Gigantic mission for University of Arizona scientists rides on little craft

On Sept. 8, give or take a few days, an Atlas V rocket will launch from Cape Canaveral, Florida, carrying a spacecraft the size of a backyard shed on a mission to grab a couple ounces of sand and gravel from a near-Earth asteroid and return them to Earth.

NASA’s OSIRIS-REx mission, conceived and run by a team at the University of Arizona’s Lunar and Planetary Laboratory, has a simple goal that can be accomplished only if a myriad of maneuvers are flawlessly performed.

Complicating the mission is the reality that many of those maneuvers can’t be planned in full detail until the spacecraft arrives at its target — a 500-meter diameter asteroid named Bennu.

If all goes well, really well — “wildest dreams” well — the mission will uncover the origin of life, jump-start human exploration of the solar system and prevent the future annihilation of life on Earth in an asteroid impact.

For scientists at the UA, some of whom have been working on this mission for more than 12 years, things are getting real as the countdown clock at the Tucson mission headquarters ticks down to 137 days today.

The journey begins on May 20, when Dante Lauretta and mission leaders accompany the spacecraft on a flight in an Air Force C-17 cargo jet from Lockheed Martin Space Systems in Littleton, Colorado, to Cape Canaveral for placement on a launch pad.

It’s been a long obsession for Lauretta, a planetary scientist at the UA’s Lunar and Planetary Lab (LPL) who specializes in the study of meteorites. He was tapped for the role of deputy principal investigator in 2004 by the late Michael Drake, then director of the LPL, who was already talking with colleagues at Lockheed Martin about proposing a university-led mission to an asteroid.

It took three NASA proposals to finally win the $805 million contract in May 2011.

Lauretta took on leadership of the mission after Drake’s death less than four months later.

Lauretta is responsible for the mission’s name. OSIRIS-REx is a partial acronym whose letters stand for concepts that don’t sound all that exciting at first blush — Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer.

Saving the world

Lauretta, however, is certain that the public will get excited as the mission proceeds, especially about “Security” which might be juicier if he called it the “save civilization thing.”

The asteroid, officially known as 1999 RQ36 and nicknamed “Bennu” in a naming contest won by 9-year-old Michael Puzio of North Carolina, is, in the words of LPL scientist Carl Hergenrother “the most dangerous asteroid out there.”

Bennu comes close to Earth every six years and twice in the 22nd century, it will come very close. The overall odds of it hitting Earth are about one in 25,000.

The asteroid — tall as the Empire State Building and five football fields wide — would not cause an “extinction event,” said Hergenrother, but “you wouldn’t want it to hit your city.”

OSIRIS-REx will measure the forces that could change the asteroid’s orbit and assess that threat more precisely. It will give the scientists who study asteroids and comets more information to apply to other near-Earth objects.

It will also provide NASA engineers with information about navigating around asteroids — essential for future goals to capture and mine them for resources or to develop methods to change their orbits if they are found to be on a collision course with Earth.

Lauretta calls that the mission’s “gift to the future.”

“A lot of people think that’s a lot more valuable than putting a lander on Mars, not to — you know — compare,” said Lauretta.

The danger represented by Bennu was not the reason for its selection. Hergenrother, who led the campaign to select an asteroid for sampling, said its makeup, not its trajectory, was the main criterion.

Bennu is a carbonaceous asteroid, part of a class that might contain organics and possibly water. One theory holds that such asteroids brought the building blocks of life to Earth during a continual bombardment in the early days of the solar system.

Bringing a sample back to Earth for scientific study is the main goal of the mission. Doing that is complicated, and just getting to launch readiness was not always a smooth path.

Scary Frangibolts

The biggest scare for the team assembling and testing the spacecraft at Lockheed Martin Space Systems in Littleton, Colorado, was caused by the switches that activate the Frangibolts on the sample return capsule, said Lauretta.

The four bolts of the sample return capsule did not always release when the capsule was spun in a centrifuge to mimic the gravitational pressure that triggers the switches.

That’s not good. If the Frangibolts don’t release, the parachute doesn’t deploy. If the parachute doesn’t deploy, the capsule, with its billion-dollar cargo of pristine space rocks, disintegrates in a high-speed plunge through the Earth’s atmosphere — a seven-year space mission ruined in a literal flash.

“To lose it on the parachute would be a real tragedy,” said Lauretta, “so we are paying a lot of attention to that system.”

He is not an engineer, but he said some engineer gene turned on during the testing of the spacecraft this year. The team found that the switches varied in thickness and ordered replacements.

The watchwords are “test how you fly,” Lauretta said. Every part of the spacecraft and every instrument on it was subjected to the forces and environmental conditions it will face in space.

When possible.

Not everything can be replicated. They wanted to know, for instance, how the all-important touch-and-go sampling arm called TAGSAM would operate in a vacuum, subject only to micro-gravitational forces.

A vacuum requires a sealable room and big fans. Microgravity can be mimicked in an airplane doing dips. But you cannot replicate that combination. In that case, said Lauretta: “We extrapolate and log an exception.”

The spacecraft’s systems and equipment are almost totally redundant, he said.

You can’t MacGyver a fix, especially with no MacGyver on board.

A few little blips

There were other blips.

A fire in a Los Angeles plating factory destroyed the main housing for an optics box for a spectrometer built at Goddard Space Flight Center for the mission. Two new boxes were built and plated in time for scheduled delivery.

REXIS, an X-ray imaging spectrometer built by students at Harvard and MIT, was delivered on time in September but found to have flaws.

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“It was not ready for primetime,” said Richard Binzel, an asteroid authority and REXIS instrument scientist at MIT. Lauretta found some flexibility in the schedule and sent it back to the students for fixes. Those were made and the instrument is now on board, tested and ready.

Lauretta talks about overseeing the mission at the “CEO level,” leaving the details of how things get done to teams of international scientists and engineers, with specialties ranging from lens-crafting to orbital dynamics.

He said he’s become adept at 20-person conference calls and is ready to deal with a bigger crowd in person.

When 200 members of the team assembled last month in Tucson for a pre-launch shakedown, desk space and Internet connectivity were at a premium in the Michael Drake Building, the off-campus site LPL first developed for the Phoenix Mars Lander mission.

It is being partitioned into workspaces and an auditorium for the hundreds of scientists who will periodically convene in Tucson to interpret the science coming back and program the spacecraft’s maneuvers for ultimate scientific gain.

The spacecraft is outfitted with an array of instruments designed to do two major tasks — to characterize the asteroid’s composition and to find a spot where it can safely deploy its collecting arm and gather up the most scientifically valuable rock.

Unlike robotic missions to planets, the overwhelming force at work is not gravity. Bennu’s force on the spacecraft competes with a bunch of other weak forces, including the sun’s radiation.

Flying in formation with the big space rock, orbiting it and approaching it safely will rely on measurements made by those instruments.

The fun begins

“When we get to Bennu, that’s when the fun begins,” said Ed Beshore, deputy principal investigator, who left his post as head of the asteroid-spotting Catalina Sky Survey to join the team. “It’s a world nobody’s visited before.”

All the data gathered so far in a massive telescope campaign predicts that the team should be able to find sites where there are no boulders or slopes and where the regolith on and just beneath the surface is pebbly, small enough to collect.

“I wish I knew,” said Beshore. “It’s either going to be a battle or a walk on the beach — boulders everywhere or beach, literally.”

The spacecraft’s array of instruments should answer the question.

Cameras, spectrometers and laser pulses in a gamut of wavelengths from infrared through X-ray, will allow scientists to determine where they will find the most scientifically interesting specimen and collect it safely.

Three of those cameras were built by a UA team headed by Bashar Rizk of the LPL. PolyCam, a telescope with an 8-inch-diameter mirror and a narrow field of view, will give the spacecraft its first view of Bennu from 2 million kilometers and will be refocused for close-up views of the asteroid’s surface, Rizk said.

It will be aided in its investigation by the wide-field MapCam and by a thermal-emission spectrometer built by a team at Arizona State University, headed by Phil Christensen.

Mapping the heat retained and given off by the surface will help identify the regions where the sand and gravel bits are small enough to be collected.

“At night, the rocky, blocky material stays warm,” he said. “We can figure out where the blockiest places are and avoid them.”

Christensen has a track record for such instruments. He has built five similar instruments for NASA space missions.

“He’s absolutely the king of this business. You’d be crazy to go to anybody else,” said Beshore.

This one was special, said Christensen, because it was built entirely at ASU’s School of Earth and Space Exploration.

Previous projects had been built at a Raytheon facility in Santa Barbara, he said. When Raytheon moved that division to Los Angeles, ASU hired away some of its scientists and built two clean rooms for this and future projects.

His instrument will work in tandem with the UA cameras and other instruments, including one built by students in space and engineering programs at Harvard University and Massachusetts Institute of Technology. It is an X-ray spectrometer that will map the elemental makeup of the asteroid.

It’s important to have as much information as possible, said Christensen. You could identify carbon, for example, and not know whether it was in the form of graphite or diamonds.

He said he doesn’t expect the spacecraft’s collecting arm to scoop up a handful of diamonds and, in fact, would be quite disappointed if that occurred.

“Diamonds are cheap,” said Beshore. “This is going to be really precious cargo.”

What they would like to find, in these pristine rocks that have existed for 4.5 billion years, are the building blocks of life.

Some have been found before on space rocks that made their way to Earth but all such findings are suspect. Any rock entering and landing on Earth is contaminated, no matter how carefully it is handled.

“Biology is everywhere,” said Lauretta. “You get a rock landing in the desert. It’s going to get contaminated.”

For Lauretta, the most important word in the OSIRIS-REx acronym is “origins.”

“That’s my career and it’s the prime driver for the mission as far as I’m concerned.

“Everyone wants to understand where we came from and the answer may lie in those samples from Bennu,” he said.

The goal for the sample is 60 grams (about 2 ounces) but the sampling head can hold more than 30 times that amount.

Lauretta said most of the sample will be archived by NASA for future research, on the premise that new methods will produce better results.

The OSIRIS-REx science team will get 25 percent of the sample and the Canadian Space Agency will get 4 percent.

The Japanese Space Agency, which is conducting its own asteroid-return mission, will swap 10 percent of its smaller sample for a 0.5 percent share of the OSIRIS-REx haul.

A little goes a long way, Lauretta said. “It has to do with the phenomenal analytical capabilities that exist today. You can go molecule-by-molecule. You can spend your whole career studying a grain.”