NASA’s OSIRIS-REx spacecraft appears to be leaking tiny bits of an asteroid named Bennu, following a successful attempt to collect surface samples from the object. Engineers blame a jammed lid for what NASA is calling a minor problem.
Update: NASA has decided to stow the gathered sample material on October 27, rather than on the scheduled date of November 2. The early stow is being done to “protect and return as much of the sample as possible.”
O-REx, as NASA team members like to call it, made brief contact with the surface of Bennu on Tuesday, October 20, marking the space agency’s first attempt at collecting surface material from an asteroid. Dramatic images sent back to Earth hinted at success, with NASA confirming this past Friday that the probe collected “more than enough material,” exceeding the team’s minimum goal of at least 2 ounces (60 grams) of surface material.
Indeed, it was a picture-perfect moment, with the Touch-and-Go Sample Acquisition Mechanism (TAGSAM) head appearing flush with the surface as it sank ever-so-slightly into the soft regolith. A blast of nitrogen kicked up surface material, enveloping the sample head in a cloud of debris.
A couple of days later, however, NASA noticed bits of debris escaping from the sample collection head. The team is attributing this to a mylar lid that won’t close shut, as it’s being wedged open by larger rocks.
“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,” explained OSIRIS-REx principle investigator Dante Lauretta in a NASA statement. “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.”
All is not lost, as the team simply needs to stow the collected debris in the spacecraft’s Sample Return Capsule before too much of it leaks out. In the meantime, the team, led by researchers from the University of Arizona, doesn’t want O-REx to make any superfluous movements, which is why they canceled the Sample Mass Measurement activity this past Saturday and also a braking burn that was supposed to happen on Friday, in order to minimize the craft’s acceleration.
Calling it a “curveball,” Thomas Zurbuchen, associate administrator for science at NASA’s headquarters in Washington, said in a statement, “we may have to move more quickly to stow the sample,” but “it’s not a bad problem to have.” He’s “excited to see what appears to be an abundant sample that will inspire science for decades beyond this historic moment.”
The team is finalizing a plan for storage, including a timeline for when that might happen. An update is expected very shortly. We should also find out if the team wants OSIRIS-REx to perform another sample collection attempt, which didn’t seem necessary before, but now, with the leaking cargo, who knows. Assuming all is well and the material can be stored in the Sample Return Capsule, the spacecraft will depart Bennu in March 2021, when Earth and the asteroid are in a favorable alignment.