SCIENCE

When a newly announced NASA mission to collect an asteroid sample returns to Earth, all eyes will be on the last few minutes of the seven-year flight.

This phase of the OSIRIS-REx mission announced this week is called entry, descent and landing, and it's the job of NASA's Langley Research Center in Hampton, Va., to make sure it works.

"At this point the asteroid sample has traveled millions of miles, and it will take a lot of precision to bring it back safely," said Jill Prince, a Langley aerospace engineer working on the mission.

Conceptual image of OSIRIS-REx. Credit:NASA/Goddard/University of Arizona

"The entire science is in that capsule," she said. "That's a lot riding on the entry descent and landing."

NASA announced the OSIRIS-REx mission May 25. The mission will launch in late 2016 and return to Earth seven years later carrying pieces of asteroid RQ36, which orbits the sun.

When it returns, the capsule carrying the sample will enter the planet's atmosphere at 30,000 miles per hour and begin a controlled descent to its target at the Utah Test and Training Range near Salt Lake City.

"What we do is make sure the spacecraft lands accurately and safely," Prince said.

Entry, Descent and Landing

That's where years of research by Langley scientists and engineers will be put to the test.

"This work is a specialty of Langley," said Eric Queen, lead Langley engineer for the mission. "We've been called to assist in other similar atmospheric-entry vehicles at Earth, Venus, Mars, and Titan (the largest moon of Saturn)."

"OSIRIS-REx is most similar to the Stardust mission, which successfully collected comet samples that Langley engineers helped deliver safely to Earth in 2006," Queen added.

Langley researchers will draw from decades of expertise in aerodynamics, aerothermodynamics, flight dynamics, and mission design. Prior to return of the sample, Langley engineers will develop a Sample Return Capsule (SRC) aerodynamic database and perform trajectory simulations to assess the capsule's health, and also accurately determine the final landing location in Utah.

Asteroids are leftovers formed from the cloud of gas and dust that collapsed to form our sun and the planets about 4.5 billion years ago. 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 near-Earth asteroid. Within three miles of it, the spacecraft will begin six months of 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 about $800 million.

Asteroid Holds Clues to Origins

Back on Earth, the 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 some 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.

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 determine its trajectory and devise strategies to mitigate possible Earth impacts from celestial objects.

OSIRIS-REx stands for Origins Spectral Interpretation Resource Identification Security Regolith Explorer. It is a NASA New Frontiers mission led by Principal Investigator Michael Drake of the University of Arizona. The spacecraft will be managed by NASA Goddard Space Flight Center in Greenbelt, Md., and built by Lockheed Martin Space Systems in Denver.

For more information about Langley go to http://www.nasa.gov/langley