NASA Dawn Spacecraft Sees Hydrated Minerals on Giant Asteroid

Dwayne Brown

Headquarters, Washington                          

202-358-1726

dwayne.c.brown@nasa.gov

                     

Jia-Rui C. Cook

Jet Propulsion Laboratory, Pasadena, Calif.

818-354-0850

jccook@jpl.nasa.gov

 

WASHINGTON -- NASA's Dawn spacecraft has revealed the giant asteroid Vesta has its own version of ring around the collar. Two new papers, based on observations from the low-altitude mapping orbit of the Dawn mission, show volatile, or easily evaporated, materials have colored Vesta's surface in a broad swath around its equator.

The volatiles were released from minerals likely containing water. Pothole-like features mark some of the asteroid's surface where the volatiles boiled off. Dawn did not find actual water ice at Vesta. However, it found evidence of hydrated minerals delivered by meteorites and dust in the giant asteroid's chemistry and geology. The findings appear Thursday in the journal Science.

One paper, led by Thomas Prettyman, the lead scientist for Dawn's gamma ray and neutron detector (GRaND) at the Planetary Science Institute in Tucson, Ariz., describes how the instrument found signatures of hydrogen, likely in the form of hydroxyl or water bound to minerals in Vesta's surface.

"The source of the hydrogen within Vesta's surface appears to be hydrated minerals delivered by carbon-rich space rocks that collided with Vesta at speeds slow enough to preserve their volatile content," said Prettyman.

A complementary paper, led by Brett Denevi, a Dawn participating scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., describes the presence of pitted terrain created by the release of the volatiles.

Vesta is the second most massive member of our solar system's main asteroid belt. Dawn was orbiting at an average altitude of about 130 miles (210 kilometers) above the surface when it obtained the data. Dawn left Vesta on Sept. 5 EDT (Sept. 4) and is on its way to a second target, the dwarf planet Ceres.

Scientists thought it might be possible for water ice to survive near the surface around the giant asteroid's poles. Unlike Earth's moon, however, Vesta has no permanently shadowed polar regions where ice might survive. The strongest signature for hydrogen in the latest data came from regions near the equator, where water ice is not stable.

In some cases, space rocks crashed into these deposits at high speed. The heat from the collisions converted the hydrogen bound to the minerals into water, which evaporated. Escaping water left holes as much as six-tenths of a mile (1 kilometer) wide and as deep as 700 feet (200 meters). Seen in images from Dawn's framing camera, this pitted terrain is best preserved in sections of Marcia crater.

"The pits look just like features seen on Mars, and while water was common on Mars, it was totally unexpected on Vesta in these high abundances," said Denevi. "These results provide evidence that not only were hydrated materials present, but they played an important role in shaping the asteroid's geology and the surface we see today."

GRaND's data are the first direct measurements describing the elemental composition of Vesta's surface. Dawn's elemental investigation by the instrument determined the ratios of iron to oxygen and iron to silicon in the surface materials. The new findings solidly confirm the connection between Vesta and a class of meteorites found on Earth called the Howardite, Eucrite and Diogenite meteorites, which have the same ratios for these elements. In addition, more volatile-rich fragments of other objects have been identified in these meteorites, which supports the idea the volatile-rich material was deposited on Vesta.

The Dawn mission is managed by NASA's Jet Propulsion Laboratory for the Science Mission Directorate in Washington. The spacecraft is as a project of the Discovery Program managed by NASA's Marshall Space Flight Center in Huntsville, Ala. The University of California, Los Angeles, is responsible for overall mission science. Orbital Sciences Corporation of Dulles, Va., designed and built the spacecraft.

The framing cameras that saw the pitted terrain were developed and built under the leadership of the Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, with contributions by the German Aerospace Center (DLR) Institute of Planetary Research, Berlin, and in coordination with the Institute of Computer and Communication Network Engineering, Braunschweig. The framing camera project is funded by NASA, the Max Planck Society and DLR. The gamma ray and neutron detector instrument was built by Los Alamos National Laboratory, N.M., and is operated by the Planetary Science Institute.

To view new images and for more information about Dawn, visit http://www.nasa.gov/dawn.

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NASA Kicks Off Asteroid Simulation; Media Invited to Observe

Joshua Buck

Headquarters, Washington

202-358-1100

jbuck@nasa.gov

 

Brandi Dean

Johnson Space Center, Houston

281-483-5111

brandi.k.dean@nasa.gov

HOUSTON -- A simulated mission to an asteroid is under way at NASA's Johnson Space Center in Houston. Journalists are invited to learn about the test and technologies on Thursday, Aug. 30.

Media will be able to learn about the test and see the technologies up close. Reporters interested in attending should email Brandi Dean at brandi.k.dean@nasa.gov. International media must apply for credentials by 5 p.m. CDT, Aug. 23. U.S. reporters should respond by 5 p.m. Aug. 29.

The Research and Technology Studies (RATS) test, a 10-day asteroid exploration simulation in Johnson's Space Vehicle Mockup Facility, kicked off this week. As NASA makes plans to send humans to asteroids by 2025, RATS and other mission simulations provide the agency with a way to test new operations, concepts and exploration techniques to influence the future of exploration.

The 2012 RATS test will use several technologies to simulate life and work on the surface of an asteroid. A crew of five scientists and flight controllers in pairs will take turns sleeping, eating, exercising and working inside the cabin of the multi-mission Space Exploration Vehicle (SEV) for 3 days and 2 nights at a time. They will evaluate the cabin's displays, controls and views with the help of a video wall that contours around the vehicle's windows displaying a simulation of the asteroid surface as they steer across it.

Outside of the SEV, crew members will participate in simulated spacewalks on the asteroid surface using Johnson's virtual reality laboratory and its Active Response Gravity Offload System. The laboratory uses a virtual reality helmet and gloves to simulate movement on a virtual asteroid surface. The system suspends astronauts from a specialized crane designed to offset their weight and simulate microgravity.

The team will use these technologies to evaluate various modes of movement during spacewalks while the SEV-based crew members assist from inside the vehicle. A team of flight controllers and scientists also will support the tests from the nearby Mission Control Center, with a 50-second, one-way delay in communication between the two groups to mimic what astronauts working on an asteroid would experience.

For information about the RATS tests and links to follow the mission on Facebook and Twitter, visit http://www.nasa.gov/desertrats.

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Taking Tarpeia's Temperature

This colorized image from NASA’s Dawn mission shows temperature variations at Tarpeia Crater, near the south pole of the giant asteroid Vesta. Obtained by the visible and infrared mapping spectrometer, data show the warmest areas in white, measuring about minus 10 degrees Fahrenheit (minus 23 degrees Celsius). The dark areas are the coldest, with temperatures at or below minus 150 degrees Fahrenheit (minus 100 degrees Celsius).

The variations in the red shading indicate the intensity of the emitted light in the 5-micron wavelength, which is indicative of the surface temperature.

The visible and infrared mapping spectrometer obtained the images during Dawn’s low-altitude mapping orbit (130 miles or 210 kilometers in altitude) on Feb. 5, 2012.

Image Credit: NASA/JPL-Caltech/UCLA/INAF

NASA Releases Workshop Data and Findings on Asteroid 2011 AG5

Dwayne Brown

Headquarters, Washington                                   

202-358-1726

dwayne.c.brown@nasa.gov

WASHINGTON -- Researchers anticipate that asteroid 2011 AG5, discovered in January 2011, will fly safely past and not impact Earth in 2040.

Current findings and analysis data were reported at a May 29 workshop at NASA's Goddard Space Flight Center in Greenbelt, Md., attended by scientists and engineers from around the world. Discussions focused on observations of potentially hazardous asteroids (PHAs).

Observations to date indicate there is a slight chance that AG5 could impact Earth in 2040. Attendees expressed confidence that in the next four years, analysis of space and ground-based observations will show the likelihood of 2011 AG5 missing Earth to be greater than 99 percent.

Measuring approximately 460 feet (140 meters) in size, the space rock was discovered by the NASA-supported Catalina Sky Survey operated by the University of Arizona in Tucson. Several observatories monitored 2011 AG5 for nine months before it moved too far away and grew too faint to see.

"While there is general consensus there is only a very small chance that we could be dealing with a real impact scenario for this object, we will still be watchful and ready to take further action if additional observations indicate it is warranted," said Lindley Johnson, program executive for the Near-Earth Object (NEO) Observation Program at NASA Headquarters in Washington.

Several years ago another asteroid, named Apophis, was thought to pose a similar impact threat in 2036. Additional observations taken from 2005 through 2008 enabled NASA scientists to refine their understanding of the asteroid's path, which showed a significantly reduced likelihood of a hazardous encounter.

"Any time we're able to observe an asteroid and obtain new location data, we're able to refine our calculations of the asteroid's future path," said Don Yeomans, manager of NASA's NEO Program Office at the Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "When few observations exist, our initial orbit calculation will include a wider swath to account for uncertainties. With more data points, the knowledge of the potential positions of the asteroid improves and the swath becomes smaller -- typically eliminating the risk of an impact."

Observations of 2011 AG5 have been limited to date because of its present location beyond the orbit of Mars and in the daytime sky on the other side of the sun. In fall 2013, conditions will improve to allow space- and ground-based telescopes to better track the asteroid's path. At that time, 2011 AG5 will be 91 million miles (147 million kilometers) from Earth but favorably located for observations in the late evening sky.

The level of hazard will gain even more clarity in 2023, when the asteroid is approximately 1.1 million miles (1.8 million kilometers) from Earth. If 2011 AG5 passes through a 227-mile-wide (365-kilometer) region in space called a keyhole in early February 2023, Earth's gravitational pull could influence the object's orbital path just enough to bring it back for an impact on February 5, 2040. If the asteroid misses the keyhole, an impact in 2040 will not occur.

"Given our current understanding of this asteroid's orbit, there is only a very remote chance of this keyhole passage even occurring," said Johnson.

Although scientists widely expect it to be a safe flyby, they acknowledge the slight chance that computed odds could rise as a result of observations to be taken from 2013 to 2016. According to the experts at the workshop, even if the odds do increase, there is still ample time to plan and carry out at least one of several viable missions to change the asteroid's course.

PHAs are a subset of the larger group of near-Earth asteroids. They have the closest orbits to Earth's, coming within 5 million miles (about 8 million kilometers). They are large enough to enter Earth's atmosphere intact and cause damage on at least a local scale. Damage from an asteroid the size of 2011 AG5 could cover a region at least a hundred miles wide.

NASA established the NEO Program in 1998 to coordinate the agency's efforts to detect, track and characterize Earth-approaching NEOs and comets larger than 1 kilometer in size. The program now also searches for NEOs as small as object 2011 AG5. NASA supports NEO observation, tracking and analysis activities worldwide. Activities are coordinated through the NEO Program Office at JPL.

To read the workshop report and findings, visit http://neo.jpl.nasa.gov/.

For information about NASA asteroid missions and activities, visit http://www.nasa.gov/asteroids.

EDITOR'S NOTE: Lindley Johnson and Don Yeomans are available for media interviews. To coordinate a time and date, email Dwayne Brown at dwayne.c.brown@nasa.gov.

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NASA Releases Workshop Data and Findings on Asteroid 2011 AG5

Dwayne Brown

Headquarters, Washington                                   

202-358-1726

dwayne.c.brown@nasa.gov

WASHINGTON -- Researchers anticipate that asteroid 2011 AG5, discovered in January 2011, will fly safely past and not impact Earth in 2040.

Current findings and analysis data were reported at a May 29 workshop at NASA's Goddard Space Flight Center in Greenbelt, Md., attended by scientists and engineers from around the world. Discussions focused on observations of potentially hazardous asteroids (PHAs).

Observations to date indicate there is a slight chance that AG5 could impact Earth in 2040. Attendees expressed confidence that in the next four years, analysis of space and ground-based observations will show the likelihood of 2011 AG5 missing Earth to be greater than 99 percent.

Measuring approximately 460 feet (140 meters) in size, the space rock was discovered by the NASA-supported Catalina Sky Survey operated by the University of Arizona in Tucson. Several observatories monitored 2011 AG5 for nine months before it moved too far away and grew too faint to see.

"While there is general consensus there is only a very small chance that we could be dealing with a real impact scenario for this object, we will still be watchful and ready to take further action if additional observations indicate it is warranted," said Lindley Johnson, program executive for the Near-Earth Object (NEO) Observation Program at NASA Headquarters in Washington.

Several years ago another asteroid, named Apophis, was thought to pose a similar impact threat in 2036. Additional observations taken from 2005 through 2008 enabled NASA scientists to refine their understanding of the asteroid's path, which showed a significantly reduced likelihood of a hazardous encounter.

"Any time we're able to observe an asteroid and obtain new location data, we're able to refine our calculations of the asteroid's future path," said Don Yeomans, manager of NASA's NEO Program Office at the Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "When few observations exist, our initial orbit calculation will include a wider swath to account for uncertainties. With more data points, the knowledge of the potential positions of the asteroid improves and the swath becomes smaller -- typically eliminating the risk of an impact."

Observations of 2011 AG5 have been limited to date because of its present location beyond the orbit of Mars and in the daytime sky on the other side of the sun. In fall 2013, conditions will improve to allow space- and ground-based telescopes to better track the asteroid's path. At that time, 2011 AG5 will be 91 million miles (147 million kilometers) from Earth but favorably located for observations in the late evening sky.

The level of hazard will gain even more clarity in 2023, when the asteroid is approximately 1.1 million miles (1.8 million kilometers) from Earth. If 2011 AG5 passes through a 227-mile-wide (365-kilometer) region in space called a keyhole in early February 2023, Earth's gravitational pull could influence the object's orbital path just enough to bring it back for an impact on February 5, 2040. If the asteroid misses the keyhole, an impact in 2040 will not occur.

"Given our current understanding of this asteroid's orbit, there is only a very remote chance of this keyhole passage even occurring," said Johnson.

Although scientists widely expect it to be a safe flyby, they acknowledge the slight chance that computed odds could rise as a result of observations to be taken from 2013 to 2016. According to the experts at the workshop, even if the odds do increase, there is still ample time to plan and carry out at least one of several viable missions to change the asteroid's course.

PHAs are a subset of the larger group of near-Earth asteroids. They have the closest orbits to Earth's, coming within 5 million miles (about 8 million kilometers). They are large enough to enter Earth's atmosphere intact and cause damage on at least a local scale. Damage from an asteroid the size of 2011 AG5 could cover a region at least a hundred miles wide.

NASA established the NEO Program in 1998 to coordinate the agency's efforts to detect, track and characterize Earth-approaching NEOs and comets larger than 1 kilometer in size. The program now also searches for NEOs as small as object 2011 AG5. NASA supports NEO observation, tracking and analysis activities worldwide. Activities are coordinated through the NEO Program Office at JPL.

To read the workshop report and findings, visit http://neo.jpl.nasa.gov/.

For information about NASA asteroid missions and activities, visit http://www.nasa.gov/asteroids.

EDITOR'S NOTE: Lindley Johnson and Don Yeomans are available for media interviews. To coordinate a time and date, email Dwayne Brown at dwayne.c.brown@nasa.gov.

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