If NASA’s OSIRIS-REx spacecraft were penning a memoir, it might be titled, “There and Back Again: A Spacecraft’s Tale.”
The memoir would begin at 7 p.m. eastern time on September 8th, when the launch window opens for blast-off from Kennedy Space Center at Cape Canaveral, Florida. If all goes well, OSIRIS-REx will visit the asteroid Bennu and bring pieces of it back to Earth in 2023.
OSIRIS-REx (yes that’s an acronym, more on that in a minute) is the third mission in NASA’s New Frontiers program, which previously sent the New Horizons spacecraft zooming by Pluto and the Juno spacecraft into orbit around Jupiter. Unlike its predecessors, though, this spacecraft is a) coming back and b) going to bring a bit of interplanetary rock with it.
“This is a dark asteroid that we have found, and that we’re going to hunt down, we’re going to orbit, we’re going to take a good look at it, and we’re going to bring back a sample,“ says NASA’s Jim Green.
Scientists hope the sample return mission will reveal a new understanding of the ingredients that make up the solar system, as well as help develop defenses against interloping asteroids.
But there are lots of things that could go wrong: OSIRIS-REx is a complicated mission, and space, as we’ve seen all too clearly over this last week, is a tough frontier to penetrate.
But it’s worth it.
"It really is a great adventure. We are going out into the unknown and bringing back a scientific treasure," says mission principal investigator Dante Lauretta of the University of Arizona.
Curious about this mission? Here’s everything you need to know, and possibly a few things you didn’t.
The round-trip to Bennu costs about $800 million.
And will take a minimum of seven years. First, after looping once around the sun, the spacecraft will fly passed Earth again on Sept. 22, 2017. By August 2018, Bennu will become a pixel in the spacecraft’s eyes. Over the following two years, as the spacecraft approaches its target, it will map the asteroid’s topography, and figure out where best to land and capture a sample. Ideally, mission members say, that sample will be collected in July 2020. But OSIRIS-REx won’t be leaving Bennu until March 2021 at the earliest, so there’s some wiggle room. If all goes according to plan, the spacecraft will return to Earth’s neighbourhood and release a capsule containing those bits of Bennu on September 17, 2023.
That capsule will be hurtling toward Earth at 27,700 miles per hour...
...which is also known as “extremely fast,” according to Lockheed Martin’s Rich Kuhns, OSIRIS-REx program manager. It will take seven days for that hundred-pound capsule to catch up with Earth. Once here, it will be slowed on descent by two parachutes, which should help it gently touch down in the Utah Test Range on September 24th. As you may have guessed, only the capsule is coming back: Once its primary mission ends, OSIRIS-REx will be put in a parking orbit around the sun.
It’s not entirely clear how much of Bennu the spacecraft will manage to snag.
That depends more on Bennu’s surface than on the spacecraft, but the amount collected could be anywhere between a couple of ounces and 4 pounds of material (scientists will figure out how much material is on board by spinning the spacecraft). Tests on Earth, conducted with a variety of materials, have generally collected more than 10 ounces of material, Kuhns says.
The mission team will give 4 percent of the sample to Canadian partners, 0.5 percent to the Japanese space agency, and preserve 75 percent for future investigations, says NASA’s Gordon Johnston, “for the science questions we haven’t figured out to even ask yet.
An early stage of spacecraft assembly before many of the instruments were installed [Image: NASA]
OSIRIS-REx will give Bennu a fistbump with the help of an instrument called Touch-And-Go-Sample-Acquisition-Mechanism, or TAGSAM.
The 11-foot-long arm is riding aboard along with six other science gadgets, which include cameras, spectrometers, a laser altimeter, and an X-ray imaging system. Collecting the sample will take only about five seconds, and if the first try is unsuccessful, OSIRIS-REx can try, try again – up to three times. “We want this to be a safe, slow high-five of that surface,” says NASA’s Christina Richey. (NASA is calling it a high-five, but we’re going with fistbump.)
This isn’t the first time we’ve brought bits of an asteroid back to Earth.
A Japanese spacecraft named Hayabusa did this in 2010, when it returned from a liaison with the asteroid Itokawa. That particular mission didn’t exactly go as planned, though, and Hayabusa only returned with a tiny amount of Itokawa.
Some of you will be going on a round-trip to Bennu.
In name, at least. Hundreds of thousands of names, submitted through The Planetary Society, are hitching a ride on the sample return capsule. Another device will be keeping those names aboard the spacecraft as well. Not present: Legos, a golden record, or ashes, as far as we know.
The mission takes its name from Osiris, the Egyptian god of the underworld.
OSIRIS-REx is an acronym – and a somewhat tortured one at that – which represents the mission’s objectives: Origins, Spectral Interpretation, Resource Identification (mining!), Security, Regolith Explorer. Mission principal investigator Lauretta reportedly doodled the acronym into existence and kept it because it coincided with ancient Egyptian mythology, which is really rather awesome when you think about it.
Bennu was named by a third-grader.
In 2013, Michael Puzio, a then-third-grader from North Carolina, suggested the name during an international essay contest that brought in more than 8,000 entries. Bennu, Puzio noted, is an Egyptian deity that’s represented as a heron. “He said that the spacecraft looked like a heron in flight when it went down to capture the sample,” Lauretta says. “We thought that was a really excellent connection between our engineering and our science and our theme.”
Bennu itself looks nothing like a heron.
It’s actually rather spherical, which is a nice change of pace from all those other asteroids that mostly look like floating potatoes. Bennu is dark, carbon-rich, and spins around itself once every 4.3 hours. And at 500 meters across, it’s just a little taller than the Empire State Building, Richey notes. OSIRIS-REx will spend a good deal of time selecting a suitable landing spot before touching down and hopefully grabbing enough space rubble to keep scientists occupied for a very long time.
Or at least until Bennu blows us away.
The chances are small, but one of Bennu’s pre-mission claims to fame is that it’s characterized as a Potentially Hazardous Asteroid, or PHA. In fact, that’s one of the very reasons it was chosen as a target. Bennu’s circular orbit around the sun takes about two years to complete. Every six years, it comes close to Earth. The next time it’s close to us will be in 2135, when it comes just a smidge closer to home than our own moon. It’s not entirely clear how that little encounter will nudge Bennu’s orbit (this is one of the things scientists want to figure out), but there’s a chance it could collide with Earth sometime between 2175 and 2199. How big of a chance? Well, rather minuscule, actually. At this point, NASA puts the odds at 0.037 percent, or one in 2,700.
Still, that would be a very bad day on Earth.
OK, one to grow on: Paradoxically, Bennu could hold clues about the origins of life.
Because those that giveth, also taketh away. (Or something.) One of the reasons scientists are so keen to study Bennu is that it’s a relic from the very beginning of the solar system – a time capsule that has been unchanged over these intervening 4.6 billion years. It carries a record of the solar system’s earliest beginnings, and if scientists can just catch up with the dark, speeding sphere, they’ll be able to give that record a read.
“We seek samples that date back to the very dawn of our solar system,” Lauretta says. “We want to get those back into our laboratories to understand the processes that may have led to the origin of life and to the habitability of our planet.”