Madrid (EFE) of an object from space.
The US DART mission, the first attempt to learn how to deflect an asteroid from Earth, achieved its goal last September by modifying the orbit of the Dimorphos asteroid, and Nature publishes this Wednesday the first analyzes in five international studies with Spanish participation.
What is the DART technique and why will it help in the defense of Earth?
DART was a kinetic impactor without an explosive charge, that is, a probe that, kamikaze-style, was launched at about 6 kilometers per second against Dimorphos, an asteroid similar in size to the pyramid of Cheops that orbits another, Didymos, with the which forms a binary system.
Because of the impact, the orbital period of Dimorphos around Didymos, which was 11 hours and 55 minutes, was reduced by 33 minutes. Experts had predicted that it would take about seven minutes if the spacecraft’s momentum were transferred directly to the asteroid in a perfectly inelastic collision, one of the studies notes.
The final large change in orbital period “suggests that the ejected material contributed a significant amount of momentum to the asteroid beyond that carried by the spacecraft,” write the authors of the first study, led by Northwestern Arizona University. USA).
The successful impact and the resulting change in the asteroid’s orbit “demonstrates that kinetic impactor technology is a viable technique to potentially defend the Earth if necessary,” say the authors of another of the investigations coordinated by Johns Hopkins University (EE .USA).
Understanding how the spacecraft impact modified the small asteroid’s orbit sheds light on how this approach might be able to provide a defense system against possible collisions of astronomical objects with Earth.
The collision produced the expulsion of more than 5 million kilos of material
Another of the investigations reconstructs the impact, which can help plan future missions and predict the results with greater certainty, and another describes the location and nature of the crash site, between two rocks, one of which was grazed by the probe of the size of a refrigerator.
A collision that produced the expulsion of more than five million kilos of material, according to the Higher Council for Scientific Research (CSIC), of which other Spanish institutions have participated in the studies such as the Institute of Space Sciences (ICE), the Institute of Astrophysics of Andalusia (IAA) and the Center for Astrobiology (CAB).
Excavating an impact crater threw up large rocks, but many were weakened by space processing on the asteroid’s surface and preferentially shredded by the impact.
These particles “were immediately thrown into space in the opposite direction to the projectile as centimeter to micrometer-sized particles, then being subjected to the radiation pressure of the Sun’s own light”, according to Josep Maria Trigo, from ICE-CSIC and co-author on several of the studies.
The mission was followed from Earth by numerous telescopes, including a citizen science network, as well as those located in space such as Hubble, which observed the ejecta plume (debris created by the impact).
The DART probe detected its target autonomously
Hubble took images from the moment of impact and up to several months after that material to characterize its evolution.
Until DART’s arrival at the binary asteroid system, located 11 million kilometers from Earth, little was known about either, but the Draco camera aboard the probe was able to obtain high-resolution images.
Thanks to them it was possible to see that the surface of Dimorphos is strewn with rocks as in the carbonaceous asteroids Bennu and Ryugu, also no impact craters are observed, which indicates a young surface, although they could be difficult to identify in terrain covered with pebbles. rolled.
DART had to detect its target autonomously and with limited prior knowledge of it, so its success is for researchers “a key first achievement on the path to advancing kinetic impactor technology toward operational capability.”
Kinetic impactor technology requires sufficient lead time, at least several years, but this first step to demonstrate its feasibility “feeds -according to the researchers- optimism about humanity’s ability to protect Earth from the threat of a asteroid”.
