A 2008 graduate of Fountain Hills High School, Eric Sahr was doing post graduate study at University of Arizona in 2016 when he was given the opportunity to sign on with the OSIRIS REx mission to the asteroid Bennu for a sample collection and return to Earth.

The mission reached a climax Sept. 24, when the OSIRIS spacecraft released the Sample Return Capsule (SRC) for its reentry and return to Earth at the Department of Defense Utah Test and Training Range. However, after the release of the SRC the OSIRIS spacecraft fired engines and began the second leg of its long journey. It will rendezvous with the near-Earth asteroid Apophis in 2029. This mission is now known as OSIRIS APEX.

Sahr is an optical navigation engineer with the OSIRIS missions. He is employed by KinetX, which is contracted to NASA. Sahr said he will continue in his role in navigation. He said the sample collection and evaluation is not part of his expertise, but he was busy with his part of the return sequence.

“Navigation is important to ensure the safe return of the (SRC) and the precious cargo within,” Sahr said in an email interview with the Times Independent. “The SRC is designed for a particular re-entry profile, and so navigation is responsible for delivering the spacecraft to a particular location so that the SRC will fly the re-entry as designed.

“Once the capsule is released, the spacecraft is on a collision course with Earth (the only way to get the SRC back), so the navigation team has to design a maneuver to not only prevent the spacecraft from re-entering the Earth’s atmosphere (it is not designed to do this), but also to put us on a course with asteroid Apophis for our rendezvous in 2029.”

All seems to have gone according to plan. While OSRIS REx was en route to Bennu and back, planning was underway to continue the mission of the spacecraft.

“Extensive analysis was required to assess whether the spacecraft could reach another asteroid, and Apophis was the best target,” Sahr said. “We are mainly limited by the remaining fuel on board, but luckily things went very well at asteroid Bennu, and we have plenty of fuel to execute our extended mission. Once we knew it was possible for the spacecraft to reach Apophis, we also had to determine whether the cameras we had onboard would enable us to safely navigate around it.”

While the spacecraft no longer has capability to collect additional samples from Apophis, the asteroid will be making a pass close to earth in 2029 and OSIRIS APEX will be right there with it.

“We will be studying Apophis remotely with our amazing suite of cameras and other sensors, just as we did at asteroid Bennu before we sampled in October 2020,” Sahr said. “Unfortunately, we only had one TAGSAM (Touch-and-Go Sample Acquisition Mechanism) and one Sample Return Capsule, so the spacecraft will be unable to return a sample from Apophis.”

The OSIRIS APEX spacecraft will orbit the sun near Earth’s orbit between now and 2029. Currently, there are no plans for the spacecraft after completing the studies of asteroid Apophis.

“Whatever choices we make will be limited by the remaining fuel on-board, health of the spacecraft and instruments (which at this point will be pushing 14 years in space), and congressional funding,” Sahr said.

Originally launched in 2016, OSIRIS REx made its contact with Bennu in 2020 and just made its return to Earth. Now the spacecraft continues on to its next rendezvous with Apophis in 2029. Needless to say there is significant flying time between actions, but those involved in the project stay busy planning and preparing.

“There is always plenty of work to do while we patiently wait for the spacecraft to arrive at its destination,” Sahr said. “One example is we need to plan how many images we will need to safely navigate around Apophis, and how those images will be taken. Just like your camera, we need to make decisions like how long the exposure will be and where to point the cameras.

“However, we don’t have autofocus or autoexposure, so we need to get the pictures right the first time. This can depend a lot on the surface of Apophis, which we won’t know too much about until we arrive. So, the challenge is to come up with a plan that is robust to all of the possibilities, and then also think of how you will handle things when you are inevitably surprised.”

While his work takes him on a journey of millions of miles, Sahr said the routine with KinetX is pretty much normal.

“I do some work with mentoring interns each summer, which is a rewarding experience in and of itself,” he said. “For a very long time I thought of people that get to work with NASA spacecraft as super geniuses. It took a long time for me to realize that many of the people in this industry are normal people, and that with dedicated work I could achieve similar outcomes. It’s a delight to be able to inspire our interns in that way.”

Sahr’s mother remains a Fountain Hills resident.