samedi 6 avril 2019

Music for space













ISS - International Space Station logo.

6 April 2019

Music has long been known to affect people’s mood. A certain tune can lift you up or bring you to tears, make you focus, relax or even run faster. Now a study is investigating how the power of music may improve human performance in one of the most stressful and alien environments we know – space.

Thomas Pesquet with saxophone in Cupola

Music can help release a cocktail of hormones that have a positive effect on us: oxytocin, endorphin, serotonin and dopamine. Besides the pleasure we get from it, music can be used to prolong efficiency and reduce anxiety.

Stress factors in space can lead to disrupted sleep, impaired time perception and spatial orientation.

“Space appeared to me as the perfect testing ground to use anti-stress music,” says violin teacher Luis Luque Álvarez, whose ‘Music for space’ project puts the psycho-physiological research of music at the service of space exploration.

As a child, Luis dreamt of two things: playing violin in an orchestra and space travel.

Catherine Coleman plays a flute on the Space Station

In his thirties as a talented violinist in Hungary, he noticed some videos of astronauts playing instruments in space.

He started to research and learned that music is a part of the astronauts’ daily lives in space, from launch, when mission control plays music to the crews during the countdown, to orbit, where every astronaut has their own playlist to listen to in off-duty moments.

Could he scientifically select the best music to reduce the stress of a crew member?

Press play - Experimenting with music

Fast forward to the ‘Music for Space’ experiment, which ran last year at DLR’s Short Arm Human Centrifuge as part of the first Spin Your Thesis! – Human Edition.

Ten volunteers rode on a centrifuge, being spun until they felt one and a half times the weight of their bodies.  Half of them listened to Beethoven’s ninth symphony and the Planet Earth II soundtrack by Hans Zimmer, Jasha Klebe and Jacob Shea, while the other five spun with no music.

Music for Space experiment

“Exposing people to repeated hypergravity could help us finding countermeasures to maintain wellbeing on space exploration missions,” explains David Green, education coordinator at the European Astronaut Centre in Cologne, Germany.

Coping with hypergravity is not always easy. Changes in the vestibular system can lead to disorientation and dizziness. Test subjects can become tense, anxious or even fearful.

The team from Hungarian and French universities evaluated the stress levels on the subjects by looking at muscle tone with a device called the Myoton, as well as measuring the levels of stress hormones and recording the subjects’ feelings.

The music samples were shortlisted after taking into account both the changes in speed of the centrifuge and the preferences of the listeners.

A subject being connected to all the various sensors prior to the spin

The study showed that music had a positive impact, but would need more tests to get statistically meaningful results. Participants had a tendency to prefer a slow pace, constant pitch music to ease through the acceleration.

Jasha Klebe, co-composer of the Planet Earth II music, said, “It's amazing to hear our music has had the ability to exist far beyond the series itself.  I have such tremendous respect for anyone involved in space exploration and can only imagine the pressures astronauts endure.

“It's an incredible honour to have our music used in experiments by ESA. We wrote the music for Planet Earth II to evoke wonder, curiosity and the importance of preserving this natural world, so it's inspiring to hear our music included within a programme dedicated to exploring worlds beyond our own.”

Space oddities

Luis believes in music therapy beyond Earth, and says “My dream would be to play tailored sets of music to the crew in deep space missions. Mission control could pick up the playlist according to the needs of the mission, and astronauts could also make their choices according to their mood or goals.”

Astronaut Chris Hadfield plays guitar in space

Today, there are two guitars, a keyboard and a saxophone on the International Space Station, but instruments would also be part of future trips, too. Scientists have found that playing an instrument can result in immediate benefits to several brain functions, strengthening memory and reading skills as well as increasing reaction times.

Chris Hadfield sings & plays guitar on ISS - Space Oddity - David Bowie

Back on Earth, the ‘Music for Space’ project aims to putt the space music library at the service of communities in distress. “Music is not just leisure. It is a very special gift to humankind, to be used with care and intelligence,” concludes Luis.

Related links:

Spin Your Thesis! – Human Edition: https://www.esa.int/Education/Spin_Your_Thesis!_Human_Edition/First_ever_Spin_Your_Thesis!_Human_Edition_Campaign_concludes

Spin your thesis!: http://www.esa.int/ESA_Multimedia/Images/2017/11/Spin_Your_Thesis!_Human_Edition_logo

ESA on Soundcloud: https://soundcloud.com/esa

European space laboratory Columbus: http://www.esa.int/Our_Activities/Human_and_Robotic_Exploration/Columbus

Human and Robotic Exploration: http://www.esa.int/Our_Activities/Human_and_Robotic_Exploration

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Images, Videos, Text, Credits: ESA/NASA/ASC-CSA/ROSCOSMOS.

Best regards, Orbiter.ch

vendredi 5 avril 2019

Spacewalk This Monday Ahead of Two U.S. Cargo Missions This Month











ISS - Expedition 59 Mission patch.

April 5, 2019

The Expedition 59 crew is going into the weekend preparing for another spacewalk on Monday. The International Space Station residents also continue microgravity research as they wait for two U.S. cargo ships to arrive before the end of the month.

Astronauts Anne McClain and David Saint-Jacques are getting their tools ready for another power upgrades spacewalk and will wrap up their final procedures review on Sunday. The spacewalkers will set their spacesuits to battery power around 8:05 a.m. EDT Monday signifying the start of their spacewalk and exit the space station’s Quest airlock.


Image above: Astronaut David Saint-Jacques of the Canadian Space Agency works on a pair of U.S. spacesuits inside the Quest airlock ahead of a trio of spacewalks to upgrade power systems on the International Space Station. Image Credit: NASA.

The duo will work outside for about six-and-a-half hours installing truss jumpers to provide a redundant power source to the Canadarm2 robotic arm. McClain and Saint-Jacques will also install cables to update the station’s External Wireless Communications system. NASA TV starts its live coverage at 6:30 a.m. Monday.

Russia’s Progress 72 (72P) resupply ship delivered over 3.7 tons of food, fuel and supplies after docking to the Pirs docking compartment Thursday morning. Next up is Northrop Grumman’s Cygnus space freighter when it launches from Virginia on April 17 on a two-day ride to the station’s Unity module. SpaceX follows in late April when its Dragon cargo craft blasts off from Florida on a two-day trip to the orbital lab’s Harmony module.

International Space Station (ISS)

Virtual reality filming and space research continued full pace inside the orbital lab today. Flight Engineer Christina Koch first strapped herself into an exercise bike to measure her aerobic capacity then set up a virtual reality camera inside the Unity module today. Nick Hague of NASA then recorded himself describing his space experiences for a short immersive, cinematic film.

Cosmonauts Oleg Kononenko and Alexey Ovchinin unloaded the new 72P and worked on an array of life science experiments in the orbital lab’s Russian segment. The duo photographed red blood samples and microbes to help doctors keep long-term crews healthy in space.

Related article:

Express Delivery from Russia Brings 3.7 Tons of Station Supplies
https://orbiterchspacenews.blogspot.com/2019/04/express-delivery-from-russia-brings-37.html

Related links:

Expedition 59: https://www.nasa.gov/mission_pages/station/expeditions/expedition59/index.html

Quest airlock: https://www.nasa.gov/mission_pages/station/structure/elements/joint-quest-airlock

Canadarm2 robotic arm: https://www.nasa.gov/mission_pages/station/structure/elements/mobile-servicing-system.html

NASA TV: https://www.nasa.gov/nasatv

Pirs docking compartment: https://www.nasa.gov/mission_pages/station/structure/elements/pirs-docking-compartment

Unity module: https://www.nasa.gov/mission_pages/station/structure/elements/unity

Harmony module: https://www.nasa.gov/mission_pages/station/structure/elements/harmony

Aerobic capacity: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=644

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Image (mentioned), Animation, Text, Credits: NASA/Mark Garcia.

Best regards, Orbiter.ch

Unexpected Rain on Sun Links Two Solar Mysteries













NASA - Solar Dynamics Observatory (SDO) patch.

April 5, 2019

For five months in mid 2017, Emily Mason did the same thing every day. Arriving to her office at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, she sat at her desk, opened up her computer, and stared at images of the Sun — all day, every day. “I probably looked through three or five years' worth of data,” Mason estimated. Then, in October 2017, she stopped. She realized she had been looking at the wrong thing all along.

Mason, a graduate student at The Catholic University of America in Washington, D.C., was searching for coronal rain: giant globs of plasma, or electrified gas, that drip from the Sun’s outer atmosphere back to its surface. But she expected to find it in helmet streamers, the million-mile tall magnetic loops — named for their resemblance to a knight’s pointy helmet — that can be seen protruding from the Sun during a solar eclipse. Computer simulations predicted the coronal rain could be found there. Observations of the solar wind, the gas escaping from the Sun and out into space, hinted that the rain might be happening. And if she could just find it, the underlying rain-making physics would have major implications for the 70-year-old mystery of why the Sun’s outer atmosphere, known as the corona, is so much hotter than its surface.  But after nearly half a year of searching, Mason just couldn’t find it. “It was a lot of looking,” Mason said, “for something that never ultimately happened.”


Image above: Mason searched for coronal rain in helmet streamers like the one that appears on the left side of this image, taken during the 1994 eclipse as viewed from South America. A smaller pseudostreamer appears on the western limb (right side of image). Named for their resemblance to a knight’s pointy helmet, helmet streamers extend far into the Sun’s faint corona and are most readily seen when the light from the Sun’s bright surface is occluded. Image Credits: © 1994 Úpice observatory and Vojtech Rušin, © 2007 Miloslav Druckmüller.

The problem, it turned out, wasn’t what she was looking for, but where. In a paper published today in the Astrophysical Journal Letters, Mason and her coauthors describe the first observations of coronal rain in a smaller, previously overlooked kind of magnetic loop on the Sun. After a long, winding search in the wrong direction, the findings forge a new link between the anomalous heating of the corona and the source of the slow solar wind — two of the biggest mysteries facing solar science today.

How It Rains on the Sun

Observed through the high-resolution telescopes mounted on NASA’s SDO spacecraft, the Sun – a hot ball of plasma, teeming with magnetic field lines traced by giant, fiery loops — seems to have few physical similarities with Earth. But our home planet provides a few useful guides in parsing the Sun’s chaotic tumult: among them, rain.

On Earth, rain is just one part of the larger water cycle, an endless tug-of-war between the push of heat and pull of gravity. It begins when liquid water, pooled on the planet’s surface in oceans, lakes, or streams, is heated by the Sun. Some of it evaporates and rises into the atmosphere, where it cools and condenses into clouds. Eventually, those clouds become heavy enough that gravity’s pull becomes irresistible and the water falls back to Earth as rain, before the process starts anew.

On the Sun, Mason said, coronal rain works similarly, “but instead of 60-degree water you’re dealing with a million-degree plasma.” Plasma, an electrically-charged gas, doesn’t pool like water, but instead traces the magnetic loops that emerge from the Sun’s surface like a rollercoaster on tracks. At the loop’s foot points, where it attaches to the Sun’s surface, the plasma is superheated from a few thousand to over 1.8 million degrees Fahrenheit. It then expands up the loop and gathers at its peak, far from the heat source. As the plasma cools, it condenses and gravity lures it down the loop’s legs as coronal rain.


Animation above: Coronal rain, like that shown in this movie from NASA’s SDO in 2012, is sometimes observed after solar eruptions, when the intense heating associated with a solar flare abruptly cuts off after the eruption and the remaining plasma cools and falls back to the solar surface. Mason was searching for coronal rain not associated with eruptions, but instead caused by a cyclical process of heating and cooling similar to the water cycle on Earth. Image Credits: NASA’s Solar Dynamics Observatory/Scientific Visualization Studio/Tom Bridgman, Lead Animator.

Mason was looking for coronal rain in helmet streamers, but her motivation for looking there had more to do with this underlying heating and cooling cycle than the rain itself. Since at least the mid-1990s, scientists have known that helmet streamers are one source of the slow solar wind, a comparatively slow, dense stream of gas that escapes the Sun separately from its fast-moving counterpart.  But measurements of the slow solar wind gas revealed that it had once been heated to an extreme degree before cooling and escaping the Sun. The cyclical process of heating and cooling behind coronal rain, if it was happening inside the helmet streamers, would be one piece of the puzzle.

The other reason connects to the coronal heating problem — the mystery of how and why the Sun’s outer atmosphere is some 300 times hotter than its surface. Strikingly, simulations have shown that coronal rain only forms when heat is applied to the very bottom of the loop. “If a loop has coronal rain on it, that means that the bottom 10% of it, or less, is where coronal heating is happening,” said Mason. Raining loops provide a measuring rod, a cutoff point to determine where the corona gets heated. Starting their search in the largest loops they could find — giant helmet streamers — seemed like a modest goal, and one that would maximize their chances of success.

She had the best data for the job: Images taken by NASA’s Solar Dynamics Observatory, or SDO, a spacecraft that has photographed the Sun every twelve seconds since its launch in 2010. But nearly half a year into the search, Mason still hadn’t observed a single drop of rain in a helmet streamer. She had, however, noticed a slew of tiny magnetic structures, ones she wasn’t familiar with. “They were really bright and they kept drawing my eye,” said Mason. “When I finally took a look at them, sure enough they had tens of hours of rain at a time.”

At first, Mason was so focused on her helmet streamer quest that she made nothing of the observations. “She came to group meeting and said, ‘I never found it — I see it all the time in these other structures, but they’re not helmet streamers,’” said Nicholeen Viall, a solar scientist at Goddard, and a coauthor of the paper. “And I said, ‘Wait…hold on. Where do you see it? I don’t think anybody’s ever seen that before!’”

A Measuring Rod for Heating

These structures differed from helmet streamers in several ways. But the most striking thing about them was their size.

“These loops were much smaller than what we were looking for,” said Spiro Antiochos, who is also a solar physicist at Goddard and a coauthor of the paper. “So that tells you that the heating of the corona is much more localized than we were thinking.”


Animation above: Mason’s article analyzed three observations of Raining Null-Point Topologies, or RNTPs, a previously overlooked magnetic structure shown here in two wavelengths of extreme ultraviolet light. The coronal rain observed in these comparatively small magnetic loops suggests that the corona may be heated within a far more restricted region than previously expected. Image Credits: NASA’s Solar Dynamics Observatory/Emily Mason.

While the findings don’t say exactly how the corona is heated, “they do push down the floor of where coronal heating could happen,” said Mason. She had found raining loops that were some 30,000 miles high, a mere two percent the height of some of the helmet streamers she was originally looking for. And the rain condenses the region where the key coronal heating can be happening. “We still don’t know exactly what’s heating the corona, but we know it has to happen in this layer,” said Mason.

A New Source for the Slow Solar Wind

But one part of the observations didn’t jibe with previous theories.  According to the current understanding, coronal rain only forms on closed loops, where the plasma can gather and cool without any means of escape. But as Mason sifted through the data, she found cases where rain was forming on open magnetic field lines. Anchored to the Sun at only one end, the other end of these open field lines fed out into space, and plasma there could escape into the solar wind. To explain the anomaly, Mason and the team developed an alternative explanation — one that connected rain on these tiny magnetic structures to the origins of the slow solar wind.

Solar Dynamics Obsrvatory (SDO). Image Credit: NASA

In the new explanation, the raining plasma begins its journey on a closed loop, but switches — through a process known as magnetic reconnection — to an open one. The phenomenon happens frequently on the Sun, when a closed loop bumps into an open field line and the system rewires itself.  Suddenly, the superheated plasma on the closed loop finds itself on an open field line, like a train that has switched tracks. Some of that plasma will rapidly expand, cool down, and fall back to the Sun as coronal rain. But other parts of it will escape – forming, they suspect, one part of the slow solar wind.

Mason is currently working on a computer simulation of the new explanation, but she also hopes that soon-to-come observational evidence may confirm it. Now that Parker Solar Probe, launched in 2018, is traveling closer to the Sun than any spacecraft before it, it can fly through bursts of slow solar wind that can be traced back to the Sun — potentially, to one of Mason’s coronal rain events. After observing coronal rain on an open field line, the outgoing plasma, escaping to the solar wind, would normally be lost to posterity. But no longer. “Potentially we can make that connection with Parker Solar Probe and say, that was it,” said Viall.

Digging Through the Data

As for finding coronal rain in helmet streamers? The search continues. The simulations are clear: the rain should be there. “Maybe it’s so small you can’t see it?” said Antiochos.  “We really don’t know.”

But then again, if Mason had found what she was looking for she might not have made the discovery — or have spent all that time learning the ins and outs of solar data.

“It sounds like a slog, but honestly it’s my favorite thing,” said Mason. “I mean that’s why we built something that takes that many images of the Sun: So we can look at them and figure it out.”

Related links:

IRIS Spots Plasma Rain on Sun's Surface: https://www.nasa.gov/feature/goddard/2016/iris-spots-plasma-rain-on-suns-surface

And the Blobs Just Keep on Coming: https://www.nasa.gov/feature/goddard/2019/and-the-blobs-just-keep-on-coming

SDO (Solar Dynamics Observatory): http://www.nasa.gov/mission_pages/sdo/main/index.html

Images (mentioned), Animations (mentioned), Text, Credits: NASA/Rob Garner/Goddard Space Flight Center, by Miles Hatfield.

Greetings, Orbiter.ch

Space Station Science Highlights: Week of March 25, 2019











ISS - Expedition 59 Mission patch.

April 5, 2019

Last week, the six astronauts of Expedition 59  aboard the International Space Station prepared for the second spacewalk in as many weeks, and conducted science experiments on the orbiting lab. NASA astronauts Nick Hague and Christina Koch conducted the second spacewalk Friday, March 29, continuing work to install lithium-ion batteries for a pair of the station’s solar arrays.

Read more about some of the science conducted during the week of March 25 on the space station:

Muscling in on better rehabilitation

The Myotones investigation observes the biochemical properties of muscles, such as tone, stiffness, and elasticity, during long-term exposure to spaceflight. Results from this investigation could provide insight into principles of human resting muscle tone and lead to the development of new treatments for rehabilitation on future space missions and on Earth. The crew performed the first sessions of measurements for the investigation during the week of March 25.


Animation above: Astronaut Nick Hague packs the Meteor Camera and associated hardware from the Window Observational Research Facility (WORF) for return to Earth. Meteor made the first space-based observations of the chemical composition of meteors entering Earth’s atmosphere. Animation Credit: NASA.

Understanding heat transfer in microgravity

The crew altered settings for the JAXA Two Phase Flow-2 experiment, changing the valve setting to the Low-mode (pump) of the Metal Heated Tube (MHT) for several runs of the experiment. Two-Phase Flow investigates the heat transfer characteristics of flow boiling in microgravity to better understand bubble formation behavior, liquid-vapor flow in a tube, and how cooling systems transfer heat. Two-Phase Flow employs a cooling loop using perfluorohexane, often used in coolant for electronics, to establish flow rate, heating power, and other effects on different conditions.

International Space Station (ISS). Image Credit: NASA

Keeping blood flowing to the brain

Crew members took measurements for the Cerebral Autoregulation experiment. The brain needs a strong and reliable blood supply so that it is capable of self-regulating blood flow even when the heart and blood vessels cannot maintain an ideal blood pressure. The Cerebral Autoregulation investigation tests whether this self-regulation improves in the microgravity environment of space. Non-invasive tests measure blood flow in the brain before, during, and after a long-duration spaceflight and provide new insights into how the brain safeguards its blood supply in a challenging environment.

Watching daily rhythms


Image above: One of the Actiwatch devices, a waterproof, nonintrusive, sleep-wake monitor worn on the wrist of a crew member. Image Credits: Philips Respironics Inc.

The Actiwatch is a waterproof, nonintrusive, sleep-wake activity monitor that crew members wear on their wrist. The device contains an accelerometer to measure motion and color sensitive photodetectors for monitoring ambient lighting. With these capabilities, Actiwatch Spectrum can analyze the crew’s circadian rhythms, sleep-wake patterns, and activity.

Other investigations on which the crew performed work:

- Future long-duration space missions will require crew members to grow their own food. Veg-03H uses the Veggie plant growth facility to cultivate Extra Dwarf Pak Choi and Wasabi mustard for harvest on-orbit: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1159

- The Combustion Integrated Rack (CIR) includes an optics bench, combustion chamber, fuel and oxidizer control, and five different cameras for performing combustion investigations in microgravity: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=317

- Lighting Effects studies the effects that replacing fluorescent light bulbs on the space station with solid-state light-emitting diodes (LEDs) has on crew member circadian rhythms, sleep, and cognitive performance: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=2013

- RADI-N2, a Canadian Space Agency investigation, seeks to characterize the neutron environment aboard the space station, define the risk it poses to the crew, and provide data to develop better protective measures for future spaceflights: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=874

- The Material Science Research Rack (MSRR) is used for basic materials research in the microgravity environment of the ISS and can accommodate and support diverse Experiment Modules: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=318

- Food Acceptability examines changes in the appeal of food aboard the space station during long-duration missions: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7562

Space to Ground: Power Walking: 03/29/2019

Related links:

Expedition 59: https://www.nasa.gov/mission_pages/station/expeditions/expedition59/index.html

Myotones: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7573

Two Phase Flow-2: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1034

Cerebral Autoregulation: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1938

Actiwatch: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=838

Spot the Station: https://spotthestation.nasa.gov/

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Images (mentioned), Animation (mentioned), Video (NASA), Text, Credits: NASA/Michael Johnson/Jorge Sotomayor, Lead Increment Scientist Expeditions 59/60.

Best regards, Orbiter.ch

Parker Solar Probe Completes Second Close Approach to the Sun













NASA - Solar Parker Probe patch.

April 5, 2019

Parker Solar Probe has successfully completed its second close approach to the Sun, called perihelion, and is now entering the outbound phase of its second solar orbit. At 6:40 p.m. EDT on April 4, 2019, the spacecraft passed within 15 million miles of our star, tying its distance record as the closest spacecraft ever to the Sun; Parker Solar Probe was traveling at 213,200 miles per hour during this perihelion.

The Parker Solar Probe mission team at the Johns Hopkins Applied Physics Laboratory, or APL, in Laurel, Maryland scheduled a contact with the spacecraft via the Deep Space Network for four hours around the perihelion and monitored the health of the spacecraft throughout this critical part of the encounter. Parker Solar Probe sent back beacon status “A” throughout its second perihelion, indicating that the spacecraft is operating well and all instruments are collecting science data.


“The spacecraft is performing as designed, and it was great to be able to track it during this entire perihelion,” said Nickalaus Pinkine, Parker Solar Probe mission operations manager at APL.Animation of Parker Solar Probe passing close to the Sun “We’re looking forward to getting the science data down from this encounter in the coming weeks so the science teams can continue to explore the mysteries of the corona and the Sun.”

Parker Solar Probe began this solar encounter on March 30, and it will conclude on April 10. The solar encounter phase is roughly defined as when the spacecraft is within 0.25 AU — or 23,250,000 miles — of the Sun. One AU, or astronomical unit, is about 93 million miles, the average distance from the Sun to Earth.

Solar Parker Probe: https://www.nasa.gov/content/goddard/parker-solar-probe

Animation, Text, Credits: NASA/Johns Hopkins University Applied Physics Lab, by Geoff Brown.

Greetings, Orbiter.ch

Aeolus well on the way to improving forecasts









ESA - AEOLUS Mission logo.

5 April 2019

Assessing the accuracy of data being returned by completely new technology in space is a challenging task. But this is exactly what engineers and scientists have been dedicating their time to over the last months so that measurements of the world’s winds being gathered by Aeolus can be fed confidently into weather forecast models.

Carrying breakthrough laser technology, the Aeolus satellite – an ESA Earth Explorer mission – was launched in August 2018.

Strong wind over western Europe

Its novel Aladin instrument, which comprises a powerful laser, a large telescope and a very sensitive receiver, measures the wind by emitting short, powerful pulses of ultraviolet light down into the atmosphere.

It is the first satellite mission to provide profiles of Earth’s wind globally. Its near-realtime observations will soon be made available to weather forecasters around the world. These observations are set to improve the accuracy of weather forecasts as well as advance our understanding of atmospheric dynamics and processes linked to climate variability.

Before ESA can declare that the data good enough to be included in forecasts, the data have to be carefully calibrated and validated. Part of this process has involved gathering measurements of wind, aerosols and clouds from the ground, aircraft and from other satellites to compare with measurements being delivered by Aeolus.

Understanding Earth’s winds

Also, in preparation for ingesting the data into their forecasts, a number of weather forecasting centres around the world have started to compare the Aeolus winds with their models.

So, after several months of calibration and validation exercises, around 100 scientists and engineers from universities, research institutes and weather centres in Europe, the US, Canada, Japan and China gathered recently at ESA’s centre of Earth observation in Italy to review the latest results from the Aeolus data investigations.

The European Centre for Medium-range Weather Forecast (ECMWF) and the German Weather Service (DWD) preliminary analyses showed that Aeolus winds are improving forecasts, particularly in the troposphere, which is the part of the atmosphere between the ground and about 16 km high.

Lars Isaksen, principal scientist at ECMWF, said, “Aeolus’ Aladin is the only instrument that provides wind profiles from space. Wind profiles, especially over remote areas, are very important for numerical weather prediction.

 Cyclone Idai

“ECMWF is heavily involved in processing, calibrating and validating the Aeolus wind data, and in just seven months after the satellite was launched, we and other weather centres have carried out numerous impact studies.

“These results are very promising and indicate that Aeolus winds will improve weather forecasts and help us better understand global wind circulation.”

Examples of results presented at the workshop included the storm that hit the UK and parts of Europe on 10 March and Cyclone Idai that devastated Mozambique, Malawi and Zimbabwe.

The value of having different satellite instruments observing the same weather event is important for gathering as much information as possible to improve the accuracy of weather forecasts and so that people affected by severe weather can take necessary action.

Cyclone Idai from Copernicus Sentinel-3

Tommaso Parrinello, ESA’s Aeolus Mission Manager, said, “We are really happy with the data Aeolus is returning. We also see how the mission can add complementary information to satellites carrying optical instruments such as the Copernicus Sentinel-3 and the satellites carrying radar such as the Copernicus Sentinel-1.

“While comparisons with ground-based instrumentation and weather models are currently ongoing to refine the calibration and data processing, we expect that the quality of the Aeolus data will be high enough around the end of this year – after which the data will be ready for scientific research and for weather forecasting.”

Related links:

Cyclone Idai: http://www.esa.int/Our_Activities/Observing_the_Earth/Copernicus/Sentinel-1/Copernicus_Sentinel-1_maps_floods_in_wake_of_Idai

Aeolus: http://www.esa.int/Our_Activities/Observing_the_Earth/Aeolus

Aeolus ca/val & science workshop: https://nikal.eventsair.com/QuickEventWebsitePortal/aeolus-calval-and-science-workshop-2019/aeolus

DLR–Institute of Atmospheric Physics: https://www.dlr.de/pa/en/

ECMWF: https://www.ecmwf.int/

Images, Video, Text, Credits: ESA/ECMWF/M. Rennie/Contains modified Copernicus Sentinel data (2019), processed by ESA, CC BY-SA 3.0 IGO.

Greetings, Orbiter.ch

Self-driving spacecraft set for planetary defence expedition












ESA - Hera Mission logo.

5 April 2019

Engineers designing ESA’s Hera planetary defence mission to the Didymos asteroid pair are developing advanced technology to let the spacecraft steer itself through space, taking a similar approach to self-driving cars.

Infrared imaging of asteroids

“If you think self-driving cars are the future on Earth, then Hera is the pioneer of autonomy in deep space,” explains Paolo Martino, lead systems engineer of ESA's proposed Hera mission. “While the mission is designed to be fully operated manually from ground, the new technology will be tested once the core mission objectives are achieved and higher risks can be taken.”

Hera is currently the subject of detailed design work, ahead of being presented to Europe’s space ministers at the Space19+ Ministerial Council this November. The spacecraft will survey a tiny 160-m diameter moon of the 780-m diameter Didymos asteroid, in the aftermath of a pioneering planetary defence experiment.

Hera spacecraft self-driving navigation test

“The spacecraft will operate like an autonomous vehicle, fusing data from different sensors to build up a coherent model of its surroundings,” says ESA guidance, navigation and control (GNC) engineer Jesus Gil Fernandez.

“Hera’s most crucial data source will be its Asteroid Framing Camera, combined with inputs from a star-tracker, laser altimeter, thermal infrared camera plus inertial sensors including accelerometers.”

Laser scan of Didymoon

The resulting autonomy should let Hera navigate safely as close at 200 metres from the surface of the smaller asteroid ‘Didymoon’, enabling the acquisition of high-resolution scientific observations down to 2 cm per pixel – focused in particular on the impact crater left by the US DART spacecraft crashing into Didymoon to divert its orbit.

GNC engineer Massimo Casasco adds: “All other deep-space missions, by comparison, have had a definite driver back on Earth, with navigation commands planned at mission control in ESA’s European Space Operations Centre, before being uplinked to the spacecraft hours later. During Hera’s experimental phase, equivalent decisions will be performed aboard on an autonomous basis in real time.”

Hera spacecraft

For maximum navigation reliability, Hera’s main onboard computer will be complemented by a dedicated image processing unit – in the same way desktop PCs often have separate graphics cards – while borrowing machine vision techniques from industrial cameras employed on production lines.

Image-based navigation

Due for launch in October 2023 and reaching its target Didymos near-Earth asteroids three years later, ESA’s proposed Hera mission will navigate itself in three different modes. On initial approach the main asteroid will appear as one more bright star among many.

Hera mission timeline

“From afar, it will be only a tiny dot,” explains Jesus. “We would have to take several pictures to observe its motion against the background starfield.”

This imaging technique is similar to those developed to detect small items of space debris and to eventually permit future robotic debris-removal missions to rendezvous with them.

The next mode will be the dominant one for the bulk of Hera’s mission between 30 km to 8 km distance, with the larger ‘Didymain’ asteroid framed in its camera view as an overall reference point.

“This mode depends on having the big asteroid smaller than our overall camera field of view, and detecting the contrast of its edges giving way to the space beyond,” says Massimo. “We take advantage of its roughly-spherical shape to fit it within a circle and estimate the line-of-sight distance between the spacecraft and the asteroid ‘centroid’.”

Asteroid Framing Camera

Didymain has been selected as the navigation reference point as it is the body where most of the system’s gravity is concentrated, and much more is known about it than the smaller Didymoon.

This method will become unworkable however once Hera comes closer than 8 km from Didymain, and the asteroid fills its field of view. Then comes the most ambitious navigation mode of all, based on autonomous feature tracking with no absolute reference.

Jesus explains: “This will be a matter of imaging the same features – such as boulders and craters – in different pictures to gain a sense of how we’re moving with respect to the surface, combined in turn with other information including onboard accelerometers for dead reckoning and the thermal infrared camera for overflying the asteroid’s night side.”

Camera being tested

Feature tracking will also be used to measure the mass of Didymoon, by measuring the ‘wobble’ it causes its parent, relative to the common centre of gravity of the overall binary Didymos system. This will be achieved by identifying small metre-scale variations in the rotation of fixed landmarks around this centre of gravity over time.

Mars sample return

In practice, there will undoubtedly be surprises, observes Massimo: “A flatter surface would be worse than something with a lot of boulders with high contrast, making it easier to unambiguously identify features. Plus a less spherical body with lots of irregular shapes and shadows would be more of a challenge for the kind of edge detection we’re employing.”

Europe-wide development team

GMV in Spain is leading development of this vision-based navigation system, supported by OHB in Sweden with other partners including GMV in Poland and Romania. A replica of the Asteroid Framing Camera Hera will rely on is currently being used for practical testing of the software together with a high-resolution model of Didymos.

Hera mission

This technology will have wider uses in many other missions, including ESA’s planned Space Servicing Vehicle for refurbishing satellites and removing space debris, as well as the ambitious Mars Sample Return mission, the homeward leg of which will involve autonomous rendezvous in Mars orbit. Ultimately, once proven, this technology would be an enabling building block for low-cost planetary probes into deep space.

Related links:

Hera: http://www.esa.int/Our_Activities/Operations/Space_Safety_Security/Hera

Space19+: http://www.esa.int/spaceinvideos/Videos/2019/01/What_is_Space19

DART spacecraft: http://www.esa.int/Our_Activities/Operations/Space_Safety_Security/Hera/DART

Asteroid Framing Camera: https://www.esa.int/Our_Activities/Operations/Space_Safety_Security/Hera/ESA_s_Hera_asteroid_mission_borrows_eyes_of_NASA_s_Dawn

ESA’s European Space Operations Centre: https://www.esa.int/About_Us/ESOC

Mars Sample Return mission: https://www.esa.int/Our_Activities/Human_and_Robotic_Exploration/Exploration/Mars_sample_return

Images, Videos, Text, Credits: ESA/ScienceOffice.org/Max Planck Institute for Solar System Research/NASA.

Best regards, Orbiter.ch

BepiColombo is ready for its long cruise













ESA - BepiColombo Mission patch.

April 5, 2019

Following a series of tests conducted in space over the past five months, the ESA-JAXA BepiColombo mission has successfully completed its near-Earth commissioning phase and is now ready for the operations that will take place during the cruise and, eventually, for its scientific investigations at Mercury.

BepiColombo started its seven-year long journey to the Solar System’s innermost planet on 20 October 2018, lifting off on an Ariane 5 rocket from Europe’s spaceport in Kourou, French Guiana.

BepiColombo in cruise configuration

After completing the launch and early orbit phase on 22 October, an extensive series of in-orbit commissioning activities started. During this near-Earth commissioning phase, which was concluded on 16 December, the European and Japanese mission teams performed tests to ensure the health of BepiColombo’s science instruments, its propulsion and other spacecraft platform systems. 

On 26 March 2019, a review board confirmed that the overall capabilities and performance at the end of the near-Earth commissioning phase meet the mission requirements.

“We are very pleased with the performance of BepiColombo and proud of the work of all teams who made such a challenging mission a reality”, says Ulrich Reininghaus, ESA BepiColombo project manager.

BepiColombo handover

This marks the end of the commissioning activities, and the operations team can focus on routine operations and on preparations for the mission’s first planetary gravity assist next year.

“BepiColombo has successfully passed its health check and is now officially in operations,” says ESA mission manager Patrick Martin.

The mission comprises two science orbiters: ESA’s Mercury Planetary Orbiter (MPO) and JAXA’s Mercury Magnetospheric Orbiter (MMO). The ESA-built Mercury Transfer Module (MTM) will carry the orbiters to Mercury using a combination of solar electric propulsion and gravity assist flybys – one of Earth, two at Venus, and six at Mercury – prior to MPO and MMO orbit insertions.

The first electric propulsion ‘arc’ started on 17 December, after verification of the four individual thrusters as well as the so-called ‘twin firing’ configuration, operating two thrusters in close proximity for a prolonged period of time, which was monitored closely by the operations engineers. The solar propulsion arc – the first in a series of 22 – was successfully completed in early March.

"Solar electric propulsion is one of the key flight challenges of this complex mission, and we are very pleased to see the system now in full operation," says Elsa Montagnon, BepiColombo spacecraft operations manager.

BepiColombo electric propulsion

Since launch, BepiColombo has already covered over 450 million km – just about four percent of the total distance it will have to travel before arriving at Mercury at the end of 2025. The composite spacecraft is now some 50 million km from Earth, and telecommands take about three minutes to reach it.

The near-Earth commissioning activities for all science instruments on both orbiters have been completed as planned, and both ground segments – on the operations and science sides – are ready to support the next chapter of the mission. 

“Besides the health checks that were successfully executed on all instruments, several of them are already operated in full science mode. The instrument teams are ready to go,” says ESA project scientist, Johannes Benkhoff.

Earth flyby

In the coming weeks, the BepiColombo teams will investigate some remaining issues and carry out high-voltage related instrument checks while looking forward to the next major mission milestone, as the spacecraft will come back to some 11 000 km from Earth for a flyby on 13 April 2020.

Later next year, in October, BepiColombo will perform the first of its two flybys of Venus – the second planned for August 2021. These will provide an exciting opportunity to operate some of the instruments on both orbiters and to collect scientifically valuable data to further study this fascinating planet while en route to the mission’s destination – Mercury.

How we make a space mission

ESA is the space agency for Europe, enabling its 22 Member States to achieve results that no individual nation can match. ESA combines space mission development with supporting labs, test and operational facilities plus in-house experts covering every aspect of space, supported through the Agency’s Basic Activities.

Related links:

BepiColombo: http://www.esa.int/Our_Activities/Space_Science/BepiColombo

Operations: http://www.esa.int/Our_Activities/Operations

Images, Text, Credits: ESA/Markus Bauer/Daniel Scuka/R. Palmari/ATG medialab.

Greetibgs, Orbiter.ch

Jupiter Spiral













NASA - JUNO Mission logo.

April 5, 2019


A cyclonic storm in Jupiter's northern hemisphere is captured in this image from NASA's Juno spacecraft. Many bright white cloud tops can be seen popping up in and around the arms of the rotating storm.

The color-enhanced image was taken at 9:25 a.m. PST (12:25 p.m. EST) on Feb. 12, 2019, as the spacecraft performed its 17th science flyby of Jupiter. At the time, Juno was about 5,000 miles (8,000 kilometers) from the planet's cloud tops, above approximately 44 degrees north latitude.

Citizen scientists Gerald Eichstädt and Seán Doran created this image using data from the spacecraft's JunoCam imager.

JunoCam's raw images are available for the public to peruse and process into image products at https://missionjuno.swri.edu/junocam/processing.

More information about Juno is online at http://www.nasa.gov/juno and http://missionjuno.swri.edu.

JUNO spacecraft orbiting Jupiter

NASA's Jet Propulsion Laboratory manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. Juno is part of NASA's New Frontiers Program, which is managed at NASA's Marshall Space Flight Center in Huntsville, Alabama, for NASA's Science Mission Directorate. Lockheed Martin Space Systems, Denver, built the spacecraft. Caltech in Pasadena, California, manages JPL for NASA.

Image, Animation, Text, credits: NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstadt/Sean Doran.

Greetings, Orbiter.ch

Asteroid Explorer Hayabusa2’s Science - Put into Operation












JAXA - Hayabusa2 Mission patch.

April 5, 2019

The National Research and Development Agency Japan Aerospace Exploration Agency (JAXA) separated the SCI (Small Carry-on Impactor) onboard the asteroid explorer Hayabusa2 for deployment to Ryugu and put the SCI into operation.

Artists impression of the Hayabusa2 probes encounter with Ryugu. Image Credit: JAXA

After the start of the operation, the camera (DCAM3) separated from Hayabusa2 captured an image that shows ejection from Ryugu’s surface, which implies that the SCI had functioned as planned.

Hayabusa2 is operating normally. We will be providing further information once we have confirmed whether a crater has been created on Ryugu.


This image captured by the camera separated from Hayabusa2 (DCAM3) shows ejection from Ryugu’s surface, which was caused by the collision of the SCI against Ryugu.

Image taken at 11:36 a.m., April 5, 2019 (Indicated by the camera, Japan time)
Image credit: JAXA, Kobe University, Chiba Institute of Technology, The University of Occupational and Environmental Health, Kochi University, Aichi Toho University, The University of Aizu, and Tokyo University of Science.

Operational Status of Asteroid Explorer Hayabusa2's SCI

The National Research and Development Agency Japan Aerospace Exploration Agency (JAXA) has carried out operations to separate the SCI (Small Carry-on Impactor) onboard the asteroid explorer Hayabusa2 for deployment to the asteroid Ryugu.

The SCI separation has been confirmed using Hayabusa2’s Optical Navigation Camera-Wide (ONC-W1), it is our assessment that separation of the SCI went as planned.


An image of separated SCI taken with the Optical Navigation Camera - Wide angle (ONC-W1) on April 5, 2019 at an onboard time of around 10:56 JST. Photographed from approximately 500 meters above Ryugu. Image credits: JAXA, The University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, The University of Aizu, AIST.

In order to avoid the impact given by the operation of the small carry-on impactor (SCI), Hayabusa2 was moved to the safety zone on the backside of the asteroid before the SCI began to be operated. Hayabusa2 is operating normally.

Latest Navigation Images from the SCI operation. Image Credit: JAXA

We will be providing further information once we have confirmed whether the SCI is operating and whether a crater has been created on Ryugu.

Related Links:

Hayabusa2 Asteroid Probe (ISAS): http://www.isas.jaxa.jp/en/missions/spacecraft/current/hayabusa2.html

Asteroid Explorer "Hayabusa2": http://global.jaxa.jp/projects/sas/hayabusa2/index.html

Images (mentioned), Text, Credits: Japan Aerospace Exploration Agency (JAXA)/National Research and Development Agency.

Best regards, Orbiter.ch

jeudi 4 avril 2019

Record-Breaking Satellite Advances NASA’s Exploration of High-Altitude GPS













NASA - Magnetospheric Multiscale (MMS) patch.

April 4, 2019

The four Magnetospheric Multiscale (MMS) spacecraft recently broke the world record for navigating with GPS signals farther from Earth than ever before. MMS’ success indicates that NASA spacecraft may soon be able to navigate via GPS as far away as the Moon, which will prove important to the Gateway, a planned space station in lunar orbit.


Image above: Illustration of the four MMS spacecraft in orbit in Earth's magnetic field. Image Credit: NASA.

After navigation maneuvers conducted this February, MMS now reaches over 116,300 miles from Earth at the highest point of its orbit, or about halfway to the Moon. At this altitude, MMS continued to receive strong enough GPS signals to determine its position, shattering previous records it set first in October 2016 and again in February 2017. This demonstrates that GPS signals extend farther than expected and that future missions can reliably use GPS at extreme altitudes.

“At the first apogee after the maneuvers, MMS1 had 12 GPS fixes, each requiring signals from four GPS satellites,” said Trevor Williams, the MMS flight dynamics lead at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “When we began the mission, we had no idea high-altitude GPS would be such a robust capability.”

NASA's MMS Captures Magnetic Reconnection in Action

Video above: On Oct. 16, 2015, MMS traveled straight through a magnetic reconnection event at the boundary where Earth’s magnetic field bumps up against the sun’s magnetic field. Video Credits: NASA's Goddard Space Flight Center/Duberstein.

MMS’ orbit shift allows it to continue its mission to better understand the complex magnetic processes around Earth. MMS studies a fundamental process that occurs throughout the universe, called magnetic reconnection, in which magnetic fields collide and explosively release particles in all directions. Near Earth, reconnection is a key driver of space weather, the dynamic system of energy, particles and magnetic fields around Earth which can adversely impact communications networks, electrical grids and GPS navigation. Magnetic reconnection was long predicted by physicists, but not directly observed until the MMS mission.

To study Earth’s magnetosphere, the region of space dominated by the planet’s magnetic field, MMS spacecraft maintain a highly elliptical orbit around Earth. A highly elliptical orbit resembles a long oval around the globe with an extreme high point, or apogee, and low point, or perigee.

MMS’ tight formation and highly elliptical orbit require extremely accurate navigation data from GPS satellites, which are operated by the U.S. Air Force. The main GPS antenna signals enable navigation down on Earth, but precise high-altitude navigation requires both these as well as signals from the antenna’s side lobes. Side lobe signals radiate out to the side of the direction an antenna is pointing and extend past Earth.


Image above: A simplified antenna radiation pattern with different lobes of radiation extending from the antenna. Image Credit: NASA.

Communications engineers usually consider these side lobes wasted energy. However, the signals can be used by satellites at high altitudes on the opposite side of the globe as the GPS satellite. (Such high-altitude missions fly above GPS satellites’ orbit.) Previously, most engineers considered the upper limits of the GPS navigation in space to be an altitude of about 22,000 miles, or the altitude of satellites in geosynchronous orbit — until MMS.

Additionally, the navigation maneuvers allowed the spacecraft to gather data not available to scientists during normal operations.

MMS Spacecraft Transition to Tetrahedral Flying Formation

Video above: Visualization of MMS’ transition to its tight, tetrahedral formation in July, 2015. Video Credits: NASA's Goddard Space Flight Center.

“MMS usually flies in a close, tetrahedral formation [that looks like a pyramid],” said Thomas Moore, the project scientist for MMS at Goddard. “During the orbit-raising maneuvers, the spacecraft became a [straight line or] ‘string of pearls,’ which gave us unique data about the magnetosphere that may further our understanding of magnetic reconnection.”

MMS’ tight configuration and record-breaking GPS fixes would not be possible without the mission’s Navigator GPS Receiver, an instrument developed at Goddard. It can detect faint GPS signals while withstanding the harsh radiation environment within the magnetosphere. NASA has made this revolutionary technology available for licensing through the Technology Transfer program, ensuring that commercial enterprise can also benefit from this innovation.


Image above: A diagram showing how GPS antenna signals can serve spacecraft at high altitudes. Image Credit: NASA.

NASA is exploring the upper limits of GPS service with more than just MMS. NASA navigation experts have run simulations demonstrating that these services could extend even farther when taking into account the collection of six international GPS-like constellations. These constellations are collectively referred to as global navigation satellite systems (GNSS).

In fact, NASA simulations show GNSS signals could even be used for reliable navigation in lunar orbit, just as a car uses GPS on an interstate highway. Engineers are considering using GNSS signals in the navigation architecture for the Gateway, an outpost in orbit around the Moon that will enable sustained lunar surface exploration.

“We’re working with the international community to document GNSS performance for space users, including side lobe signals,” said Joel Parker, a Goddard navigation engineer representing NASA internationally in GNSS policy. “A better understanding of GNSS capabilities will allow high-altitude missions to take advantage of the robust navigation signals they provide.”

Thanks to MMS and NASA’s navigation engineers, the sky is no longer the limit.

NASA’s Science Mission Directorate provides strategic oversight to MMS. Goddard’s Explorers and Heliophysics Projects Division manages the mission. The four MMS spacecraft launched on March 13, 2015, from NASA’s Kennedy Space Center in Cape Canaveral, Florida, on board an Atlas V launch vehicle.

NASA’s Space Communications and Navigation (SCaN) program office oversees the agency’s work in navigation policy related to GNSS. NASA, consulting the United Nations International Committee on GNSS (ICG), collaborates with other U.S. agencies and the six international GNSS providers to define GNSS requirements and develop additional capabilities. The team of SCaN navigation specialists charged with aiding the ICG are based out of the Exploration and Space Communications projects division at Goddard.

Related links:

Magnetospheric Multiscale (MMS): https://mms.gsfc.nasa.gov/

Navigator GPS Receiver: https://ntts-prod.s3.amazonaws.com/t2p/prod/t2media/tops/pdf/NavigatorSpecSheet_Final1.pdf

Technology Transfer: https://technology.nasa.gov/

Space Communications and Navigation (SCaN): https://www.nasa.gov/directorates/heo/scan/index.html

Goddard Space Flight Center (GSFC): https://www.nasa.gov/centers/goddard/home/index.html

Images (mentioned), Videos (mentioned), Text, Credits: NASA/Rob Garner/Goddard Space Flight Center, by Danny Baird.

Greetings, Orbiter.ch

Curiosity Captured Two Solar Eclipses on Mars













NASA - Mars Science Laboratory (MSL) patch.

April 4, 2019

When NASA's Curiosity Mars rover landed in 2012, it brought along eclipse glasses. The solar filters on its Mast Camera (Mastcam) allow it to stare directly at the Sun. Over the past few weeks, Curiosity has been putting them to good use by sending back some spectacular imagery of solar eclipses caused by Phobos and Deimos, Mars' two moons.


Animation above: This series of images shows the Martian moon Phobos as it crossed in front of the Sun, as seen by NASA's Curiosity Mars rover on Tuesday, March 26, 2019 (Sol 2359). Animation Credits: NASA/JPL-Caltech/MSSS.

Phobos, which is about 7 miles (11.5 kilometers) across, was imaged on March 26, 2019 (the 2,359th sol, or Martian day, of Curiosity’s mission); Deimos, which is about 1.5 miles (2.3 kilometers) across, was photographed on March 17, 2019 (Sol 2350). Phobos doesn't completely cover the Sun, so it would be considered an annular eclipse. Because Deimos is so small compared to the disk of the Sun, scientists would say it's transiting the Sun.

In addition to capturing each moon crossing in front of the Sun, one of Curiosity's Navigation Cameras (Navcams) observed the shadow of Phobos on March 25, 2019 (Sol 2358). As the moon's shadow passed over the rover during sunset, it momentarily darkened the light.


Animation above: This series of images shows the Martian moon Deimos as it crossed in front of the Sun, as seen by NASA's Curiosity Mars rover on Sunday, March 17, 2019 (the 2,350th Martian day, or sol, of the mission). Animation Credits: NASA/JPL-Caltech/MSSS.

Solar eclipses have been seen many times by Curiosity and other rovers in the past. Besides being cool — who doesn't love an eclipse? — these events also serve a scientific purpose, helping researchers fine-tune their understanding of each moon's orbit around Mars.

Before the Spirit and Opportunity rovers landed in 2004, there was much higher uncertainty in the orbit of each moon, said Mark Lemmon of Texas A&M University, College Station, a co-investigator with Curiosity's Mastcam. The first time one of the rovers tried to image Deimos eclipsing the Sun, they found the moon was 25 miles (40 kilometers) away from where they expected.

"More observations over time help pin down the details of each orbit," Lemmon said. "Those orbits change all the time in response to the gravitational pull of Mars, Jupiter or even each Martian moon pulling on the other."


Animation above: This series of images shows the shadow of Phobos as it sweeps over NASA's Curiosity Mars rover and darkens the sunlight on Monday, March 25, 2019 (Sol 2358). Animation Credits: NASA/JPL-Caltech.

These events also help make Mars relatable, Lemmon said: "Eclipses, sunrises and sunsets and weather phenomena all make Mars real to people, as a world both like and unlike what they see outside, not just a subject in a book."

To date, there have been eight observations of Deimos eclipsing the Sun from either Spirit, Opportunity or Curiosity; there have been about 40 observations of Phobos. There's still a margin of uncertainty in the orbits of both Martian moons, but that shrinks with every eclipse that's viewed from the Red Planet's surface.

About Curiosity

NASA's Jet Propulsion Laboratory, a division of Caltech, manages the Mars Science Laboratory Project for NASA's Science Mission Directorate, Washington. JPL designed and built the project's Curiosity rover.

Malin Space Science Systems, San Diego, built and operates the Mastcam instrument and two other instruments on Curiosity.

More information about Curiosity is at: http://mars.jpl.nasa.gov/msl/

More information about Mars is at: https://mars.nasa.gov

Animations (mentioned), Text, Credits: NASA/Tony Greicius/JPL/Andrew Good.

Greetings, Orbiter.ch