The time has come. We'll smash a spaceship into an asteroid.
The asteroid is Didymos B, the smaller of the two objects in Didymos' binary asteroid system. The spacecraft is NASA's Double Asteroid Redirection Test (DART). The reason: to test whether a spacecraft impact can distract the trajectory of an asteroid to protect Earth from rogue space rocks.
The Joint Asteroid Impact Assessment (AIDA) Collaboration Project, announced by the European Space Agency (ESA) and NASA, was announced in 2015. However, the recent surprising results of subsequent asteroid missions could have an impact on the test.
When JAXA's Hayabusa2 bombed the asteroid Ryugu in April this year, it formed a much larger crater than expected. In addition, the material on the surface of the asteroid behaves very much like sand. this could affect the effectiveness of the kinetic impact deflection.
"The impact with Hayabusa2 showed that there was no cohesion on the surface and that the regolith behaved like pure sand, and that gravity dominated the process rather than the intrinsic strength of the material." If Didymos B, gravity dominates, even though it does is much smaller, we could end up with a much larger crater than our models and laboratories. "Previous experiments have shown that ultimately little is known about the behavior of these small bodies during an impact, and this could have major consequences for planetary defense . "
Following an AIDA workshop last week in Rome, scientists have met at the EPS-DPS Joint Meeting 201
"The key question that still needs to be answered is: Are the technologies and models we have good? T enough to actually work? Before you drive a car, you must have insurance. Well, AIDA is the insurance policy for Planet Earth. "
The Didymos system is also the perfect test rig, it's a near-Earth object – not too far away – not on a collision course with Earth, meaning that our tests are unlikely to backfire.  "DART's goal, Didymos, is an ideal candidate for humanity's first planetary defense experiment," said planetary scientist Nancy Chabot of the Applied Physics Laboratory at Johns Hopkins University.
"It is not activated A path that goes with Earth collides and therefore does not present a current threat to the planet. However, because of its binary nature, DART can test and evaluate the effects of a kinetic impactor. "
In this asteroid Binay, the larger object, Didymos A, has a diameter of approximately 780 meters, the smaller, Didymos B, a diameter of approximately 780 meters 160 meters and is sometimes referred to as" Didymoon ". It circles the larger asteroid every 11.92 hours.
When DART enters Didymos B at a speed of 23,760 kilometers per hour, only the asteroids are changed speed very low – by as little as one centimeter per second or so.
In a Single Asteroid We may not be able to recognize this at all, but in the Didymos system The influence is expected to slightly change the orbital period: instead of 11.92 hours, Didymos B may take a few minutes longer to get around Didymos B.  That does not sound like much, but if we're earthbound Asteroids can catch early enough, then that's a small change. A change of location could make all the difference.
The launch of DART is scheduled for July 2021 for an impact in September 2022. A small cube called LICIAcube will disengage from the spacecraft shortly before the impact is being photographed, to which it is to re-beam Earth. Earth-based telescopes then monitor Didymos to see if run times change due to regular dips in the system's light curve.
The second part of the mission is the ESA Hera. This is a small observation spacecraft that will launch in 2023 and watch Didymos B in 2027. Since we can not really see the asteroid system from Earth, Hera will be able to tell us all the details – for example, if the DART impact Didymos B wiggles in the longitudinal direction.
Hera has passed the review of system requirements and is now entering the development phase.
"Planet defense is truly a global endeavor," said Carnelli Technology Review.
"Besides technology and science, AIDA is also a really good collaborative experiment between scientists and agencies around the world, it's the kind of thing that would be needed if an asteroid were on a collision course. " for the earth.