The Perseverance rover will soon land on the surface of Mars. This entry phase could generate seismic signals strong enough for the Insight lander to “hear” them. These data could then provide a better understanding of the structure of the red planet.
On July 30, the American mission March 2020 was launched. Its objective: to deliver the Perseverance rover to the surface in order to search for any traces of past life. It will also be a question of putting some samples under seal for a future return to Earth. In the meantime, the rover continues on its way. The landing is scheduled for February 18 inside the Jezero crater.
According to a recent study, this epic entry phase should be able to generate seismic signals that theamerican lander InSight, on site for two years, could detect more than 3,200 kilometers away. As a reminder, this instrument-packed “machine” aims to detect the tiny seismic waves crossing the lower layers of the road planet, in order to learn more about its internal composition.
The Perseverance Landing
March 2020 will use the same entry, descent and landing (EDL) strategy as its predecessor, the Curiosity rover. The capsule will hit the thin Martian atmosphere hard at around 12,000 km / h, before being slowed down by friction. A parachute will then be released to decelerate even further.
Then, about seven minutes after atmospheric entry, while the descent stage will be 21 meters above the ground, the rover will be lowered after three cables. It will then deploy its wheels and will be released as soon as the system controlling the descent detects that the traction forces exerted on the cables have weakened, as a result of the effective removal of Perseverance.
A unique opportunity
During this entry-landing phase, two important steps are likely to produce relatively strong signals, according to the study.
The first will be generated by a “sonic boom” produced when the rover is about 100 km from the Martian surface. At this altitude, the atmosphere will indeed be dense enough “for substantial compression to occur ‘, according to the researchers. Some of the energy from this boom will reach the Martian surface and be converted into seismic waves. However, the researchers calculated that this signal will only be not powerful enough to be picked up by InSight.
On the other hand, the signals generated by the release of the two “Cruise Mass Balance Devices” (CMBD), aimed at correcting the center of mass of the vessel, could be picked up by the lander. These two CMBDs, each of which weighs 77 kg, will be dropped at a altitude of about 1450 km, before hitting the ground at over 14,000 km / h.
Such a detection would be a great opportunity for the members of the InSight team. They will indeed know precisely where these waves come from and how fast they have traveled. With this information, they can then determine the structures through which they have spread.
Finally, remember that Perseverance is not the only rover to land on Mars this year. Chinese mission Tianwen-1 will indeed arrive on site on February 10, to then drop off the vehicle in May. Here again, the InSight team would like to take the opportunity to “listen” to this landing. However, the details of this mission – in particular, its exact time and place of landing – may not be communicated by the Chinese authorities.