After a decade and $1.2 billion, NASA reveals its booty from Bennu: 121 grams

After years of speculation, NASA finally revealed on Thursday the totality of the asteroid sample returned from Bennu to Earth last fall: 4.29 ounces (121.6 grams).

To put that number into perspective, the total mass is only slightly more than one-half cup of sugar or a box of 100 paper clips. It's about the same mass as a small avocado, and you can't even smear it on toast.

So, in some sense, it's a pretty small sample. Especially when you consider the lengths to which NASA and its partners went to retrieve it. The space agency's Goddard Space Flight Center worked with the University of Arizona and Lockheed Martin to build the OSIRIS-REx spacecraft for $800 million. It launched in September 2016 on an Atlas V rocket, which cost an additional $183.5 million. And as it has traipsed across the inner Solar System and back, NASA has spent an additional $200 million on mission operations.

A tin of tuna

Putting that all together, NASA has invested $1.2 billion and the better part of a decade to retrieve a volume of asteroid dust that could fit—comfortably—within a small can of tuna.

But, as the saying goes, good things come in small packages. And small though the sample may be, it is 20 times greater than the amount of asteroid material previously returned to Earth by a pair of Japanese sample return missions. A little will go a long way as scientists study the organics and other materials in this asteroid dust to divine clues to the origin of life and conditions that existed at the dawn of our Solar System. You don't need handfuls of material to get a meaningful result from an electron microscope.

Moreover, the sample retrieval was double the minimum requirement for the mission, 60 grams. So, OSIRIS-REx can now definitively be labeled as an unqualified success.

Biding their time

The scientific community had to wait longer than expected to know how much material OSIRIS-REx brought back to Earth. As engineers and technicians at Johnson Space Center in Houston worked to open the sample container last October, they were stymied by two stubborn fasteners. Only after new tools were devised was the sample container finally opened to reveal the tiny treasure in January.

In the coming weeks, some Bennu material will be packaged and distributed for researchers to study. As part of the OSIRIS-REx mission, a cohort of more than 200 scientists around the world will explore the regolith’s properties, including researchers from many US institutions, the Japan Aerospace Exploration Agency, and the Canadian Space Agency.

NASA, however, intends to reserve about 70 percent of the material for future study.