Orbiter.ch Space News

lundi 22 février 2021

NASA’s Mars Perseverance Rover Provides Front-Row Seat to Landing, First Video Recording of Red Planet

NASA - Mars 2020 Perseverance Rover logo.

February 22, 2021

New video from NASA’s Mars 2020 Perseverance rover chronicles major milestones during the final minutes of its entry, descent, and landing (EDL) on the Red Planet on Feb. 18 as the spacecraft plummeted, parachuted, and rocketed toward the surface of Mars. A microphone on the rover also has provided the first audio recording of sounds from Mars.

From the moment of parachute inflation, the camera system covers the entirety of the descent process, showing some of the rover’s intense ride to Mars’ Jezero Crater. The footage from high-definition cameras aboard the spacecraft starts 7 miles (11 kilometers) above the surface, showing the supersonic deployment of the most massive parachute ever sent to another world, and ends with the rover’s touchdown in the crater.

First panorama taken from Jezero Crater by Perseverance rover. Image Credits: NASA/JPL-Caltech

A microphone attached to the rover did not collect usable data during the descent, but the commercial off-the-shelf device survived the highly dynamic descent to the surface and obtained sounds from Jezero Crater on Feb. 20. About 10 seconds into the 60-second recording, a Martian breeze is audible for a few seconds, as are mechanical sounds of the rover operating on the surface.

“For those who wonder how you land on Mars – or why it is so difficult – or how cool it would be to do so – you need look no further,” said acting NASA Administrator Steve Jurczyk. “Perseverance is just getting started, and already has provided some of the most iconic visuals in space exploration history. It reinforces the remarkable level of engineering and precision that is required to build and fly a vehicle to the Red Planet.”

Perseverance Rover’s Descent and Touchdown on Mars. Image Credits: NASA/JPL-Caltech

Also released Monday was the mission’s first panorama of the rover’s landing location, taken by the two Navigation Cameras located on its mast. The six-wheeled robotic astrobiologist, the fifth rover the agency has landed on Mars, currently is undergoing an extensive checkout of all its systems and instruments.

“This video of Perseverance’s descent is the closest you can get to landing on Mars without putting on a pressure suit,” said Thomas Zurbuchen, NASA associate administrator for science. “It should become mandatory viewing for young women and men who not only want to explore other worlds and build the spacecraft that will take them there, but also want to be part of the diverse teams achieving all the audacious goals in our future.”

The world’s most intimate view of a Mars landing begins about 230 seconds after the spacecraft entered the Red Planet’s upper atmosphere at 12,500 mph (20,100 kph). The video opens in black, with the camera lens still covered within the parachute compartment. Within less than a second, the spacecraft’s parachute deploys and transforms from a compressed 18-by-26 inch (46-by-66 centimeter) cylinder of nylon, Technora, and Kevlar into a fully inflated 70.5-foot-wide (21.5-meter-wide) canopy – the largest ever sent to Mars. The tens of thousands of pounds of force that the parachute generates in such a short period stresses both the parachute and the vehicle.

“Now we finally have a front-row view to what we call ‘the seven minutes of terror’ while landing on Mars,” said Michael Watkins, director of NASA’s Jet Propulsion Laboratory in Southern California, which manages the mission for the agency. “From the explosive opening of the parachute to the landing rockets’ plume sending dust and debris flying at touchdown, it’s absolutely awe-inspiring.”

The video also captures the heat shield dropping away after protecting Perseverance from scorching temperatures during its entry into the Martian atmosphere. The downward view from the rover sways gently like a pendulum as the descent stage, with Perseverance attached, hangs from the back shell and parachute. The Martian landscape quickly pitches as the descent stage – the rover’s free-flying “jetpack,” which decelerates using rocket engines and then lowers the rover on cables to the surface – breaks free, its eight thrusters engaging to put distance between it and the now-discarded back shell and the parachute.

Then, 80 seconds and 7,000 feet (2,130 meters) later, the cameras capture the descent stage performing the sky crane maneuver over the landing site – the plume of its rocket engines kicking up dust and small rocks that have likely been in place for billions of years.

Perseverance Rover’s Descent and Touchdown on Mars (Official NASA Video)

Video above: NASA's Mars 2020 Perseverance mission captured thrilling footage of its rover landing in Mars' Jezero Crater on Feb. 18, 2021. The real footage in this video was captured by several cameras that are part of the rover's entry, descent, and landing suite. The views include a camera looking down from the spacecraft's descent stage (a kind of rocket-powered jet pack that helps fly the rover to its landing site), a camera on the rover looking up at the descent stage, a camera on the top of the aeroshell (a capsule protecting the rover) looking up at that parachute, and a camera on the bottom of the rover looking down at the Martian surface. The audio embedded in the video comes from the mission control call-outs during entry, descent, and landing. Video Credits: NASA/JPL-Caltech.

“We put the EDL camera system onto the spacecraft not only for the opportunity to gain a better understanding of our spacecraft’s performance during entry, descent, and landing, but also because we wanted to take the public along for the ride of a lifetime – landing on the surface of Mars,” said Dave Gruel, lead engineer for Mars 2020 Perseverance’s EDL camera and microphone subsystem at JPL. “We know the public is fascinated with Mars exploration, so we added the EDL Cam microphone to the vehicle because we hoped it could enhance the experience, especially for visually-impaired space fans, and engage and inspire people around the world.”

The footage ends with Perseverance’s aluminum wheels making contact with the surface at 1.61 mph (2.6 kilometers per second), and then pyrotechnically fired blades sever the cables connecting it to the still-hovering descent stage. The descent stage then climbs and accelerates away in the preplanned flyaway maneuver.

“If this were an old Western movie, I’d say the descent stage was our hero riding slowly into the setting Sun, but the heroes are actually back here on Earth,” said Matt Wallace, Mars 2020 Perseverance deputy project manager at JPL. “I’ve been waiting 25 years for the opportunity to see a spacecraft land on Mars. It was worth the wait. Being able to share this with the world is a great moment for our team.”

Five commercial off-the-shelf cameras located on three different spacecraft components collected the imagery. Two cameras on the back shell, which encapsulated the rover on its journey, took pictures of the parachute inflating. A camera on the descent stage provided a downward view – including the top of the rover – while two on the rover chassis offered both upward and downward perspectives.

The rover team continues its initial inspection of Perseverance’s systems and its immediate surroundings. Monday, the team will check out five of the rover’s seven instruments and take the first weather observations with the Mars Environmental Dynamics Analyzer instrument. In the coming days, a 360-degree panorama of Jezero by the Mastcam-Z should be transmitted down, providing the highest resolution look at the road ahead.

More About the Mission

A key objective of Perseverance's mission on Mars is astrobiology, including the search for signs of ancient microbial life. The rover will characterize the planet’s geology and past climate, pave the way for human exploration of the Red Planet, and be the first mission to collect and cache Martian rock and regolith.

Subsequent NASA missions, in cooperation with ESA (European Space Agency), would send spacecraft to Mars to collect these sealed samples from the surface and return them to Earth for in-depth analysis.

The Mars 2020 Perseverance mission is part of NASA’s Moon to Mars exploration approach, which includes Artemis missions to the Moon that will help prepare for human exploration of the Red Planet.

JPL, which is managed for NASA by Caltech in Pasadena, California, built and manages operations of the Perseverance rover.

For more about Perseverance:

https://www.nasa.gov/perseverance and https://mars.nasa.gov/mars2020

For more information about NASA’s Mars missions, go to: https://www.nasa.gov/mars

Images (mentioned), Video (mentioned), Text, Credits: NASA/Alana Johnson/Grey Hautaluoma/JPL/DC Agle.

Best regards, Orbiter.ch

NASA’s Swift Helps Tie Neutrino to Star-shredding Black Hole

NASA - Swift Mission patch.

Feb 22, 2021

For only the second time, astronomers have linked an elusive particle called a high-energy neutrino to an object outside our galaxy. Using ground- and space-based facilities, including NASA’s Neil Gehrels Swift Observatory, they traced the neutrino to a black hole tearing apart a star, a rare cataclysmic occurrence called a tidal disruption event.

Swift observatory. Image Credit: NASA

“Astrophysicists have long theorized that tidal disruptions could produce high-energy neutrinos, but this is the first time we’ve actually been able to connect them with observational evidence,” said Robert Stein, a doctoral student at the German Electron-Synchrotron (DESY) research center in Zeuthen, Germany, and Humboldt University in Berlin. “But it seems like this particular event, called AT2019dsg, didn’t generate the neutrino when or how we expected. It’s helping us better understand how these phenomena work.”

The findings, led by Stein, were published in the Feb. 22 issue of Nature Astronomy and are available online: https://www.nature.com/articles/s41550-020-01295-8

Swift Links Neutrino to Star-destroying Black Hole

Video above: Watch how a monster black hole ripping apart a star may have launched a ghost particle toward Earth. Astronomers have long predicted that tidal disruption events could produce high-energy neutrinos, nearly massless particles from outside our galaxy traveling close to the speed of light. One recent event, named AT2019dsg, provides the first proof this prediction is true but has challenged scientists’ assumptions of where and when these elusive particles might form during these destructive outbursts. Video Credits: NASA’s Goddard Space Flight Center.

Neutrinos are fundamental particles that far outnumber all the atoms in the universe but rarely interact with other matter. Astrophysicists are particularly interested in high-energy neutrinos, which have energies up to 1,000 times greater than those produced by the most powerful particle colliders on Earth. They think the most extreme events in the universe, like violent galactic outbursts, accelerate particles to nearly the speed of light. Those particles then collide with light or other particles to generate high-energy neutrinos. The first confirmed high-energy neutrino source, announced in 2018, was a type of active galaxy called a blazar.

Tidal disruption events occur when an unlucky star strays too close to a black hole. Gravitational forces create intense tides that break the star apart into a stream of gas. The trailing part of the stream escapes the system, while the leading part swings back around, surrounding the black hole with a disk of debris. In some cases, the black hole launches fast-moving particle jets. Scientists hypothesized that tidal disruptions would produce high-energy neutrinos within such particle jets. They also expected the events would produce neutrinos early in their evolution, at peak brightness, whatever the particles’ production process.

AT2019dsg was discovered on April 9, 2019, by the Zwicky Transient Facility (ZTF), a robotic camera at Caltech’s Palomar Observatory in Southern California. The event occurred over 690 million light-years away in a galaxy called 2MASX J20570298+1412165, located in the constellation Delphinus.

As part of a routine follow-up survey of tidal disruptions, Stein and his team requested visible, ultraviolet, and X-ray observations with Swift. They also took X-ray measurements using the European Space Agency’s XMM-Newton satellite and radio measurements with facilities including the National Radio Astronomy Observatory’s Karl G. Jansky Very Large Array in Socorro, New Mexico, and the South African Radio Astronomy Observatory's MeerKAT telescope.

Peak brightness came and went in May. No clear jet appeared. According to theoretical predictions, AT2019dsg was looking like a poor neutrino candidate.

Then, on Oct. 1, 2019, the National Science Foundation’s IceCube Neutrino Observatory at the Amundsen-Scott South Pole Station in Antarctica detected a high-energy neutrino called IC191001A and backtracked along its trajectory to a location in the sky. About seven hours later, ZTF noted that this same patch of sky included AT2019dsg. Stein and his team think there is only one chance in 500 that the tidal disruption is not the neutrino’s source. Because the detection came about five months after the event reached peak brightness, it raises questions about when and how these occurrences produce neutrinos.

“Tidal disruption events are incredibly rare phenomena, only occurring once every 10,000 to 100,000 years in a large galaxy like our own. Astronomers have only observed a few dozen at this point,” said Swift Principal Investigator S. Bradley Cenko at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Multiwavelength measurements of each event help us learn more about them as a class, so AT2019dsg was of great interest even without an initial neutrino detection.”

For example, tidal disruptions generate visible and UV light in the outer regions of their hot accretion disks. In AT2019dsg, these wavelengths plateaued shortly after they peaked. That was unusual because such plateaus typically appear only after a few years. The researchers suspect the galaxy’s monster black hole, with a mass estimated at 30 million times the Sun’s, could have forced the stellar debris to settle into a disk more quickly than it might have around a less massive black hole.

AT2019dsg is one of only a handful of known X-ray-emitting tidal disruptions. Scientists think the X-rays come from either the inner part of the accretion disk, close to the black hole, or from high-speed particle jets. The outburst’s X-rays faded by an unprecedented 98% over 160 days. Stein’s team doesn’t see clear evidence indicating the presence of jets and instead suggests rapid cooling in the disk most likely explains the precipitous drop in X-rays.

Not everyone agrees with this analysis. Another explanation, authored by DESY’s Walter Winter and Cecilia Lunardini, a professor at Arizona State University in Tempe, proposes that the emission came from a jet that was swiftly obscured by a cloud of debris. The researchers published their alternative interpretation in the same issue of Nature Astronomy: https://www.nature.com/articles/s41550-021-01305-3

Image above: The Zwicky Transient Facility captured this snapshot of tidal disruption event AT2019dsg, circled, on Oct. 19, 2019. Image Credits: ZTF/Caltech Optical Observatories.

Astronomers think radio emission in these phenomena comes from the black hole accelerating particles, either in jets or more moderate outflows. Stein’s team thinks AT2019dsg falls into the latter category. The scientists also discovered that the radio emission continued steadily for months and did not fade along with the visible and UV light, as previously assumed.

The neutrino detection, combined with the multiwavelength measurements, prompted Stein and his colleagues to rethink how tidal disruptions might produce high-energy neutrinos.

The radio emission shows that particle acceleration happens even without clear, powerful jets and can operate well after peak UV and visible brightness. Stein and his colleagues suggest those accelerated particles could produce neutrinos in three distinct regions of the tidal disruption: in the outer disk through collisions with UV light, in the inner disk through collisions with X-rays, and in the moderate outflow of particles through collisions with other particles.

Stein’s team suggests AT2019dsg’s neutrino likely originated from the UV-bright outer part of the disk, based on the fact that the particle’s energy was more than 10 times greater than can be achieved by particle colliders.

“We predicted that neutrinos and tidal disruptions could be related, and seeing that for the first time in the data is just very exciting,” said co-author Sjoert van Velzen, an assistant professor at Leiden University in the Netherlands. “This is another example of the power of multimessenger astronomy, using a combination of light, particles, and space-time ripples to learn more about the cosmos. When I was a graduate student, it was often predicted this new era of astronomy was coming, but now to actually be part of it is very rewarding.”

Goddard manages the Swift mission in collaboration with Penn State, the Los Alamos National Laboratory in New Mexico, and Northrop Grumman Innovation Systems in Dulles, Virginia. Other partners include the University of Leicester and Mullard Space Science Laboratory in the United Kingdom, Brera Observatory, and the Italian Space Agency in Italy.

Related links:

Zwicky Transient Facility (ZTF): https://www.ztf.caltech.edu/

Caltech’s Palomar Observatory: https://www.astro.caltech.edu/palomar/homepage.html

National Science Foundation’s IceCube Neutrino Observatory: https://icecube.wisc.edu/

German Electron-Synchrotron (DESY): https://www.desy.de/index_eng.html

Humboldt University: https://www.hu-berlin.de/en?set_language=en

Arizona State University: https://www.asu.edu/

Leiden University: https://www.universiteitleiden.nl/en

Swift: http://www.nasa.gov/mission_pages/swift/main/index.html

Image (mentioned), Video (mentioned), Text, Credits: NASA/Jeanette Kazmierczak/GSFC/Claire Andreoli, by Jeanette Kazmierczak.

Best regards, Orbiter.ch

No sign of Planet Nine? Trail runs cold for hypothetical world

Astrophysics logo.

22 February 2021

Analysis of three astronomical surveys provides some of the best evidence yet against the existence of a giant planet at the fringes of the Solar System.

Image above: The hypothetical ninth planet (illustration). Image Credit: Shutterstock.

Planet Nine is dead; long live Planet Nine? For some years, scientists have debated the existence of an unseen planet at least five times the mass of Earth in the outer reaches of the Solar System. Now, the hypothesis has been dealt a blow by a new analysis of distant, icy objects, which questions the evidence that they are under the gravitational pull of a huge planet.

The findings do not rule out the possibility of a ninth planet orbiting the Sun, and astronomers say more data will be needed to put the debate to rest.

The presence of Planet Nine was proposed (1) in 2016, when astronomers Mike Brown and Konstantin Batygin at the California Institute of Technology in Pasadena observed that the orbits of six trans-Neptunian objects (TNOs) — part of the Kuiper belt, a collection of small bodies orbiting the Sun beyond Neptune — seemed to be clustered together.

This clustering, they said, had to be due to the gravitational influence of a huge planet hiding somewhere in the outer Solar System, at least 400 times as far from the Sun as Earth, or around 10 times as far as the most famous TNO, the dwarf planet Pluto. If proved to exist, the distant world would be a major discovery — a giant beyond Neptune that would unquestionably be classed as a planet.

But not all astronomers were convinced. Other surveys cast doubt on whether TNOs were in fact clustered — or whether they merely appeared to be, because researchers had conducted detailed observations in only certain directions.

A team led by Kevin Napier, a physicist at the University of Michigan in Ann Arbor, has now taken this analysis further. Combining 3 surveys to examine the orbits of 14 ‘extreme’ TNOs (ETNOs) — those orbiting far beyond Neptune — the researchers found that the objects’ orbits could be explained without the presence of a nearby planet. After accounting for selection bias — the fact that researchers have observed only a small portion of the outer Solar System — the data suggest that ETNOs are uniformly distributed across the sky.

“This is the first meta-analysis of all three of the most productive ETNO-discovery surveys,” says Napier. The team’s findings (2) were posted on the preprint server arXiv on 10 February.

Horses, not zebras

To investigate whether the objects were truly clustered, Napier’s team built a computer model simulating ten billion evenly distributed ETNOs in the outer Solar System, and then calculated the chances that observing a small sample of these would produce results matching existing observations. The team concluded that there is no reason to think that ETNOs are not uniformly distributed, and that it’s possible that observed objects only seem to be clustered because of selection bias. “That doesn’t mean that Planet Nine isn’t there, but it’s not necessary to explain the data,” says Napier. “You could fit this data with clustered ETNOs as well — but if you hear hoofbeats, you should think horses, not zebras.”

Brown, however, disagrees. “I plotted all their data on top of our old paper, and you just simply look at it, and it’s very clustered,” he says. “There’s actually strong evidence for Planet Nine in their data.” He points out that the paper does not include the six TNOs that he and Batygin used in their original research. He also argues that the researchers are “mixing dirt in with their ice cream”, because their analysis considers objects whose orbits might be affected by their proximity to Neptune.

Napier says the team didn’t include Brown and Batygin’s original six objects in its analysis because not enough data are available on the surveys that found them earlier this century. “We need to know when and where the telescope pointed, and how faint of an object the telescope was able to detect,” he says. “In the past, surveys did not tend to do that.”

Samantha Lawler, an astronomer at the University of Regina in Canada who worked on the Outer Solar System Origins Survey — one of the surveys that Napier’s team used in its analysis — agrees with the team’s conclusions, arguing that there is no need for Planet Nine when the simpler explanation of selection bias accounts for the data.

“There is no evidence for any sort of clustering in the orbits of these distant TNOs, they’re consistent with being uniformly distributed,” she says. “I can’t say that Planet Nine is dead, but I can say there’s no evidence for it.”

Thousands more objects

Lawler says new surveys of the outer Solar System are needed to look for any other evidence of clustering. One of the best chances will come from the Vera C. Rubin Observatory in Chile, which will begin a ten-year survey of the sky in 2022.

“They’re going to detect thousands more Kuiper belt objects,” says Lawler. “I think we’ve really done all that we can with the data we currently have.”

Even if it turns out Planet Nine isn’t there, Lawler says, it has sparked a lot of useful interest in the outer Solar System from astronomers. “The theory of Planet Nine has been fantastic for the study of the Kuiper belt,” she says.

doi: https://doi.org/10.1038/d41586-021-00456-7

References:

1. Batygin, K. & Brown, M. E. Astron. J. 151, 22 (2016).

2. Napier, K. J. et al. Preprint at https://arxiv.org/abs/2102.05601 (2021).

Image (mentioned), Text, Credits: Nature/Jonathan O'Callaghan.

Greetings, Orbiter.ch

How Were the Trojan Asteroids Discovered and Named?

NASA - LUCY Mission patch.

Feb 22, 2021

On Feb. 22, 1906, German astrophotographer Max Wolf helped reshape our understanding of the solar system. Again.

Born in 1863, Wolf had a habit of dramatically altering the astronomy landscape. Something of a prodigy, he discovered his first comet at only 21 years old. Then in 1890, he boldly declared that he planned to use wide-field photography in his quest to discover new asteroids, which would make him the first to do so. Two years later, Wolf had found 18 new asteroids. He later became the first person to use the “stereo comparator,” a View-Master-like device that showed two photographs of the sky at once so that moving asteroids appeared to pop out from the starry background.

Image above: Illustration of the Lucy mission's seven targets: the binary asteroid Patroclus/Menoetius, Eurybates, Orus, Leucus, Polymele, and the main belt asteroid DonaldJohanson. Image Credits: NASA's Goddard Space Flight Center Conceptual Image Lab.

It is perhaps unsurprising, then, that on Feb. 22, 1906, Wolf made another important discovery: an asteroid with a particularly unusual orbit. As Jupiter moved, this asteroid remained ahead of Jupiter, as though it was somehow trapped in Jupiter’s orbit around the Sun. German astronomer Adolf Berberich observed that the asteroid was nearly 60 degrees in front of Jupiter. This specific position reminded Swedish astronomer Carl Charlier of a peculiar behavior predicted by the Italian-French mathematician Joseph-Louis Lagrange over 100 years earlier. Lagrange argued that if a small body (such as an asteroid) is placed at one of two stable points in a planet’s orbit around the Sun (called the L4 and L5 Lagrange Points), the asteroid would remain stationary from the planet’s perspective due to the combined gravitational forces of the planet and the Sun. Charlier realized that Wolf’s asteroid was actually caught in Jupiter’s L4 Lagrange point. Until Wolf’s discovery, Lagrange’s prediction had only been a mathematical exercise. Now, these astronomers had photographic proof that Lagrange was right.

Eight months later, one of Wolf’s graduate students August Kopff discovered an asteroid in Jupiter’s other stable Lagrange point L5, as well as another asteroid caught in L4 a few months afterward.

Once three of these Lagrange point-inhabiting asteroids had been discovered, astronomers began wondering what to call them. At this point, most asteroids were given the names of women from Roman or Greek mythology, unless their orbits were particularly strange. The asteroids in question certainly had bizarre orbits, so Austrian astronomer Johann Palisa suggested the names Achilles, Patroclus, and Hektor after characters from The Iliad. Achilles was a nigh-invulnerable Greek hero (except for his heel), and Patroclus was a friend of his. Hektor, prince of the Trojans, eventually killed Patroclus, and Achilles exacted revenge by killing Hektor. The recently discovered asteroids were then given Iliad-inspired names.

Jupiter's Trojan Asteroids

Video above: This is a view of the inner solar system in a Jupiter-rotating reference frame. The camera begins at viewpoint oblique to the ecliptic plane, then moves up to a top-down view. Clusters of Trojan asteroids appear behind and ahead of Jupiter in its orbit. Video Credits: NASA's Scientific Visualization Studio.

As astronomers continued discovering asteroids hiding in Jupiter’s Lagrange points, they continued naming them after heroes of the Trojan War and began referring to them as “Trojan asteroids.” (“Trojan asteroids” would eventually refer to asteroids inhabiting any planet’s stable Lagrange points, though names from The Iliad are reserved for Jupiter’s Trojans.) It later became convention to name Jupiter’s L4 asteroids after Greek characters and Jupiter’s L5 asteroids after Trojan characters, so L4 and L5 became the “Greek camp” and the “Trojan camp” respectively. Palisa apparently did not foresee this tradition, for his naming of first three asteroids led to a Greek “spy” residing in the Trojan camp (Patroclus) and a confused Trojan (Hektor) who probably wandered into the Greek camp hoping to order some of their famous custom-built wooden horses.

No spacecraft has ever been to this population of small bodies, called the Trojan asteroids. Now, a new NASA Discovery Program mission called Lucy will fly by seven Trojan asteroids, plus a main belt asteroid, to survey the diversity of this population in a single 12-year record-breaking mission. The Lucy spacecraft launch window opens Oct. 16, 2021.

Lucy Mission Overview: Journey to Explore the Trojan Asteroids

Video above: Launching in late 2021, Lucy will be the first space mission to explore the Trojan asteroids. These are a population of small bodies that are left over from the formation of the solar system. They lead or follow Jupiter in their orbit around the Sun, and may tell us about the origins of organic materials on Earth. Video Credits: NASA's Goddard Space Flight Center.

Southwest Research Institute in Boulder, Colorado, is the principal investigator institution and leads the science investigation. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering, and safety and mission assurance. Lockheed Martin Space Systems in Denver is building the spacecraft. Spacecraft payload is being provided by Goddard, the Johns Hopkins University Applied Physics Lab, and Arizona State University. The Discovery Program management is executed by NASA’s Marshall Space Flight Center in Huntsville, Alabama.

Lucy (Asteroid Mission): https://www.nasa.gov/lucy

Image (mentioned), Videos (mentioned), Text, Credits: NASA/Rob Garner/GSFC/Nancy Neal Jones/Southwest Research Institute, by David Dezell Turner.

Best regards, Orbiter.ch

Fuel for world’s largest fusion reactor ITER is set for test run

Fusion Power Reactor logo.

22 February 2021

Nuclear fusion experiments with deuterium and tritium at the Joint European Torus are a crucial dress rehearsal for the mega-experiment.

Image above: The Joint European Torus has started conducting experiments with tritium fuel. Image Credit: EUROfusion (CC BY 4.0).

A pioneering reactor in Britain is gearing up to start pivotal tests of a fuel mix that will eventually power ITER — the world’s biggest nuclear-fusion experiment. Nuclear fusion is the phenomenon that powers the Sun and, if physicists can harness it on Earth, it would be a source of almost limitless energy.

In December, researchers at the Joint European Torus (JET) started conducting fusion experiments with tritium — a rare and radioactive isotope of hydrogen. The facility is a one-tenth-volume mock-up of the US$22-billion ITER project and has the same doughnut-shaped ‘tokomak’ design— the world's most developed approach to fusion energy. It is the first time since 1997 that researchers have done experiments in a tokamak with any significant amount of tritium.

In June, JET will begin fusing even quantities of tritium and deuterium, another isotope of hydrogen. It is this fuel mix that ITER will use in its attempt to create more power from a fusion reaction than is put in — something that has never before been demonstrated. The reactor should heat and confine a plasma of deuterium and tritium such that the fusion of the isotopes into helium produces enough heat to sustain further fusion reactions.

“It’s very exciting now to, at last, get to the point where we can put into practice what we’ve been preparing all these years,” says Joelle Mailloux, who co-leads the scientific programme at JET. “We’re ready for it.”

Trial run

JET’s experiments will help scientists to predict how the plasma in the ITER tokamak will behave and to craft the mega-experiment’s operating settings. “It’s the closest we can get to achieving ITER conditions in present-day machines,” says Tim Luce, chief scientist at ITER, near Cadarache in France. The experiments are the culmination of around two decade’s work, says Luce. ITER will begin operations with low-power hydrogen reactions in 2025. But from 2035, it will run on a 50:50 mix of deuterium and tritium.

Both ITER and JET, based at the Culham Centre for Fusion Energy (CCFE) near Oxford, use extreme magnetic fields to confine plasma into a ring and heat it until fusion occurs. The temperatures in JET can reach 100 million degrees, many times hotter than the Sun’s core.

ITER fusion reactor tokamak. Animation Credit: ITER

The world’s last tokamak fusion experiments with tritium also took place at JET. The goal then was to hit peak power, and the facility succeeded in achieving a record ratio of power out to power in (known as a Q value) of 0.67. That record still stands today; 1 would be break-even. But this year, the aim is to sustain a similar level of fusion power for 5 seconds or more, to eke out as much data from the experiments as possible and to understand the behaviour of longer-lasting plasmas.

Working with tritium poses unique challenges — JET researchers have spent more than two years refitting elements of their machine and preparing to handle the radioactive material. The isotope decays quickly, so it occurs only in trace amounts in nature and is usually be made as a by-product in nuclear-fission reactors; the world’s supply is just 20 kilograms.

Part of the challenge of handling tritium is that its reactions with deuterium produce neutrons at a much higher rate than deuterium reactions alone. Commercial reactors will capture the energy of these neutrons to generate electricity, but in JET, the high-energy particles will pepper the machine’s interior and damage diagnostic systems. That means that the JET team has had to move cameras and other instruments behind concrete shielding, says Ian Chapman, who leads the CCFE.

“We’ve had to refresh and renew all of our processes”, from storage to handling, Chapman says. Once tritium experiments start, neutron bombardment will make the inner facility radioactive, so it will become a no-go zone for humans for 18 months. Staff have therefore had to get used to a mindset similar to that of the engineers who send craft into space: “You can’t just go in and fix things, it has to work first time,” Chapman says.

Tritium pulses

JET’s campaign will use less than 60 grams of tritium, which it will recycle. Fuel containing a fraction of a gram of tritium will be pulsed into the tokamak 3–14 times a day. Each of these discharges will be an individual experiment with slightly different parameters, and will generate between 3 and 10 seconds of useful data, says Mailloux. “What we are after is physics information that we can use to validate our understanding, and then we can apply that to preparing the future machine,” she says.

Some experiments will use just tritium; others will combine deuterium and tritium in equal proportions. Both types of experiment are important, because a key goal is to understand the effect of tritium’s larger mass on plasma behaviour (tritium has two neutrons in its nucleus, whereas deuterium has one and hydrogen has none). That will help in predicting the impact of using different isotopes in ITER. The mass of the isotopes influences the conditions — such as magnetic field, current, external heating — needed for the plasma to reach a crucial state known as confinement. (In this state, the highest-energy particles remain within the ionized gas, and that is important for sustaining the plasma’s temperature). “We want to explore this and understand why,” says Anne White, a plasma physicist at the Massachusetts Institute of Technology in Cambridge.

Another major difference from the 1997 experiments is that JET has been refitted so that the inner materials that protect the machine against the effects of heat and neutron bombardment, and remove impurities from the plasma, match those in ITER’s design. Because these materials could radiate back into the plasma and cool it down, understanding how they interact with the fusion process is crucial.

The latest generation of fusion scientists has never worked with tritium, which makes it all the more important to do the experiments, says Chapman. “It’s a big deal. People are watching,” adds Luce.

doi: https://doi.org/10.1038/d41586-021-00408-1

Joint European Torus (JET): https://www.euro-fusion.org/devices/jet/

Image (mentioned), Animation (mentioned), Text, Credits: Nature/Elizabeth Gibney.

Greetings, Orbiter.ch

Cygnus Resupply Ship Bolted to Station’s Unity Module

Northrop Grumman - Cygnus NG-15 Mission patch.

Feb. 22, 2021

Image above: Feb. 22, 2021: International Space Station Configuration. Five spaceships are attached to the space station including the SpaceX Crew Dragon, the Northrop Grumman Cygnus cargo craft, and Russia’s Progress 76 and 77 resupply ships and Soyuz MS-17 crew ship. Image Credit: NASA.

The Northrop Grumman Cygnus cargo spacecraft was berthed to the International Space Station’s Earth-facing port of the Unity module at 7:16 a.m. EST Monday morning and subsequently bolted into place. Cygnus will remain at the space station until May, when the spacecraft will depart the station. Following departure, the Cygnus will dispose of several tons of trash during a fiery reentry into Earth’s atmosphere.

NG-15 S.S. Katherine Johnson Cygnus capture

The spacecraft, which launched at 12:36 p.m. EST Saturday, Feb. 20, on an Antares rocket from NASA’s Wallops Flight Facility in Virginia, brings approximately 8,000 pounds of research, hardware, and supplies to the orbiting laboratory to support the Expedition 64 and 65 crews. The Cygnus was captured earlier Monday morning at 4:38 a.m. EST.

NG-15 S.S. Katherine Johnson Cygnus berthing

Highlights of science investigations aboard this Cygnus include:

A new vision

Millions of people on Earth suffer from retinal degenerative diseases. These conditions have no cure, although treatments can slow their progression. Artificial retinas or retinal implants may provide a way to restore meaningful vision for those affected. In 2018, startup LambdaVision sent their first experiment to the space station to determine whether the process used to create artificial retinal implants by forming a thin film one layer at a time may work better in microgravity.

A second experiment by LambdaVision launching on NG CRS-15, Protein-Based Artificial Retina Manufacturing, builds on the first project, evaluating a manufacturing system that uses a light-activated protein to replace the function of damaged cells in the eye. This information may help LambdaVision uncover whether microgravity optimizes production of these retinas, and could assist people back on Earth.

Bringing advanced computing aboard the space station

Due to a need to prioritize reliability over performance, computing capabilities in space are reduced compared to capabilities on the ground, creating challenges when transmitting data to and from space. Although relying on ground-based computers is possible for exploration on the Moon or in low-Earth orbit, this solution will not work for exploration farther into the solar system. Launched in 2017, the SpaceborneComputer study ran a high-performance commercial off-the-shelf computer system in space with the goal of having the system operate seamlessly for one year. It successfully performed more than 1 trillion calculations (or one teraflop) per second for 207 days without requiring reset.

Spaceborne Computer-2 builds on the successes of this first study, exploring how off-the-shelf computer systems can advance exploration by processing data significantly faster in space with edge computing and artificial intelligence (AI) capabilities. This experiment plans to demonstrate that Earth-based data processing of current station science data can instead be performed on station. Eliminating the need for researchers to send all raw data back to Earth for analysis could speed scientists’ time-to-insight from months to minutes.

Space worms to the rescue

Tiny worms could help us determine the cause of muscle weakening that astronauts can experience in microgravity. Astronauts work out more than two hours a day aboard the space station to prevent bone and muscle loss caused by living in a microgravity environment during long-duration missions. Thanks to a new device for measuring the muscle strength of tiny C. elegans worms, researchers with the Micro-16 study can test whether decreased expression of muscle proteins is associated with this decreased strength. The device consists of a small microscope slide filled with little rubber pillars. The strength of the worms is measured by how much force the worms apply to the pillars as they move around the slide.

Preparing for the Moon

The International Space Station serves as a testing ground for technologies we plan to use on future Artemis missions to the Moon. The NASA A-HoSS investigation puts to the test tools planned for use on the crewed Artemis II mission that will orbit the Moon. Built as the primary radiation detection system for the Orion spacecraft, the Hybrid Electronic Radiation Assessor (HERA) was modified for operation on the space station.

Image above: The Northrop Grumman Cygnus resupply ship is pictured about 30 meters away from the space station approaching its capture point near the Canadarm2 robotic arm. Image Credit: NASA TV.

Verifying that HERA can operate without error for 30 days validates the system for crewed Artemis mission operations. A related investigation, ISS HERA, flew in 2019 aboard the space station. ISS HERA provided data and operational feedback in preparation for the Orion spacecraft’s uncrewed Artemis I mission that will launch in 2021.

Related link:

Cygnus Spaceship Lifts Off to Resupply Station on Monday
https://orbiterchspacenews.blogspot.com/2021/02/cygnus-spaceship-lifts-off-to-resupply.html

Related links:

Expedition 64: https://www.nasa.gov/mission_pages/station/expeditions/expedition64/index.html

Protein-Based Artificial Retina Manufacturing: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=8377

SpaceborneComputer: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=2037

Spaceborne Computer-2: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=8221

Micro-16: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7654

A-HoSS: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=8234

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

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

Images (mentioned), Videos, Text, Credits: NASA/Mark Garcia/NASA TV/SciNews.

Best regards, Orbiter.ch

dimanche 21 février 2021

Space Station Science Highlights: Week of February 15, 2021

ISS - Expedition 64 Mission patch.

Feb 21, 2021

Scientific investigations conducted aboard the International Space Station the week of Feb. 15 included studies of flame spread in confined spaces, direct RNA sequencing from tissue samples, and acoustic monitoring of equipment. Crew members finalized preparations for the arrival of new supplies and scientific experiments aboard the NG-15 cargo craft, scheduled to launch Feb. 20.

Image above: This oblique view of Mount Ararat in eastern Turkey was taken as the International Space Station orbited 262 miles above Iran just south of the Caspian Sea. Image Credit: Roscosmos.

The seven crew members currently inhabiting the station include four from NASA’s Commercial Crew Program, providing increased crew time for science activities on the orbiting lab. The space station has been continuously inhabited by humans for 20 years and has supported many scientific breakthroughs during that time. The station provides a platform for long-duration research in microgravity and for learning to live and work in space, experience that supports Artemis, NASA’s program to go forward to the Moon and on to Mars.

Here are details on some of the microgravity investigations currently taking place:

Examining the behavior of flames

Image above: This fabric sample was part of operations for the Confined Combustion investigation, which examines flame spread in differently-shaped confined spaces in microgravity. Image Credit: NASA.

The crew installed hardware for the Confined Combustion investigation and conducted a flame test. This investigation examines the behavior of flames as they spread in differently-shaped spaces in microgravity, including the interactions between spreading flames and surrounding walls. Flame spread in confined spaces such as a spacecraft may pose a more serious fire hazard than in open spaces because heat radiating from the walls and flow conditions can accelerate flames. Observations from this investigation can be translated into mathematical models to help designers and planners anticipate fire behavior and create plans for preventing or extinguishing fires effectively in space.

Reading radish RNA

Animation above: NASA astronaut Kate Rubins works on the One-Step Gene Sampling Tool investigation, which uses radish samples to test a technology for genetic analysis of ribonucleic acid (RNA) directly from tissue. Animation Credit: NASA.

During the week, the crew set up hardware and performed analysis on a radish harvested from the station’s Advanced Plant Habitat for One-Step Gene Sampling Tool. This investigation tests a technology that collects ribonucleic acid (RNA) directly from tissue, enabling quick genetic analysis of multiple samples without the need to destroy the specimen. These brief and repeatable screenings could help researchers make more informed decisions about plant and animal growth investigations as well as extract a full genetic library from these organisms.

Listening in on equipment

Image above: An audio sensor for the SoundSee investigation floats in the space station. SoundSee tests using these sensors on the Astrobee robotic platforms to monitor the station’s acoustic environment, which can provide early indication of equipment failure. Image Credit: NASA.

SoundSee tests a way to monitor the space station’s acoustic environment using monitors attached to free-flying Astrobee robots. Autonomous audio monitoring could detect equipment malfunction based on sound anomalies, helping to protect the health and safety of crew members by keeping equipment in good working order and reducing crew workload. During the week, crew members installed SoundSee onto an Astrobee and performed recordings.

Other investigations on which the crew performed work:

- VECTION, a Canadian Space Agency investigation, determines to what extent microgravity disrupts an astronaut's ability to visually interpret motion, orientation, and distance as well as how those abilities may adapt in space and change again upon return to Earth.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7484

- Time Perception, an ESA (European Space Agency) experiment, quantifies the subjective changes in time perception that humans experience during and after long-duration spaceflight.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7504

- Plant Water Management tests using concepts of capillary fluidics such as surface tension, wetting, and geometry to deliver adequate water and nutrients to plants.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7884

- The 3D Microbial Monitoring investigation conducts a series of sample collections and uses DNA sequencing and other analyses to construct a three dimensional map of bacteria and bacterial products on surfaces in the space station.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=8345

- Bacterial Adhesion and Corrosion tests an antimicrobial coating on materials used to represent typical surfaces on the space station, which could provide insight into better ways to control and remove resistant biofilms for long-duration spaceflight.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7956

- Antimicrobial Coatings tests a coating to control microbial growth on several different materials that represent high-touch surfaces. Some microbes change characteristics in microgravity, potentially creating new risks to crew health and spacecraft.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=8352

- Food Physiology characterizes how an enhanced spaceflight diet affects immune function, the gut microbiome, and nutritional status. Results could help define targeted, efficient dietary interventions to maintain crew health and performance.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7870

- APM measures and quantifies the concentration of both small and large particles in cabin air as part of efforts to maintain air quality in the occupied environment on station, vital for the crew’s health.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7936

- AstroRad Vest tests a wearable vest designed to protect astronauts from radiation caused by unpredictable solar particle events. Astronauts provide input on how easy the garment is to put on, how it fits and feels, and the range of motion it allows.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7803

- The ISS Experience is creating an immersive virtual reality (VR) series documenting life and research aboard the space station using customized 360-degree cameras.
https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7877

International Space Station (ISS). Animation Credit: ESA

Best regards, Orbiter.ch