NASA’s OSIRIS-APEX Completes 1st Perihelion

Preliminary telemetry indicates that NASA’s OSIRIS-APEX spacecraft successfully completed a two-month operation that brought it 25 million miles closer to the Sun than it was designed to function. The spacecraft continues its journey to reach asteroid Apophis in April 2029.

The OSIRIS-APEX spacecraft, formerly known as OSIRIS-REx, repositioned one of its two solar arrays to shade critical components from the Sun’s heat during its Jan. 2 close pass, or “perihelion.” When it returned to a thermally safe distance of about 60 million miles from the Sun in early February, OSIRIS-APEX rotated its array back into place to help generate power.

The limited telemetry available suggests that OSIRIS-APEX performed as predicted during the perihelion. It will take a few months for the mission team to conduct a full assessment of the spacecraft’s performance, during which it flew to roughly half the distance between Earth and the Sun.

Since early December 2023, engineers have had limited information about spacecraft status, as the spacecraft was configured for its safety. This included orienting its main antenna such that high-speed communication with Earth wasn’t possible.

But, in mid-March, the team finally will be able to point the spacecraft’s powerful high-gain antenna toward Earth and download the data OSIRIS-APEX collected during perihelion.

Engineers also plan to turn on and test the spacecraft’s instruments in early April and will provide a spacecraft health assessment in May to determine any possible degradation to surfaces or components caused by the extreme heat it endured. Until then, the team will carefully monitor the spacecraft to ensure it continues to function as expected.

The January perihelion was the first of seven perihelions the spacecraft will complete to reach Apophis, six of which will bring OSIRIS-APEX within 46.5 million miles of the Sun. The second perihelion is scheduled for Sept. 1, 2024.

By Lonnie Shekhtman
NASA’s Goddard Space Flight Center, Greenbelt, Md.