An asteroid hitting our planet is an absolutely real threat, not just the subject of dozens of Hollywood movies. The US space agency has long classified any approaching space body, with one “potentially hazardous” asteroid passing within 2 million km (about five distances from the Earth to the Moon) in January of this year. There was a similar asteroid in March – 2009 JF1. The Apophis flyby in 2029 was also considered dangerous, but now the odds of hitting Earth are estimated at 1 in 230,000.
And yet – there is a risk of an asteroid hitting the Earth and NASA, together with the European Space Agency, are actively working to find a solution.
A SpaceX Falcon 9 rocket lifted off at 10:21 PM PT on November 24, 2021, from Vandenberg Space Base. Thus began a DART mission.
DART is the Double Asteroid Redirection Test. Atop the rocket was a vehicle the size of a small car, which was released minutes after launch and began a 10-month journey into outer space. The device reached 11 million kilometers from Earth.
The device flies to Didymos (Didymos – twins in Greek) – an asteroid that does not pose a threat to Earth. It is small and its orbit is not dangerous, but it is perfect for a sample of this type. The asteroid is so named because it is double – its second part is called Dimorphos or Didymos B, or even Didymoon.
The plan is for DART to hit the smaller of the two asteroids at a speed of 24,000 km/h. The probe is expected to crash into the asteroid on September 27 at 2:14 a.m. Bulgarian time.
Although the sizes are incomparable – like a golf cart hitting a huge pyramid, DART’s high speed should also knock the larger asteroid out of its orbit. Ground-based telescopes will measure how much it changes. The expectation is that the orbit will be shortened by 10 minutes, but the team will accept 73 seconds as a success. At that distance, that would be enough to safely deflect an asteroid.
DART will be controlled by NASA until the final hours when control will pass to the vehicle’s autonomous navigation system.
Although DART is equipped with a large number of cameras, incl. a camera for optical navigation (DRACO), these instruments will be used next to Didymos, as well as to photograph the surface of the asteroid as DART approaches. But the impact would interrupt the camera’s data feed, the entire spacecraft would be destroyed. Therefore, in 2024, the European Space Agency (ESA) will launch the Hera spacecraft. It will arrive at the asteroid in December 2026 and examine any damage caused by the DART device. In addition, Hera will be equipped with two small satellites that will land on the surface of the object and study its composition.