credit: Ken Kremer/kenkremer.com

April 20, 2017April 20, 2017 by Ken Kremer

Soyuz Launches and Fast Track Docks to ISS with Russian-American Duo

The Soyuz MS-04 rocket launches from the Baikonur Cosmodrome in Kazakhstan April 20, 2017, carrying Expedition 51 Soyuz Commander Fyodor Yurchikhin of Roscosmos and Flight Engineer Jack Fischer of NASA into orbit to begin their four and a half month mission on the International Space Station. Credits: NASA/Aubrey Gemignani

KENNEDY SPACE CENTER, FL – A new Russian/American duo has arrived at the International Space Station this morning, April 20, after a six-hour flight following their successful launch aboard a Russian Soyuz capsule on a fast track trajectory to the orbiting outpost.

The two person international crew comprising NASA astronaut Jack Fischer and cosmonaut Fyodor Yurchikhin of the Russian space agency Roscosmos launched aboard a Russian Soyuz MS-04 spacecraft from the Baikonur Cosmodrome in Kazakhstan at 3:13 a.m. (1:13 p.m. Baikonur time).

After orbiting the Earth just four times on a planned accelerated trajectory they reached the station six hours later and safely docked at the station at 9:18 a.m. EDT.

“We have contact and capture confirmed at the space station at 9:18 am EDT,” said the NASA Houston mission control commentator.
The station and Soyuz vehicles were flying some 250 mi (400 km) over the northern Atlantic at the time of docking.

The dynamic duo of Yurchikhin and Fischer join three Expedition 51 crew members already onboard – Expedition 51 Commander Peggy Whitson of NASA and Flight Engineers Oleg Novitskiy of Roscosmos and Thomas Pesquet of ESA (European Space Agency).

Thus the overall station crew complement of astronauts and cosmonauts increases to five – from the US, Russia and France – representing their respective space agencies and countries.

Jack Fisher is a rookie space flyer whereas Yurchikhin is an accomplished veteran on this his 5th mission to orbit.

Expedition 51 Soyuz Commander Fyodor Yurchikhin of Roscosmos and Flight Engineer Jack Fischer of NASA wave farewell prior to boarding the Soyuz MS-04 spacecraft for launch April 20, 2017, at the Baikonur Cosmodrome in Kazakhstan. Credits: NASA/Aubrey Gemignani

Prior to docking the crew accomplished an approximately 10 min flyaround inside the Soyuz shortly before sunrise and beautyfully backdropped by earth towards the end at a distance of roughly several hundred meters away.

All Soyuz systems performed as planned for what was an entirely automated rendezvous and docking using the Russian KURS docking system. The crew could have intervened if needed.

The new pair of Expedition 51 crew members will spend about four and a half months aboard the station during their increment.

They will be very busy conducting approximately 250 science investigations in fields such as biology, Earth science, human research, physical sciences and technology development.

And there will be no time to rest! Because this week’s just launched unpiloted ‘SS John Glenn’ Cygnus resupply ship is eagerly awaiting its chance to join the station and deliver nearly 4 tons of science experiment, gear and crew provisions to stock the station and further enhance its research output.

Orbital ATK’s seventh Cygnus cargo delivery flight to the station – dubbed OA-7 or CRS-7 – launched at 11:11 a.m. EDT Tuesday, April 18 atop a United Launch Alliance Atlas V rocket from Space Launch Complex 41 on Cape Canaveral Air Force Station in Florida.

The SS John Glenn is expected to arrive at the station early Saturday morning on April 22.
Expedition 51 astronauts Thomas Pesquet of ESA and Peggy Whitson of NASA will use the space station’s Canadian-built robotic arm to grapple Cygnus, about 6:05 a.m. Saturday.

They will use the arm to maneuver and berth the unmanned vehicle to the Node-1 Earth-facing nadir port on the Unity module.

“Investigations arriving will include an antibody investigation that could increase the effectiveness of chemotherapy drugs for cancer treatment and an advanced plant habitat for studying plant physiology and growth of fresh food in space,” says NASA.

“Another new investigation bound for the U.S. National Laboratory will look at using magnetized cells and tools to make it easier to handle cells and cultures, and improve the reproducibility of experiments. Cygnus also is carrying 38 CubeSats, including many built by university students from around the world, as part of the QB50 program. The CubeSats are scheduled to deploy from either the spacecraft or space station in the coming months.”

Cygnus will remain at the space station for about 85 days until July before its destructive reentry into Earth’s atmosphere, disposing of several thousand pounds of trash.

Watch for Ken’s onsite launch reports direct from the Kennedy Space Center in Florida.

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer

March 21, 2017 by Matt Williams

Rosetta Images Show Comet’s Changing Surface Close Up

Rosetta mission poster showing the deployment of the Philae lander to comet 67P/Churyumov-Gerasimenko.. Credit: ESA/ATG medialab (Rosetta/Philae); ESA/Rosetta/NavCam (comet)

The Rosetta spacecraft learned a great deal during the two years that it spent monitoring Comet 67P/Churyumov-Gerasimenko – from August 6th, 2014 to September 30th, 2016. As the first spacecraft to orbit the nucleus of a comet, Rosetta was the first space probe to directly image the surface of a comet, and observed some fascinating things in the process.

For instance, the probe was able to document some remarkable changes that took place during the mission with its OSIRIS camera. According to a study published today (March. 21st) in Science, these included growing fractures, collapsing cliffs, rolling boulders and moving material on the comet’s surface that buried some features and exhumed others.

These changes were noticed by comparing images from before and after the comet reached perihelion on August 13th, 2015 – the closets point in its orbit around the Sun. Like all comets, it is during this point in 67P/Churyumov-Gerasimenko’s orbit that the surface experiences its highest levels of activity, since perihelion results in greater levels of surface heating, as well as increased tidal stresses.

Images taken by Rosetta’s OSIRIS camera show changes in the surface between 2015 and 2016. Credit: ESA/Rosetta/NAVCAM (top center images); ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA (all others)

Basically, as comets gets closer to the Sun, they experience a combination of in-situ weathering and erosion, sublimation of water-ice, and mechanical stresses arising from an increased spin rate. These processes can be either unique and transient, or they can place over longer periods of time.

As Ramy El-Maarry, a scientist from the Max-Planck Institute for Solar System Research and the lead author of the study, said in an ESA press statement:

“Monitoring the comet continuously as it traversed the inner Solar System gave us an unprecedented insight not only into how comets change when they travel close to the Sun, but also how fast these changes take place.”

For instance, in-situ weathering occurs all over the comet and is the result of heating and cooling cycles that happen on both a daily and a seasonal basis. In the case of 67P/Churyumov-Gerasimenko’s (6.44 Earth years), temperatures range from 180 K (-93 °C; -135 °F) to 230 K (-43 °C; -45 °F) during the course of its orbit. When the comet’s volatile ices warm, they cause consolidated material to weaken, which can cause fragmentation.

Combined with the heating of subsurface ices – which leads to outgassing – this process can result in the sudden collapse of cliff walls. As other photographic evidence that was recently released by the Rosetta science team can attest, this sort of process appears to have taken place in several locations across the comet’s surface.

*Images showing a new fracture and boulder movement in Anuket. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/ID*

Similarly, comets experience increased stress because their spin rates speed up as they gets closer to the Sun. This is believed to be what caused the 500 meter-long (1640 ft) fracture that has been observed in the Anuket region. Originally discovered in August of 2014, this fracture appeared to have grown by 30 meters (~100 ft) when it was observed again in December of 2014.

This same process is believed to be responsible for a new fracture that was identified from OSIRIS images taken in June 2016. This 150-300 meter-long (492 – 984 ft) fracture appears to have formed parallel to the original. In addition, photographs taken in February of 2015 and June of 2016 (shown above) revealed how a 4 meter-wide (13 ft) boulder that was sitting close to the fractures appeared to have moved by about 15 meters (49 ft).

Whether or not the two phenomena are related is unclear. But it is clear that something very similar appears to have taken place in the Khonsu region. In this section of the comet (which corresponds to one of its larger lobes), images taken between May of 2015 and June 2016 (shown below) revealed how a much larger boulder appeared to have moved even farther between the two time periods.

*Images showing a moving boulder in the Khonsu region. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA*

This boulder – which measures some 30 meters (98 ft) across and weighs an estimated 12,800 metric tonnes (~14,100 US tons) – moved a distance of about 140 meters (~460 ft). In this case, outgassing during perihelion is believed to be the culprit. On the one hand, it could have caused the surface material to erode beneath it (thus causing it to roll downslope) or by forcibly pushing it.

For some time, it has been known that comets undergo changes during the course of their orbits. Thanks to the Rosetta mission, scientists have been able to see these processes in action for the first time. Much like all space probes, vital information continues to be discovered long after the Rosetta mission officially came to an end. Who knows what else the probe managed to witness during its historic mission, and which we will be privy to?

Further Reading: ESA

March 14, 2017April 4, 2017 by Nancy Atkinson

Warm Poles Suggest Enceladus’ Liquid Water Near Surface

Saturn's moon Enceladus could harbor microbial life in the warm salty water thought to exist under its frozen surface. Respondents in the study seemed to like that possibility. Credits: NASA/JPL-Caltech/Space Science Institute

One of the biggest surprises from the Cassini mission to Saturn has been the discovery of active geysers at the south pole of the moon Enceladus. At only about 500 km (310 miles) in diameter, the bright and ice-covered moon should be too small and too far from the Sun to be active. Instead, this little moon is one of the most geothermally active places in the Solar System.

Now, a new study from Cassini data shows that the south polar region of Enceladus is even warmer than expected just a few feet below its icy surface. While previous studies have confirmed an ocean of liquid water inside Enceladus which fuels the geysers, this new study shows the ocean is likely closer to the surface than previously thought. Additionally – and most enticing – there has to be a source of heat inside the moon that is not completely understood.

“These observations provide a unique insight into what is going on beneath the surface,” said Alice Le Gall, who is part of the Cassini RADAR instrument team, from Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), and Université Versailles Saint-Quentin (UVSQ), France. “They show that the first few meters below the surface of the area that we investigated, although at a glacial 50-60 K, are much warmer than we had expected: likely up to 20 K warmer in some places. This cannot be explained only as a result of the Sun’s illumination and, to a lesser extent, Saturn’s heating so there must be an additional source of heat.”

Tiger stripes on the south pole of Enceladus. The region studied is indicated by the coloured band. NASA/JPL-Caltech/Space Science Institute; Acknowledgement: A. Lucas

Microwave data taken during a close flyby in 2011 shows there is excess heat at three fractures in the surface of Enceladus. While similar to the so-called “tiger-stripe” features on this moon that are actively venting ice and water molecules into space, these three fractures don’t appear to be active, at least not in 2011.

Scientists say the seemingly dormant fractures lying above the moon’s warm, underground sea point to the dynamic character of Enceladus’ geology, suggesting the moon might have experienced several episodes of activity, in different places on its surface.

The 2011 flyby provided the first – and unfortunately, the only — high-resolution observations of Enceladus’ south pole at microwave wavelengths.

It looked at a narrow, arc-shaped swathe of the southern polar region, about 25 km (15 miles) wide, and located just 30 km to 50 km (18-30 miles) north of the tiger-stripe fractures.

The heat that was detected appears to be lying under a much colder layer of frost.

Because of operational constraints of the 2011 flyby, it was not possible to obtain microwave observations of the active fractures themselves. But this allowed the scientists to observe that the thermally anomalous terrains of Enceladus extend well beyond the tiger stripes.

Cassini’s view down into a jetting “tiger stripe” in August 2010. Credit: NASA

Their findings show it is likely that the entire south pole region is warm underneath, meaning Enceladus’ ocean could be just 2 km under the moon’s icy surface in that area. The finding agrees with a 2016 study, led by another Cassini team member, Ondrej Cadek, which estimated the thickness of the crust on Enceladus’ south pole to be less than the rest of the moon. That study estimated the depth of the ice shell to be less than 5 km (1.2 miles) at the south pole, while average depth on other areas of Enceladus is between 18–22 km (11-13 miles).

What generates the internal heat at Enceladus? The main source of heat remains a mystery, but scientists think gravitational forces between Enceladus, Saturn, and another moon, Dione pull and flex Enceladus’ interior. Known as tidal forces, the tugging causes the moon’s interior to rub, creating friction and heat. It also creates stress compressions and deformations on the crust, leading to the formation of faults and fractures. This in turn creates more heat in the sub-surface layers. In this scenario, the thinner icy crust in the south pole region is subject to a larger tidal deformation that means more heat being created to help keep the underground water warm.

Dramatic plumes, both large and small, spray water ice out from many locations along the famed “tiger stripes” near the south pole of Saturn’s moon Enceladus. Credit: NASA/JPL/Space Science Institute

Since the geysers weren’t known until Cassini’s arrival at Saturn, the spacecraft didn’t have a specific payload to study them, but scientists used the instruments at their disposal to make the best observations they could, flying the spacecraft to within 49 km (30 miles) of the surface. To fully study the tidal heating — or to determine if there is another source of heat — scientists will continue to study the data already taken by various Cassini instruments. But since the mission will be ending in September 2017, it may require another mission to this intriguing moon to fully figure out this mystery.

“This discovery opens new perspectives to investigate the emergence of habitable conditions on the icy moons of the gas giant planets,” says Nicolas Altobelli, ESA’s Project Scientist for Cassini–Huygens. “If Enceladus’ underground sea is really as close to the surface as this study indicates, then a future mission to this moon carrying an ice-penetrating radar sounding instrument might be able to detect it.”

“Finding temperatures near these three inactive fractures that are unexpectedly higher than those outside them adds to the intrigue of Enceladus,” said Cassini Project Scientist Linda Spilker at the Jet Propulsion Laboratory. “What is the warm underground ocean really like and could life have evolved there? These questions remain to be answered by future missions to this ocean world.”

Feel free to submit your mission proposals in the comment section below…

An artist’s illustration of Cassini entering orbit around Saturn. Credit: NASA/JPL.

Sources: ESA
JPL
Paper: Thermally anomalous features in the subsurface of Enceladus’s south polar terrain” by A. Le Gall et al. (2017), published in Nature Astronomy

January 25, 2017January 26, 2017 by Ken Kremer

NASA Webb Telescope Resumes Rigorous Vibration Qualification Tests

NASA engineers and technicians position the James Webb Space Telescope (inside a large tent) onto the shaker table used for vibration testing. Credits: NASA/Chris Gunn

Engineers have resumed a series of critical and rigorous vibration qualification tests on NASA’s mammoth James Webb Space Telescope (JWST) at NASA’s Goddard Space Flight Center, in Greenbelt, Maryland to confirm its safety, integrity and readiness for the unforgiving environment of space flight, after pausing due to a testing ‘anomaly’ detected in early December 2016.

The vibration tests are conducted by the team on a shaker table at Goddard to ensure Webb’s worthiness and that it will survive the rough and rumbling ride experienced during the thunderous rocket launch to the heavens slated for late 2018.

“Testing on the ground is critical to proving a spacecraft is safe to launch,” said Lee Feinberg, an engineer and James Webb Space Telescope Optical Telescope Element Manager at Goddard, in a statement.

“The Webb telescope is the most dynamically complicated article of space hardware that we’ve ever tested.”

The 18-segment gold coated primary mirror of NASA’s James Webb Space Telescope is raised into vertical alignment in the largest clean room at the agency’s Goddard Space Flight Center in Greenbelt, Maryland, on Nov. 2, 2016. The secondary mirror mount booms are folded down into stowed for launch configuration. Credit: Ken Kremer/kenkremer.com

Testing of the gargantuan Webb Telescope had ground to a halt after a brief scare in early December when technicians initially detected “anomalous readings” that raised potential concerns about the observatories structural integrity partway through a preplanned series of vibration tests.

“On December 3, 2016, vibration testing automatically shut down early due to some sensor readings that exceeded predicted levels,” officials said.

Thereafter, engineers and technicians carried out a new batch of intensive inspections of the observatory’s structure during December.

Shortly before Christmas, NASA announced on Dec. 23 that JWST was deemed “sound” and apparently unscathed after engineers conducted both “visual and ultrasonic examinations” at NASA’s Goddard Space Flight Center in Maryland. Officials said the telescope was found to be safe at this point with “no visible signs of damage.”

As it turned out the culprit of the sensor anomaly was the many “tie-down … restraint mechanisms ” that hold the telescope in place.

“After a thorough investigation, the James Webb Space Telescope team at NASA Goddard determined that the cause was extremely small motions of the numerous tie-downs or “launch restraint mechanisms” that keep one of the telescope’s mirror wings folded-up for launch,” NASA officials explained in a statement.

Furthermore engineers revealingly discovered that “the ground vibration test itself is more severe than the launch vibration environment.”

Technicians work on the James Webb Space Telescope in the massive clean room at NASA’s Goddard Space Flight Center, Greenbelt, Maryland, on Nov. 2, 2016, as the completed golden primary mirror and observatory structure stands gloriously vertical on a work stand, reflecting incoming light from the area and observation deck. Credit: Ken Kremer/kenkremer.com

NASA reported today (Jan. 25) that the testing resumed last week at the point where it had been paused. Furthermore the testing was completed along the first of three axis.

“In-depth analysis of the test sensor data and detailed computer simulations confirmed that the input vibration was strong enough and the resonance of the telescope high enough at specific vibration frequencies to generate these tiny motions. Now that we understand how it happened, we have implemented changes to the test profile to prevent it from happening again,” explained Feinberg.

“We have learned valuable lessons that will be applied to the final pre-launch tests of Webb at the observatory level once it is fully assembled in 2018. Fortunately, by learning these lessons early, we’ve been able to add diagnostic tests that let us show how the ground vibration test itself is more severe than the launch vibration environment in a way that can give us confidence that the launch itself will be fully successful.”

The next step is to resume and complete shaking the telescope in the other two axis, or “two directions to show that it can withstand vibrations in all three dimensions.”

“This was a great team effort between the NASA Goddard team, Northrop Grumman, Orbital ATK, Ball Aerospace, the European Space Agency, and Arianespace,” Feinberg said. “We can now proceed with the rest of the planned tests of the telescope and instruments.”

NASA’s James Webb Space Telescope is the most powerful space telescope ever built and is the scientific successor to the phenomenally successful Hubble Space Telescope (HST). The mammoth 6.5 meter diameter primary mirror has enough light gathering capability to scan back over 13.5 billion years and see the formation of the first stars and galaxies in the early universe.

The Webb telescope will launch on an ESA Ariane V booster from the Guiana Space Center in Kourou, French Guiana in 2018.

But Webb and its 18 segment “golden” primary mirror have to be carefully folded up to fit inside the nosecone of the Ariane V booster.

“Due to its immense size, Webb has to be folded-up for launch and then unfolded in space. Prior generations of telescopes relied on rigid, non-moving structures for their stability. Because our mirror is larger than the rocket fairing we needed structures folded for launch and moved once we’re out of Earth’s atmosphere. Webb is the first time we’re building for both stability and mobility.” Feinberg said.

“This means that JWST testing is very unique, complex, and challenging.”

View showing actual flight structure of mirror backplane unit for NASA’s James Webb Space Telescope (JWST) that holds 18 segment primary mirror array and secondary mirror mount at front, in stowed-for-launch configuration. JWST is being assembled here by technicians inside the world’s largest cleanroom at NASA Goddard Space Flight Center, Greenbelt, Md. Credit: Ken Kremer/kenkremer.com

The environmental testing is being done at Goddard before shipping the huge structure to NASA’s Johnson Space Center in February 2017 for further ultra low temperature testing in the cryovac thermal vacuum chamber.

The 6.5 meter diameter ‘golden’ primary mirror is comprised of 18 hexagonal segments – looking honeycomb-like in appearance.

And it’s just mesmerizing to gaze at – as I had the opportunity to do on a few occasions at Goddard this past year – standing vertically in November and seated horizontally in May.

Each of the 18 hexagonal-shaped primary mirror segments measures just over 4.2 feet (1.3 meters) across and weighs approximately 88 pounds (40 kilograms). They are made of beryllium, gold coated and about the size of a coffee table.

All 18 gold coated primary mirrors of NASA’s James Webb Space Telescope are seen fully unveiled after removal of protective covers installed onto the backplane structure, as technicians work inside the massive clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland on May 3, 2016. The secondary mirror mount booms are folded down into stowed for launch configuration. Credit: Ken Kremer/kenkremer.com

The Webb Telescope is a joint international collaborative project between NASA, the European Space Agency (ESA) and the Canadian Space Agency (CSA).

Webb is designed to look at the first light of the Universe and will be able to peer back in time to when the first stars and first galaxies were forming. It will also study the history of our universe and the formation of our solar system as well as other solar systems and exoplanets, some of which may be capable of supporting life on planets similar to Earth.

Gold coated primary mirrors newly exposed on spacecraft structure of NASA’s James Webb Space Telescope inside the massive clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland on May 3, 2016. Aft optics subsystem stands upright at center of 18 mirror segments between stowed secondary mirror mount booms. Credit: Ken Kremer/kenkremer.com

Watch this space for my ongoing reports on JWST mirrors, science, construction and testing.

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer

James Webb Space Telescope. Image credit: NASA/JPL

December 25, 2016December 25, 2016 by Ken Kremer

Merry Christmas From Space 2016

All six members of the Expedition 50 crew aboard the International Space Station celebrated the holidays together with a festive meal on Christmas Day, Dec. 25, 2016 Image Credit: NASA

As we celebrate the Christmas tidings of 2016 here on Earth, a lucky multinational crew of astronauts and cosmonauts celebrate the festive season floating in Zero-G while living and working together in space aboard the Earth orbiting International Space Station (ISS) complex – peacefully cooperating to benefit all humanity.

Today, Dec. 25, 2016, the six person Expedition 50 crew of five men and one woman marked the joyous holiday of Christ’s birth by gathering for a festive meal in space – as billions of Earthlings celebrated this Christmas season of giving, remembrance and peace to all here on our home planet.

This year is an especially noteworthy Space Christmas because it counts as Expedition 50. This is the 50th crew to reside on board since the space station began operating with permanent occupancy by rotating crews all the way back to 1998.

The Expedition 50 crew currently comprises of people from three nations supporting the ISS – namely the US, Russia and France; Commander Shane Kimbrough from NASA and flight engineers Andrey Borisenko (Roscosmos), Sergey Ryzhikov (Roscosmos), Thomas Pesquet (ESA), Peggy Whitson (NASA), and Oleg Novitskiy (Roscosmos).

Here a short video of holiday greetings from a trio of crew members explaining what Christmas in Space means to them:

Video Caption: Space Station Crew Celebrates the Holidays Aboard the Orbital Lab. Aboard the International Space Station, Expedition 50 Commander Shane Kimbrough and Peggy Whitson of NASA and Thomas Pesquet of the European Space Agency discussed their thoughts about being in space during the holidays and how they plan to celebrate Christmas and New Year’s in a downlink. Credit: NASA

“Hello from the Expedition 50 Crew! We’d like to share what Christmas means to us,” said Expedition 50 Commander Shane Kimbrough.

“For me it’s a lot about family,” said Expedition 50 Commander Shane Kimbrough. “We always travel to meet up with our family which is dispersed across the country. And we go home to Georgia and Florida … quite abit to meet up. Always a great time to get together and share with each other.”

“Although its typically thought of a season to get things, we in our family think about the giving aspect. Giving of our many talents and resources. Especially to those less fortunate.”

Kimbrough arrived on the complex in October, followed a month later by Whitson and Pesquet in November.

They were all launched aboard Russian Soyuz capsules from the Baikonur Cosmodrome in Kazakhstan.

Aboard the International Space Station, Expedition 50 Flight Engineer Peggy Whitson of NASA sent holiday greetings and festive imagery from the cupola on Dec. 18, 2016. Credit: NASA.

And Peggy Whitson especially has a lot to celebrate in space!

Because not only is Whitson currently enjoying her third long-duration flight aboard the station – as an Expedition 50 flight engineer. Soon she will become the first woman to command the station twice ! That momentous event happens when she assumes the role of Space Station Commander early in 2017 during the start of Expedition 51.

“In addition to family, there is another very important aspect to being on the ISS,” said Whitson.

“That is seeing the planet as a whole. It actually reinforces I think, that fact that we should live as one people and strive for peace.”

“I second the comments already made. I grew up in a family of 25 cousins,” said ESA’s Thomas Pesquet. “The only time we could catch up was around Christmas time…. So I always looked forward to that, although this year I can’t be with them of course … and will think of them.”

“I am making the most of this opportunity to look at the Earth. Reflect about what Christmas means to us as individuals and to the world in general. And we will have a good time on board the ISS and share a Christmas meal together.”

The crew is enjoying a light weekend of work and a day off tomorrow, Dec. 26.

After that they begin preparing for a pair of spacewalks in the new year by Kimbrough and Whitson – scheduled for Jan. 6 and 13. The crew is checking the spacesuits by testing the water among other activities.

The goal of the excursions is to “complete the replacement of old nickel-hydrogen batteries with new lithium-ion batteries on the station’s truss structure,” says NASA.

Research work also continues.

“Whitson, who is spending her second Christmas in space, and Pesquet drew blood, urine and saliva samples for the Fluid Shifts study. That experiment investigates the upward flow of body fluids in space potentially causing lasting vision changes in astronauts.”

NASA astronaut Peggy Whitson floats through the Unity module aboard the International Space Station. On her third long-duration flight aboard the station, Whitson will become the first woman to command the station twice when she assumes the role during Expedition 51. Credit: NASA

Among other activities, the crew is also unloading 4.5 tons of internal and external cargo, gear and fresh food – including six lithium-ion batteries – from Japan’s sixth H-II Transfer Vehicle (HTV-6), which recently arrived at the ISS on Dec 13.

The next regular US cargo delivery is likely to be in March 2017, when an unmanned Orbital ATK Cygnus cargo freighter is slated to launch on a ULA Atlas V from Cape Canaveral. A Cygnus was also launched on a ULA Atlas V in March 2016.

A Cygnus cargo spacecraft named the SS Rick Husband is being prepared inside the Payload Hazardous Servicing Facility at NASA’s Kennedy Space Center for upcoming Orbital ATK CRS-6/OA-6 mission to deliver hardware and supplies to the International Space Station. Cygnus is scheduled to lift off atop a United Launch Alliance Atlas V rocket on March 22, 2016. Credit: Ken Kremer/kenkremer.com

SpaceX also hopes to resume Dragon cargo launches sometime in the new year after they resolve the issues that led to the destruction of a SpaceX Falcon 9 on Sept. 1 during fueling operations at pad 40 on the Cape.

Meanwhile Roscosmos continues to investigate the causes of the failed launch of the unmanned Russian Progress 65 resupply ship on Dec. 1 due to a 3rd stage anomaly.

Stay tuned here for Ken’s continuing Earth and Planetary science and human spaceflight news.

Ken Kremer

November 28, 2016December 18, 2016 by Evan Gough

Sentinel-1 Satellites Confirm San Francisco’s Millenium Tower Is Sinking

The Millennium Tower luxury skyscraper in San Francisco is sinking and tilting. Image by MichaelTG - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=51657571

The Millennium Tower is a luxury skyscraper in San Francisco. It has been sinking and tilting since it’s construction 8 years ago. In fact, the 58 story building has sunk 8 inches, and tilted at least 2 inches. San Francisco is experiencing a building boom, and planners and politicians want to know why the Millennium Tower is having these problems.

Now they’re getting a little help from space.

The European Space Agency’s (ESA) Copernicus Sentinel-1 satellites have trained their radar on San Francisco. They’ve found that the Millennium Tower is sinking, or subsiding, at the alarming rate of almost 50 mm per year. Although the exact cause is not yet known for sure, it’s suspected that the building’s supporting piles are not resting on solid bedrock.

An artist's illustration of the Sentinel-1. Image: ESA/ATG Medialab — An artist’s illustration of the Sentinel-1. Image: ESA/ATG Medialab

The Sentinel-1 satellites are part of the ESA’s Copernicus Program. There are two of the satellites in operation, and two more are on the way. They employ Synthetic Aperture Radar to provide continuous imagery during the day, during the night, and through any kind of weather.

The satellites have several applications:

Monitoring sea ice in the arctic
Monitoring the arctic environment and other marine environments
Monitoring land surface motion
Mapping land surfaces, including forest, water, and soil
Mapping in support of humanitarian aid in crisis situations

Though the Sentinels were not specifically designed to monitor buildings, they’re actually pretty good at it. Buildings like the Millennium Tower are especially good at reflecting radar. When multiple passes are made with the satellites, they provide a very accurate measurement of ground subsidence.

Radar data from Sentinel-1 shows the displacement in San Francisco's Bay Area. Yellow-red areas are sinking, while blue areas are rising. Green areas are not moving. Image: ESA SEOM INSARAP study / PPO.labs / Norut / NGU — Radar data from Sentinel-1 shows the displacement in San Francisco’s Bay Area. Yellow-red areas are sinking, while blue areas are rising. Green areas are not moving. Image: ESA SEOM INSARAP study / PPO.labs / Norut / NGU

The Millennium Tower is not the only thing in San Francisco Bay Area that Sentinel-1 can see moving. It’s also spotted movement in buildings along the Hayward Fault, an area prone to earthquakes, and the sinking of reclaimed land in San Rafael Bay. It’s also spotted some rising land near the city of Pleasanton. The recent replenishing of groundwater is thought to be the cause of the rising land.

Now other parts of the world, especially in Europe, are poised to benefit from Sentinel-1’s newfound prowess at reading the ground. In Oslo, Norway, the train station is built on reclaimed land. Newer buildings have proper foundations right on solid bedrock, but the older parts of the station are experiencing severe subsidence.

Sentinel-1 data shows that the Oslo train station, the red/yellow area in the center of the image, is sinking at the rate of 12-18mm per year. Image: Copernicus Sentinel data (2014–16) / ESA SEOM INSARAP study / InSAR Norway project / NGU / Norut / PPO.labs

John Dehls is from the Geological Survey of Norway. He had this to say about Sentinel: “Experience and knowledge gained within the ESA’s Scientific Exploitation of Operational Missions programme give us strong confidence that Sentinel-1 will be a highly versatile and reliable platform for operational deformation monitoring in Norway, and worldwide.”

As for the Millennium Tower in San Francisco, the problems continue. The developer of the building is blaming the problems on the construction of a new transit center for the city. But the agency in charge of that, the Transbay Joint Powers Authority, denies that they are at fault. They blame the developer’s poor structural design, saying that it’s not properly built on bedrock.

Now, the whole thing is before the courts. A $500 million class-action lawsuit has been filed on behalf of the residents, against the developer, the transit authority, and other parties.

It’s a good bet that data from the Sentinel satellites will be part of the evidence in that lawsuit.

November 25, 2016November 26, 2016 by Matt Williams

Schiaparelli’s One Second Of Terror

Artist's impression of the ExoMars Schiaparelli lander passing into Mars' atmosphere. Credit: ESA

The European Space Agency (ESA) and Roscomos (the Russian federal space agency) had high hopes for the Schiaparelli lander, which crashed on the surface of Mars on October 19th. As part of the ExoMars program, its purpose was to test the technologies that will be used to deploy a rover to the Red Planet in 2020.

However, investigators are making progress towards determining what went wrong during the lander’s descent. Based on their most recent findings, they concluded that an anomaly took place with an on-board instrument that led to the lander detaching from its parachute and backshell prematurely. This ultimately caused it to land hard and be destroyed.

According to investigators, the data retrieved from the lander indicates that for the most part, Schiaparelli was functioning normally before it crashed. This included the parachute deploying once it had reached an altitude of 12 km and achieved a speed of 1730 km/h. When it reached an altitude of 7.8 km, the lander’s heatshield was released, and it radar altimeter provided accurate data to the lander’s on-board guidance, navigation and control system.

Schiaparelli lander descent sequence. Image: ESA/ATG medialab — Schiaparelli lander descent sequence. According to their investigation, the ESA has determined that an error led the parachute and backshell to be jettisoned prematurely, causing the lander to crash. Credit: ESA/ATG medialab

All of this happened according to plan and did not contribute to the fatal crash. However, an anomaly then took place with the Inertial Measurement Unit (IMU), which is there to measure the rotation rates of the vehicle. Apparently, the IMU experienced saturation shortly after the parachute was deployed, causing it to persist for one second longer than required.

This error was then fed to the navigation system, which caused it to generate an estimate altitude that was below Mars’ actual ground level. In essence, the lander thought it was closer to the ground than it actually was. As such, the the parachute and backshell of the Entry and Descent Module (EDM) were jettisoned and the braking thrusters fired prematurely – at an altitude of 3.7 km instead of 1.2 km, as planned.

This briefest of errors caused the lander to free-fall for one second longer than it was supposed to, causing it to land hard and be destroyed. The investigators have confirmed this assessment using multiple computer simulations, all of which indicate that the IMU error was responsible. However, this is still a tentative conclusion that awaits final confirmation from the agency.

Schiaparelli on Mars. Credit: ESA/ATG medialab — *Artist’s impression of the Schiaparelli lander on Mars. Credit: ESA/ATG medialab*

As David Parker, the ESA’s Director of Human Spaceflight and Robotic Exploration, said on on Wednesday, Nov. 23rd in a ESA press release:

“This is still a very preliminary conclusion of our technical investigations. The full picture will be provided in early 2017 by the future report of an external independent inquiry board, which is now being set up, as requested by ESA’s Director General, under the chairmanship of ESA’s Inspector General. But we will have learned much from Schiaparelli that will directly contribute to the second ExoMars mission being developed with our international partners for launch in 2020.”

In other words, this accident has not deterred the ESA and Roscosmos from pursuing the next stage in the ExoMars program – which is the deployment of the ExoMars rover in 2020. When it reaches Mars in 2021, the rover will be capable of navigating autonomously across the surface, using a on-board laboratory suite to search for signs of biological life, both past and present.

In the meantime, data retrieved from Schiaparelli’s other instruments is still being analyzed, as well as information from orbiters that observed the lander’s descent. It is hoped that this will shed further light on the accident, as well as salvage something from the mission. The Trace Gas Orbiter is also starting its first series of observations since it made its arrival in orbit on Oct. 19th, and will reach its operational orbit towards the end of 2017.

Further Reading: ESA