vendredi 19 janvier 2018

Space Station Orbits Earth for 7000th Day









ISS - Expedition 54 Mission patch.

Jan. 19, 2018

The International Space Station has been orbiting Earth for 7,000 days as of today Friday, Jan. 19, 2018. The first module, the Russian Zarya cargo module, launched to space in November of 1998. The first crew arrived at the young three-module orbital laboratory in November of 2000.

54 crews and 205 spacewalks later, the current six-member Expedition 54 crew is gearing up for a pair of spacewalks on Jan. 23 and 29. NASA astronaut Mark Vande Hei will lead both spacewalks with Flight Engineer Scott Tingle joining him on the first spacewalk. Japanese astronaut Norishige Kanai will join Vande Hei for the second spacewalk.


Image above: Clockwise from top left: The first station module, Zarya from Russia, is pictured December 1998 from Space Shuttle Endeavour; the first station crew, Expedition 1, was onboard the station in February of 2001; a growing station was pictured in June of 2007; the station in its near final configuration in February 2010.

All three astronauts were joined today by Flight Engineer Acaba for a spacewalk procedures review with specialists on the ground. The spacewalking trio will be swapping and stowing robotics parts to maintain the upkeep of the Canadarm2 robotic arm. Both spacewalks will start each day at 7:10 a.m. EST with live NASA Television coverage beginning at 5:30 a.m.

The two cosmonauts aboard the space station, Commander Alexander Misurkin and Flight Engineer Anton Shkaplerov, conducted regularly scheduled eye checks today. The veteran orbital residents worked with doctors on the ground using a fundoscope to view the interior of the eye. Crew members aboard the station participate in regular eye exams to understand how living in space affects vision.

Related links:

Expedition 54: https://www.nasa.gov/mission_pages/station/expeditions/expedition54/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

Image, Text, Credits: NASA/Mark Garcia.

Best regards, Orbiter.ch

Hubble’s Cartwheel












NASA - Hubble Space Telescope patch.

Jan. 19, 2018


This is an image of the Cartwheel Galaxy taken with the NASA/ESA (European Space Agency) Hubble Space Telescope.

The object was first spotted on wide-field images from the U.K. Schmidt telescope and then studied in detail using the Anglo-Australian Telescope.

Lying about 500 million light-years away in the constellation of Sculptor, the cartwheel shape of this galaxy is the result of a violent galactic collision. A smaller galaxy has passed right through a large disk galaxy and produced shock waves that swept up gas and dust — much like the ripples produced when a stone is dropped into a lake — and sparked regions of intense star formation (appearing blue). The outermost ring of the galaxy, which is 1.5 times the size of our Milky Way, marks the shock wave’s leading edge. This object is one of the most dramatic examples of the small class of ring galaxies.

This image is based on earlier Hubble data of the Cartwheel Galaxy that was reprocessed in 2010, bringing out more detail in the image than seen before.

For more information about Hubble, visit:

http://hubblesite.org/
http://www.nasa.gov/hubble
http://www.spacetelescope.org/

Image credits: ESA/Hubble & NASA/Text credits: ESA/NASA/Rob Garner.

Greetings, Orbiter.ch

Asteroid 2002 AJ129 to Fly Safely Past Earth February 4










Asteroid Watch logo.

Jan. 19, 2018

Asteroid 2002 AJ129 will make a close approach to Earth on Feb. 4, 2018 at 1:30 p.m. PST (4:30 p.m. EST / 21:30 UTC). At the time of closest approach, the asteroid will be no closer than 10 times the distance between Earth and the Moon (about 2.6 million miles, or 4.2 million kilometers).

Trajectory of Asteroid 2002 AJ129

Video above: Asteroid 2002 AJ129 will make a close approach to Earth on Feb. 4, 2018, at 1:30 p.m. PST (4:30 p.m. EST). At the time of closest approach, the asteroid will be at a distance of 2.6 million miles, or 4.2 million kilometers -- about 10 times the distance between Earth and the moon.

2002 AJ129 is an intermediate-sized near-Earth asteroid, somewhere between 0.3 miles (0.5 kilometers) and 0.75 miles (1.2 kilometers) across. It was discovered on Jan. 15, 2002, by the former NASA-sponsored Near Earth Asteroid Tracking project at the Maui Space Surveillance Site on Haleakala, Hawaii. The asteroid’s velocity at the time of closest approach, 76,000 mph (34 kilometers per second), is higher than the majority of near-Earth objects during an Earth flyby. The high flyby velocity is a result of the asteroid’s orbit, which approaches very close to the Sun -- 11 million miles (18 million kilometers). Although asteroid 2002 AJ129 is categorized as a Potentially Hazardous Asteroid (PHA), it does not pose an actual threat of colliding with our planet for the foreseeable future.

Near-Earth asteroid. Image Credit: ESA

“We have been tracking this asteroid for over 14 years and know its orbit very accurately,” said Paul Chodas, manager of NASA’s Center for Near-Earth Object Studies at the Jet Propulsion Laboratory, Pasadena, California.  “Our calculations indicate that asteroid 2002 AJ129 has no chance — zero — of colliding with Earth on Feb. 4 or any time over the next 100 years.”

JPL hosts the Center for Near-Earth Object Studies for NASA's Near-Earth Object Observations Program, an element of the Planetary Defense Coordination Office within the agency's Science Mission Directorate.

More information about asteroids and near-Earth objects can be found at:

https://cneos.jpl.nasa.gov

https://www.jpl.nasa.gov/asteroidwatch

Asteroids: https://www.nasa.gov/mission_pages/asteroids/main/index.html

For more information about NASA's Planetary Defense Coordination Office, visit:

https://www.nasa.gov/planetarydefense

For asteroid and comet news and updates, follow AsteroidWatch on Twitter:

https://twitter.com/AsteroidWatch

Video, Image (mentioned), Text, Credits: NASA/Tony Greicius/JPL/DC Agle.

Greetings, Orbiter.ch

jeudi 18 janvier 2018

NASA Team Studies Middle-aged Sun by Tracking Motion of Mercury












NASA - MESSENGER Mission patch.

Jan. 18, 2018

Mercury. Image Credits: NASA/MESSENGER/JHUAPL/CW

Like the waistband of a couch potato in midlife, the orbits of planets in our solar system are expanding. It happens because the Sun’s gravitational grip gradually weakens as our star ages and loses mass. Now, a team of NASA and MIT scientists has indirectly measured this mass loss and other solar parameters by looking at changes in Mercury’s orbit.

The new values improve upon earlier predictions by reducing the amount of uncertainty. That’s especially important for the rate of solar mass loss, because it’s related to the stability of G, the gravitational constant. Although G is considered a fixed number, whether it’s really constant is still a fundamental question in physics.

“Mercury is the perfect test object for these experiments because it is so sensitive to the gravitational effect and activity of the Sun,” said Antonio Genova, the lead author of the study published in Nature Communications and a Massachusetts Institute of Technology researcher working at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

The study began by improving Mercury’s charted ephemeris — the road map of the planet’s position in our sky over time. For that, the team drew on radio tracking data that monitored the location of NASA’s MESSENGER spacecraft while the mission was active. Short for Mercury Surface, Space Environment, Geochemistry, and Ranging, the robotic spacecraft made three flybys of Mercury in 2008 and 2009 and orbited the planet from March 2011 through April 2015. The scientists worked backward, analyzing subtle changes in Mercury’s motion as a way of learning about the Sun and how its physical parameters influence the planet’s orbit.


Image above: NASA and MIT scientists analyzed subtle changes in Mercury’s motion to learn about the Sun and how its dynamics influence the planet’s orbit. The position of Mercury over time was determined from radio tracking data obtained while NASA’s MESSENGER mission was active. Image Credits: NASA's Goddard Space Flight Center.

For centuries, scientists have studied Mercury’s motion, paying particular attention to its perihelion, or the closest point to the Sun during its orbit. Observations long ago revealed that the perihelion shifts over time, called precession. Although the gravitational tugs of other planets account for most of Mercury’s precession, they don’t account for all of it.

The second-largest contribution comes from the warping of space-time around the Sun because of the star’s own gravity, which is covered by Einstein’s theory of general relativity. The success of general relativity in explaining most of Mercury’s remaining precession helped persuade scientists that Einstein’s theory was right.

Other, much smaller contributions to Mercury’s precession, are attributed to the Sun’s interior structure and dynamics. One of those is the Sun’s oblateness, a measure of how much it bulges at the middle — its own version of a “spare tire” around the waist — rather than being a perfect sphere. The researchers obtained an improved estimate of oblateness that is consistent with other types of studies.

The researchers were able to separate some of the solar parameters from the relativistic effects, something not accomplished by earlier studies that relied on ephemeris data. The team developed a novel technique that simultaneously estimated and integrated the orbits of both MESSENGER and Mercury, leading to a comprehensive solution that includes quantities related to the evolution of Sun’s interior and to relativistic effects.


Image above: Mercury’s proximity to the Sun and small size make it exquisitely sensitive to the dynamics of the Sun and its gravitational pull. Image Credits: NASA/SDO.

“We’re addressing long-standing and very important questions both in fundamental physics and solar science by using a planetary-science approach,” said Goddard geophysicist Erwan Mazarico. “By coming at these problems from a different perspective, we can gain more confidence in the numbers, and we can learn more about the interplay between the Sun and the planets.”

The team’s new estimate of the rate of solar mass loss represents one of the first times this value has been constrained based on observations rather than theoretical calculations. From the theoretical work, scientists previously predicted a loss of one-tenth of a percent of the Sun’s mass over 10 billion years; that’s enough to reduce the star’s gravitational pull and allow the orbits of the planets to spread by about half an inch, or 1.5 centimeters, per year per AU (an AU, or astronomical unit, is the distance between Earth and the Sun: about 93 million miles).

The new value is slightly lower than earlier predictions but has less uncertainty. That made it possible for the team to improve the stability of G by a factor of 10, compared to values derived from studies of the motion of the Moon.

“The study demonstrates how making measurements of planetary orbit changes throughout the solar system opens the possibility of future discoveries about the nature of the Sun and planets, and indeed, about the basic workings of the universe,” said co-author Maria Zuber, vice president for research at MIT.

Related links:

Nature Communications: http://nature.com/articles/doi:10.1038/s41467-017-02558-1

MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging): http://www.nasa.gov/mission_pages/messenger/main/index.html

Images (mentioned), Text, Credits: NASA/Rob Garner/Goddard Space Flight Center, By Elizabeth Zubritsky.

Best regards, Orbiter.ch

Jupiter’s Swirling South Pole












NASA - JUNO Mission logo.

Jan. 18, 2018


This image of Jupiter’s swirling south polar region was captured by NASA’s Juno spacecraft as it neared completion of its tenth close flyby of the gas giant planet.

The “empty” space above and below Jupiter in this color-enhanced image can trick the mind, causing the viewer to perceive our solar system’s largest planet as less colossal than it is. In reality, Jupiter is wide enough to fit 11 Earths across its clouded disk.

The spacecraft captured this image on Dec. 16, 2017, at 11:07 PST (2:07 p.m. EST) when the spacecraft was about 64,899 miles (104,446 kilometers) from the tops of the clouds of the planet at a latitude of 83.9 degrees south — almost directly over Jupiter’s south pole.

The spatial scale in this image is 43.6 miles/pixel (70.2 kilometers/pixel).

Citizen scientist Gerald Eichstädt processed this image using data from the JunoCam imager.

JunoCam's raw images are available for the public to peruse and process into image products at:

http://www.missionjuno.swri.edu/junocam     

More information about Juno is at:

https://www.nasa.gov/juno and http://missionjuno.swri.edu

Image, Text, Credits: NASA/Tony Greicius/JPL-Caltech/SwRI/MSSS/Gerald Eichstädt.

Greetings, Orbiter.ch

North, east, south, west: The many faces of Abell 1758












ESA - Hubble Space Telescope logo.

18 January 2018

Northern part of Abell 1758

Resembling a swarm of flickering fireflies, this beautiful galaxy cluster glows intensely in the dark cosmos, accompanied by the myriad bright lights of foreground stars and swirling spiral galaxies. A1758N is a sub-cluster of Abell 1758, a massive cluster containing hundreds of galaxies. Although it may appear serene in this NASA/ESA Hubble Space Telescope image, the sub-cluster actually comprises two even smaller structures currently in the turbulent process of merging.

Although often overshadowed by its more famous cousins — including the Fornax Cluster and Pandora’s Cluster — Abell 1758 contains more than its fair share of intrigue. The cluster was first identified in 1958, and initially logged as a single massive object. However, some 40 years later the cluster was observed again by the ROSAT satellite X-ray telescope, and astronomers spotted something peculiar: the cluster was not a single concentration of galaxies, but two!

Wide-field view of Abell 1758 (ground-based view)

Abell 1758 has since been observed many more times by various observatories — Hubble, NASA’s Chandra X-ray Observatory, ESA’s XMM-Newton, and more — and is now known to have both a double structure and a complex history. It contains two massive sub-clusters sitting some 2.4 million light-years apart. These components, known as A1758N (North) and A1758S (South), are bound together by gravity but without showing signs of interacting.

In this Hubble image only the northern structure of the cluster, A1758N, is visible. A1758N is further split into two sub-structures, known as East (A1758NE) and West (A1758NW). There appear to be disturbances within each of of the two sub-clusters of A1758A — strong evidence that they are the result of smaller clusters colliding and merging.

Zooming into the galaxy cluster A1758N

Studies have also revealed a radio halo and two radio relics within Abell 1758. Through Hubble’s eyes these radio structures are invisible, but radio telescopes reveal an oddly-shaped halo of emission around the cluster. Radio halos are vast sources of diffuse radio emission usually found around the centres of galaxy clusters. They are thought to form when clusters collide and accelerate fast-moving particles to even higher speeds, implying that clusters with radio halos are still forming and merging.

Collisions such as the one A1758N is undergoing are the most energetic events in the Universe apart from the Big Bang itself. Understanding how clusters merge helps astronomers to understand how structures grow and evolve in the Universe. It also helps them to study dark matter, the intracluster medium and galaxies, and to explore how these three components interact — particularly during mergers.

Panning across the galaxy cluster A1725N

This image was taken by Hubble’s Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3) as part of an observing programme called RELICS. The programme is imaging 41 massive galaxy clusters, using them as cosmic lenses to search for bright distant galaxies. These will then be studied in more detail using both current telescopes and the future NASA/ESA/CSA James Webb Space Telescope.
More information

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

Links:

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

Hubble Space Telescope: http://www.spacetelescope.org/

Images, Text, Credits: NASA, ESA/Nicole Shearer/Digitized Sky Survey 2/Videos: Akira Fujii/David Malin Images, DSS, ESA/Hubble/Music: Johan B. Monell.

Best regards, Orbiter.ch

Crater Neukum named after Mars Express founder












ESA - Mars Express Mission patch.

18 January 2018

A fascinating martian crater has been chosen to honour the German physicist and planetary scientist, Gerhard Neukum, one of the founders of ESA’s Mars Express mission.

 Neukum Crater

The International Astronomical Union named the 102 km-wide crater in the Noachis Terra region “Neukum” in September last year after the camera’s leader, who died in 2014. Professor Neukum inspired and led the development of the high-resolution stereo camera on Mars Express, which helped to establish the regional geology and topography of Mars.

Observations by the camera in December 2005 and May 2007 were used to create the image mosaic of Neukum Crater presented here.

Neukum Crater in context

Neukum Crater sits in the Noachis Terra region in the densely cratered southern highlands of Mars, some 800 km to the west of the planet’s largest impact basin, Hellas. Noachis Terra is one of the oldest known regions on the Red Planet, dating back at least 3.9 billion years – the earliest martian era, the Noachian epoch, is named after it.

It is representative of the ancient surface of Mars, which is characteristically peppered with craters that have been preserved for billions of years, although many have degraded over time.

Neukum Crater perspective view

Many impact craters in Noachis Terra host dune fields, and in this scene, Neukum Crater displays a particularly interesting pattern with dunes covering an area of about 12 x 17 km in the southeast corner of the crater.

The individual dunes stretch out in a north–south direction, with the dominant slipface towards the west, pointing to a prevailing wind coming from the east. In addition, dark sands have been blown to the west and north of the dunes, indicative of the strong easterly – and some southerly – winds.

Neukum Crater topography

The formation of light-toned deposits west of the dune field is unclear: they might be boulders or erosional remnants from the rocky crater interior.

The crater’s shallow interior has likely been infilled by sediments over its history. It is also marked with two irregular depressions. Perhaps they are a sign of a weaker material that has since eroded away, leaving behind some islands of more resistant material.

Neukum Crater in 3D

Over time the interior of the crater rim has undergone varying degrees of collapse, with landslides visible in the perspective view. Many smaller craters have also overprinted the rim and pockmarked the interior since Neukum Crater was formed, highlighting its long history.

Related links:

Professor Neukum: http://www.esa.int/Our_Activities/Space_Science/People/Man_with_a_plan_An_interview_with_Gerhard_Neukum

Mars Express: http://www.esa.int/Our_Activities/Space_Science/Mars_Express

Mars Express overview: http://www.esa.int/Our_Activities/Space_Science/Mars_Express_overview

Mars Express in-depth: http://sci.esa.int/marsexpress

ESA Planetary Science archive (PSA): http://www.rssd.esa.int/PSA

High Resolution Stereo Camera: http://berlinadmin.dlr.de/Missions/express/indexeng.shtml

HRSC data viewer: http://hrscview.fu-berlin.de/

Behind the lens... http://www.esa.int/Our_Activities/Space_Science/Mars_Express/Behind_the_lens

Frequently asked questions: http://www.esa.int/Our_Activities/Space_Science/Mars_Express/Frequently_asked_questions

Images, Text, Credits: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO/NASA MGS MOLA Science Team.

Best regards, Orbiter.ch