The OSIRIS Asteroid Return Mission: Sample Return to Earth and the First Sample Return from an Asteroidal Source (Revised Version)
If found to be intact, that single serving of space rock will mark the biggest haul of extraterrestrial material brought back by any nation on Earth since the Apollo astronauts carried pieces of the moon home, and the culmination of NASA’s first attempt to bring samples of an asteroid back to Earth.
The rest of OSIRIS is still in space after dropping off its sample-return capsule. Apophis is an asteroid with a different chemical composition that is going to fly past Earth in 2029.
The science capsule was slowed by parachutes and landed in the Department of Defense’s Utah Test and Training Range at 10:52 AM ET, a landing area chosen as it is the largest restricted airspace in the United States and has been used for previous NASA sample return missions like Genesis and Stardust.
The entire mission has required a very high level of precision, particularly for the rendezvous with the asteroid and the collection of the sample in 2020.
“The really precise navigation required to orbit Bennu and to touch down and collect our sample, we were under a meter away from our target,” Sandra Freund, OSIRIS-REx program manager, said in a pre-landing briefing. “So that illustrates what kind of navigation precision we’ve had throughout this mission.”
It’s important to be clear that the theory is not that life itself arose elsewhere and was delivered to Earth, but rather that the basic building blocks of life — often referred to as organic compounds — could have arrived here billions of years ago carried by asteroids.
That’s been a theory for decades; but to test it out, scientists need access to asteroidal material. Going to visit an asteroid and using instruments on a spacecraft to study it is a good start, but to do the kind of detailed analysis scientists want requires a much bigger laboratory, equipped with instruments like a mile-wide type of particle accelerator called a synchrotron which would be impossible to fit onto a spacecraft.
meteorites are pieces of matter (including from asteroids) that fall to Earth’s surface. That’s how most of this research has been performed historically, using these tiny fragments as samples.
There are two problems with this approach. The meteorite does not have a context for where it came from in the solar system. Researchers can’t know its origin, or see what other bodies it was close to, which can give important clues to the interpretation of any data. By the time a meteorite passes through Earth’s atmosphere and lands, it may be contaminated by the local environment.
Bennu vs. Ryugu: A case study of the origin of the Earth’s meteorites and the asteroid Apophis
“Not all asteroids are the same,” said Lauretta, who is also a member of the Hayabusa 2 team. Both Ryugu and Bennu have a similar spinning-top-like shape, but they look very different. Bennu is smaller and more blue than Ryugu, which is red in color. Scientists still don’t know what that difference in color means, but having the ability to compare samples on Earth will help understand how asteroids are similar and how they differ.
When scientists want to understand how the Earth formed, they need to look beyond our planet and out into the solar system. A disk of material spins around a star after it collapses into a cloud of gas.
“The asteroids date from about 500 million years earlier in time than the oldest rocks on Earth. Lauretta said that he wants to go back all the way to the beginning. “And the fun thing is, when you’re looking at asteroids you go literally to the very beginning of the solar system.”
Thompson says that the samples might look like meteorites that have fallen to Earth. organic compounds are carbon-based molecule that are the building blocks of many exciting types of chemistry, including those that will be favorable to life. The components of the genetic code that make up life are fascinating, according to the senior scientist for sample return at NASA. These compounds have been found in meteorites before, but those rocks have not been as pristine as the Bennu samples are expected to be. “We can trust the results, because this stuff is clean,” he says.
Now that the OSIRIS-REx has dropped off the capsule containing the sample, its initial job is over. The spacecraft is still in the air and able to perform a number of functions even though it can’t collect another sample.
Rather than waste this craft, it will become OSIRIS-APEX so that it can go on to study the asteroid Apophis. It will be able to rendezvous with this asteroid because it will come close to Earth in the next few years, so it will study it.
“In 2029, in April, Apophis is gonna fly within 30,000 kilometers of the surface of the Earth, which is about the altitude that our weather satellites orbit at,” Lauretta said. It may be visible to the naked eye from a few places on Earth, as it is the largest flyby of an asteroid for a thousand years.
The Bennu capsule in the Great Salt Lake Desert: launching the first science mission out there, in the future, at the end of the next chapter
The first scientific results from NASA will be unveiled at a press conference on 11 October. But its work on the mission could be interrupted if the US government shuts down on 1 October. Republicans and Democrats in Congress have been battling over priorities for funding the federal government in 2024. If the situation remains in a stalemate by the time the US fiscal year ends on 30 September, then federal agencies, including NASA, might close until an agreement can be reached. If that were to happen while the Bennu sample is at NASA, then “certain steps leading to its highly anticipated analysis will possibly be delayed, but the sample will remain protected and safe”, says Lori Glaze, head of NASA’s planetary sciences division. “The sample waited for more than 4 billion years for humans to study it, and if it takes us a little longer, I think we’ll be okay.”
Getting the sample back to Earth is just the beginning of the science research, and the team is anxiously awaiting this culmination of all their efforts.
“I get to be one of the very first people on earth to see the capsule, as it is in position out there in the desert. Lauretta said it was going to be an emotional moment. “We’ve been building and testing and designing this thing for over 12 years. So it’s the end of a very, very long journey, and the beginning of the next chapter.”
The capsule was flown to a laboratory clean room after being suspended under a helicopter for a safety assessment.
But for that to happen, that canister had to make the final leg of its journey alone, bearing temperatures hotter than lava. The Osiris-REx spacecraft released the capsule as it flew within 63,000 miles of the planet. The capsule then entered the atmosphere at a screaming 36 times the speed of sound before slowing down enough to land in Utah’s Great Salt Lake Desert.
The first 250 grams of rock and dirt that OSIRIS-REx has collected: A big cupful of dust from the asteroid Itokawa
After that, the plan is to store part of the sample so that future generations of scientists can also study these samples with more advanced tools — just as scientists today are still studying moon rocks that Apollo astronauts brought back so many decades ago.
Thompson, a planetary scientist at Purdue University in West Lafayette, Indiana, says she feels like a child on Christmas Eve when she is excited to study the rocks.
Still, the spacecraft managed to collect around 250 grams of rocks and dirt — a large cupful — including several chunks that are at least one centimetre long. It is by far the largest amount of material ever brought back from an asteroid. The Japan Aerospace Exploration Agency (JAXA) had previously collected less than one milligram from the asteroid Itokawa in 2005, and 5.4 grams from the asteroid Ryugu in 2019.
The quick-look team will get 100 milligrams from the curators in the first 72 hours. That initial sample will probably be made up of fine-grained material obtained from the outermost parts of the sample capsule, Thompson says. After that, the team will get a chance to study grains that were picked up by 24 stainless-steel contact pads on the outside of the sample container — which were the first things to actually come into contact with Bennu. It will likely take a few weeks for the curators to open the heart of the sample container and start pulling material from it.
Early experiments could include looking at how material that was on the surface of Bennu compares with what came from deeper inside the asteroid, Thompson says. Bennu has a rubbly surface that might have given OSIRIS-REx’s robotic arm as deep a dive as 40 centimetres.
