Deception at TU’s Astrodynamics & Space Missions section. ESA decided not to send a satellite to asteroid Didymos to test the cannonball technique to deflect asteroids hurtling toward Earth. Delft researchers were involved in this mission.
First the good news. If a killer object (comet, asteroid) hurtles toward Earth – like the one that wiped out dinosaurs 60 million years ago – we just might survive. In 2022 NASA will for the first time test a technique to slightly change an asteroid’s or comet’s trajectory by smacking a satellite against it.
The insights that this kinetic impactor technique, or cannonball method, produce, should help us get prepared for the real – extremely rare, but devastating – thing. The mission is called the Asteroid Impact and Deflection Assessment (AIDA).
Bad news
Now the bad news. ESA withdrew its support. And with that, TU Delft’s part in what could possibly become a planet-saving technology shrinks to nearly null.
ESA was supposed to send a satellite to the near-Earth asteroid Didymos, to watch from nearby the effects of the American blast. The satellite would do so from above. But it would also deploy a lander. Getting the timing and ballistics right for the touchdown is what TU Delft master’s student Pablo Minguijon Pallas (Aerospace Faculty) and his supervisors from the Astrodynamics & Space Missions section were set to do.
Minquijon Pallas will continue his work, but it will only be a theoretical exercise now. That is still useful, though, said Ron Noomen, one of his supervisors. “Research on asteroids is popular. There are bound to be new missions to asteroids involving landers to further develop techniques to deflect them.”
Fundamental
Asteroid missions are also interesting from a fundamental point of view. These chunks of space debris can tell us a lot about our history, according to Noomen. One of the key questions planet researchers would like to answer is whether we owe our water supplies on earth to incoming asteroids or comets.
Besides the kinetic impactor technique, there are many more doomsday stopping scenario’s. “They are all extremely wild,” said Noomen.
“One idea is to paint one side of an asteroid white and another black, thereby changing the reflective properties. Due to a change in the radiation pressure – the momentum of impinging and reflected photons – the asteroid will slightly change its course. You would have to send two huge buckets of paint to an asteroid.”
“Blowing an asteroid to crumbs is another option. But then you are bound to get hit by some of the shreds.”
Ionic engines
Other options include sending ionic engines that gently push the rock out of harm’s way or furnishing them with solar sails.
But the actual redirection of the celestial projectile is only part of the challenge. Determining its trajectory and deciding whether it poses a threat is just as problematic.
Asteroids and comets are like loose cannons. The latter have geysers on their surfaces that emit gasses – hence their tails. These spouts are like jet engines leading to capricious trajectories.
Lack of precision
“As it stands now, we are unable to tell if an asteroid will hit us, simply due to lack of precision in our measurements,” said Dirk Ryckbosch, head of the department of physics and astronomy of the Ghent University.
“The highest resolution we obtain is 500 thousand kilometres, meaning that at best we can predict if an asteroid will flash by somewhere between earth and the moon. If we intervene, we might just as well drive the asteroid closer towards earth.”
What NASA has to say about the AIDA mission, excerpts from its website (that has not yet been changed since ESA withdrew):
“AIDA is a dual-mission concept, involving two independent spacecraft – NASA’s Double Asteroid Redirection Test (DART), and ESA’s Asteroid Impact Mission (AIM).
AIDA’s primary objective is to demonstrate, and to measure the effects of, a kinetic impact on a small asteroid. Its target is the binary near-Earth asteroid (65803) Didymos, which consists of a primary body approximately 800 metres across, and a secondary body (or “moonlet”) whose 150-metre size is more typical of the size of asteroids that could pose a more common hazard to Earth.
“The DART spacecraft will achieve the kinetic impact by deliberately crashing itself into the moonlet at a speed of approximately 6 km/s, with the aid of an onboard camera and sophisticated autonomous navigation software. The collision will change the speed of the moonlet in its orbit around the main body by a fraction of one percent, enough to be measured using telescopes on Earth.
“The AIM spacecraft will arrive at Didymos before DART’s impact, and perform the first-ever close-up study of a binary asteroid, providing high-resolution imagery of the surfaces of the binary system as well as measurements of the masses, densities, and shapes of its two bodies.
“AIM will deploy a surface package, MASCOT-2 [Mobile Asteroid Surface Scout] to characterise the moonlet before, during and after the DART impact.”
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