A new image from NASA’s Dawn spacecraft shows a mountain three times as high as Mt. Everest, amidst the topography in the south polar region of the giant asteroid Vesta.
The peak of Vesta’s south pole mountain, seen in the center of the image, rises about 13 miles (22 kilometers) above the average height of the surrounding terrain. Another impressive structure is a large scarp, a cliff with a steep slope, on the right side of this image. The scarp bounds part of the south polar depression, and the Dawn team’s scientists believe features around its base are probably the result of landslides.
The image is online at: http://www.nasa.gov/mission_pages/dawn/multimedia/pia14869.html . It was created from a shape model of Vesta, and shows an oblique perspective view of the topography of the south polar region. The image resolution is about 300 meters per pixel, and the vertical scale is 1.5 times that of the horizontal scale.
Dawn entered orbit around Vesta in July. Members of the mission team will discuss what the spacecraft has seen so far during a news conference at the Annual Meeting of the Geological Society of America in Minneapolis. Among other things, they’ll share their hypotheses on the origins of Vesta’s curious craters.
An international team of astronomers has discovered over two-dozen new free-floating brown dwarfs that reside in two young star clusters. One brown dwarf is a lightweight youngster only about six times heftier than Jupiter. What’s more, one cluster contains a surprising surplus of brown dwarfs; it harbors half as many of these astronomical oddballs as normal stars. These findings come from deep surveys and extensive follow-up observations using the Subaru Telescope in Hawaii and the Very Large Telescope (VLT) in Chile, two of the world’s largest optical-infrared telescopes.
Sometimes described as failed stars, brown dwarfs are unusual celestial objects that straddle the boundary between stars and planets. When young, they glow brightly from the heat of formation, but they eventually cool down and end up with atmospheres that exhibit planet-like characteristics.
During the course of the SONYC (Substellar Objects in Nearby Young Clusters) Survey, astronomers used Subaru Telescope to take extremely deep images of the NGC 1333 and rho Ophiuchi star clusters at both optical and infrared wavelengths. Once they identified candidate brown dwarfs from their very red colours, the research team verified their nature with spectra taken at Subaru and the VLT. The team’s findings are reported in two upcoming papers in the Astrophysical Journal and will be presented this week at a scientific conference in Garching, Germany.
Newly released images taken by ESA’s Mars Express show an unusual accumulation of young craters in the large outflow channel called Ares Vallis. Older craters have been reduced to ghostly outlines by the scouring effects of ancient water.
In the distant past, probably over 3.8 billion years ago, large volumes of water must have rushed through the Ares Vallis with considerable force. Mars Express imaged the preserved aftermath of this scene on 11 May 2011.
The prominent Oraibi crater lies in the channel and is about 32 km across. It is filled with sediments and its southern rim has been eroded by water. NASA’s Pathfinder mission landed in this region in 1997, 100 km to the north of the crater and off the right-hand side of this image.
A map of the Moon combining observations in visible and ultraviolet wavelengths shows a treasure trove of areas rich in Titanium ores. Not only is Titanium a valuable mineral, it is key to helping scientists unravel the mysteries of the Moon’s interior. Mark Robinson and Brett Denevi will be presenting the results from the Lunar Reconnaissance Orbiter mission today at the joint meeting of the European Planetary Science Congress and the American Astronomical Society’s Division for Planetary Sciences.
“Looking up at the Moon, its surface appears painted with shades of grey – at least to the human eye. But with the right instruments, the Moon can appear colourful,” said Robinson, of Arizona State University. “The maria appear reddish in some places and blue in others. Although subtle, these colour variations tell us important things about the chemistry and evolution of the lunar surface. They indicate the titanium and iron abundance, as well as the maturity of a lunar soil.”
The Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) is imaging the surface in seven different wavelengths at a resolution of between 100 and 400 metres per pixel. Specific minerals reflect or absorb strongly certain parts of the electromagnetic spectrum, so the wavelengths detected by LROC WAC help scientists better understand the chemical composition of the lunar surface.
A remarkable discovery was made by astronomers on 12 December 2010: an asteroid named Scheila had changed its appearance and looked more like a comet, complete with bright tail. An international team of scientists have used innovative modeling techniques to support the idea that the cause was another object impacting Scheila, ejecting material from the asteroid. The lead scientist of this study, Fernando Moreno of the Instituto de Astrofísica de Andalucía in Granada, Spain, will present the group’s theory — complete with up-to-date and refined estimates of impact date and size — on Friday 7th October in Nantes, France at the joint meeting of the European Planetary Science Congress and the American Astronomical Society’s Division for Planetary Sciences.
Asteroid are rocks that primarily circle the Sun between the orbits of Mars and Jupiter. In contrast, comets tend to have highly elliptical orbits taking them from the frozen extreme edges of our Solar System to within distances so close to the Sun that solar radiation causes material in the comet to vaporize and stream out, forming the characteristic tails. That an asteroid was observed with a comet-like tail puzzled astronomers and required some inventive modeling to explain.
Moreno and his team charted the brightness of Scheila’s tail, noting how it dipped over the course of several weeks. They reached the conclusion that this unconventional tail was caused by another object smashing into Scheila and causing pieces to be blasted off.
Analysis of fragments of the Almahata Sitta meteorite, which landed in Sudan in 2008, has shown that the parent asteroid was probably formed through collisions of three different types of asteroids. The meteorites are of particular interest because they contain material both primitive and evolved types of asteroids. The results will be presented at the EPSC-DPS Joint Meeting 2011 in Nantes, France, by Dr Julie Gayon-Markt on Friday 7th October.
The meteorites are fragments of the asteroid 2008 TC3, which impacted the Earth exactly three years ago on 7th October 2008. More than 600 fragments were collected from the Nubian Desert in Sudan. They are collectively known as Almahata Sitta, which is Arabic for “Station Six”, a train station between Wadi Halfa and Khartoum near where the fragments were found. The impact was historic because it was the first time that an asteroid was observed in space and tracked as it descended through the Earth’s atmosphere.
“Because falls of meteorites of different types are rare, the question of the origin of an asteroid harbouring both primitive and evolved characteristics is a challenging and intriguing problem,” said Gayon-Markt. “Our recent studies of the dynamics and spectroscopy of asteroids in the main asteroid belt shed light on the origin of the Almahata Sitta fragments. We show that the Nysa-Polana asteroid family, located in the inner Main Belt is a very good candidate for the origin of 2008TC3.”
NASA is inviting its Twitter followers to register for a Tweetup and behind-the-scenes tour of the agency’s first laboratory, NASA’s Langley Research Center. NASA will host 50 social media guests from 10 a.m. to 4 p.m. EDT on Tuesday, Nov. 8, at the Hampton, Va., facility.
The Tweetup will give participants the chance to have lunch with an astronaut, interact with NASA experts, and tour a wind tunnel, lunar habitat concept and the historic Landing and Impact Research Facility, where Neil Armstrong trained to land on the moon.
Established in 1917, Langley’s current role at NASA includes aviation, science and space research. Langley researchers are testing space capsules for water landings, developing technologies to make aircraft faster, quieter, safer and greener, and studying Earth’s atmosphere to understand global climate change.
NASA’s Gravity Recovery And Interior Laboratory (GRAIL)-B spacecraft successfully executed its first flight path correction maneuver Wednesday, Oct. 5. The rocket burn helped refine the spacecraft’s trajectory as it travels from Earth to the moon and provides separation between itself and its mirror twin, GRAIL-A. The first burn for GRAIL-A occurred on Sept. 30.
“Both spacecraft are alive and with these burns, prove that they’re kicking too, as expected,” said David Lehman, GRAIL project manager at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “There is a lot of time and space between now and lunar orbit insertion, but everything is looking good.”
GRAIL-B’s rocket burn took place on Oct. 5 at 11 a.m. PDT (2 p.m. EDT). The spacecraft’s main engine burned for 234 seconds and imparted a velocity change of 56.1 mph (25.1 meters per second) while expending 8.2 pounds (3.7 kilograms) of propellant. GRAIL-A’s burn on Sept. 30 also took place at 11 a.m. PDT. It lasted 127 seconds and imparted a 31.3 mph (14 meters per second) velocity change on the spacecraft while expending 4 pounds (1.87 kilograms) of propellant.
The most recent spacecraft telemetry was acquired on Oct.4 from the Deep Space Network tracking complex at Canberra, Australia. The Cassini spacecraft is in an excellent state of health and with the exception of the CAPS instrument being powered off, all subsystems are operating normally. Information on the present position and speed of the Cassini spacecraft may be found on the “Present Position” page at: http://saturn.jpl.nasa.gov/mission/presentposition/.