OSIRIS-APEX to Make Close Approach to Sun

Simulation of OSIRIS-APEX using its thrusters to stir up rocks and dust on the surface of Apophis | Image by NASA

NASA’s OSIRIS-APEX spacecraft is set to make a close approach to the sun early next year, just one of many close encounters before the craft reaches its final destination in six years.

The OSIRIS-APEX mission is a follow-up to the OSIRIS-REx mission, which was completed earlier this year. In September, the OSIRIS-REx craft brought back the largest-ever sample of an asteroid, estimated to be about 4.6 billion years old, as previously reported by The Dallas Express.

The craft is now set on a journey to the asteroid Apophis, a near-earth asteroid expected to pass within 20,000 miles of the Earth’s surface by 2029. The craft will study changes to the surface of the asteroid that are predicted to occur on this close approach to the planet as well as the asteroid’s composition.

“Our planet’s gravitational pull is expected to alter the asteroid’s orbit, change how and how fast it spins on its axis, and possibly cause quakes or landslides that will alter its surface. OSIRIS-APEX will allow scientists on Earth to observe these changes,” says NASA on its website. “Additionally, the OSIRIS-APEX spacecraft will dip toward the surface of Apophis ­– a ‘stony’ asteroid made of silicate (or rocky) material and a mixture of metallic nickel and iron ­ – and fire its engines to kick up loose rocks and dust.”

Scientists are now preparing the craft for a close encounter with the sun that pushes it beyond the bounds of its original design.

The craft is expected to pass within 46.5 million miles of the sun’s surface on January 2, closer than the orbit of Venus and 25 million miles closer to the sun than it was originally designed for. This approach was not taken into account since the mission to Apophis was not part of the original mission of the craft, according to NASA.

“We are most creative when the spacecraft is in flight and we’re pushing boundaries to meet mission needs,” said Sandy Freund, OSIRIS-APEX program manager, according to NASA.

Scientists are expected to have the craft complete this encounter at a fixed angle and reposition a solar array to provide shade to sensitive instruments and prevent overheating. Simulations conducted of the event suggest that the craft will remain operational.

“We’ve done a lot of modeling to ensure the spacecraft will be safe,” said Dani Mendoza DellaGiustina, principal investigator for OSIRIS-APEX. “But any time you take a piece of space flight hardware beyond the design criteria you incur risk.”

OSIRIS-APEX will make a total of six of these close approaches to the sun before reaching the asteroid.

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