vendredi 8 décembre 2017

NASA Explores Artificial Intelligence for Space Communications










NASA - SCaN Mission patch.

Dec. 8, 2017

NASA spacecraft typically rely on human-controlled radio systems to communicate with Earth. As collection of space data increases, NASA looks to cognitive radio, the infusion of artificial intelligence into space communications networks, to meet demand and increase efficiency.

“Modern space communications systems use complex software to support science and exploration missions,” said Janette C. Briones, principal investigator in the cognitive communication project at NASA’s Glenn Research Center in Cleveland, Ohio. “By applying artificial intelligence and machine learning, satellites control these systems seamlessly, making real-time decisions without awaiting instruction.”

To understand cognitive radio, it’s easiest to start with ground-based applications. In the U.S., the Federal Communications Commission (FCC) allocates portions of the electromagnetic spectrum used for communications to various users. For example, the FCC allocates spectrum to cell service, satellite radio, Bluetooth, Wi-Fi, etc. Imagine the spectrum divided into a limited number of taps connected to a water main.


Image above: his photo was taken of NASA's Space Communications and Navigation Testbed before launch. Currently affixed to the International Space Station, the SCaN Testbed is used to conduct a variety of experiments with the goal of further advancing other technologies, reducing risks on other space missions, and enabling future mission capabilities. Image Credit: NASA.

What happens when no faucets are left? How could a device access the electromagnetic spectrum when all the taps are taken?

Software-defined radios like cognitive radio use artificial intelligence to employ underutilized portions of the electromagnetic spectrum without human intervention. These “white spaces” are currently unused, but already licensed, segments of the spectrum. The FCC permits a cognitive radio to use the frequency while unused by its primary user until the user becomes active again.

In terms of our metaphorical watering hole, cognitive radio draws on water that would otherwise be wasted. The cognitive radio can use many “faucets,” no matter the frequency of that “faucet.” When a licensed device stops using its frequency, cognitive radio draws from that customer’s “faucet” until the primary user needs it again. Cognitive radio switches from one white space to another, using electromagnetic spigots as they become available.

“The recent development of cognitive technologies is a new thrust in the architecture of communications systems,” said Briones. “We envision these technologies will make our communications networks more efficient and resilient for missions exploring the depths of space. By integrating artificial intelligence and cognitive radios into our networks, we will increase the efficiency, autonomy and reliability of space communications systems.”

For NASA, the space environment presents unique challenges that cognitive radio could mitigate. Space weather, electromagnetic radiation emitted by the sun and other celestial bodies, fills space with noise that can interrupt certain frequencies.


Image above: The SCaN Testbed payload aboard the space station. In April 2013, it began conducting experiments after completing its checkout and commissioning operations. Image Credit: NASA.

“Glenn Research Center is experimenting in creating cognitive radio applications capable of identifying and adapting to space weather,” said Rigoberto Roche, a NASA cognitive engine development lead at Glenn. “They would transmit outside the range of the interference or cancel distortions within the range using machine learning.”

In the future, a NASA cognitive radio could even learn to shut itself down temporarily to mitigate radiation damage during severe space weather events. Adaptive radio software could circumvent the harmful effects of space weather, increasing science and exploration data returns.

A cognitive radio network could also suggest alternate data paths to the ground. These processes could prioritize and route data through multiple paths simultaneously to avoid interference. The cognitive radio’s artificial intelligence could also allocate ground station downlinks just hours in advance, as opposed to weeks, leading to more efficient scheduling.

Additionally, cognitive radio may make communications network operations more efficient by decreasing the need for human intervention. An intelligent radio could adapt to new electromagnetic landscapes without human help and predict common operational settings for different environments, automating time-consuming processes previously handled by humans.

The Space Communications and Navigation (SCaN) Testbed aboard the International Space Station provides engineers and researchers with tools to test cognitive radio in the space environment. The testbed houses three software-defined radios in addition to a variety of antennas and apparatus that can be configured from the ground or other spacecraft.

“The testbed keeps us honest about the environment in orbit,” said Dave Chelmins, project manager for the SCaN Testbed and cognitive communications at Glenn. “While it can be simulated on the ground, there is an element of unpredictability to space. The testbed provides this environment, a setting that requires the resiliency of technology advancements like cognitive radio.”

Chelmins, Rioche and Briones are just a few of many NASA engineers adapting cognitive radio technologies to space. As with most terrestrial technologies, cognitive techniques can be more challenging to implement in space due to orbital mechanics, the electromagnetic environment and interactions with legacy instruments. In spite of these challenges, integrating machine learning into existing space communications infrastructure will increase the efficiency, autonomy and reliability of these systems.

The SCaN program office at NASA Headquarters in Washington provides strategic and programmatic oversight for communications infrastructure and development. Its research provides critical improvements in connectivity from spacecraft to ground.

For more information about SCaN, visit:  http://www.nasa.gov/scan

The Space Communications and Navigation (SCaN) Testbed: https://www.nasa.gov/directorates/heo/scan/engineering/technology/txt_scantestbed.html

High-Tech Computing: https://www.nasa.gov/topics/technology/high-tech-computing/index.html

NASA’s Glenn Research Center: https://www.nasa.gov/centers/glenn/home/index.html

Images (mentioned), Text, Credits: NASA’s Space Communications and Navigation Program Office, by Danny Baird/Rob Garner.

Best regards, Orbiter.ch

Heads Up, Earthlings! The Geminids Are Here










Asteroid Watch logo.

Dec. 8, 2017

2017 Geminids Will Be Dazzling!

Maybe you've already seen a bright meteor streak across the December sky? The annual Geminid meteor shower has arrived. It's a good time to bundle up, go outside and let the universe blow your mind!

"With August's Perseids obscured by bright moonlight, the Geminids will be the best shower this year," said Bill Cooke with NASA's Meteoroid Environment Office. "The thin, waning crescent Moon won't spoil the show."

The shower will peak overnight Dec. 13-14 with rates around one per minute under good conditions, according to Cooke. Geminids can be seen on nights before and after the Dec. 14 peak, although they will appear less frequently.

"Geminid activity is broad," said Cooke. "Good rates will be seen between 7:30 p.m. on Dec. 13 and dawn local time the morning of Dec. 14, with the most meteors visible from midnight to 4 a.m. on Dec. 14, when the radiant is highest in the sky."

About the Geminid Shower

The Geminids are active every December, when Earth passes through a massive trail of dusty debris shed by a weird, rocky object named 3200 Phaethon. The dust and grit burn up when they run into Earth's atmosphere in a flurry of "shooting stars."

"Phaethon's nature is debated," said Cooke. "It's either a near-Earth asteroid or an extinct comet, sometimes called a rock comet."

As an added bonus this year, astronomers will have a chance to study Phaethon up close in mid-December, when it passes nearest to Earth since its discovery in 1983.

Geminid Shower

Meteor showers are named after the location of the radiant, usually a star or constellation close to where they appear in the night sky. The Geminid radiant is in the constellation Gemini.

The Geminids can be seen with the naked eye under clear, dark skies over most of the world, though the best view is from the Northern Hemisphere. Observers will see fewer Geminids in the Southern Hemisphere, where the radiant doesn't climb very high over the horizon.

Observing the Geminids

Skywatching is easy. Just get away from bright lights and look up in any direction! Give your eyes time to adjust to the dark. Meteors appear all over the sky.

Not all the meteors you might see belong to the Geminid shower, however. Some might be sporadic background meteors, and some might be from weaker, active showers like the Monocerotids, Sigma Hydrids and the Comae Berenicids.

"When you see a meteor, try to trace it backwards," said Cooke. "If you end up in the constellation Gemini there's a good chance you've seen a Geminid."

Learn More about the Geminids

Cooke and other meteor experts from NASA's Meteoroid Environment Office will be live on Facebook to discuss the Geminids and why meteors and meteoroids are important to NASA beginning at 8 p.m. EST on Dec. 12.

And if it's cloudy where you are, NASA will broadcast the Geminid shower live via Ustream starting at sunset Dec. 13 from the Automated Lunar and Meteor Observatory at NASA's Marshall Space Flight Center in Huntsville, Alabama: http://www.ustream.tv/channel/nasa-msfc

You can also see Geminid meteors on NASA’s All Sky Fireball network page. Follow NASA Meteor Watch on Facebook for information about meteor showers and fireballs throughout the year.

Related links:

NASA's Meteoroid Environment Office: https://www.nasa.gov/offices/meo/home/index.html

NASA’s All Sky Fireball network page: https://fireballs.ndc.nasa.gov/

Facebook: https://www.facebook.com/NasaMeteorWatch/?fref=ts

Meteors & Meteorites: http://www.nasa.gov/topics/solarsystem/features/watchtheskies/index.html

Image, Video, Text, Credits: NASA/Lee Mohon/Marshall Space Flight Center/Molly Porter.

Greetings, Orbiter.ch

The Pilatus PC-24 authorized in Europe and the United States






Pilatus Aircraft Ltd logo.

Dec 8, 2017

Pilatus PC-24

The Pilatus business jet will fly in January across the Atlantic to be handed over to the first customers.

The way is free for the first deliveries to customers of the Pilatus business jet, the PC-24. The aircraft has obtained permission from European and US authorities.

The first PC-24 can now be received this month by the US airline sharing company PlaneSense. In January, the jet will then fly to the United States and will be handed over to customers. In total, 23 of the 84 PC-24 ordered will be delivered in January to customers around the world.

Pilatus PC-24

"We took a big risk with this project, but we all believed without compromise in PC-24 and worked to the limit of the bearable for its success," noted in the statement Oscar Schwenk, chairman of the board of Pilatus. "Certification is now the reward for our tireless efforts for many years," he added.

The requirements to certify such an aircraft are extremely high and have represented great challenges for Pilatus, writes the company. The goal of completing the PC-24 development project in 2017 was achieved shortly before the end of the year.

More than a decade of work

The prototypes flew 2205 hours worldwide for the certification program, in extreme conditions such as freezing cold, high heat, high altitude and speed limit. Added to this were tests like bird strikes.

Characteristics

Pilatus had presented the project publicly for the first time four years ago. Internally, work around the Super Versatile Jet had begun eleven and a half years ago, explains the company.

Pilatus has invested more than 500 million francs in the project. To this is added another 150 million francs engaged in buildings and modern production machinery, as well as investments in the United States in a new factory dedicated to the final stages of production.

PC-12 NG and PC-24 fly to NBAA 2017

The PC-24 is the first jet model produced by Pilatus. It offers up to ten seats depending on the options chosen and has a range of 3600 kilometers. 17 meters long, this business jet can reach 815 km / h, and take off or land on both short sandy and dirt tracks.

Pilatus Aircraft Ltd: https://www.pilatus-aircraft.com/en

Images, Video, Text, Credits: Pilatus Aircraft Ltd/ATS/Orbiter.ch Aerospace/Roland Berga.

Best regards, Orbiter.ch

JPL Deploys a CubeSat for Astronomy












JPL - Jet Propulsion Laboratory logo.

December 8, 2017


Image above: A JPL CubeSat named ASTERIA was deployed from the International Space Station on November 21. It will test the use of CubeSats for astronomy research. Image Credits: NASA/JPL-Caltech.

Tiny satellites called CubeSats have attracted a lot of attention in recent years. Besides allowing researchers to test new technologies, their relative simplicity also offers hands-on training to early-career engineers.

A CubeSat recently deployed from the International Space Station is a key example of their potential, experimenting with CubeSats applied to astronomy.

For the next few months, a technology demonstration called ASTERIA (Arcsecond Space Telescope Enabling Research in Astrophysics) will test whether a CubeSat can perform precise measurements of change in a star's light. This fluctuation is useful for a number of commercial and astrophysics applications, including the discovery and study of planets outside of our solar system, known as exoplanets.

ASTERIA was developed under the Phaeton Program at NASA's Jet Propulsion Laboratory in Pasadena, California. Phaeton was developed to provide early-career hires, under the guidance of experienced mentors, with the challenges of a flight project. ASTERIA is a collaboration with the Massachusetts Institute of Technology in Cambridge; MIT's Sara Seager is principal investigator on the project.

A New Space Telescope Model

ASTERIA relies on precision photometry, a field that measures the flux, or intensity, of an object's light. To be useful to any scientist, a space telescope has to correct for internal sources of error while making these measurements.

Engineers have learned to correct for "noise" in much larger space telescopes. If they were able to do the same for CubeSats, it could open an entirely new class of astronomy tools.


Image above: Electrical Test Engineer Esha Murty (left) and Integration and Test Lead Cody Colley (right) prepare the ASTERIA spacecraft for mass properties measurements in April 2017 prior to spacecraft delivery. Image Credits: NASA/JPL-Caltech.

"CubeSats offer a relatively inexpensive means to test new technologies," said Amanda Donner of JPL, mission assurance manager for ASTERIA. "The modular design of CubeSats also makes them customizable, giving even a small group of researchers and students access to space."

She said it's even possible for constellations of these CubeSats to work in concert, covering more of the cosmos at one time.

A Steady Astronomy Camera

Its small size requires ASTERIA to have unique engineering characteristics.

- A steady astronomy camera will keep the telescope locked on a specific star for up to 20 minutes continuously as the spacecraft orbits Earth.

- An active thermal control system will stabilize temperatures within the tiny telescope while in Earth's shadow. This helps to minimize "noise" caused by shifting temperatures - essential when the measurement is trying to detect slight variations in the target star's light.

Both technologies proved challenging to miniaturize.

"One of the biggest engineering challenges has been fitting the pointing and thermal control electronics into such a small package," said JPL's Matthew Smith, ASTERIA's lead systems engineer and mission manager. "Typically, those components alone are larger than our entire spacecraft. Now that we've miniaturized the technology for ASTERIA, it can be applied to other CubeSats or small instruments."

Though it's only a technology demonstration, ASTERIA might point the way to future CubeSats useful to astronomy.

That's impressive, especially considering it was effectively a training project: many team members only graduated from college within the last five years, Donner said.

"We designed, built, tested and delivered ASTERIA, and now we're flying it," she said. "JPL takes the training approach of learning-by-doing seriously."

Caltech in Pasadena, California, manages JPL for NASA.

For more information about ASTERIA, visit: https://www.jpl.nasa.gov/cubesat/missions/asteria.php

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

Images (mentioned), Text, Credits: NASA/JPL/Andrew Good.

Greetings, Orbiter.ch

jeudi 7 décembre 2017

Crews Prepare to Swap Places as Station Eyes California Wildfires












ISS - Expedition 53 Mission patch.

Dec. 7, 2017


Image above: Expedition 53 Commander Randy Bresnik aboard the International Space Station took this photo of the California wildfires in the Los Angeles on Dec. 6, 2017. Image Credits: NASA/Randy Bresnik.

Two International Space Station crews are preparing to swap places at the orbital lab next week. In the midst of the crew swap activities, Commander Randy Bresnik also sent down dramatic photographs of the wildfires in California.

The Expedition 52-53 trio is getting its Soyuz MS-05 spacecraft ready for a three-and-a-half hour ride back to Earth on Dec. 14 after 139 days in space. Sergey Ryazanskiy, the Soyuz Commander, will lead his crewmates Randy Bresnik of NASA and Paolo Nespoli of the European Space Agency to a parachuted landing on the steppe Kazakhstan.

Next, the Expedition 54-55 trio will blast off Dec. 17 aboard the Soyuz MS-07 spacecraft and take a two-day trip to its new home in space. Anton Shkaplerov, a veteran cosmonaut from Roscosmos, will lead the flight to the station flanked by first-time astronauts Scott Tingle of NASA and Norishige Kanai of the Japan Aerospace Exploration Agency.


Image above: At the Gagarin Cosmonaut Training Center in Star City, Russia, Expedition 54-55 prime crewmembers Scott Tingle of NASA (left) Anton Shkaplerov of the Russian Federal Space Agency (Roscosmos, center) and Norishige Kanai of the Japan Aerospace Exploration Agency (JAXA, right) pose for pictures Nov. 29 in front of a Soyuz spacecraft simulator as part of their final crew qualification exam activities. Image Credits: NASA/Elizabeth Weissinger.

Back on orbit, Bresnik shared pictures he took on social media of the wildfires threatening the greater Los Angeles area in southern California. He wrote on his Twitter account, “Thank you to all the first responders, firefighters, and citizens willing to help fight these California wildfires.”
https://twitter.com/AstroKomrade/status/938565975636508672

More wildfire photos can be viewed on the NASA portal and Flickr:
https://www.nasa.gov/mission_pages/fires/main/usa/index.html
https://www.flickr.com/photos/nasa2explore/sets/72157689311279611

Rlated links:

Expedition 53: https://www.nasa.gov/mission_pages/station/expeditions/expedition53/index.html

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

NASA/Mark Garcia.

Herschel data links mysterious quasar winds to furious starbursts












ESA - Herschel Mission patch.

07 December 2017

Since their discovery in the 1960s quasars have provided a treasure trove of questions for astronomers to answer. These energetic sources – up to 10 000 times brighter than the Milky Way – are the nuclei of distant galaxies with supermassive black holes at their heart. As gas is pulled into an accretion disc towards the black hole it heats to very high temperatures and radiates energy across the electromagnetic spectrum from radio to X-rays – in this way the signature luminosity of the quasar is born.


Image above: Artist's impression of radio-loud quasar in star-forming galaxy. Image Credit: ESA/C. Carreau.

For five decades, astronomers have studied the spectra of quasars to uncover the origin of the electromagnetic radiation they emit and to trace the path the light has traversed to reach us.

A valuable tool in understanding this journey are the absorption lines in the quasars' radiation spectra. These lines indicate the wavelength ranges which have been absorbed as the radiation travelled from source to observer, giving clues to the material it passed through. Over time, the study of these lines has traced the composition of galaxies and gas clouds that lie between us and these distant luminous objects, but one set of absorption lines has remained unexplained.

Astronomers have observed absorption lines in many quasars that are indicative of absorption en route by cool gas with heavy metal elements like carbon, magnesium and silicon. The lines signal that the light has travelled through winds of cold gas travelling at speeds of thousands of kilometres per second within the quasars' host galaxies. Whilst knowledge that these winds exist is nothing new their origin, and why they are able to reach such impressive speeds, has remained an unknown.

Now, astronomer Peter Barthel and his PhD student Pece Podigachoski, both from the Groningen University Kapteyn Institute, together with colleagues Belinda Wilkes from the Harvard-Smithsonian Center for Astrophysics (USA) and Martin Haas at Ruhr-Universität Bochum (Germany) have shed light on the cold winds' origins. Using data obtained with ESA's Herschel Space Observatory the astronomers have shown, for the first time, that the strength of the metal absorption lines associated with these mysterious gas winds is directly linked to the rate of star formation within the quasar host galaxies. In finding this trend the astronomers are able to say with some confidence that prodigious star formation within the host galaxy may be the mechanism driving these mysterious and powerful winds.


Image above: The Herschel Space Observatory. Image Credit: ESA/Herschel/NASA/JPL-Caltech; acknowledgement T. Pyle & R. Hurt (JPL-Caltech).

"Identifying this tendency for prolific star formation to be closely related to powerful quasar winds is an exciting find for us," explains Pece Podigachoski. "A natural explanation for this is that the winds are starburst driven and produced by supernovas – which are known to occur with great frequency during periods of extreme star formation."

This new connection not only solves one puzzle about quasars but may also contribute to unravelling an even bigger mystery: why does the size of galaxies observed in our Universe appear to be capped in practice, although not in theory.

"Aside from the question of which processes are responsible for the gas winds, their net effect is a very important topic in today's astrophysics," explains Peter Barthel. "Although theories predict that galaxies can grow very large, ultra-massive galaxies have not been observed. It appears that there is a process which acts as a brake on the formation of such galaxies: internal gas winds for example could be responsible for this so-called negative feedback."

Theory predicts that galaxies should be able to grow to masses a hundred times larger than any ever observed. The fact that there is a deficit of behemoths in the Universe implies that there is a process depleting galaxies' gas reserves before they are able to reach their full potential. There are two mechanisms likely to lead to this depletion of gas: the first is the supernova winds associated with starbursts, the second, the winds associated with the supermassive black hole at the heart of every quasar. Although both mechanisms are likely to play a role, the evidence of correlation between cold gas winds and star formation rate found by this team suggests that in the case of quasars, star formation, which requires a steady supply of cold gas, may be the key culprit in sapping the galaxy of gas and supressing its ability to grow the next generation of stars.

"This is an important result for quasar science, and one that relied on the unique capabilities of Herschel," explains Göran Pilbratt, Herschel Project Scientist at ESA. "Herschel observes light in the far infrared and submillimetre enabling the detailed knowledge of the star formation rate in the galaxies observed that was needed to make this discovery."

More information:

The results described here are reported in "Starburst-driven Superwinds in Quasar Host Galaxies" by Peter Barthel, Pece Podigachoski, Belinda Wilkes, and Martin Haas, published in The Astrophysical Journal Letters, V843, No. 1, 2017; doi: 10.3847/2041-8213/aa7631 https://dx.doi.org/10.3847/2041-8213/aa7631

Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Herschel was launched on 14 May 2009 and completed science observations on 29 April 2013.

All Herschel data can be accessed from the Herschel Science Archive at http://archives.esac.esa.int/hsa/whsa/

For more information about Heschel: http://sci.esa.int/herschel/

Images (mentioned), Text, Credits: ESA/Göran Pilbratt/University of Groningen/Peter Barthel.

Greetings, Orbiter.ch

mercredi 6 décembre 2017

NASA Mars Rover Team's Tilted Winter Strategy Works











NASA - Mars Exploration Rover B (MER-B) patch.

December 6, 2017

NASA's senior Mars rover, Opportunity, has just passed the shortest-daylight weeks of the long Martian year with its solar panels in encouragingly clean condition for entering a potential dust-storm season in 2018.

Before dust season will come the 14th Earth-year anniversaries of Mars landings by the twin rovers Spirit and Opportunity in January 2004. Their missions were scheduled to last 90 Martian days, or sols, equivalent to about three months.

 View From Within 'Perseverance Valley' on Mars

Image above: This view from within "Perseverance Valley," on the rim of Endurance Crater, includes wheel tracks from the Opportunity Mars rover's descent of the valley to investigate its origin. The rover's Pancam took component images in September and October of 2017 for this approximately true-color scene. Image Credits: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.

"I didn't start working on this project until about Sol 300, and I was told not to get too settled in because Spirit and Opportunity probably wouldn't make it through that first Martian winter," recalls Jennifer Herman, power subsystem operations team lead for Opportunity at NASA's Jet Propulsion Laboratory in Pasadena, California. "Now, Opportunity has made it through the worst part of its eighth Martian winter."

The minimum-sunlight period for southern Mars this year was in October and November. Mars takes 1.88 Earth years to orbit the Sun and, like Earth, it has a tilted axis, so it gets seasons resembling Earth's but nearly twice as long.

Both Opportunity and Spirit are in Mars' southern hemisphere, where the Sun appears in the northern sky during fall and winter, so solar-array output is enhanced by tilting the rover northward. Spirit could not maintain enough energy to survive through its fourth Martian winter, in 2009, after losing use of two wheels, long past their planned lifetime. It became unable to maneuver out of a sand trap to the favorable northward tilt.

Opportunity's View Downhill Catches Martian Shadows

Image above: Late-afternoon shadows include one cast by the rover itself in this look toward the floor of Endeavour Crater by NASA's Mars Exploration Rover Opportunity. The rover's Navcam recorded the three component images on Nov. 11, 2017, about a week before Opportunity's eighth Martian winter solstice. Image Credits: NASA/JPL-Caltech.

Opportunity's current exploration of fluid-carved "Perseverance Valley" positioned it well for working productively through late fall and early winter this year. The rover has used stops at energy-favorable locations to inspect local rocks, examine the valley's shape and image the surroundings from inside the valley.

The valley runs downhill eastward on the inner slope of the western rim of Endurance Crater, which is 14 miles (22 kilometers) in diameter. Since entering the top of the valley five months ago, Opportunity's stops between drives have been at north-facing sites, on the south edge of the channel. The rover team calls the sites "lily pads" and plans routes from each one safely to the next, like a frog hopping from lily pad to lily pad.

Herman's role includes advising others on the team how much energy is available each sol for activities such as science observations and driving. "Relying on solar energy for Opportunity keeps us constantly aware of the season on Mars and the terrain that the rover is on, more than for Curiosity," she said. She performs the same role for NASA's younger Mars rover, Curiosity, which gets its electrical energy from a radioisotope thermoelectric generator instead of solar panels. Wintertime conditions affect use of electrical heaters and batteries on both rovers, but influence Opportunity's activities much more than Curiosity's.

Opportunity has not always been on such suitable terrain for winter operations. In its fifth winter, in 2011-2012, it spent 19 weeks at one spot because no other places with favorable tilt were within acceptable driving distance. In contrast, it kept busy its first winter in the southern half of a stadium-size crater, where all of the ground faced north.


Image above: This enhanced-color view of ground sloping downward to the right in "Perseverance Valley" shows textures that may be due to abrasion by wind-driven sand. The Pancam on NASA's Mars rover Opportunity's imaged this scene in October 2017. Image Credits: NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.

Besides tilt and daylight length, other factors in Opportunity's power status include how much dust is on the solar array and in the sky. Wind can clean some dust off the array, but can also stir up dust storms that block sunlight and then drop dust onto the rover. Southern-hemisphere autumn and winter tend to have clear skies over Opportunity, but the amount of dust on the solar array going into autumn has varied year-to-year, and this year the array was dustier than in all but one of the preceding autumns.

"We were worried that the dust accumulation this winter would be similar to some of the worst winters we've had, and that we might come out of the winter with a very dusty array, but we've had some recent dust cleaning that was nice to see," Herman said. "Now I'm more optimistic. If Opportunity's solar arrays keep getting cleaned as they have recently, she'll be in a good position to survive a major dust storm. It's been more than 10 Earth years since the last one and we need to be vigilant."

Mars Exploration Rover (MER). Image Credits: NASA/JPL-Caltech

Planet-encircling dust storms are most likely in southern spring and summer on Mars, though these storms don't happen every Martian year. The latest such storm, in 2007, sharply reduced available sunlight for Spirit and Opportunity, prompting emergency cutbacks in operations and communications to save energy. Some atmospheric scientists anticipate that Mars may get its next planet-encircling dust storm in 2018.

In coming months, scientists and engineers plan to continue using Opportunity to investigate how Perseverance Valley was cut into the crater rim. "We have not been seeing anything screamingly diagnostic, in the valley itself, about how much water was involved in the flow," said Opportunity Project Scientist Matt Golombek, of JPL. "We may get good diagnostic clues from the deposits at the bottom of the valley, but we don't want to be there yet, because that's level ground with no more lily pads."

For more information about Opportunity, visit:

https://www.nasa.gov/rovers

https://marsrovers.jpl.nasa.gov

Images (mentioned), Text, Credits: NASA/Laurie Cantillo/Dwayne Brown/JPL/Guy Webster.

Greetings, Orbiter.ch

NASA’s CATS Concludes Successful Mission on Space Station












ISS - International Space Station patch.

Dec. 6, 2017


Image above: This image shows an example of cloud and aerosol data taken by CATS. Image Credit: NASA's Goddard Space Flight Center.

A spaceborne lidar instrument that fired more laser pulses than any previous orbiting instrument has ended its operations on the International Space Station, after a successful 33-month mission to measure clouds and tiny atmospheric particles that play key roles in Earth's climate and weather.

During its mission, NASA’s Cloud-Aerosol Transport System (CATS) lidar provided measurements of the vertical structure of clouds and aerosols, including volcanic eruptions, man-made pollution in China and India, smoke from wildfires in North America and dust storms in the Middle East. The CATS data products are freely available to the science community and have already been cited in numerous research studies as well as at national and international scientific conferences.

The CATS measurements enabled more accurate aerosol modeling and forecasting and improved tracking and forecasting of volcanic plumes and associated costly aviation hazards. It also advanced our understanding of aerosol proximity to clouds, which is critically important to predicting the effects of cloud-aerosol interaction on the Earth's climate system.

CATS was funded by the International Space Station Program to advance the use of the orbiting laboratory as a platform for Earth science research. CATS helped pave the way for future low-cost missions to the station and advanced laser technology designed to measure clouds and aerosols.


Image above: CATS observed part of a plume streaming on July 11, 2015 from the Raung Volcano on the Indonesian island of Java. The top image was taken by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite. The red line shows where, less than an hour after Suomi NPP passed over, CATS scanned a vertical slice through the atmosphere (bottom image). CATS observed this plume after dark, even though other spaceborne instruments did not detect the plume at nighttime. Image Credit: NASA's Earth Observatory.

"The CATS project was a spectacular opportunity to provide first-of-its-kind science from the space station. CATS was an amazing combination of enterprising science pathfinder, technology demonstration and programmatic forcing function," said Matt McGill, CATS principal investigator at NASA's Goddard Space Flight Center, Greenbelt, Maryland. "The CATS payload operated for more than 200 billion laser pulses - an unprecedented achievement for a spaceborne lidar."

Launched on Jan. 10, 2015, CATS was designed to operate at least six months, but lasted five times its life expectancy. On Oct. 30, 2017, the onboard power and data system stopped working and could not be resuscitated.

The station orbit was valuable for gathering a diverse and important set of cloud and aerosol observations. The CATS instrument was able to observe the same locations at different times of day, allowing scientists to study day-to-night changes in cloud and aerosol effects from space. The instrument was also the first space-based lidar to provide cloud and aerosol data to users in near real time – less than six hours – allowing for more accurate computer models and forecasting of dust storms, fires and volcanic eruptions.

The project was also unique because of its rapid construction, small budget and placement on the space station. Unlike larger missions, the experiment had a small team, limited budget and shorter timeline – only two years – to be built for the station. The mission helped refine and streamline the process for putting future NASA payloads on the station.

International Space Station (ISS). Image Credits: NASA/STS-134

Although ending, CATS will be remembered for its many notable and pioneering accomplishments in technology and science:

- First high repetition-rate, photon-counting lidar in space

- First NASA-developed payload for the Japanese Experiment Module - Exposed Facility (JEM-EF) on the space station

- First space-based lidar to provide data products in near real time, with latency of less than six hours, to enable more accurate aerosol modeling and forecasting
   
- Improved tracking and forecasting of volcanic plumes, which are well-known and costly aviation hazards

- Improved our understanding of aerosol proximity to clouds, which is critically important to predicting the effects of cloud-aerosol interaction on the Earth's climate system

“CATS provided the opportunity to utilize a small team and streamlined process to highlight that it is possible to build and deliver a low-cost instrument that still provides critical, cutting-edge science measurements," said McGill.

Related links:

CATS website: https://cats.gsfc.nasa.gov/

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

Images (mentioned), Text, Credits: NASA/Sara Blumberg/Goddard Space Flight Center, by Kasha Patel.

Greetings, Orbiter.ch

First Light for ESPRESSO — the Next Generation Planet Hunter












ESO - European Southern Observatory logo.

6 December 2017

Data from ESPRESSO First Light

The Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations (ESPRESSO) has successfully made its first observations. Installed on ESO’s Very Large Telescope (VLT) in Chile, ESPRESSO will search for exoplanets with unprecedented precision by looking at the minuscule changes in the light of their host stars. For the first time ever, an instrument will be able to sum up the light from all four VLT telescopes and achieve the light collecting power of a 16-metre telescope.

ESPRESSO achieves First Light

ESPRESSO has achieved first light on ESO’s Very Large Telescope at the Paranal Observatory in northern Chile [1]. This new, third-generation echelle spectrograph is the successor to ESO’s hugely successful HARPS instrument at the La Silla Observatory. HARPS can attain a precision of around one metre per second in velocity measurements, whereas ESPRESSO aims to achieve a precision of just a few centimetres per second, due to advances in technology and its placement on a much bigger telescope.

ESPRESSO achieves First Light: the front-end structure

The lead scientist for ESPRESSO, Francesco Pepe from the University of Geneva in Switzerland, explains its significance: “This success is the result of the work of many people over 10 years. ESPRESSO isn’t just the evolution of our previous instruments like HARPS, but it will be transformational, with its higher resolution and higher precision. And unlike earlier instruments it can exploit the VLT’s full collecting power — it can be used with all four of the VLT Unit Telescopes at the same time to simulate a 16-metre telescope. ESPRESSO will be unsurpassed for at least a decade — now I am just impatient to find our first rocky planet!”

ESPRESSO achieves First Light: inside the front-end structure 
 
ESPRESSO achieves First Light: vacuum vessel

ESPRESSO can detect tiny changes in the spectra of stars as a planet orbits. This radial velocity method works because a planet’s gravitational pull influences its host star, causing it to “wobble” slightly. The less massive the planet, the smaller the wobble, and so for rocky and possibly life-bearing exoplanets to be detected, an instrument with very high precision is required. With this method, ESPRESSO will be able to detect some of the lightest planets ever found [2].

ESPRESSO achieves First Light: inside the spectrograph

The test observations included observations of stars and known planetary systems. Comparisons with existing HARPS data showed that ESPRESSO can obtain similar quality data with dramatically less exposure time.

ESPRESSO achieves First Light: group picture

Instrument scientist Gaspare Lo Curto (ESO) is delighted: “Bringing ESPRESSO this far has been a great accomplishment, with contributions from an international consortium as well as many different groups within ESO: engineers, astronomers and administration. They had to not just install the spectrograph itself, but also the very complex optics that bring the light together from the four VLT Unit Telescopes.”

ESPRESSO achieves First Light: in the control room

Although the main goal of ESPRESSO is to push planet hunting to the next level, finding and characterising less massive planets and their atmospheres, it also has many other applications. ESPRESSO will also be the world’s most powerful tool to test whether the physical constants of nature have changed since the Universe was young. Such tiny changes are predicted by some theories of fundamental physics, but have never been convincingly observed.

ESPRESSO achieves First Light: the first data

When ESO’s Extremely Large Telescope comes on line, the instrument HIRES, which is currently under conceptual design, will enable the detection and characterisation of even smaller and lighter exoplanets, down to Earth-like planets, as well as the study of exoplanet atmospheres with the prospect of the detection of signatures of life on rocky planets.

ESPRESSO achieves First Light

Notes:

[1] ESPRESSO was designed and built by a consortium consisting of: the Astronomical Observatory of the University of Geneva and University of Bern, Switzerland; INAF–Osservatorio Astronomico di Trieste and INAF–Osservatorio Astronomico di Brera, Italy; Instituto de Astrofísica de Canarias, Spain; Instituto de Astrofisica e Ciências do Espaço, Universidade do Porto and Universidade de Lisboa, Portugal; and ESO. The co-principal investigators are Francesco Pepe (University of Geneva, Switzerland), Stefano Cristiani (INAF–Osservatorio Astronomico di Trieste, Italy), Rafael Rebolo (IAC, Tenerife, Spain) and Nuno Santos (Instituto de Astrofisica e Ciencias do Espaco, Universidade do Porto, Portugal).

[2] The radial velocity method allows astronomers to measure the mass and orbit of the planet. Combined with other methods such as the transit method, more information can be inferred — for example, the size and density of the exoplanet. The Next-Generation Transit Survey (NGTS) at ESO’s Paranal Observatory hunts for exoplanets in this way.

More information:

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile and by Australia as a strategic partner. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.

Links:

ESOcast 141 Light: ESPRESSO — the Next Generation Planet Hunter
http://www.eso.org/public/videos/eso1739a/

Photos of ESPRESSO: http://www.eso.org/public/images/archive/search/?adv=&title=espresso

Photos of the VLT: http://eso.org/public/images/archive/search/list/2/?ranking=0&fov=0&release_id=&minimum_size=0&description=&published_until_year=0&published_until_month=0&title=&subject_name=Very+Large+Telescope&credit=&published_until_day=0&published_since_day=0&published_since_month=0&id=&published_since_year=0

Images, Video, Text, Credits: ESO/Richard Hook/Gaspare Lo Curto/Instituto de Astrofísica de Canarias/Rafael Rebolo/Instituto de Astrofísica e Ciências do Espaço and Universidade do Porto/Nuno Santos/INAF–Osservatorio Astronomico di Trieste/Stefano Cristiani/University of Geneva/Francesco Pepe.

Best regards, Orbiter.ch

Found: Most Distant Black Hole









NASA - WISE Mission patch.

Dec. 6, 2017

Scientists have uncovered a rare relic from the early universe: the farthest known supermassive black hole. This matter-eating beast is 800 million times the mass of our Sun, which is astonishingly large for its young age. Researchers report the find in the journal Nature.


Image above: This artist's concept shows the most distant supermassive black hole ever discovered. It is part of a quasar from just 690 million years after the Big Bang. Image Credits: Robin Dienel/Carnegie Institution for Science.

"This black hole grew far larger than we expected in only 690 million years after the Big Bang, which challenges our theories about how black holes form," said study co-author Daniel Stern of NASA's Jet Propulsion Laboratory in Pasadena, California.

Astronomers combined data from NASA's Wide-field Infrared Survey Explorer (WISE) with ground-based surveys to identify potential distant objects to study, then followed up with Carnegie Observatories' Magellan telescopes in Chile. Carnegie astronomer Eduardo Bañados led the effort to identify candidates out of the hundreds of millions of objects WISE found that would be worthy of follow-up with Magellan.

For black holes to become so large in the early universe, astronomers speculate there must have been special conditions to allow rapid growth -- but the underlying reason remains mysterious.

The newly found black hole is voraciously devouring material at the center of a galaxy -- a phenomenon called a quasar. This quasar is especially interesting because it comes from a time when the universe was just beginning to emerge from its dark ages. The discovery will provide fundamental information about the universe when it was only 5 percent of its current age.

"Quasars are among the brightest and most distant known celestial objects and are crucial to understanding the early universe," said co-author Bram Venemans of the Max Planck Institute for Astronomy in Germany.

The universe began in a hot soup of particles that rapidly spread apart in a period called inflation. About 400,000 years after the Big Bang, these particles cooled and coalesced into neutral hydrogen gas. But the universe stayed dark, without any luminous sources, until gravity condensed matter into the first stars and galaxies. The energy released by these ancient galaxies caused the neutral hydrogen to get excited and ionize, or lose an electron. The gas has remained in that state since that time. Once the universe became reionzed, photons could travel freely throughout space. This is the point at which the universe became transparent to light.

Wide-field Infrared Survey Explorer or WISE. Image Credit: NASA

Much of the hydrogen surrounding the newly discovered quasar is neutral. That means the quasar is not only the most distant -- it is also the only example we have that can be seen before the universe became reionized.

“It was the universe's last major transition and one of the current frontiers of astrophysics,” Bañados said.

The quasar's distance is determined by what's called its redshift, a measurement of how much the wavelength of its light is stretched by the expansion of the universe before reaching Earth. The higher the redshift, the greater the distance, and the farther back astronomers are looking in time when they observe the object. This newly discovered quasar has a redshift of 7.54, based on the detection of ionized carbon emissions from the galaxy that hosts the massive black hole. That means it took more than 13 billion years for the light from the quasar to reach us.

Scientists predict the sky contains between 20 and 100 quasars as bright and as distant as this quasar. Astronomers look forward to the European Space Agency's Euclid mission, which has significant NASA participation, and NASA's Wide-field Infrared Survey Telescope (WFIRST) mission, to find more such distant objects.

"With several next-generation, even-more-sensitive facilities currently being built, we can expect many exciting discoveries in the very early universe in the coming years," Stern said.

Caltech in Pasadena, California, manages JPL for NASA.

WISE (Wide-field Infrared Survey Explorer): http://www.nasa.gov/mission_pages/WISE/main/index.html

Images (mentioned), Text, Credits: NASA/Tony Greicius/JPL/Elizabeth Landau/Carnegie Observatories/Eduardo Bañados.

Greetings, Orbiter.ch

Astronauts Command Robotic Arm to Release Cygnus Cargo Craft












NASA / Orbital ATK - Cygnus OA-8 Mission patch.

Dec. 6, 2017


Image above: The Cygnus cargo craft is seen from an International Space Station video camera moments after it was released from the Canadarm2 robotic arm. Image Credit: NASA TV.

After delivering almost 7,400 pounds of cargo to support dozens of science experiments from around the world, the Orbital ATK Cygnus cargo spacecraft has departed the International Space Station. At 8:11 a.m., Expedition 53 Flight Engineers Mark Vande Hei and Joe Acaba of NASA gave the command to release Cygnus.

On Tuesday, Dec. 5, ground controllers used the Canadarm2 robotic arm to detach the Cygnus spacecraft from the Earth-facing side of the station’s Unity module. The spacecraft, which arrived at the station Nov. 14, then maneuvered above the Harmony module to gather data overnight that will aid in rendezvous and docking operations for future U.S. commercial crew vehicles arriving for a linkup to Harmony’s international docking adapters.

Experiments delivered on Cygnus supported NASA and other research investigations during Expedition 53, including studies in biology, biotechnology, physical science and Earth science.


Image above: NASA astronaut Randy Bresnik photographed Orbital ATK's Cygnus cargo spacecraft at sunrise, prior to its departure from the International Space Station at 8:11 a.m., Dec. 6, 2017. Expedition 53 Flight Engineers Mark Vande Hei and Joe Acaba of NASA gave the station's Canadarm2 robotic arm the command to release Cygnus. Image Credits: NASA/Randy Bresnik.

Later today, Cygnus will release 14 CubeSats from an external NanoRacks deployer. Cygnus also is packed with more than 6,200 pounds of trash and other items marked for disposal during its destructive reentry Monday, Dec. 18.

The Cygnus launched Nov. 12 on Orbital ATK’s upgraded Antares 230 rocket from NASA’s Wallops Flight Facility in Virginia for the company’s eighth NASA-contracted commercial resupply mission.

Related links:

Orbital ATK Cygnus: http://www.nasa.gov/orbitalatk

External NanoRacks deployer: http://nanoracks.com/launch-of-full-external-cygnus-deployer/

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

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

Best regards, Orbiter.ch

Cygnus Cargo Craft Leaves Station today












NASA / Orbital ATK - Cygnus OA-8 Mission patch.

December 6, 2017

The Orbital ATK Cygnus cargo spacecraft is set to leave the International Space Station today, Dec. 6. NASA Television and the agency’s website will provide live coverage of Cygnus’ departure beginning at 7:45 a.m. EST. Cygnus arrived to the space station Nov. 14 with nearly 7,400 pounds of cargo to support dozens of science experiments.


Image above: The Orbital ATK Cygnus cargo craft was pictured February 19, 2016, attached to the Canadarm2 before it was released back into Earth orbit. Read more about the Cygnus missions to the space station. Image Credit: NASA.

At approximately 8:10 a.m., Expedition 53 Flight Engineers Mark Vande Hei and Joe Acaba of NASA will give the command to release Cygnus.

Earlier today, ground controllers used the Canadarm2 robotic arm to detach the Cygnus spacecraft from the Earth-facing side of the station’s Unity module.

This was Orbital ATK’s eighth contracted commercial resupply mission.

Related links:

Orbital ATK Cygnus: http://www.nasa.gov/orbitalatk

Live coverage of Cygnus’ departure: http://www.nasa.gov/live

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

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

Greetings, Orbiter.ch

mardi 5 décembre 2017

At the LHC, tomorrow is already here












CERN - European Organization for Nuclear Research logo.

Dec. 5, 2017


Image above: The CERN Control Centre in 2017, from where all the Laboratory's accelerators and technical infrastructure are controlled. The accelerator complex and the LHC produced a record amount of data in 2017. (Image: Julien Ordan/CERN).

On Monday, 4 December at 4.00 a.m., the accelerator operators hit the stop button on the accelerator complex and the Large Hadron Collider for their usual winter break. But while the machines are hibernating, there’s no rest for the humans, as CERN teams will be busy with all the maintenance and upgrade work required before the machines are restarted in the spring.

The LHC has ended the year with yet another luminosity record, having produced 50 inverse femtobarns of data, i.e. 5 million billion collisions, in 2017. But the accelerator hasn’t just produced lots of data for the physics programmes.

Before the technical stop, a number of new techniques for increasing the luminosity of the machine were tested. These techniques are mostly being developed for the LHC’s successor, the High-Luminosity LHC. With a planned start-up date of 2026, the High-Luminosity LHC will produce five to ten times as many collisions as the current LHC. To do this, it will be kitted out with new equipment and will use a new optics scheme, based on ATS (Achromatic Telescopic Squeezing), a configuration that was tested this year at the LHC.

Large Hadron Collider (LHC). Animation Credit: CERN

Handling beams of particles is a bit like handling beams of light. In an accelerator, dipole magnets act like mirrors, guiding the beams around the bends. Quadrupole magnets act alternately like concave or convex lenses, keeping the beams in line transversally, but also and above all focusing them as much as possible at the interaction points of the experiments. Corrector magnets (hexapoles) correct chromatic aberrations (a bit like corrective lenses for astigmatism). Configuring the optics of an accelerator is all about combining the strengths of these different magnets.

One particularly efficient approach to increasing luminosity, and therefore the number of collisions, is to reduce the size of the beam at the interaction points, or in other words to compress the bunches of particles as much as possible. In the High-Luminosity LHC, more powerful quadrupole magnets with larger apertures, installed either side of the experiments, will focus the bunches before collision. However, for these magnets to be as effective as possible, the beam must first be considerably expanded: a bit like a stretching a spring as much as possible so that it retracts as much as possible. And this is where the new configuration comes in. Instead of just using the quadrupole magnets either side of the collision points, the ATS system also makes use of magnets situated further away from the experiments in the machine, transforming seven kilometres of the accelerator into a giant focusing system.


Graphic above: Graph showing the integrated luminosity over the various runs of the LHC. In 2017, the LHC produced 50 inverse femtobarns of data, the equivalent of 5 million billion collisions. (Image: CERN).

These techniques have been used in part this year at the LHC and will be used even more during future runs. “The heart of the High-Luminosity LHC is already beating in the LHC,” explains Stéphane Fartoukh, the physicist who came up with the new concept.  “The latest tests, carried out last week, have once again proved the reliability of the scheme and demonstrated other potential applications, sometimes beyond our initial expectations.”

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.

For further information:

See the article in the Accelerating news newsletter: https://home.cern/about/updates/2017/12/lhc-tomorrow-already-here#http://acceleratingnews.web.cern.ch/content/novel-optics-scheme-meet-hl-lhc-targeted-performance

Related links:

High-Luminosity LHC: https://home.web.cern.ch/topics/high-luminosity-lhc

Large Hadron Collider (LHC): https://home.cern/topics/large-hadron-collider

For more information about European Organization for Nuclear Research (CERN), Visit: http://home.cern/

Image (mentioned), Graphic (mentioned), Animation (mentioned), Text, Credits: CERN/Stefania Pandolfi.

Best regards, Orbiter.ch

NASA-funded Simulations Show How Massive Collisions Delivered Metal to Early Earth











NASA logo.

Dec. 5, 2017

Planetary collisions are at the core of our solar system’s formation. Scientists have long believed that after the Moon’s formation, the early Earth experienced a long period of bombardment that diminished about 3.8 billion years ago.


Image above: Artist concept shows the collision of a large moon-sized planetary body penetrating all the way down to the Earth's core, with some particles ricocheting back into space. Image Credits: Southwest Research Institute/Simone Marchi.

During this period, called “late accretion,” collisions with moon-sized planetary bodies, known as planetesimals, embedded extensive amounts of metal and rock-forming minerals into the Earth's mantle and crust. It is estimated that approximately 0.5 percent of Earth’s present mass was delivered during this stage of planetary evolution.

With the support from a NASA Exobiology grant and NASA’s Solar System Exploration Research Virtual Institute, or SSERVI, researchers at the Southwest Research Institute, or SwRI, and University of Maryland have created high-resolution impact simulations that show significant portions of a large planetesimal’s core could penetrate all the way down to merge with Earth’s core—or ricochet back into space and escape the planet entirely.


Animation above: The simulations show significant portions of a large moon-sized planetary body penetrating all the way down to the Earth's core, and ricocheting back into space. On the right, particles are color coded with temperature, indicated in Kelvin. Animation Credits: Southwest Research Institute/Simone Marchi.

For a recently published paper in Nature Geoscience about the topic, Simone Marchi and his colleagues found evidence of more massive accretion onto the Earth than previously thought after the Moon’s formation. The mantle abundances of certain trace elements such as platinum, iridium and gold, which tend to bond chemically with metallic iron, are much higher than what would be expected to result from core formation. This discrepancy can most easily be explained by late accretion after core formation was complete. The team determined the total amount of material delivered to Earth may have been 2-5 times greater than previously thought, and the impacts altered Earth in a profound way while depositing familiar elements like gold.

“These results have far-reaching implications for Moon-forming theories and beyond,” said Marchi. “Interestingly, our findings elucidate the role of large collisions in delivering precious metals like gold and platinum found here on Earth.”

Researchers at SwRI and the University of Maryland are part of 13 teams within SSERVI, based and managed at NASA’s Ames Research Center in California’s Silicon Valley. SSERVI is funded by the Science Mission Directorate and Human Exploration and Operations Mission Directorate at NASA Headquarters in Washington.

Related links:

Solar System Exploration Research Virtual Institute, or SSERVI: http://sservi.nasa.gov/

Science Mission Directorate: https://science.nasa.gov/solar-system

Human Exploration and Operations Mission Directorate: https://www.nasa.gov/directorates/heo/index.html

Planets: https://www.nasa.gov/subject/6960/planets

Ames Research Center: https://www.nasa.gov/centers/ames/home/index.html

Animation (mentioned), Image (mentioned), Text, Credits: NASA/Kimberly Williams/Ames Research Center/Kimberly Minafra.

Greetings, Orbiter.ch