Science Return on Earth aboard SpaceX Dragon Spacecraft

SpaceX - Dragon CRS-14 Mission patch.

May 5, 2018

SpaceX's Dragon cargo spacecraft splash down in the Pacific Ocean today, Saturday May 5, west of Baja California, with more than 4,000 pounds of NASA cargo, science and technology demonstration samples from the International Space Station.

The Dragon spacecraft will be taken by ship to Long Beach, where some cargo will be removed immediately for return to NASA. Dragon then will be prepared for a return trip to SpaceX's test facility in McGregor, Texas, for final processing.

Image above: The SpaceX Dragon splashes down in the Pacific Ocean in May of 2016 after resupplying the Expedition 47 mission. Image Credit: SpaceX.

A variety of technological and biological studies are returning in Dragon:

Samples from the Metabolic Tracking study will help researchers understand the effects of microgravity on the metabolic impact of five different therapeutic compounds. This investigation determines the feasibility of developing improved pharmaceuticals in microgravity using a new method to test the metabolic impacts of drug compounds. This could lead to more effective, less expensive drugs.

The APEX-06 investigation studied the growth, development, and gene expression profiles of seedlings from the monocot Brachypodium distachyon. Most major cereal grain crops used to produce food belong to a class of plants called monocotyledons or monocots, flowering plants whose seeds typically contain only one embryonic leaf. This investigation will lead to a better understanding of the molecular and developmental mechanisms that contribute to adaptation to spaceflight conditions. In the long term, results may also lead to the development of strategies aimed at improving monocot adaptability to spaceflight parameters, which would be beneficial for future human space exploration as monocots provide many food staples.

Dragon waiting its recovery. Image Credit: SpaceX

Fruit Fly Lab–03 is the third mission of the Fruit Fly Lab aboard the station using the model organism Drosophila melanogaster. Drosophila are used for research because approximately 75 percent of human disease genes have analogs in the fruit fly genome. This mission studied the effects of the space environment on innate immunity, which is the branch of the immune system responsible for quick, non-specific responses to infection. This subject is important for preparing for future exploration as immune system dysfunction and infections are potential risks for astronauts on long-duration space exploration missions.

Dragon is the only space station resupply spacecraft currently capable of returning cargo to Earth, and this was the second trip to the orbiting laboratory for this spacecraft, which completed its first mission nearly two years ago. SpaceX launched its 14th NASA-contracted commercial resupply mission to the station April 2 from Space Launch Complex 40 from Cape Canaveral Air Force Station in Florida on a Falcon 9 rocket that also previously launched its 12th NASA-contracted commercial resupply mission to the station.

For more than 17 years, humans have lived and worked continuously aboard the International Space Station, advancing scientific knowledge and demonstrating new technologies, making research breakthroughs not possible on Earth that will enable long-duration human and robotic exploration into deep space. A global endeavor, more than 200 people from 18 countries have visited the unique microgravity laboratory that has hosted more than 2,300 research investigations from researchers in more than 100 countries.

Related links:

Metabolic Tracking: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7517

APEX-06: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7524

Fruit Fly Lab–03: https://www.nasa.gov/ames/research/space-biosciences/fruit-fly-lab-03-spacex-14

Commercial Resupply: http://www.nasa.gov/mission_pages/station/structure/launch/index.html

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

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

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

Greetings, Orbiter.ch

Dragon Heads Home After Month Long Stay at Station

SpaceX - Dragon CRS-14 Mission patch.

May 5, 2018

Robotic flight controllers released the SpaceX Dragon cargo spacecraft from the International Space Station’s robotic arm at 9:23 a.m. EDT, and Expedition 55 Flight Engineer Scott Tingle of NASA is monitoring its departure.

Image above: Dragon attached at Canarm2 just before its release, seen by EarthCam on ISS, images captured by Roland Berga (on Earth in Switzerland) from International Space Station (ISS) using ISS-HD Live application with EarthCam's from ISS on May 5, 2018. Image Credits:NASA TV/ Orbiter.ch Aerospace/Roland Berga.

Dragon’s thrusters will be fired to move the spacecraft a safe distance from the station before SpaceX flight controllers in Hawthorne, California, command its deorbit burn about 2:06 p.m. The capsule will splashdown about 3 p.m. in the Pacific Ocean, where recovery forces will retrieve the capsule and its more than 4,000 pounds of cargo, including a variety of technological and biological studies.

Image above: Cameras on the Canadarm2 robotic arm monitored the SpaceX Dragon resupply ship as it departed the space station Saturday morning. Image Credit: NASA TV.

The deorbit burn and splashdown will not be broadcast on NASA TV.

NASA and the Center for the Advancement of Science in Space (CASIS), the non-profit organization that manages research aboard the U.S. National Laboratory portion of the space station, will receive time-sensitive samples and begin working with researchers to process and distribute them within 48 hours of splashdown.

SpaceX CRS-14: Dragon departure from the ISS

Dragon is the only space station resupply spacecraft currently capable of returning cargo to Earth, and this was the second trip to the orbiting laboratory for this spacecraft, which completed its first mission nearly two years ago. SpaceX launched its 14th NASA-contracted commercial resupply mission to the station April 2 from Space Launch Complex 40 from Cape Canaveral Air Force Station in Florida on a Falcon 9 rocket that also previously launched its 12th NASA-contracted commercial resupply mission to the station.

Related links:

Technological and biological studies: https://www.nasa.gov/feature/nasa-science-to-return-to-earth-aboard-spacex-dragon-spacecraft-1

SpaceX Dragon: http://www.nasa.gov/spacex

Expedition 55: https://www.nasa.gov/mission_pages/station/expeditions/expedition55/index.html

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

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

Images (mentioned), Video, Text, Credits: NASA/Mark Garcia/Orbiter.ch Aerospace/Roland Berga/NASA TV/SciNews.

Best regards, Orbiter.ch

Atlas V Lifts Off Carrying InSight Mission

ULA - Atlas V / InSight Mission poster.


May 5, 2018

Image above: A United Launch Alliance Atlas V rocket lifts off from Space Launch Complex 3 at Vandenberg Air Force Base, California, carrying NASA's Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, or InSight, Mars lander. Liftoff was at 4:05 a.m. PDT (7:05 a.m. EDT). Photo credit: NASA.

Liftoff of InSight

Booster ignition and liftoff of the United Launch Alliance Atlas V rocket at 7:05 a.m. EDT (4:05 a.m. PDT), from Space Launch Complex 3 at Vandenberg Air Force Base in California, carrying NASA’s InSight spacecraft. The rocket is on its way, carrying NASA’s Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) to begin its six  month voyage to Mars.

InSight will be the first mission to look deep beneath the Martian surface studying the planet's interior by measuring its heat output and listen for marsquakes. InSight will use the seismic waves generated by marsquakes to develop a map of the planet’s deep interior. The resulting insight into Mars’ formation will provide a better understanding of how other rocky planets, including Earth, were created.

Image above: This artist's concept shows the InSight lander, its sensors, cameras and instruments. Image Credits: NASA/JPL-Caltech.

Mars Cube One Will Launch with NASA’s InSight Spacecraft

Hitching a ride with InSight is NASA’s technology experiment known as Mars Cube One (MarCO), a separate mission of its own. Designed and built by NASA’s Jet Propulsion Laboratory in Pasadena, California, MarCO consists of two mini-spacecraft and will be the first test of CubeSat technology in deep space. They are designed to test new communications and navigation capabilities for future missions and may provide real-time communication relay to cover the entry, descent and landing of InSight on Mars.

After InSight has separated from the Atlas V Centaur second stage, MarCO will launch one at a time from dispensers mounted on the aft bulkhead carrier of the second stage.

Image above: An artist’s rendering of the twin Mars Cube One (MarCO) spacecraft as they fly through deep space. Image credits: NASA/JPL-Caltech.

"It’s an exciting day for NASA. The agency’s twin Mars Cube One (MarCO) mini-spacecraft have launched from dispensers mounted on the aft bulkhead carrier of the Atlas V Centaur second stage. Designed and built by NASA’s Jet Propulsion Laboratory in Pasadena, California, MarCO will be the first test of CubeSat technology in deep space. They are designed to test new communications and navigation capabilities for future missions and may provide real-time communication relay to cover the entry, descent and landing of InSight on Mars".

For more information about MarCo, visit http://www.jpl.nasa.gov/cubesat/missions/marco.php.

JPL manages InSight for NASA's Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by the agency's Marshall Space Flight Center in Huntsville, Alabama. The InSight spacecraft, including cruise stage and lander, was built and tested by Lockheed Martin Space in Denver. NASA's Launch Services Program at the agency's Kennedy Space Center in Florida provides launch management. United Launch Alliance of Centennial, Colorado, is NASA's launch service provider of the Atlas 5 rocket. A number of European partners, including France's Centre National d'Études Spatiales (CNES) and the German Aerospace Center (DLR), are supporting the InSight mission.  In particular, CNES provided the Seismic Experiment for Interior Structure (SEIS) instrument, with significant contributions from the Max Planck Institute for Solar Systems Research (MPS).  DLR provided the Heat Flow and Physical Properties Package (HP3) instrument.

For more information about InSight, visit: https://mars.nasa.gov/insight/ and

InSight Mars Lander: https://www.nasa.gov/mission_pages/insight/main/index.html

United Launch Alliance (ULA): https://www.ulalaunch.com/

Images (mentioned),Video, Text, Credits: ULA/NASA/Bob Granath/Linda Herridge.

Greetings, Orbiter.ch

InSight - Surviving the Inferno of Entry, Descent and Landing

NASA - InSight Mission logo.

May 4, 2018

Anticipation is building as preparations are well underway for the launch of NASA’s next Mars mission, InSight. But before the roar of the rocket lifting off from Vandenberg Air Force Base has subsided, a NASA team will be hard at work preparing for the lander’s eventual plunge through the Martian atmosphere.

Landing on Mars

Video above: NASA Langley researchers are experts in modeling and simulations for entry, descent and landing, working on missions since the Viking lander in 1976. In this episode, we explore the challenges of guiding landers like Mars InSight through the Martian atmosphere for a safe landing. Video Credits: NASA Langley.

Experts from NASA’s Langley Research Center are key to providing modeling and computer simulations, which will be used by the InSight entry, descent and landing (EDL) team led by NASA’s Jet Propulsion Laboratory along with Lockheed Martin Space and NASA’s Ames Research Center.

Since early missions, such as Viking in 1976, Langley has played a central role in EDL simulations. The Langley group, led by Rob Maddock with Carlie Zumwalt, Alicia Dwyer Cianciolo, and Daniel Litton, is continuing that job today, building on previous projects including the Mars Science Laboratory, one of the largest and most complicated landings so far, and Phoenix, which is very similar to InSight.

Image above: Langley researchers from left, Carlie Zumwalt, flight dynamics engineer, Rob Maddock, team lead, and Daniel Litton, flight dynamics engineer, compiled thousands of lines of code and used models trying to run through as many possible entry, descent and landing scenarios for Mars InSight as possible. Image Credits: NASA/David C. Bowman.

“EDL has historically been a NASA Langley role in missions, ever since Viking, we’ve been known as ‘the center’ for EDL simulations,” Maddock said.

And it’s not an easy job. It’s difficult to land on other planets, there are a lot of factors, and EDL performance assessment seeks to accurately predict what conditions will be like.

“We run simulations given all of the unknowns so that we can safely land where we want to,” Maddock said. “The atmosphere is the biggest uncertainty.”

The team has been running through as many possible scenarios as possible, using unique simulations first developed during the 1960s that have been validated and updated with experience. After launch, however, they will be able to verify their models against the actual performance.

During the six-month flight to Mars, the team will acquire data allowing them to add current conditions to their models and simulations, replacing some of the unknowns and estimates. There are opportunities to make adjustments to the trajectory and the flight software starting about a month after launch all the way up to entry into the Martian atmosphere. The data collected during flight analyses will help inform the decision to make any potential modifications.

Image above: An artist's rendering of the NASA InSight lander on Mars. Image Credit: NASA.

InSight's launch period is May 5 through June 8, 2018. Whichever date the launch occurs, InSight's landing on Mars is planned for Nov. 26, 2018, around 3 p.m. EST.

The team will support operations at landing. EDL begins when the spacecraft arrives about 80 miles above the surface of Mars and ends after about six minutes with the lander safe on the ground.

For InSight, this phase will be very similar to NASA’s Phoenix Mars Lander with a few key differences. InSight will enter the atmosphere at a higher velocity than Phoenix and has more mass. It will also land at a higher elevation so it has less atmosphere to use for deceleration, and the area is prone to dust storms. To address these challenges, InSight uses a thicker heat shield and its parachute will open at higher speed with stronger suspension lines.

After landing, the EDL team’s job is not over. They will complete what they call ‘reconstruction.’

“We will take the data (acceleration, inertial measurement unit, trajectory) and rebuild what happened during the actual landing to try and update our simulations and build better predictions,” Maddock said.

InSight capsule plunge through the Martian atmosphere. Image Credit: NASA

NASA's Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport (InSight) lander will study the deep interior of Mars to learn how all rocky planets formed, including Earth and its moon. The lander's instruments include a seismometer to detect marsquakes and a probe that will monitor the flow of heat in the planet's subsurface.

NASA' s Jet Propulsion Laboratory in Pasadena, California, manages InSight for NASA's Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by the agency's Marshall Space Flight Center in Huntsville, Alabama. The InSight spacecraft, including cruise stage and lander, was built and tested by Lockheed Martin Space in Denver.

NASA's Launch Services Program at the agency's Kennedy Space Center in Florida provides launch management. United Launch Alliance of Centennial, Colorado, is NASA's launch service provider of the Atlas 5 rocket. A number of European partners, including France's Centre National d'Études Spatiales (CNES) and the German Aerospace Center (DLR), are supporting the InSight mission.

Live televised coverage of the launch will be available at https://www.nasa.gov/live.

InSight Mars Lander: https://www.nasa.gov/mission_pages/insight/main/index.html

Images (mentioned), Video, Text, Credits: NASA Langley Research Center/Kristyn Damadeo.

Greetings, Orbiter.ch

An EPFZ seismometer will fly to Mars

EPFZ - ETH Zurich logo.

May 04, 2018

The launch of the American robot InSight to Mars is scheduled this Saturday at 13:05 from the Vandenberg base in California. Seismologists from ETH Zurich play a key role.

InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) is the first mission dedicated to the study of the basement of Mars. It will last two years - a Martian year - and aims to advance understanding of the formation processes of all rock planets, including the Earth, as well as their evolution.

Last check. Image Credit: NASA

The NASA spacecraft will include a seismic measuring instrument developed under the guidance of the French Center for Space Studies (CNES). Various European teams participated in its elaboration.

The Swiss Federal Institute of Technology Zurich (ETH Zurich) has contributed to the ultra-sensitive electronics of the device, in collaboration with SYDERAL SA in Chules (BE). The latter has provided a housing that controls the operation of the seismometer and measure the minute movements of the Martian soil.

If the launch of the robot by an Atlas V-401 rocket takes place on Saturday as planned - the firing window is open two hours a day until Tuesday - it will arrive on the red planet on November 26th.

Geophysical Station

InSight aims to study the internal structure of Mars, through the deployment on its surface of a geophysical station embedded in a fixed lander. Once on the Martian soil, a robotic arm will deploy Seismic Experiment for Interior Structures (SEIS), a stethoscope of about 30 kilograms and a diameter of 60 centimeters.

A few weeks later, this "very wide band" seismic sensor of unparalleled precision should already deliver usable data, and EPFZ seismologists will be the first to consult them. The device will measure the tectonic activity of Mars, which will allow to deduce information on its structure, among others the size of the core and the thickness of the mantle.

Image above: This artist's concept shows the InSight lander, its sensors, cameras and instruments. Image Credits: NASA/JPL-Caltech.

The goal is to determine if the heart of the red planet is solid or liquid and why its surface is not composed of moving tectonic plates like on Earth.

The impacts of meteorites will also be analyzed, via the generated seismic waves. The seismometer will be covered with a shield that will isolate it from the storms of Martian wind and temperature variations.

Martian magnitude scale

As explained by Domenico Giardini, professor of seismology and geodynamics at ETH Zurich, the waves picked up by the seismometer will make it possible to draw conclusions about the density of the rock and the temperature inside Mars. Of the 728 Earth days that will last the mission, the specialist expects about fifty events.

By cross-checking the location, strength and distance elements, the researchers expect to obtain "a very good data structure", says the former director of the Swiss Seismological Service.

NASA InSight: ETH Zurich fuehlt Mars den Puls (in German)

One of the questions is how terrestrial models will apply. Professor Giardini's team has created for Mars a new scale of magnitude inspired by that of Richter. Earthquakes are indeed of low intensity.

Thermal history

The ground-based device also includes the Heat Flow and Physical Properties Package (HP3) sensor, capable of capturing heat flow to a depth of five meters. It must evaluate the cooling rate of the planet in order to reconstruct its "thermal history".

Another instrument, RISE (Rotation and Interior Structure Experiment), quantifies the variations of the axis of rotation of the red planet.

The researchers hope to understand "why this planet that was habitable a priori 4 billion years ago has ceased to be little by little", as the formula Philippe Lognonné, scientific leader of SEIS at CNES.

The mission had to be postponed for two years because of problems on the seismometer. Its cost is of the order of one billion dollars. And nothing is yet won, missions on Mars being deemed difficult, with a success rate of only 40%. The United States is the only one to date to have successfully placed and operated a lander.

Related links:

EPFZ - ETH Zurich: https://www.ethz.ch/en.html

Live televised coverage of the launch will be available at: https://www.nasa.gov/live

InSight Mars Lander: https://www.nasa.gov/mission_pages/insight/main/index.html

Images (mentioned), Video, Text, Credits: ATS/NASA/EPFZ-ETH Zurich/Orbiter.ch Aerospace/Roland Berga.

Best regards, Orbiter.ch

CASC - Long March 3B launches APStar-6C satellite

CASC - China Aerospace Science and Technology Corporation logo.

May 3, 2018

Long March-3B carrying APStar-6C launch

China launched the APStar-6C communications satellite from the Xichang Satellite Launch Center, Sichuan province, using a Long March-3B/G2 ‘Chang Zheng-3B/G2’ launch vehicle on Thursday. Launch took place at 16:06 UTC from the LC2 Launch Complex.

APT entered into the in-orbit delivery contract for the APSTAR-6C satellite with China Great Wall Industry (Hong Kong) Corp. on 17 October 2015. APSTAR-6C is based on CASC DFH-4 platform equipped with 45 transponders in C, Ku, and Ka bands, with a designed service life of 15 years.

The satellite will replace the in-orbit APSTAR-6 satellite in 2018, providing high power transponder services to customers across the Asia-Pacific region for VSAT, video distribution, DTH and cellular backhaul applications.

The Xichang launch site

The DFH-4 (DongFangHong-4) platform is a large telecommunications satellite platform from a new generation that keeps high capability in output power and communication capacity ranking with international advanced satellite platforms.

The applications for the DFH-4 platform aren’t limited to high capacity broadcast communication satellites and can be used for tracking and data relay satellites, regional mobile communication satellites, etc.

The platform comprises propulsion module, service module and solar array. It has a payload capacity of 588 kg and an output power of 10.5 kW by the end of its lifetime. Its design lifetime is 15 years and its reliability by the end of life is more than 0.78. Based on versatility, inheritance, expandability and promptness principles and mature technology, the platform will reach world advanced level to meet the needs of international and domestic large communication satellite markets.

 APStar-6C satellite

The platform is equipped with 22 Ku-band transponders (four 54MHz and 18 36MHz), 3 receiver antennas, and 2 transmission antennas. With a designed operational life of 15 years, the DFH-4 can support the transmission of 150~200 TV programs simultaneously to ground users using a 0.45m antenna device. The DFH-4 satellite also features strong capabilities against hostile disturbance and jamming. The satellite’s power supply includes two 6m solar panels.

Established in 1980, the China Great Wall Industry Corporation (CGWIC) is a commercial organization authorized by the Chinese government to provide satellites, commercial launch services and to carry out international space cooperation.

For more information about China Aerospace Science and Technology Corporation (CASC), visit: http://english.spacechina.com/n16421/index.html

Images, Text, Credits: CASC/Günter Space Page/NASA Spaceflight.com/Rui C. Barbosa.

Greetings, Orbiter.ch

NASA's Rossi X-ray Timing Explorer Leaves Scientific ‘Treasure Trove’

NASA - Rossi X-ray Timing Explorer (RXTE) logo.

May 3, 2018

NASA’s decommissioned Rossi X-ray Timing Explorer (RXTE) satellite re-entered Earth’s atmosphere on April 30. Orbiting for more than 22 years, the 6,700-pound satellite operated from 1996 to 2012, providing scientists with an unprecedented look into the extreme environments around neutron stars — also known as pulsars — and black holes.

NASA - RXTE Detects 'Heartbeat' Of Smallest Black Hole Candidate

Video above: This animation compares the X-ray “heartbeats” of two different black holes that ingest gas from their companion stars. GRS 1915 has nearly five times the mass of IGR J17091, which at three solar masses may be the smallest black hole known. Video Credits: NASA's Goddard Space Flight Center.

The strong gravity of these objects can pull streams of gas from a nearby companion star and corral it in a vast storage zone called an accretion disk. The orbiting gas becomes heated by friction and reaches temperatures of millions of degrees — so hot, it emits X-rays. As the gas spirals inward, powerful bursts, flares and rapid pulsations can occur in the innermost accretion disk and on the surfaces of neutron stars. These X-ray signals vary on time scales ranging from a few seconds to less than a millisecond, providing important information on the nature of the compact object.

“Observing these X-ray phenomena with precise high-resolution timing was RXTE’s specialty,” said Jean Swank, an astrophysicist emeritus at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who served as the mission’s project scientist until 2010. “During RXTE’s run, no other observatory could provide these measurements.”

RXTE far exceeded its original science goals and leaves behind an important scientific legacy. All data from the mission is open to the public and is maintained by Goddard’s High Energy Astrophysics Science Archive Research Center.

“The data remain a treasure trove for studying compact objects, whether pulsars and stellar-mass black holes in our own galaxy or supermassive black holes in the cores of distant galaxies,” said Goddard’s Tod Strohmayer, who served as RXTE’s project scientist from 2010 through the end of the mission. “So far, more than 3,100 published papers in refereed journals, totaling over 95,000 citations, include RXTE measurements.”

Image above: NASA's Rossi X-ray Timing Explorer undergoes processing in Hangar AO at Cape Canaveral Air Station, Florida, in summer 1995. The spacecraft is shown being installed onto the Delta launch vehicle’s payload attach fitting in preparation for transport to Pad A, Complex 17, and mating with the second stage of its Delta II rocket. Image Credits: NASA's Kennedy Space Center.

Watching how matter behaves in the vicinity of a black hole helps astronomers glimpse details about the nature of gravity itself. In 1997, RXTE provided what is widely regarded as the first observational evidence of “frame dragging,” an effect predicted 79 years earlier by Austrian physicists Joseph Lense and Hans Thirring using Einstein’s general theory of relativity. In binary systems where black holes strip gas from a normal companion star, fast X-ray oscillations track hot blobs of gas orbiting deep within the accretion disk. These changes indicate that the inner disk wobbles in just the way relativity predicts. Like a bowling bowl spinning in molasses, the rotating black hole drags along nearby space-time — and with it, the inner accretion disk.

RXTE also showed that black holes of extremely different masses produce similar kinds of X-ray activity, just at varying time scales proportional to their masses. Stellar-mass black holes undergo key changes in a matter of hours, while their supermassive cousins, containing millions of solar masses, exhibit similar changes over years.

Only slightly less extreme than a black hole is a neutron star, the crushed core of a massive star that ran out of nuclear fuel, collapsed under its own weight and exploded as a supernova. Each one squeezes more than the Sun’s mass into a ball roughly 12 miles (20 kilometers) across — about the length of New York City's Manhattan Island. Neutron stars typically possess magnetic fields up to 10 trillion times stronger than Earth's. RXTE data helped establish the existence of a new class of neutron stars with magnetic fields a thousand times stronger. Dubbed magnetars, these objects boast the most powerful magnetic fields known in the cosmos. Of some 2,600 neutron stars now cataloged, only 29 rank as magnetars.

In the absence of RXTE, NASA’s Neutron star Interior Composition Explorer (NICER), an instrument installed on the skyward side of the International Space Station, continues the study of variable X-ray sources.

Image above: This graph based on RXTE data illustrates the changing character of X-ray outbursts from a neutron star called T5X2 in October and November 2010. As the persistent X-ray emission rises (upward steps in the plot), the number of bursts increases while their brightness declines. The abrupt dropout on Oct. 13 occurred when the Moon briefly eclipsed the source. Image Credits: NASA's Goddard Space Flight Center.

“NICER is the successor to RXTE, with an order-of-magnitude improvement in sensitivity, energy resolution and time resolution,” said Goddard’s Keith Gendreau, the mission’s principal investigator. “The X-ray band NICER observes overlaps the lower end of RXTE’s range, which means we can more easily take advantage of its long observational record.”

The astronomical community has recognized the importance of RXTE research with five major awards. These include four Bruno Rossi Prizes (1999, 2003, 2006 and 2009) from the High Energy Astrophysics Division of the American Astronomical Society and the 2004 NWO Spinoza Prize, the highest Dutch science award, from the Netherlands Organization for Scientific Research. (To learn more about the mission’s accomplishments, see our RXTE gallery.)

Rossi X-ray Timing Explorer (RXTE) satellite. Image Credit: NASA

The mission was launched as XTE aboard a Delta II 7920 rocket on Dec. 30, 1995, from Cape Canaveral Air Force Station in Florida. It was renamed RXTE in early 1996 to honor Bruno Rossi, an MIT astronomer and a pioneer of X-ray astronomy and space plasma physics who died in 1993. RXTE relayed its last scientific observations to the ground on Jan. 4, 2012. The following day, controllers at Goddard, which managed the mission, powered down the satellite.

Related links:

RXTE (Rossi X-ray Timing Explorer): http://www.nasa.gov/centers/goddard/missions/rxte.html

RXTE gallery: https://svs.gsfc.nasa.gov/Gallery/RXTE.html

Neutron star Interior Composition Explorer (NICER): https://www.nasa.gov/nicer

2004 NWO Spinoza Prize: https://www.nwo.nl/en/news-and-events/news/2003/NWO%252FSpinoza+prize+for+economist,+historian+and+two+physicists.html

Images, Video, Text, Credits: NASA/Rob Garner/Goddard Space Flight Center, by Francis Reddy.

Greetings, Orbiter.ch

Tangled Up in Blue

NASA - Solar Dynamics Observatory (SDO) patch.

May 3, 2018

The lone active region visible on our Sun put on a fine display with its tangled magnetic field lines swaying and twisting above it (Apr. 24-26, 2018) when viewed in a wavelength of extreme ultraviolet light.

The charged particles spinning along these field lines illuminate them. The region did not erupt with any significant solar storms, although it still might.

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

Image, Video, Text, Credits: NASA/Yvette Smith/GSFC/Solar Dynamics Observatory.

Greetings, Orbiter.ch

Astronauts Assembling Gear for Installation During Upcoming Spacewalk

ISS - Expedition 55 Mission patch.

May 3, 2018

Image above: Astronaut Ricky Arnold completes the scrubbing of water cooling loops inside a pair of U.S. spacesuits after the completion of spacewalk on March 29, 2018. Image Credit: NASA.

The Expedition 55 crew members are getting their U.S. spacesuits and equipment ready for a spacewalk in two weeks. The Dragon cargo craft from SpaceX is nearly loaded with NASA science and gear ahead of its Saturday return to Earth.

Image above: Flying over North Atlantic Ocean, seen by EarthCam on ISS, speed: 27'609 Km/h, altitude: 405,54 Km, image captured by Roland Berga (on Earth in Switzerland) from International Space Station (ISS) using ISS-HD Live application with EarthCam's from ISS on May 3, 2018 at 14:28 UTC. Image Credits: Orbiter.ch Aerospace/Roland Berga.

NASA astronauts Ricky Arnold and Drew Feustel are assembling hardware today that will be installed on the International Space Station when they conduct a spacewalk on May 16. The duo were assisted throughout the day by fellow NASA astronaut Scott Tingle scrubbing U.S. spacesuit water cooling loops and testing water samples for conductivity.

The veteran spacewalkers were mating repaired components from an external television camera group (ETVCG) that will be attached to the starboard side of the Destiny laboratory module. Their primary spacewalking task however, will be the swap out of thermal control gear that circulates ammonia to keep station systems cool.

Animation above: Sunrise over North Pacific Ocean, seen by EarthCam on ISS, speed: 27'626 Km/h, altitude: 404,18 Km, images captured by Roland Berga (on Earth in Switzerland) from International Space Station (ISS) using ISS-HD Live application with EarthCam's from ISS on May 2, 2018 at 16:21 UTC. Animation Credits: Orbiter.ch Aerospace/Roland Berga.

Final packing is taking place inside the Dragon space freighter today as Tingle loads critical time-sensitive research samples inside the Earth-bound resupply ship. Robotics controllers will detach Dragon from the Harmony module Friday before releasing it Saturday at 9:24 a.m. from the grips of the Canadarm2. NASA TV will begin its live broadcast of the departure at 9 a.m. but will not televise its 3 p.m. splashdown in the Pacific Ocean.

Related links:

Critical time-sensitive research samples: https://cms.nasa.gov/feature/nasa-science-to-return-to-earth-aboard-spacex-dragon-spacecraft-1

SpaceX Dragon: http://www.nasa.gov/spacex

NASA TV: https://www.nasa.gov/multimedia/nasatv/index.html

Expedition 55: https://www.nasa.gov/mission_pages/station/expeditions/expedition55/index.html

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

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

Images (mentioned), Animation (mentioned), Text, Credits: NASA/Mark Garcia/Orbiter.ch Aerospace/Roland Berga.

Best regards, Orbiter.ch

NASA Expands Plans for Moon Exploration: More Missions, More Science

NASA logo.

May 3, 2018

NASA is returning to the Moon with commercial and international partners as part of an overall agency Exploration Campaign in support of Space Policy Directive 1. It all starts with robotic missions on the lunar surface, as well as a Lunar Orbital Platform-Gateway for astronauts in space beyond the Moon. Right now, NASA is preparing to purchase new small lunar payload delivery services, develop lunar landers, and conduct more research on the Moon’s surface ahead of a human return. And that long-term exploration and development of the Moon will give us the experience for the next giant leap – human missions to Mars and destinations beyond.

Lunar Orbital Platform-Gateway

The agency released a draft Request for Proposals April 27, encouraging the U.S. commercial space industry to introduce new technologies to deliver payloads to the Moon. This request for Commercial Lunar Payload Services (CLPS) will further expand efforts to support development and partnership opportunities on the lunar surface. Using these services, the agency will accelerate a robotic return to Moon, with upcoming missions targeted for two to three years earlier than previously planned. NASA intends to award multiple contracts for these services through the next decade, with contract missions to the lunar surface expected to begin as early as 2019, and with a company’s first delivery no later than Dec. 31, 2021.

NASA’s expanding Moon strategy seeks to harness the innovation of American space companies to build new lunar landers. This solicitation for payload delivery services is a sign of NASA’s ongoing confidence in U.S. industries’ abilities to meet needs for delivery services in space. These early deliveries to the lunar surface will support stronger scientific and exploration mission activities for NASA, and empower commercial industry to show the agency what they have to offer.

“We’ll draw on the interests and capabilities of U.S. industry and international partners as American innovation leads astronauts back to the Moon and to destinations farther into the solar system, including Mars,” said NASA Administrator Jim Bridenstine. “Our successful investments with a strong and continually growing U.S. space industry in low-Earth orbit allows us to focus on lunar activities. We’ll leverage commercial capabilities for these small payload deliveries, and CLPS missions will play an important role in our expanding and sustainable lunar exploration strategy.”

Moon

NASA has identified a variety of exploration, science, and technology objectives that could be addressed by regularly sending instruments, experiments and other small payloads to the Moon. Some of those payloads will be developed from the agency’s Resource Prospector mission concept. This project was intended as a one-time effort to explore a specific location on the Moon, and as designed, now is too limited in scope for the agency’s expanded lunar exploration focus. NASA’s return to the Moon will include many missions to locate, extract and process elements across bigger areas of the lunar surface. The agency is evolving Resource Prospector to fit into its broader exploration strategy, and selected robotic instruments will be among the early deliveries to the Moon on CLPS missions.

Simultaneously, the agency is asking U.S. industry how to best progressively advance lander capabilities through its Lunar Surface Transportation Capability request for information, which closed April 30. NASA is assessing commercial interest in lander development to help mature plans for two upcoming landers built through public/private partnerships.

NASA will review responses to the transportation capability request for information, and use the information for development of a minimum 1,100 pound (500 kilogram) lander, which is targeted to launch in 2022. The agency’s two mid-size lander demonstration missions will help NASA understand the requirements and systems needed for a human class lander. The ongoing small payload delivery missions, will provide important data on landing precision, long-term survivability, guidance and navigation for future landers.

These landers will be capable of sample return, resource prospecting, demonstrating use of in-space resources, and this will reduce the risk when building landers for humans.

Discussions on how to use the Lunar Orbital Platform-Gateway for scientific activity are expected to continue. Robotically collecting lunar samples for investigation aboard the gateway or safekeeping until they can be returned to Earth were among the suggestions discussed at a science workshop hosted by NASA.

“It is critical that America leads this sustained presence with commercial and international partners on and around the Moon. And this integrated effort will support returning astronauts to the Moon as called for by Space Policy Directive 1,” said Bridenstine.

Related links:

Exploration Campaign: https://www.nasa.gov/feature/nasa-outlines-new-lunar-science-human-exploration-missions

Lunar Orbital Platform-Gateway: https://www.nasa.gov/feature/nasa-s-lunar-outpost-will-extend-human-presence-in-deep-space

Commercial Lunar Payload Services (CLPS): https://www.fbo.gov/index?s=opportunity&mode=form&id=46b23a8f2c06da6ac08e1d1d2ae97d35&tab=core&_cview=0

Resource Prospector: https://www.nasa.gov/resource-prospector

Lunar Surface Transportation Capability: https://www.fbo.gov/index?s=opportunity&mode=form&tab=core&id=f9ab19e797b4be15cb250816cbcee959

Science workshop: https://www.nasa.gov/feature/scientists-share-ideas-for-gateway-activities-near-the-moon

Future Human Spaceflight: https://www.nasa.gov/subject/3204/future-human-spaceflight

For more information about NASA’s deep space exploration plans, visit: https://www.nasa.gov/journeytomars

Images, Text, Credits: NASA/Cheryl Warner.

Greetings, Orbiter.ch

Hubble detects helium in the atmosphere of an exoplanet for the first time

ESA - Hubble Space Telescope logo.

3 May 2018

Artist’s impression of WASP-107b

Astronomers using the NASA/ESA Hubble Space Telescope have detected helium in the atmosphere of the exoplanet WASP-107b. This is the first time this element has been detected in the atmosphere of a planet outside the Solar System. The discovery demonstrates the ability to use infrared spectra to study exoplanet extended atmospheres.

Hubble Space Telescope (HST)

The international team of astronomers, led by Jessica Spake, a PhD student at the University of Exeter in the UK, used Hubble’s Wide Field Camera 3 to discover helium in the atmosphere of the exoplanet WASP-107b This is the first detection of its kind.

Spake explains the importance of the discovery: “Helium is the second-most common element in the Universe after hydrogen. It is also one of the main constituents of the planets Jupiter and Saturn in our Solar System. However, up until now helium had not been detected on exoplanets - despite searches for it.”

Artist’s impression of WASP-107b

The team made the detection by analysing the infrared spectrum of the atmosphere of WASP-107b [1]. Previous detections of extended exoplanet atmospheres have been made by studying the spectrum at ultraviolet and optical wavelengths; this detection therefore demonstrates that exoplanet atmospheres can also be studied at longer wavelengths.

“The strong signal from helium we measured demonstrates a new technique to study upper layers of exoplanet atmospheres in a wider range of planets,” says Spake “Current methods, which use ultraviolet light, are limited to the closest exoplanets. We know there is helium in the Earth’s upper atmosphere and this new technique may help us to detect atmospheres around Earth-sized exoplanets – which is very difficult with current technology.”

Creation of absorption lines

WASP-107b is one of the lowest density planets known: While the planet is about the same size as Jupiter, it has only 12% of Jupiter’s mass. The exoplanet is about 200 light-years from Earth and takes less than six days to orbit its host star.

The amount of helium detected in the atmosphere of WASP-107b is so large that its upper atmosphere must extend tens of thousands of kilometres out into space. This also makes it the first time that an extended atmosphere has been discovered at infrared wavelengths.

Since its atmosphere is so extended, the planet is losing a significant amount of its atmospheric gases into space — between ~0.1-4% of its atmosphere’s total mass every billion years [2].

Light interacting with atmosphere

As far back as the year 2000, it was predicted that helium would be one of the most readily-detectable gases on giant exoplanets, but until now, searches were unsuccessful.

David Sing, co-author of the study also from the University of Exeter, concludes: “Our new method, along with future telescopes such as the NASA/ESA/CSA James Webb Space Telescope, will allow us to analyse atmospheres of exoplanets in far greater detail than ever before.”

Notes:

[1] The measurement of an exoplanet’s atmosphere is performed when the planet passes in front of its host star. A tiny portion of the star’s light passes through the exoplanet’s atmosphere, leaving detectable fingerprints in the spectrum of the star. The larger the amount of an element present in the atmosphere, the easier the detection becomes.

[2] Stellar radiation has a significant effect on the rate at which a planet’s atmosphere escapes. The star WASP-107 is highly active, supporting the atmospheric loss. As the atmosphere absorbs radiation it heats up, so the gas rapidly expands and escapes more quickly into space.

More information:

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

The study was published in the paper “Helium in the eroding atmosphere of an exoplanet”, published in Nature.

The international team of astronomers in this study consists of J. J. Spake (University of Exeter, UK), D. K. Sing (University of Exeter, UK; Johns Hopkins University, USA), T. M. Evans (University of Exeter, UK), A. Oklopčić (Harvard-Smithsonian Center for Astrophysics, USA), V. Bourrier (Observatoire de l’Université de Genève, Switzerland), L. Kreidberg (Harvard Society of Fellows, USA; Harvard-Smithsonian Center for Astrophysics, USA), B. V. Rackham (University of Arizona, USA), J. Irwin (Harvard-Smithsonian Center for Astrophysics, USA), D. Ehrenreich (Observatoire de l’Université de Genève, Switzerland), A. Wyttenbach (Observatoire de l’Université de Genève, Switzerland), H. R. Wakeford (Space Telescope Science Institute, USA), Y. Zhou (University of Arizona, USA), K. L. Chubb (University College London, UK), N. Nikolov (University of Exeter, UK), J. Goyal (University of Exeter, UK), G. W. Henry (Tennessee State University, USA), M. H. Williamson (Tennessee State University, USA), S. Blumenthal (Space Telescope Science Institute, USA), D. Anderson (Keele University, UK), C. Hellier (Keele University, UK), D. Charbonneau (Harvard-Smithsonian Center for Astrophysics, USA), S. Udry (Observatoire de l’Université de Genève, Switzerland), and N. Madhusudhan (University of Cambridge, UK)

Links:

Images of Hubble: http://www.spacetelescope.org/images/archive/category/spacecraft/

Science paper: http://www.spacetelescope.org/static/archives/releases/science_papers/heic1809/heic1809a.pdf

Hubblecast 102: Taking the fingerprint of exoplanet atmospheres: http://spacetelescope.org/videos/hubblecast102a/

Related links:

Hubble’s Wide Field Camera 3: https://www.spacetelescope.org/about/general/instruments/wfc3/

NASA/ESA/CSA James Webb Space Telescope (JWST): http://sci.esa.int/jwst/

Image, Animation, Videos, Text, Credits: NASA, ESA/Mathias Jäger/University of Exeter/David Sing/Jessica Spake/Hubble/M. Kornmesser.

Best regards, Orbiter.ch

Station Readies Dragon for Departure Ahead of Upcoming Spacewalk

ISS - Expedition 55 Mission patch.

May 2, 2018

Image above: Sunrise over North Pacific Ocean horizon, seen by EarthCam on ISS, speed: 27'626 Km/h, altitude: 404,18 Km, image captured by Roland Berga (on Earth in Switzerland) from International Space Station (ISS) using ISS-HD Live application with EarthCam's from ISS on May 2, 2018 at 16:21 UTC. Image Credits: Orbiter.ch Aerospace/Roland Berga.

The SpaceX Dragon resupply ship’s stay at the International Space Station has been extended until Saturday after unfavorable conditions were reported at the splashdown zone in the Pacific Ocean. In the meantime, time-sensitive payloads are still being readied for return to Earth as the crew wraps up final cargo packing.

Robotics controllers will operate the Canadarm2 to detach Dragon from the International Space Station’s Harmony module on Friday. It will be remotely released into Earth orbit Saturday at 9:24 a.m. EDT before finally splashing down in the Pacific Ocean around 3 p.m. Flight Engineer Scott Tingle will be in the Cupola monitoring Dragon as it slowly backs away from the space station.

NASA TV’s live coverage of Dragon’s departure begins Saturday at 9 a.m. The space freighter’s parachuted splashdown 403 miles off the coast of Long Beach, Calif. will not be televised.

Image above: NASA astronaut Scott Tingle replaces a failed light bulb in a light to be used on a new external television camera group (ETVCG) that will be installed on an upcoming spacewalk. Image Credit: NASA.

Two NASA astronauts are looking ahead to their next spacewalk scheduled for May 16. Veteran spacewalkers Ricky Arnold and Drew Feustel took their body measurements today to ensure a proper fit inside their U.S. spacesuits. The duo will work outside the orbital lab for about 6.5 hours to swap out thermal control gear that circulates ammonia to keep station systems cool.

Japanese astronaut Norishige Kanai, who will assist the spacewalkers in two weeks, began configuring the Quest airlock where the 210th spacewalk at the station will be staged. He also trained to detect and clean ammonia from the spacesuits should they become contaminated during the maintenance spacewalk.

Related links:

SpaceX Dragon: http://www.nasa.gov/spacex

NASA TV: https://www.nasa.gov/multimedia/nasatv/index.html

Expedition 55: https://www.nasa.gov/mission_pages/station/expeditions/expedition55/index.html

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

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

Images (mentioned), Text, Credits: NASA/Mark Garcia/Orbiter.ch Aerospace/Roland Berga.

Best regards, Orbiter.ch

Demonstration Proves Nuclear Fission System Can Provide Space Exploration Power

NASA logo.

May 2, 2018

NASA and the Department of Energy’s National Nuclear Security Administration (NNSA) have successfully demonstrated a new nuclear reactor power system that could enable long-duration crewed missions to the Moon, Mars and destinations beyond.

Image above: Artist's concept of new fission power system on the lunar surface. Image Credit: NASA.

NASA announced the results of the demonstration, called the Kilopower Reactor Using Stirling Technology (KRUSTY) experiment,during a news conference Wednesday at its Glenn Research Center in Cleveland. The Kilopower experimentwas conducted at the NNSA’s Nevada National Security Site from November 2017 through March.

“Safe, efficient and plentiful energy will be the key to future robotic and human exploration,” said Jim Reuter, NASA’s acting associate administrator for the Space Technology Mission Directorate (STMD) in Washington. “I expect the Kilopower project to be an essential part of lunar and Mars power architectures as they evolve.”

Kilopower is a small, lightweight fission power system capable of providing up to 10 kilowatts of electrical power - enough to run several average households - continuously for at least 10 years. Four Kilopower units would provide enough power to establish an outpost.

According to Marc Gibson, lead Kilopower engineer at Glenn, the pioneering power system is ideal for the Moon, where power generation from sunlight is difficult because lunar nights are equivalent to 14 days on Earth.

Image above: NASA and NNSA engineers lower the wall of the vacuum chamber around the Kilowatt Reactor Using Stirling TechnologY (KRUSTY system). The vacuum chamber is later evacuated to simulate the conditions of space when KRUSTY operates. Image Credits: Los Alamos National Laboratory.

“Kilopower gives us the ability to do much higher power missions, and to explore the shadowed craters of the Moon,” said Gibson. “When we start sending astronauts for long stays on the Moon and to other planets, that’s going to require a new class of power that we’ve never needed before.”

The prototype power system uses a solid, cast uranium-235 reactor core, about the size of a paper towel roll. Passive sodium heat pipes transfer reactor heat to high-efficiency Stirling engines, which convert the heat to electricity.

According to David Poston, the chief reactor designer at NNSA’s Los Alamos National Laboratory, the purpose of the recent experiment in Nevada was two-fold: to demonstrate that the system can create electricity with fission power, and to show the system is stable and safe no matter what environment it encounters.

“We threw everything we could at this reactor, in terms of nominal and off-normal operating scenarios and KRUSTY passed with flying colors,” said Poston.

The Kilopower team conducted the experiment in four phases. The first two phases, conducted without power, confirmed that each component of the system behaved as expected. During the third phase, the team increased power to heat the core incrementally before moving on to the final phase. The experiment culminated with a 28-hour, full-power test that simulated a mission, including reactor startup, ramp to full power, steady operation and shutdown.

Throughout the experiment, the team simulated power reduction, failed engines and failed heat pipes, showing that the system could continue to operate and successfully handle multiple failures.

Image above: Kilowatt Reactor Using Stirling TechnologY (KRUSTY) control room during the full-power run, Marc Gibson (GRC/NASA) and David Poston (LANL/NNSA) in foreground, Geordie McKenzie (LANL/NNSA) and Joetta Goda (LANL/NNSA) in background. Image Credits: Los Alamos National Laboratory.

“We put the system through its paces,” said Gibson. “We understand the reactor very well, and this test proved that the system works the way we designed it to work. No matter what environment we expose it to, the reactor performs very well.”

The Kilopower project is developing mission concepts and performing additional risk reduction activities to prepare for a possible future flight demonstration. The project will remain a part of the STMD’s Game Changing Development program with the goal of transitioning to the Technology Demonstration Mission program in Fiscal Year 2020.

Such a demonstration could pave the way for future Kilopower systems that power human outposts on the Moon and Mars, including missions that rely on In-situ Resource Utilizationto produce local propellants and other materials.

The Kilopower project is led by Glenn, in partnership with NASA’s Marshall Space Flight Center in Huntsville, Alabama,and NNSA, including its Los Alamos National Laboratory, Nevada National Security Site and Y-12 National Security Complex.

For more information about the Kilopower project, including images and video, visit:

https://www.nasa.gov/directorates/spacetech/kilopower

For more information about NASA’s investments in space technology, visit: https://www.nasa.gov/spacetech

Images (mentioned), Text, Credits: NASA/Gina Anderson/Sean Potter/Glenn Research Center/Jan Wittry.

Greetings, Orbiter.ch

Stellar Family Portrait in X-rays

NASA - Chandra X-ray Observatory patch.

May 2, 2018

In some ways, star clusters are like giant families with thousands of stellar siblings. These stars come from the same origins – a common cloud of gas and dust – and are bound to one another by gravity. Astronomers think that our Sun was born in a star cluster about 4.6 billion years ago that quickly dispersed.

By studying young star clusters, astronomers hope to learn more about how stars – including our Sun – are born. NGC 6231, located about 5,200 light years from Earth, is an ideal testbed for studying a stellar cluster at a critical stage of its evolution: not long after star formation has stopped.

The discovery of NGC 6231 is attributed to Giovanni Battista Hodierna, an Italian mathematician and priest who published observations of the cluster in 1654. Sky watchers today can find the star cluster to the southwest of the tail of the constellation Scorpius.

NASA’s Chandra X-ray Observatory has been used to identify the young Sun-like stars in NGC 6231, which have, until recently, been hiding in plain sight. Young star clusters like NGC 6231 are found in the band of the Milky Way on the sky. As a result, interloping stars lying in front of or behind NGC 6231 greatly outnumber the stars in the cluster. These stars will generally be much older than those in NGC 6231, so members of the cluster can be identified by selecting signs of stellar youth.

Young stars stand out to Chandra because they have strong magnetic activity that heats their outer atmosphere to tens of millions of degrees Celsius and causes them to emit X-rays. Infrared measurements assist in verifying that an X-ray source is a young star and in inferring the star's properties.

This Chandra X-ray image of NGC 6231 shows a close-up of the inner region of the cluster. Chandra can detect a range of X-ray light, which has been split into three bands to create this image. Red, green, and blue represents the lower, medium, and high-energy X-rays. The brightest X-ray emission is white.

The Chandra data, combined with infrared data from the Visible and Infrared Survey Telescope for Astronomy (VISTA) Variables in the Vía Lactéa survey has provided the best census of young stars in NGC 6231 available. An infrared image from NASA’s Wide-field Infrared Survey explorer is shown on the left.

There are an estimated 5,700 to 7,500 young stars in NGC 6231 in the Chandra field of view, about twice the number of stars in the well-known Orion star cluster. The stars in NGC 6231 are slightly older (3.2 million years on average) than those in Orion (2.5 million years old). However, NGC 6231 is much larger in volume and therefore the number density of its stars, that is, their proximity to one another, is much lower, by a factor of about 30. These differences enable scientists to study the diversity of properties for star clusters during the first few million years of their life.

Chandra X-ray Observatory

Chandra studies of this and other young star clusters, have allowed astronomers to build up a sample from which cluster evolution can be studied. These clusters come from dozens of star-forming regions, but NGC 6231 adds a crucial piece to this puzzle because it shows how a cluster looks after the end of star formation. A comparison of the ages, sizes and masses of clusters in this sample implies that NGC 6231 has expanded from a more compact initial state, but it has not expanded sufficiently fast for its stars to break free from the cluster’s gravitational pull. Astronomers are not sure what will happen next: will it remain held together by gravity? Or will its constituents one day disperse as our Sun’s ancestral cluster once did?

Nearby star-forming regions frequently contain multiple star clusters, most of which are individually less massive than NGC 6231. The simple structure of NGC 6231, along with its relatively high mass, suggests that NGC 6231 was built up by mergers of several star clusters early its lifetime, a process known as “hierarchical cluster assembly”.


Two papers describing recent studies of NGC 6231, both led by Michael Kuhn while at the Universidad de Valparaíso in Chile, have been published and are available online at https://arxiv.org/abs/1706.00017 and https://arxiv.org/abs/1710.01731.

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.

Read More from NASA's Chandra X-ray Observatory: http://chandra.harvard.edu/photo/2018/ngc6231/

For more Chandra images, multimedia and related materials, visit: http://www.nasa.gov/chandra

Image, Animation, Text, Credits: NASA/Lee Mohon/CXC/University of Valparaiso/M. Kuhn et. al WISE:NASA/JPL/WISE.

Greetings, Orbiter.ch