When NASA’s DART spacecraft crashes into the asteroid Dimorphos on September 26, it will have a silent witness: an Italian cube satellite called LICIACube will follow the groundbreaking experiment in real time for eager scientists on Earth.
LICIACubeor the Light Italian Cubesat for Imaging of Asteroids, is a 31-pound (14-kilogram) microsatellite that was hitchhiked ARROW (Double Asteroid Redirection Test) for Didymos-Dimorphos binary asteroid system. DART deployed the CubeSat at 19:14 EDT (2314 GMT) Sunday (September 11) to give LICIACube 15 days to establish a safe position and observe DART’s collision with Dimorphos. Impact is a unique experiment designed to determine the orbit of a space rock in a crucial test of a planetary defense Concept that could one day save the lives of millions of people on earth.
“LICIACube is released from the donor on one of DART’s outer plates and guided (braking and rotating) to begin its autonomous journey towards Dimorphos,” says Elena Mazzotta Epifani, astronomer at Italy’s National Institute for Astrophysics (INAF) and a Co -Investigators on the LICIACube mission, Space.com said in an email. “The CubeSat will point its cameras at the asteroid system but also at DART and probably take some pictures of it.”
Related: NASA’s DART asteroid impact mission explained in pictures
The only first hand witness
LICIACube, equipped with two optical cameras, will follow DART toward Dimorphos, eventually settling in to watch the drama from a safe distance of 600 miles (1,000 kilometers) when the 1,345-pound (610 kg) spacecraft launches on September 26 hits the rock. Added Mazzotta Epifani. “The impact of DART will be [seen] as increasing target brightness by comparing images of Dimorphos taken before and after impact,” she wrote.
At the time of impact, Dimorphos and Didymos will be approximately 6.8 million miles (11 million km) from Earth. according to NASA (opens in new tab). Although ground-based astronomers cannot see the impact, they will be watching the system closely over the coming weeks to determine if the 12-hour orbit of the 560-foot-wide (170 meters) Dimorphos is around the 2,600-foot-wide (800 m ) Didymos will have accelerated as expected. They do this by measuring the intervals between the periods of brief dimming that occur when the two occur asteroids obscure each other.
But while such observations might be enough to confirm that the experiment worked, they would provide no details on the effects of DART’s impact with the asteroid. And so, right after DART hits Dimorphos, LICIACube will come closer to inspect the scene.
“LICIACube will … perform a ‘fast flyby’ approximately 3 minutes after the DART impact at a minimum distance of approximately 55 km [34 miles] from the surface of Dimorphos at its closest approach,” Mazzotta Epifani wrote.
LICIACube then sends the images to Earthbut Mazzotta Epifani warned it could take weeks to download all the data.
We don’t know anything about Dimorphos
Understanding in detail the impact of DART’s impact on Dimorphos is crucial, as a similar system may one day be needed to deflect a rock on a collision course with Earth. An asteroid the size of Dimorphos could cause continent-wide destruction, while the effects of an asteroid the size of the larger Didymos would be felt worldwide.
But there’s a catch: Although astronomers know in minute detail the orbits of most of the 26,115 currently known near-Earth asteroids (of which 2,000 are classified as “potentially dangerous” because of their size and proximity to Earth), they know surprisingly little about these rocks. In particular, scientists don’t understand the density of the material that makes up the rocks and can only guess how the surface might behave on impact.
The team behind NASA’s OSIRIS-REx missionwhich landed on nearby earth Asteroid Bennu experienced the pitfalls of these strangers firsthand in October 2020. The asteroid’s unexpectedly soft surface nearly engulfed the spacecraft, and the landing produced what Dante Lauretta, OSIRIS-REx principal investigator, described “A Huge Wall of Debris” that could easily have destroyed the spaceship.
Lauretta, a planetary scientist at the University of Arizona, said Space.com When the incident was announced, it suggested that a diversion attempt might be more difficult than thought, as soft-surfaced asteroids might just absorb the impact.
The team behind DART knows just as little about Dimorphos as the OSIRIS-REx team knew about Bennu before the spacecraft reached the asteroid. The images, taken by DART itself before impact and then by LICIACube, will be the first detailed views Dimorphos astronomers will ever see.
“We know the general surface properties of the larger Didymos thanks to ground-based spectroscopic and photometric measurements, but we know almost nothing about Dimorphos, which is too small to produce an effect separate from that of the main body,” wrote Mazzotta Epifani. “We *guess* from theoretical models of binary asteroid formation that Dimorphos Didymos is very similar, but we know virtually nothing about the degree of cohesion of surface materials, the size distribution of surface debris, and so on.”
Scientists think of Dimorphos as a so-called “debris pile asteroid” like Bennu: a conglomerate of boulders and soil that broke away from the main asteroid Didymos in the past and is now held together only by the asteroid’s momentum heaviness. Since the asteroid is quite small, this force is quite weak. Because of this, astronomers don’t understand what impact DART will have, how much matter it might hurl into space, and how big a crater it might leave in its wake.
lessons for the future
“Together, DART and LICIACube will, for the first time and in great detail, analyze the physical properties of a binary near-Earth asteroid, allowing us to probe its nature and obtain clues to its formation and evolution,” wrote Mazzotta Epifani. “LICIACube will receive multiple images of the ejection plume generated by the impact itself, the DART impact [crater] size and the non-impact hemisphere to help us study the size and morphology of the crater and the impact on surface properties in the area.”
The good news is that the more information scientists get together, the better they can predict the impact of possible future interventions on similar asteroids.
The Italian space agency overseeing the LICIACube mission is currently evaluating plans to expand the mission to conduct other studies of the Didymos-Dimorphos binary asteroid system, Mazzotta Epifani wrote, adding that any decisions to extend the mission are based on the immediate consequences of the Impact additions will only be made after September 26th.
Italy’s first space mission
For the Italians, who boast a burgeoning space industry that has contributed to some of Europe’s best-known space projects (including the International Space Station’s Columbus module in Europe), LICIACube is the first space mission the country will participate in on its own. Designed and built in less than three and a half years, LICIACube, similar to ArgoMoon, is one of the CubeSats hitchhiking to the moon on NASA’s Artemis 1 missionwhat still is waiting for departure after a fuel leak halted a September 3 launch attempt.
“LICIACube is not only the first mission in space that Italy will operate, it is also the first designed, realized and managed entirely in Italy, including data reception and management,” wrote Mazzotta Epifani.
With LICIACube, Italy stepped in to fill the gap created by delays in approving the European Space Agency’s (ESA) budget. HERA missiona much larger spacecraft originally scheduled to arrive at the Didymos-Dimorphos duo prior to the DART impact to inspect the system and then observe the crash and study its aftermath in detail. ESA still plans to launch HERAbut the spacecraft will not reach Didymos until 2027.
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