NASA’s OSIRIS-APEX Spacecraft Remains Unscathed After Closest-Ever Encounter With the Sun

NASA's OSIRIS-APEX spacecraft survived after making its first-ever closest contact with the Sun.

NASA's OSIRIS-APEX After Closest Encounter With the Sun

OSIRIS-APEX emerged "unscathed" following its closest-ever direct pass through our Sun on Jan. 2, scientists revealed on Tuesday (May 28), after completing its sample-return mission to the asteroid Bennu, the probe-originally named OSIRIS-REx-is on an extended journey to the space rock Apophysis.

To carry out the new mission, OSIRIS-APEX must glide 25 million miles (40 million kilometers) closer to the Sun than intended. According to scientists, the probe must make multiple near approaches to set itself up for a 2029 arrival to Apophis.

Throughout its elliptical orbit around our Sun, OSIRIS-APEX passes through the closest point to the star once every nine months. It came within a hair's breadth of each other on Jan. 2.

In early December, the OSIRIS-APEX mission team tucked in one of its two solar panels to shield the probe's most delicate instruments from the severe radiation bombardment. The second panel, which powers the spacecraft, faces the Sun.

As computer simulations had previously shown, this feat of ingenious engineering saved the spacecraft during its perilous close approach to the Sun, the mission crew revealed this week in a NASA statement.

"It's phenomenal how well our spacecraft configuration protected OSIRIS-APEX, so I'm really encouraged by this first close perihelion pass," said Ron Mink, the mission systems engineer for OSIRIS-APEX at NASA's Goddard Space Flight Center in Maryland.

Mission team members expressed relief that OSIRIS-APEX is safe following its first close encounter with the Sun. Still, they also pointed out that they are unsure of the potential effects of five more similar interactions on the probe and its equipment.

On Sept. 1, the spacecraft will again travel within 46.5 million miles (74.8 million km) of the Sun's surface, making its next closest approach. This will place the spacecraft deep within Venus's orbit and beyond the probe's initial operational limitations.

What Is OSIRIS-APEX?

OSIRIS-APEX (Origins, Spectral Interpretation, Resource Identification, and Security - Apophis Explorer) is a probe to study the physical changes of Apophis due to its uncommon close encounter with Earth in April 2029. Apophis' orbit will bring it closer to Earth than our highest-altitude satellites that year, at 20,000 miles (32,000 kilometers).

The asteroid's orbit is predicted to be altered, as well as the speed and direction of its rotation on its axis, by the gravitational influence of our planet. Landslides or earthquakes may also alter its surface. Scientists on Earth will be able to see these changes thanks to OSIRIS-APEX. In addition, the OSIRIS-APEX spacecraft will fire its engines to kick up small rocks as it approaches the surface of Apophis, a "stony" asteroid composed of silicate (or rocky) material and a mixture of metallic nickel and iron.

Scientists can see what makes up the material directly beneath the asteroid's surface through this motion.

About half of Earth's distance from the Sun, or 46.5 million miles, will separate OSIRIS-APEX from the Sun and place it deep inside Venus' orbit. The Apophis rendezvous wasn't included in the initial mission plan, which called for flying to the asteroid Bennu to gather a sample, which puts the spacecraft 25 million miles closer to the Sun than intended.

With a quarter of its fuel and excellent instrumentation, OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) departed Bennu in May 2021 carrying a sample. Therefore, the crew decided to send the spacecraft on a bonus mission to Apophis rather than shutting it down and placing it in an eternal orbit around the Sun after it delivered its Bennu sample to Earth on Sept. 24, 2023. OSIRIS-APEX was created after NASA granted its approval following the success of the OSIRIS-REx mission.

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