NASA Probe Nears Position for Year-Long Stay at Giant Asteroid

Dwayne C. Brown

Headquarters, Washington                                

 

Priscilla Vega/Jia-Rui Cook

Jet Propulsion Laboratory, Pasadena, Calif.

WASHINGTON -- NASA's Dawn spacecraft is on track to begin the first extended visit to a large asteroid. The mission expects to go into orbit around Vesta on July 16 and begin gathering science data in early August. Vesta resides in the main asteroid belt and is thought to be the source of a large number of meteorites that fall to Earth.

"The spacecraft is right on target," said Robert Mase, Dawn project manager at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "We look forward to exploring this unknown world during Dawn's one year stay in Vesta's orbit."

After traveling nearly four years and 1.7 billion miles (2.7 billion kilometers), Dawn is approximately 96,000 miles (155,000 kilometers) away from Vesta. When Vesta captures Dawn into its orbit, there will be approximately 9,900 miles (16,000 kilometers) between them. They will be approximately 117 million miles (188 million kilometers) away from Earth.

After Dawn enters Vesta's orbit, engineers will need a few days to determine the exact time of capture. Unlike other missions where a dramatic, nail-biting propulsive burn results in orbit insertion around a planet, Dawn has been using its placid ion propulsion system to subtly shape its path for years to match Vesta's orbit around the sun.

Images from Dawn's framing camera, taken for navigation purposes, show the slow progress toward Vesta. They also show Vesta rotating about 65 degrees in the field of view. The images are about twice as sharp as the best images of Vesta from NASA's Hubble Space Telescope, but the surface details Dawn will obtain are still a mystery.

"Navigation images from Dawn's framing camera have given us intriguing hints of Vesta, but we're looking forward to the heart of Vesta operations, when we begin officially collecting science data," said Christopher Russell, Dawn principal investigator, at the University of California, Los Angeles (UCLA). "We can't wait for Dawn to peel back the layers of time and reveal the early history of our solar system."

Dawn's three instruments are all functioning and appear to be properly calibrated. The visible and infrared mapping spectrometer, for example, has started to obtain images of Vesta that are larger than a few pixels in size. During the initial reconnaissance orbit, at approximately 1,700 miles (2,700 kilometers), the spacecraft will get a broad overview of Vesta with color pictures and data in different wavelengths of reflected light. The spacecraft will move into a high altitude mapping orbit, about 420 miles (680 kilometers) above the surface to systematically map the parts of Vesta's surface illuminated by the sun; collect stereo images to see topographic highs and lows; acquire higher resolution data to map rock types at the surface; and learn more about Vesta's thermal properties.

Dawn then will move even closer, to a low-altitude mapping orbit approximately 120 miles (200 kilometers) above the surface. The primary science goals of this orbit are to detect the byproducts of cosmic rays hitting the surface and help scientists determine the many kinds of atoms there, and probe the protoplanet's internal structure. As Dawn spirals away from Vesta, it will pause again at the high-altitude mapping orbit altitude. Because the sun's angle on the surface will have progressed, scientists will be able to see previously hidden terrain while obtaining different views of surface features.

"We've packed our year at Vesta chock-full of science observations to help us unravel the mysteries of Vesta," said Carol Raymond, Dawn's deputy principal investigator at JPL. Vesta is considered a protoplanet, or body that never quite became a full-fledged planet.

Dawn launched in September 2007. Following a year at Vesta, the spacecraft will depart for its second destination, the dwarf planet Ceres, in July 2012. Dawn's mission to Vesta and Ceres is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Ala.

UCLA is responsible for overall Dawn mission science. Orbital Sciences Corp. of Dulles, Va., designed and built the spacecraft. The German Aerospace Center, the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute are part of the mission team.

For more information about Dawn, visit http://www.nasa.gov/dawn

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NASA Hosts Briefing To Preview Spacecraft Visit Of Large Asteroid

Dwayne Brown

Headquarters, Washington

 

Jia-Rui Cook/Priscilla Vega                    

Jet Propulsion Laboratory, Pasadena, Calif.

WASHINGTON -- NASA will host a news briefing at 2 p.m. EDT on Thursday, June 23, to discuss the Dawn spacecraft's year-long visit to the large asteroid Vesta. The mission expects to go into orbit around Vesta on July 16 and begin gathering science data in early August. The briefing will be held in the NASA Headquarters auditorium located at 300 E St. SW, in Washington. NASA Television and the agency's website will broadcast the event.

Dawn's visit to Vesta will be the first prolonged encounter to a main belt asteroid and the first trip to a protoplanet, or large body that almost became a planet. Observations will help understand the earliest chapter of our solar system's history.

The briefing panelists are:

-- W. James Adams, deputy director, Planetary Science Directorate, NASA Headquarters

-- Robert Mase, Dawn project manager, Jet Propulsion Laboratory (JPL), Pasadena, Calif.

-- Christopher Russell, Dawn principal investigator, UCLA

-- Carol Raymond, Dawn deputy principal investigator, JPL

Reporters may attend the event, ask questions from participating NASA locations or join by phone. To obtain dial-in information, journalists must e-mail Dwayne Brown at dwayne.c.brown@nasa.gov with their name, media affiliation and work telephone number by 11 a.m. on June 23.

For more information about Dawn, visit http://www.nasa.gov/dawn.

For NASA TV streaming video, downlink and schedule information, visit http://www.nasa.gov/ntv.

The briefing also will be carried live on Ustream, with a live chat box available, at http://www.ustream.tv/nasajpl2.

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NASA To Launch New Science Mission To Asteroid In 2016

Dwayne C. Brown

Headquarters, Washington                               

 

WASHINGTON -- NASA will launch a spacecraft to an asteroid in 2016 and use a robotic arm to pluck samples that could better explain our solar system's formation and how life began. The mission, called Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer, or OSIRIS-REx, will be the first U.S. mission to carry samples from an asteroid back to Earth.

"This is a critical step in meeting the objectives outlined by President Obama to extend our reach beyond low-Earth orbit and explore into deep space," said NASA Administrator Charlie Bolden. "It's robotic missions like these that will pave the way for future human space missions to an asteroid and other deep space destinations."

NASA selected OSIRIS-REx after reviewing three concept study reports for new scientific missions, which also included a sample return mission from the far side of the moon and a mission to the surface of Venus.

Asteroids are leftovers formed from the cloud of gas and dust -- the solar nebula -- that collapsed to form our sun and the planets about 4.5 billion years ago. As such, they contain the original material from the solar nebula, which can tell us about the conditions of our solar system's birth.

After traveling four years, OSIRIS-REx will approach the primitive, near Earth asteroid designated 1999 RQ36 in 2020. Once within three miles of the asteroid, the spacecraft will begin six months of comprehensive surface mapping. The science team then will pick a location from where the spacecraft's arm will take a sample. The spacecraft gradually will move closer to the site, and the arm will extend to collect more than two ounces of material for return to Earth in 2023. The mission, excluding the launch vehicle, is expected to cost approximately $800 million.

The sample will be stored in a capsule that will land at Utah's Test and Training Range in 2023. The capsule's design will be similar to that used by NASA's Stardust spacecraft, which returned the world's first comet particles from comet Wild 2 in 2006. The OSIRIS-REx sample capsule will be taken to NASA's Johnson Space Center in Houston. The material will be removed and delivered to a dedicated research facility following stringent planetary protection protocol. Precise analysis will be performed that cannot be duplicated by spacecraft-based instruments.

RQ36 is approximately 1,900 feet in diameter or roughly the size of five football fields. The asteroid, little altered over time, is likely to represent a snapshot of our solar system's infancy. The asteroid also is likely rich in carbon, a key element in the organic molecules necessary for life. Organic molecules have been found in meteorite and comet samples, indicating some of life's ingredients can be created in space. Scientists want to see if they also are present on RQ36.

"This asteroid is a time capsule from the birth of our solar system and ushers in a new era of planetary exploration," said Jim Green, director, NASA's Planetary Science Division in Washington. "The knowledge from the mission also will help us to develop methods to better track the orbits of asteroids."

The mission will accurately measure the "Yarkovsky effect" for the first time. The effect is a small push caused by the sun on an asteroid, as it absorbs sunlight and re-emits that energy as heat. The small push adds up over time, but it is uneven due to an asteroid's shape, wobble, surface composition and rotation. For scientists to predict an Earth-approaching asteroid's path, they must understand how the effect will change its orbit. OSIRIS-REx will help refine RQ36's orbit to ascertain its trajectory and devise future strategies to mitigate possible Earth impacts from celestial objects.

Michael Drake of the University of Arizona in Tucson is the mission's principal investigator. NASA's Goddard Space Flight Center in Greenbelt, Md., will provide overall mission management, systems engineering, and safety and mission assurance. Lockheed Martin Space Systems in Denver will build the spacecraft. The OSIRIS-REx payload includes instruments from the University of Arizona, Goddard, Arizona State University in Tempe and the Canadian Space Agency. NASA’s Ames Research Center at Moffett Field, Calif., the Langley Research Center in Hampton Va., and the Jet Propulsion Laboratory in Pasadena, Calif., also are involved. The science team is composed of numerous researchers from universities, private and government agencies.

This is the third mission in NASA's New Frontiers Program. The first, New Horizons, was launched in 2006. It will fly by the Pluto-Charon system in July 2015, then target another Kuiper Belt object for study. The second mission, Juno, will launch in August to become the first spacecraft to orbit Jupiter from pole to pole and study the giant planet's atmosphere and interior. NASA's Marshall Space Flight Center in Huntsville, Ala., manages New Frontiers for the agency's Science Mission Directorate in Washington.

For more information about OSIRIS-REx, visit http://www.nasa.gov.

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NASA Dawn Spacecraft Reaches Milestone Approaching Asteroid

Dwayne C. Brown

Headquarters, Washington

 

Jia-Rui Cook

Jet Propulsion Laboratory, Pasadena, Calif.

WASHINGTON -- NASA's Dawn spacecraft has reached its official approach phase to the asteroid Vesta and will begin using cameras for the first time to aid navigation for an expected July 16 orbital encounter. The large asteroid is known as a protoplanet – a celestial body that almost formed into a planet.

At the start of this three-month final approach to this massive body in the asteroid belt, Dawn is 752,000 miles (1.21 million kilometers) from Vesta, or about three times the distance between the Earth and the moon. During the approach phase, the spacecraft's main activity will be thrusting with a special, hyper-efficient ion engine that uses electricity to ionize and accelerate xenon to generate thrust. The 12-inch-wide ion thrusters provide less thrust than conventional engines, but will provide propulsion for years during the mission and provide far greater capability to change velocity.

"We feel a little like Columbus approaching the shores of the New World," said Christopher Russell, Dawn principal investigator, based at the University of California in Los Angeles (UCLA). "The Dawn team can't wait to start mapping this Terra Incognita."

Dawn previously navigated by measuring the radio signal between the spacecraft and Earth, and used other methods that did not involve Vesta. But as the spacecraft closes in on its target, navigation requires more precise measurements. By analyzing where Vesta appears relative to stars, navigators will pin down its location and enable engineers to refine the spacecraft's trajectory. Using its ion engine to match Vesta's orbit around the sun, the spacecraft will spiral gently into orbit around the asteroid. When Dawn gets approximately 9,900 miles (16,000 kilometers) from Vesta, the asteroid's gravity will capture the spacecraft in orbit.

"After more than three and a half years of interplanetary travel, we are finally closing in on our first destination," said Marc Rayman, Dawn's chief engineer, at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "We're not there yet, but Dawn will soon bring into focus an entire world that has been, for most of the two centuries scientists have been studying it, little more than a pinpoint of light."

Scientists will search the framing camera images for possible moons around Vesta. None of the images from ground-based and Earth-orbiting telescopes have seen any moons, but Dawn will give scientists much more detailed images to determine whether small objects have gone undiscovered.

The gamma ray and neutron detector instrument also will gather information on cosmic rays during the approach phase, providing a baseline for comparison when Dawn is much closer to Vesta. Simultaneously, Dawn's visible and infrared mapping spectrometer will take early measurements to ensure it is calibrated and ready when the spacecraft enters orbit around Vesta.

Dawn's odyssey, which will take it on a 3-billion-mile journey, began on Sept. 27, 2007, with its launch from Cape Canaveral Air Force Station in Florida. It will stay in orbit around Vesta for one year. After another long cruise phase, Dawn will arrive at its second destination, an even more massive body in the asteroid belt called Ceres, in 2015.

These two icons of the asteroid belt will help scientists unlock the secrets of our solar system's early history. The mission will compare and contrast the two giant asteroids, which were shaped by different forces. Dawn's science instrument suite will measure surface composition, topography and texture. In addition, the Dawn spacecraft will measure the tug of gravity from Vesta and Ceres to learn more about their internal structures.

The Dawn mission to Vesta and Ceres is managed by JPL for NASA's Science Mission Directorate (SMD) in Washington. Dawn is a project of SMD's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Ala. UCLA is responsible for overall Dawn mission science. Orbital Sciences Corp. of Dulles, Va., designed and built the Dawn spacecraft. The framing cameras have been developed and built under the leadership of the Max Planck Institute for Solar System Research in Katlenburg-Lindau in Germany, with significant contributions by the German Aerospace Center (DLR) Institute of Planetary Research in Berlin, and in coordination with the Institute of Computer and Communication Network Engineering in Braunschweig. The framing camera project is funded by NASA, the Max Planck Society and DLR.

For more information about Dawn, visit http://www.nasa.gov/dawn.

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