

Asteroid Hunter to Be First Private Deep-Space Mission?

Sentinel space telescope to map near-Earth hazards, group says.

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A diagram shows the privately funded Sentinel spacecraft in its planned orbit around the sun.

The first privately funded deep-space mission will launch an asteroid-hunting telescope in 2017 or 2018, project managers announced today.

The ambitious project is being developed by the B612 Foundation, a nonprofit named for the asteroid home of the title character in Antoine de Saint-Exupéry's book The Little Prince.

Led by former astronauts and veteran NASA astronomers, the foundation today kicked off a fundraising effort to build and launch the infrared telescope—dubbed Sentinel—which will create an "asteroid map" of the inner solar system.

Cost estimates for the full mission haven't been released, but the spacecraft itself is expected to have a price tag of a few hundred million U.S. dollars.

The mission's goal is to illustrate the present and future paths of near-Earth asteroids, including any that may pose collision threats to our planet.

"We've found and tracked maybe ten thousand [near-Earth asteroids] thus far and most of the very largest and most dangerous stuff, but that still leaves a lot of undiscovered territory," said Ed Lu, a former NASA astronaut and astrophysicist who serves as B612's chair and CEO.

Foundation managers are particularly concerned about relatively small, harder-to-spot space rocks that, while not risks for planetwide extinctions, could hit Earth with enough force to wipe out cities.

For example, Lu said, current estimates suggest there are half a million or so near-Earth asteroids around the size of the one thought to have caused the mysterious Tunguska event, which leveled a large swath of remote Siberian forest more than a century ago.

Charting and tracking the asteroid populations in our local neighborhood might help not only to prevent catastrophe on Earth but also to aid future interplanetary missions, because spacecraft would no longer have to "fly blind" through our solar system.

"In the great explorations, the first thing people do is create a map—think of Lewis and Clark or Magellan. That's what we want to do for the inner solar system," Lu said.

"NASA has started it already, but 98 or 99 percent of the territory that crosses Earth's orbit is unmapped. We said, You know what, rather than try to convince the government to do this, why don't we do it? And that's what we're going to do."

Charting Solar System Hazards

Right now, NASA's Near Earth Object Program coordinates the government agency's efforts to identify and track potentially hazardous asteroids and comets.

As of June 21, those efforts had uncovered 9,054 near-Earth objects, 1,317 of which are classified as potentially hazardous asteroids. Of those, 849 are at least 0.62 mile (a kilometer) wide—which means they pose the greatest potential hazards to Earth.

Still, the Task Force on Planetary Defense, part of NASA's advisory council, has recommended that an infrared space telescope be placed in an orbit close to that of Venus to spot ever smaller asteroids that approach Earth.

Putting the craft in orbit between Earth and the sun is key, because a space telescope in that position would be able to scan Earth's orbit while looking away from the glare of our bright star at all times.

It's also important for the telescope to scan in infrared wavelengths. In visible light, small, dark asteroids can pass by undetected. But space rocks absorb heat from the sun, so in infrared they tend to stand out against the cold void of space.

"Perfect Storm" in Private Spaceflight

The B612 Foundation says it can deploy such a telescope entirely with private funds. The SpaceX Falcon 9 rocket, another private space venture, is slated for use as a launch vehicle.

"We saw that it was possible to do something like this as a nongovernmental group," Lu said.

"It has only been possible for a few years, and ten years ago it wouldn't have been possible for even a government to do it. But computing power on spacecraft has gotten much better, and to track half a million objects, you need to do lots of computations on board," Lu said.

"Also, infrared detectors have advanced greatly in the past two years and, with the availability of radically less expensive launchers, like SpaceX, it was a perfect storm."

A Question of Risk

If things go as planned, Sentinel will orbit between 30 and 170 million miles (48 and 274 million kilometers) closer to the sun than Earth.

The spacecraft will scan the entire night sky every 26 days to identify moving objects and will beam the data back to Earth for analysis.

Within 5.5 years, the Sentinel program is expected to have discovered and tracked half a million near-Earth asteroids, 90 percent of which should be larger than 460 feet (140 meters).

"This is exciting," said University of Arizona astronomer Ed Beshore.

"There's no doubt about it that a properly designed, space-based observatory could rapidly find most of the near-Earth objects that could represent a potential threat to the Earth."

Beshore, the former principal investigator for the Catalina Sky Survey's near-Earth object program, added that a ground-based system could do the job for a lot less money, but it would likely take 40 years or more to complete such a survey.

The question is whether that extra time might make a critical difference, something Beshore thinks is statistically unlikely.

"When you look at the threat issue, the chance of a large asteroid hitting the Earth is extremely low. But on the other hand, when you multiply that by the cost of killing everyone on the planet, you get a large integrated risk associated with that," he said.

"I guess I'd say, as a scientist, that if this was going to rely on public funding, I think that's scarce enough for science missions that we shouldn't be doing missions that we could do from the ground," he added.

"But if private investors feel this is urgent and we need to get this wound up quickly, then a space-based mission is the only way to do it."

Sentinel will also return a wealth of scientific data that will help scientists better understand the objects in our solar system.

"Thermal infrared imaging can deliver data on things like asteroid composition that we can't get from the ground," Beshore said, "so that will be a real windfall from a science perspective."

Working in a Perfect World?

The Sentinel mission will get some support from NASA, such as use of the agency's Deep Space Network to relay science and navigation data from the probe to Earth.

And the NASA Near Earth Object Program will use data from the telescope to conduct asteroid hazard analyses and threat assessments.

What's more, Sentinel's leadership team is full of space-industry veterans with years of experience serving NASA and other aerospace ventures, foundation CEO Lu said.

"Our leadership has all run missions before and suffered some frustrations from doing things they way they've always done them," he said.

"We asked them, In a perfect world, if you could run a deep space mission, what would you do differently? And we signed them up with the opportunity to run a mission just that way—the way they always wanted to."

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