NASA’s OSIRIS-APEX (Origins, Spectral Interpretation, Resource Identification and Security – Apophis Explorer) spacecraft kept its cool again this past fall after passing within 46.5 million miles of the Sun, between the orbits of Mercury and Venus, and surpassing its designed heat tolerances.
On Jan. 23 the mission team completed its review of all the data recorded by the spacecraft and its instruments during the solar pass. “There were no surprises, and the spacecraft is operating well,” said Mike Moreau, OSIRIS-APEX deputy project manager at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
As planned, on Sept. 2, 2024, OSIRIS-APEX passed through perihelion — the phase of its orbit closest to the Sun. The trajectory to Apophis takes the spacecraft much closer to the Sun than it was originally designed for. Between Aug. 1 and Oct. 13, the spacecraft was configured in a special orientation that uses one of the solar arrays to shade the most heat-sensitive components, keeping them within safe operating temperatures.
While in perihelion configuration, communication with the spacecraft is only possible through one of the spacecraft’s low-gain antennas, thus only very limited data is available to monitor its systems. During this most recent perihelion, there was also a period of several days when no communications were possible while the spacecraft was on the other side of the Sun from Earth.
On Oct. 13 the spacecraft exited the perihelion configuration and methodically returned to full operating status, allowing flight engineers to downlink and analyze spacecraft telemetry and assess the health of the system. In November 2024, the spacecraft executed routine checkouts of instrumentation on the spacecraft. OSIRIS-APEX appears to be healthy after the second of six close perihelion passages on its six-year journey to rendezvous with asteroid Apophis.
OSIRIS-APEX successfully passed through its first perihelion earlier in 2024. To reach asteroid Apophis in 2029, the spacecraft must survive four more close encounters with the Sun, the next of which will occur in May 2025.