Here we are: on the night between 26 and 27 September, NASA’s “Dart” probe will hit Dimorphos, the smaller of the two asteroids in the Didymos system. Launched at more than 23,000 kilometers per hour, Dart will aim to deflect the orbit of its target.
No alarm or Armageddon imminent: the clash will take place 12 million kilometers from our heads, and will be wanted and monitored. Because Dart, acronym for Double Asteroid Redirection Test, is the first mission in the world of “planetary defense”. Its goal is to test the validity and effectiveness of a “kinetic impactor”, the technique with which it is believed possible to change the trajectory of a potentially dangerous body by hitting it with an object thrown on purpose. It is one of the strategies with which we think to defend our planet in case the orbit of an asteroid makes a collision plausible.
Also in this case the anxieties are appeased: the binary system Didymos (65803 Didymos, to be precise) was not chosen as a target because it points towards the Earth, but because hitting the “little moon”, Dimorphos precisely, which has a diameter of 160 meters, it will be possible to measure any changes in its orbit around the primary body, Didymos, about 780 meters wide.
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Started days before the impact, the scientific surveys will continue cumulatively over the next few months. To carry them out, the images and data that LiciaCube is already collecting, a minisatellite of the Italian Space Agency that has carried out a grazing passage – so-called flyby – approaching up to 51 kilometers to Dimorphos three minutes after impact, a time considered ideal for framing one plume – the expulsion of materials – sufficiently developed but not yet rarefied.
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Integrated in Dart and left on November 21st from Vandenberg Space Force Base, in California, LiciaCube was designed and built by Turin-based Argotec. After a ten-month joint trip, on 12 September he was released by Dart to prepare for the most important phase of the mission.
“In itself a complex thing” comments David Avino, who of Argotec is the founder (in 2008) and the managing director. “For millions of kilometers, LiciaCube was the most exposed object in the entire system to space, an environment whose extreme characteristics complicate any operation. However, I can confirm that the satellite is working and is carrying out its duties as scheduled ”.
LiciaCube is a cubesat of six units (20x10x30 centimeters), weighs almost 13 kilos and is based on Argotec’s “Hawk” platform, already used for ArgoMoon, the only European satellite of the Artemis 1 lunar mission, which should soon face its third launch attempt. ArgoMoon should have started before LiciaCube, confirming its functionality. But the opposite happened.
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“The Italian space agency has been investing in small satellites for some time,” says Simone Pirrotta, who is LiciaCube’s program manager for ASI. “We recognized the potential of the cubesats in being complementary to missions carried out with traditionally sized satellites, much larger. With ArgoMoon, LiciaCube and other similar initiatives, we have prepared a program for smaller satellites which we are now developing further. Managing the whole chain is a further added value, because today we are also able to operate the satellites on mission “.
The main tools of LiciaCube are two cameras named after the protagonists of Star Wars, “Luke” (which stands for LiciaCube Unit Key Explorer) and “Leia” (LiciaCube Explorer Imaging for Asteroid): Leia is a narrow-field panchromatic camera, capable of acquiring images from a great distance with a high level of spatial definition. Luke is a wide-field RGB, for a multicolored analysis of the asteroid environment. In addition to confirming the impact, Leia and Luke must analyze the formation of the debris cloud raised by the collision, in particular to characterize its structure and development, to detect the size and morphology of the crater, and to observe the non-impacted hemisphere of Dimorphos, to contribute to the dimensional and volumetric measurements of the target.
Technical characteristics aside, LiciaCube is the first Italian interplanetary probe, as well as the first mission in deep space entirely developed and managed by our team: in fact, using the antennas of NASA’s Deep Space Network, Argotec will manage flight operations from one of the its two Control Rooms in Turin, while at the Asi Space Science Data Center they will complete the processing and archiving of data.
The scientific sector, which involves, among others, the Politecnico di Milano (for the design of the mission trajectory) and the University of Bologna (for the determination of the orbit in real time), is coordinated by INAF, the Institute national astrophysics.
“The data provided by LiciaCube will have a significant scientific value, because today we don’t know how much plume Dart will produce ”- explains Elisabetta Dotto, for INAF coordinator of the entire scientific team since its conception -“ We are currently developing models. But the image of the plume and his study will tell us how the target is made, how porous or monolithic it is. This is information that will allow us to study for the first time on site a binary object, little known to date, and above all they will tell us how much we managed to divert it according to its structure. At that point we will be able to optimize our models and ‘scale’ them for objects of different composition and structure ”.
The importance of the mission, to which will be added the data collected by Hera, an expedition of the European Space Agency which in 2026 will reach Dimorphos with the minisatellitie Juventas and Milani, is testified by the studies underway for years by INAF. A mass so imposing that it deserved one focus issue of the scientific journal Planetary & Space Journal, dedicated to the pre-impact science of LiciaCube. Inside there are numerous investigations, such as that of Giovanni Poggiali, researcher at the Paris Observatory and associated with Inaf Firenze, which gives an account of the activities that Luke’s color images will make possible once they arrive on Earth, for example the understanding of the composition. surface of the binary asteroid and the processes that may have altered it. Or like the geological evaluation of the binary asteroid signed by Maurizio Pajola and his colleagues from INAF Padova, who in addition to proposing mapping strategies to be applied to the images expected from space, hypothesizes the surface characteristics of Didymos and Dimorphos, including landslides or of ejection of particles.
“Since this is the first time that we observe a binary asteroid in such detail – write Elisa Nichelli and Elena Mazzotta Epifani on the official page of Inaf – there will certainly be many surprises and details that we are unable to imagine and therefore anticipate. However, it is important to hypothesize what we will see, based on what we know of the Near-Earth Asteroids visited so far for the implications on the formation and origin of the binary system ”.
“This is an ambitious mission, an extreme technological challenge – confirms Dotto – it should be emphasized that LiciaCube is not only the first Italian mission in deep space (and the third worldwide, after the two NASA MARCOs launched towards Mars in 2018, ed), it is also the first time that a cubesat does something of this kind: witness a full-scale kinetic impact test. This is why whatever happens will still be a success ”.
To date, various bodies are dedicated to the constant monitoring of bodies whose orbits could intersect the Earth’s one and it is agreed that the Planet does not run risks at least in the next century.
“Planetary defense goes through several steps” Pirrotta specifies. “One is the monitoring of known asteroids, or the identification of new ones. Because it would be good to remember that we only know part of the family. This does not exclude there are others with periods and characteristics that have not yet let us intercept them. However, it should not be forgotten that some celestial bodies considered harmless can change their orbit for some reason, perhaps due to a gravitational interaction or an impact, and become threatening ”.
Does that mean that considering the Earth safe for the next century is a gamble? “More a reasonable but optimistic estimate – comments Pirrotta – and this without wishing to trigger inappropriate alarmism. This is precisely why we need to prepare ourselves not only for identifying possible threats, but also for active interventions. Dart and LiciaCube will be the protagonists of the first planetary defense intervention ”. After them, Hera’s data will help translate the test into a comprehensible and repeatable technique, which “one day may prove necessary”. Because although remote, catastrophic events are not impossible: in other words, missions like that of Dart, LiciaCube and Hera, are studying, today, how to avoid the end of the dinosaurs tomorrow.