Main Engine Cut Off

“We are coming in tens of millions of dollars under budget,” said Dante Lauretta, OSIRIS-REx’s principal investigator at the University of Arizona in Tucson. “The exact number won’t be known until we close out the development phase, which depends on how long into the window it takes us for us to go, so we’re holding some reserves just in case the launch slips.”

The development phase of the OSIRIS-REx mission ends about a month after launch, which has until Oct. 12 to get off the ground or else wait another 12 months to wait for Earth and asteroid Bennu to be in the right position again.

“The best resource that we can get in operations is time,” Lauretta said in an interview with Spaceflight Now. “The more time that we have in reserve — funded schedule margin for the operational phase — the more we can buy down the risk of the TAG (touch-and-go) event. We can do more rehearsals, more characterization of the asteroid, and developing the features that feed our natural feature tracking guidance system, which is the autonomous system on the spacecraft that does the final calculations for closure to the asteroid.

“And then the unknown unknowns,” he added. “We may have anomalies that we’re troubleshooting in flight. We may have to bring in additional experts when Bennu surprises the heck out of us, like the Rosetta (comet) target did to their team. So just having the resources to handle that.”