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Why ESA Scientists Really Want to Crash a Satellite into an Asteroid

Over 100 planetary scientists signed a letter advocating for ESA funding for the Asteroid Impact Mission.
Image: ESA

On December 1 and 2, the ministers from the European Space Agency's 22 member states will convene in Lucerne, Switzerland to discuss future ESA missions and how to fund them. This meeting will determine the scope of Europe's activities in space for the coming years, but due to current political and economic difficulties affecting many of the ESA's member states, the meeting is expected to be particularly "challenging."


One of the biggest topics on the table at the conference is the ESA's involvement in the Asteroid Impact and Deflection mission (AIDA), a joint venture between NASA and the European Space Agency which will involve the launch of two spacecraft to an asteroid in 2020. However ESA's ability to fund their part of this mission will require the member states to pledge roughly €250 million in funding (which is actually pretty modest, as far as space missions go) at the conference—which in light of the economic situation in Europe is far from certain.

"Nothing is for sure until the [mission approval] is signed," Patrick Michel, a senior researcher at the French National Center for Scientific Research and the principle AIM investigator, told Motherboard. "Even if I'm optimistic and see the high potential of this mission, I know that some countries would be happy to make this mission, but can't afford it. Their budgets are very, very tight so we need to push until the end and keep up the pressure."

This uncertainty about the ESA's role in the AIDA mission prompted Michel and his colleagues to rally well over 100 top planetary scientist from around the world to sign a letter last week which outlined why it is so important for ESA to approve the mission at the ministerial council. In brief, the scientists argue that not only will AIDA teach us about the origins of our solar system and how asteroids are formed, but it will also go a long way in terms of helping us figure out how to save Earth from a killer asteroid.


In October 2022, a binary asteroid (a large asteroid with a small moon orbiting around it) known as 65803 Didymos will pass within roughly 10 million miles of Earth, which on a cosmic scale is basically like bumping elbows. The AIDA mission will involve the launch of two spacecraft to the Didymos system, one of which is being deployed by NASA and the other by ESA.

NASA will be launching a probe called the Double Asteroid Redirection Test (DART), which will arrive at the asteroid (called 65803 Didymos) in late 2022 and then directly proceed to crash into the asteroid's moon at 6 km/s (or about 13,400 mph). This impact would then be monitored by ESA's Asteroid Impact Mission (AIM) spacecraft, which will have placed itself into orbit around the binary asteroid four months in advance of DART's arrival.

The mission is designed so that NASA can go ahead with its DART portion of the mission whether or not ESA is able to get AIM funded, but for scientists around the world, not funding AIM would be a huge missed opportunity for planetary science and defense.

"If ESA doesn't do AIM, DART can still go," said Michel. "But it's just half the mission. You wouldn't get the initial conditions or outcomes in detail, but at least you are able to complete DART to test the capacity to autonomously guide a projectile to a very small target."

Not convinced? Why don't you let Brian May, guitarist of Queen who is also an astrophysicist, explain why AIM is important.


In essence, AIM will be closely monitoring DART's impact with the asteroid's moon to study how the impact affected the structural integrity of the asteroid and altered its orbit. According to the ESA, it will be the first time that humans have "altered the dynamics of a Solar System body in a measureable way." While this is cool and all, it will allow planetary scientists on Earth to better model how asteroids react to a high energy impact, which is currently the only realistic plan we have for deflecting an asteroid bound for Earth.

Moreover, AIM will be carrying three smaller spacecraft—an asteroid lander and two cubesats—which will be mapping the asteroid and collecting geophysical data in the four month lead up to the DART collision. AIM will also be testing out optical communications in deep space (read: laser communication) as well as testing the feasibility of an inter-satellite communication network, which will help lay the groundwork for an interplanetary internet.

AIDA will also allow for the further development of technology deployed during the recently terminated Rosetta mission, which involved placing an orbiter and lander around a comet that was 4km in diameter. In this sense, the AIDA mission is much more technically challenging insofar as the main Didymos asteroid is only 800m in size and the moon is about 170m in size.

This makes for a more challenging rendezvous, but one that is particularly important considering that both of these rocks could cause serious damage were they to collide with Earth.

"Going to the asteroid is like an Indiana Jones adventure," said Michel. "You also have the aspect of saving the Earth and permitting life. But I think it's also very important for the new generations in Europe to have this mission as inspiration."