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On the afternoon of Monday, February 22 (it was night in Italy), NASA published a high-definition video of the arrival of its Perseverance rover to Mars, which took place on February 18. The images show for the first time so clearly and precisely the most prominent phases of the “seven minutes of terror”, the time required to enter the Martian atmosphere, descend and land in fully automatic mode, due to the great distance of the Land (on average 254 million kilometers) makes direct control of the rover impossible. NASA also released new photographs and a few seconds of audio recording of the environment Perseverance is now in.
Shooting on Mars
Landing on Mars is by no means straightforward, and for this reason too, NASA has understandably focused on hitting the mark, paying less attention to imaging such a complicated undertaking. In the long years of preparation for the Perseverance mission – thanks to improved systems for taking images, compressing them and sending them to Earth – NASA managers had thought that the time had come to develop solutions for seeing a landing. in addition to having the classic information on its performance derived from the data collected by the rover’s sensors. They did so using cameras already available on the market and adapting them to their needs.
As Dave Gruel, manager of Perseverance’s landing shooting activities explained, in these years of development his working group has followed a “mantra”: “We take and take home what we can, and we don’t take it” if anything comes out wrong. The priority was also to have a system that did not interfere in any way with the much more important activities to manage the rover landing; anything else would have been more welcome, but not indispensable. The result obtained by Gruel and his collaborators was well above expectations, not to mention surprising.
Perseverance resumed its landing on Mars thanks to four cameras: one placed on the outer casing and pointed towards the parachute, another downwards and placed on the descent winch and finally a video camera on top of the rover and another on its bottom. Despite some inconveniences in the filming due to the high stresses during the landing on the planet, the cameras allowed to obtain videos with an unprecedented definition of the Martian soil, while Perseverance flew over in search of the right place to land.
NASA officials did not see the live video, just as they were unable to see Perseverance land in real time. The planet is so far away from us that only after 12 minutes it was confirmed that everything had gone according to plan.
Perseverance had sent a signal when it began its descent towards the planet, but when it received it, the rover had already finished its “seven minutes of terror” and had been on the surface for five minutes. Following the landing sequence 12 minutes later, NASA still received enough data to confirm that all was well.
In the following days, the rover sent about 30 GB of images, which finally allowed us to see what happened on February 18. In this montage, the control center announcements based on the delayed data were synchronized with the images subsequently received from Mars.
What you see in the video
Perseverance left Earth in July 2020 and then made an interplanetary journey of more than 470 million kilometers, arriving close to Mars on February 18. During its seven-month journey, the rover had remained protected within a shell, a large bell-shaped shell, closed at the bottom by a heat shield, to disperse heat during the turbulent entry into the Martian atmosphere.
In the first part of the video, the parachute connected to the casing is seen opening to slow down Perseverance’s race, at an altitude between 11 and 12 thousand meters. The parachute opened very quickly because Martian atmospheric conditions are different from ours, and they allowed to significantly reduce speed. The red and white geometric shapes of the fabric are used to understand its orientation, in order to better analyze its behavior, from shots from different angles.
The video then shows the heat shield peeling off the bottom of the envelope and beginning its rapid, uncontrolled descent toward the soil of Mars. The filming in this case is done by the video camera placed in the lower part of Perseverance, which at that time was exposed for the first time to the Martian environment. The descent was advancing at almost 900 kilometers per hour (relative to Mars) and the altitude was 9,500 meters.
It follows a long sequence of shots of the Martian soil that draws ever closer, revealing the features around it. The lake, the great crater almost 50 kilometers wide chosen as the arrival point of Perseverance. The researchers believe that once in the area there was a river that emptied into a lake – the stream would have brought sediment and minerals into the lake that would have been the correct recipe for feeding microbes, and perhaps other life forms.
One of Perseverance’s tasks will be precisely to collect soil samples in search of any traces of living beings, which could have populated Mars billions of years ago, when the planet was not inhospitable and barren as it is today.
Less than a minute after hitting the ground, everything went fast, as the video posted by NASA shows. The following composite shot shows the following: at the top the winch equipped with retractors that Perseverance was holding suspended like a puppet to make it touch the ground as delicately as possible (the shot is from the video camera on top of the rover); below Perseverance seen from winch-mounted video camera; On the right, images of the approaching Martian soil, taken by the video camera on the underside of the rover and with some disturbance from the activity of the winch retractors.
The video ends with Perseverance landing on Mars as planned, as the winch quickly detaches from the rover after transporting it to its destination during the last hundred meters of descent. The winch took the opposite direction from Perseverance’s arrival, crashing at a safe distance from its precious cargo to avoid damage.
The separation was filmed by the video camera on top of the rover, however a recovery of the last moments of the winch is not visible because the images taken by its video camera were immediately transmitted to Perseverance, but once the two devices separated. they could no longer communicate.
Panorama
On the same February 18, in addition to having sensor confirmations on Perseverance, NASA had nevertheless received a first series of images of the landing site, although still poorly defined and poorly focused, due to the presence of the protections on the objectives of the aircraft. rover to avoid getting dusty while descending. In the following days, Perseverance sent thousands of camera images to Earth that are used by researchers to decide which path to take their robot to follow during their explorations and to view the surrounding landscape.
By putting together some of these images, the mission leaders created a high-definition panoramic photograph showing everything around Perseverance in the Jezero area. On both sides of the panorama, the rear and front of the rover are visible, with some deformation due to the lenses and the need to paste images from different angles.
(NASA / JPL-Caltech)
If you look at parts of the image closely, some details of the rover become apparent. The plate with the colored dots (upper center) is used to calibrate the color of the images taken by the cameras, while the black object just below the plate on the right is the video camera that captured the winch during the video of the descent.
(NASA / JPL-Caltech)
The object that looks like a lens with an antenna in the center is instead a tool to calibrate the “Mastcam-Z”, a new type of camera that, as its name suggests, will allow you to take pictures using a zoom. The antenna also has the function of a gnomon to transform the instrument into a small sundial, while the colored circles are used to calibrate the color of the images.
(NASA / JPL-Caltech / ASU / MSSS / U Copenhagen)
Between one circle and another are symbols that represent information about the origins of life on Earth: a double helix of DNA, bacteria, a fern, and a dinosaur. There is also a very simple drawing of a woman and a man (based on that of the Pioneer probe), a spaceship, and the solar system. Instead, the words “Two worlds, one beginning” refer to the fact that Earth and Mars were formed from the same dust cloud that led to the formation of our solar system.
NASA has also created a navigable version of the new Martian landscape, which can be viewed via YouTube as a 360-degree video.
Cousin
Mars Reconnaissance Orbiter, the probe in orbit around Mars since 2006, has made it possible to photograph from a distance the point where Perseverance arrived and those where the parachute collided with the outer casing, the descent winch and the heat shield.
(MRO – NASA)
In a detail, obtained by intervening in the original image, the parachute lying on the Martian soil is clearly visible.
(NASA / JPL-Caltech / University of Arizona)
Sound
At the bottom of Perseverance there is also a microphone: it failed to register the turbulent arrival on Mars, instead on February 20 it registered a few seconds of ambient noise. NASA engineers have ruled out the background noise produced by Perseverance, a soft hum, which makes the wind blowing audible in the flat area where the rover is located.
It is the first time that a gust of wind on Mars has been recorded directly and with this fidelity, a noise so familiar but from a world so far away. Among the millions of people who have already heard it, there may be the first to hear it in real life, perhaps in the not too distant future.
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