An early-stage mission concept could see laser-driven light sail probes visit a notorious asteroid.
The space rock Apophis, which poses no threat to Earth for at least 100 years, will make a harmless but very close flyby of our Earth in 2029. Scientists have already found a way to visit Apophis after the flyby: OSIRIS-REx from The NASA spacecraft will visit the asteroid after depositing samples of another space rock on Earth, the agency decided in April.
But 2029 might just be enough time to bring out a few more mission ideas. An online conference hosted May 11-12 by the Houston-based Lunar and Planetary Institute investigated possible applications for planetary defense.
Among the presentations was one outlining an idea to test a rapid launch scenario in the event of an imminent problem, although we have yet to find any asteroids to worry about. It could also serve as an early test for another laser-powered craft that could one day go interstellar, known as the Breakthrough Starshot.
Related: The huge asteroid Apophis revealed in photos
The May 12 presentation, by Paul Blase of Florida-based small satellite startup Space Initiatives Inc., outlined a mission concept that would launch a pair of mini spacecraft aboard a Black Brant sounding rocket. Each probe would be armed with a few simple instruments like tiny cameras and spectrometers.
One spacecraft would be released above the thickest part of the atmosphere at 46 miles (75 kilometers), while the other would be released at the rocket’s maximum altitude of 930 miles (1,500 kilometers). A laser array fired from Earth (potentially at NASA’s facilities on Wallops Island in Virginia, Blase suggested), would then push each probe to an apogee of 18,600 miles (30,000 km). The Friday the 13th flyby of Apophis in 2029 will see the asteroid pass in this range, which is so close that it is in the orbit of some satellites.
The first 3D-printed probe would impact the asteroid, while the second would observe the impact plume with a spectrometer, Blase explained. The data would be retrieved from the second spacecraft after re-entry.
“It’s only one gram,” he said of the mass of the impacting spacecraft, “so it’s not going to do much. But it’s going to raise a plume.”
The team is also considering other mission concepts. There could be regular overflights in the weeks before, during and after the approach, for example. Each of these concepts would cost around $2 million, Blase estimated, which is relatively inexpensive for spacecraft development.
He estimated that it would take only five years to set up the mission. “And then once Apophis comes through, it’s all done in about 12 hours,” he said.
Testing a rapid response capability to an asteroid will one day be essential for planetary defense, Blase said. Tracking of space rocks has improved, but many near-Earth (harmless) asteroids are being spotted with a week or less until their first known flyby.
The team envisions having these small, laser-powered craft on standby to quickly approach a dangerous space rock and redirect it. “All of the core technology for this proposal currently exists,” he said, adding, “We believe Apophis offers a good opportunity to develop these capabilities for future use.”
Although this early-stage and so far unfunded proposal is not associated with the ambitious Breakthrough Starshot which hopes to reach the Alpha Centauri system in a few decades, Blase said his team’s laser craft would serve as a help in planning this mission.
For example, the laser array needed for the asteroid mission would be tens of megawatts instead of gigawatts, which means testing could take place on a smaller scale for feasibility reasons. The Apophis mission would also take place very close to Earth, which would allow technical assessments to be carried out before an interstellar craft departs.
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