Dart Mission: According to NASA, the probe has changed the orbit of the asteroid Dimorphos. It was a little more complicated than a bump in physics class.
Hit-deflected: The impact of a human-launched space probe has changed the orbit of a celestial body for the first time. Asteroid Dimorphos now takes less time to orbit asteroid Didymos.
Two weeks ago, the 570-kilogram Double Asteroid Redirection Test (Dart) impactor struck the approximately 160-meter-tall Dimorphos. Analyzes have shown that this has changed the orbit of the celestial body around the 780-meter Didymos, said the US space agency National Aeronautics and Space Administration (NASA).
It wasn’t a collision like in physics class
It took Dimorphos 11 hours and 55 minutes to complete an orbit before Dart struck. He now only needs 11 hours and 23 minutes. An unrealistically small change of 73 seconds was previously set as the minimum goal for the mission. This could only have happened if Dart hit the asteroid on the very edge and nearly missed it.
A change of around 10 minutes was calculated for the case of a perfectly inelastic collision. In physics lessons, a projectile is usually fired from an airgun at a pendulum filled with modeling clay, so that both then continue to move together. When a 610 kg spacecraft collides with an asteroid at 6.58 km/s – ten times faster than a typical rifle bullet – a crater forms and much material is ejected from it, making it no longer a perfectly inelastic collision.
When a crater forms, the material is ejected into space in the opposite direction of the spacecraft’s flight. Depending on the mass and speed of the debris, the asteroid is accelerated even further in accordance with the conservation of momentum. However, it is difficult to predict how much material will be ejected in the collision, especially since the structure of the asteroid was not known before the collision.
How much additional momentum the asteroid receives as a result of the crater formation is described by the beta factor, the determination of which was an important goal of the mission. For an asteroid composed of loose debris like Dimorphos that barely adheres to one another, the value can be quite large. However, it is unclear how meaningful the value is since Dart – unlike the Deep Impact spacecraft – was not optimized to create the largest possible crater. Insights of the Dart mission.
Dart Mission: Dimorphos is harmless
From the approximately 330 million dollar asteroid defense mission, NASA still hopes to find out how the earth could be protected from approaching celestial bodies. However, Dimorphos poses no threat to Earth.
“We all have a responsibility to protect our home planet. After all, it’s the only one we have,” said NASA director Bill Nelson (directing towards the importance of the Dart mission). “This mission shows that NASA is trying to be prepared for whatever the universe throws at us.”The mission is a turning point in protecting Earth from an asteroid impact.
In the coming weeks and months, the impact of the collision will now be further investigated. Another Dart mission to Didymos is scheduled to start in 2024: Then the European Space Agency (ESA) will send the Hera probe to the two asteroids and measure Dimorphos and Didymos in 2026. Of particular interest is the crater left by Dart and an accurate determination of the mass of Dimorphos.
NASA and researchers around the world have been dealing with the question of how to defend against an asteroid for many years. An asteroid’s impact around 66 million years ago, for example, is considered by scientists to be the leading theory as to why the dinosaurs became extinct.
Scientists don’t currently know of any asteroid that could be heading straight for Earth any time soon – but researchers have identified around 27,000 asteroids near our planet, around 10,000 of them with a diameter of more than 140 meters.