Earth is such a comfortable and verdant world that it's easy to forget we actually live on a space rock that's hurtling through an orbital obstacle course (apparently, Congress frequently needs to be reminded of this fact).
But despite the long-term existential threat posed by comet and asteroid impacts, humans still haven't come up with a solid contingency plan should the planet ever be faced with imminent cosmic death.
Fortunately, the European Space Agency (ESA) is working with NASA to launch the Asteroid Impact & Deflection Assessment (AIDA)—the first ever mission to deflect the trajectory of an asteroid, and an essential maneuver for any well-rounded impact defense program.
On Tuesday, ESA announced that its contribution to this joint project, the Asteroid Impact Mission (AIM), is slated for an October 2020 launch. NASA's contribution to the mission, an impactor called the Double Asteroid Redirection Test (DART), is tentatively slated for launch in 2021. This should give the two spacecraft enough time to reach the binary asteroid system 65803 Didymos by the time it passes close to Earth in the autumn of 2022.
First, AIM will land on the smaller of Didymos' two asteroids, nicknamed "Didymoon." Compared to its 800 meter wide partner, Didymoon is only about 170 meters in size. Between the lander, orbiter, and the CubeSats ESA plans to pack along for the ride, AIM will be able to map and survey the asteroid in great detail.
That's a good thing, because once the aptly named DART turns up, all hell will break loose on Didymoon. NASA's sturdy impactor is expected to collide with the asteroid's surface at a speed of about six kilometers/second—fast enough to shift its orbit. In theory. If all goes according to plan, this impact "will mark the first time humanity has altered the dynamics of the Solar System in a measurable way," according to AIM program manager Ian Carnelli.
"AIM will be watching closely as DART hits Didymoon," Carnelli said in an ESA statement. "In the aftermath, it will perform detailed before-and-after comparisons on the structure of the body itself, as well as its orbit, to characterise DART's kinetic impact and its consequences."
"It will also give us a baseline for planning any future planetary defence strategies," he continued. "We will gain insight into the kind of force needed to shift the orbit of any incoming asteroid, and better understand how the technique could be applied if a real threat were to occur."
If this tag team mission between AIM and DART is successful, it could be a real boon for future planetary defense initiatives. Scientists have been advocating for these kinds of global security missions for decades, and recent asteroid missions like Japan's Hayabusa program or NASA's Deep Impact probe have paved the way for more ambitious investigations.
But as we reported last week, NASA is already scaling back on some of its most promising asteroid programs, and it's possible that AIDA will be similarly defanged—or worse, prevented from ever making it to the launchpad.
Indeed, despite the resounding success and public admiration for its Rosetta mission, ESA is facing similar budget problems. On Monday, the scientific journal Nature revealed that agency has been aggressively culling mission proposals, including an asteroid sample-return project.
If this trend of spartan cutbacks continues, AIDA might end up on the chopping block too, and the responsibility of initiating a comprehensive impact defense plan will be passed, yet again, to the next generation.
But if the tumultuous history of life on Earth has taught us anything, it's that this procrastinative strategy will not win out over the long term.