NASA’s spacecraft grabbed too many asteroid chunks—and now they’re drifting into space

October 27, 2020

On October 22—two days after touching down on asteroid Bennu in an attempt to gather samples of extraterrestrial rocks— NASA’s OSIRIS-REx-mission team received images confirming that the spacecraft had collected more than 2 ounces (60 grams) of the asteroid’s surface material, NASA reports.

In fact, the spacecraft “may well have bitten off more than it could chew,” several media sources noted this week: Asteroid samples seem to be escaping from the jammed NASA spacecraft and drifting off into space.

The OSIRIS-REx (an acronym for Origins, Spectral Interpretation, Resource Identification and Security-Regolith Explorer) spacecraft captured images of the sample collector head as it moved through several different positions. In reviewing these images, the team noticed both that the head appeared to be full of asteroid particles, and that some of these particles appeared to be escaping slowly from the sample collector, called the Touch-And-Go Sample Acquisition Mechanism (TAGSAM) head.

Team members suspect that bits of material are passing through small gaps where a mylar flap —the collector’s “lid”—is slightly wedged open by larger rocks.

“Bennu continues to surprise us with great science and also throwing a few curveballs,” said Thomas Zurbuchen, NASA’s associate administrator for Science at the agency’s headquarters in Washington, D.C.. “And although we may have to move more quickly to stow the sample, it’s not a bad problem to have. We are so excited to see what appears to be an abundant sample that will inspire science for decades beyond this historic moment.”

The team believes it has collected a sufficient sample and is on a path to stow the sample as quickly as possible. They came to this conclusion after comparing images of the empty collector head with October 22 images of the TAGSAM head after the sample collection event.

The images also show that any movement to the spacecraft and the TAGSAM instrument may lead to further sample loss. To preserve the remaining material, the mission team decided to forego the Sample Mass Measurement activity originally scheduled for Saturday, October 24, and canceled a braking burn scheduled for Friday to minimize any acceleration to the spacecraft.

From here, the OSIRIS-Rex team will focus on stowing the sample in the Sample Return Capsule (SRC), where any loose material will be kept safe during the spacecraft’s journey back to Earth.

“We are working to keep up with our own success here, and my job is to safely return as large a sample of Bennu as possible,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona in Tucson, who leads the science team and the mission’s science observation planning and data processing. “The loss of mass is of concern to me, so I’m strongly encouraging the team to stow this precious sample as quickly as possible.”

OSIRIS-REx remains in good health, and the mission team is finalizing a timeline for sample storage. An update will be provided once a decision is made on the sample storage timing and procedures.

NASA’s Goddard Space Flight Center in Greenbelt, Maryland, provides overall mission management, systems engineering and the safety and mission assurance for OSIRIS-REx.

Research contact: @NASAGoddard