'We' are on Mars – here we go!
On 18 February 2021, the Perseverance rover of NASA's Mars 2020 mission landed on Mars safe and sound. The research mission, initially scheduled to last two years, has begun. In this blog, DLR researcher Nicole Schmitz, together with her colleague Frank Preusker, will report regularly on the progress of the mission and the camera experiment in which they are involved. Both are part of the Science Team of the Mastcam-Z instrument, a stereo camera located on Perseverance's approximately two-metre-high mast.
We're on Mars! That's the thought I've been waking up with for the past three days. Of course, 'we' are not actually on Mars, but it feels that way since Thursday 18 February, when the NASA Mars 2020 mission rover Perseverance touched down in Jezero Crater at 21:55 CET. It was set down gently by the sky crane, the same system that delivered Curiosity safely to Gale Crater almost nine years ago. Delivered? That might not be the correct word for this exceptional space manoeuvre that has made it possible for us researchers to embark on our mission.##markend##
Prior to this manoeuvre, the rover and the entire team had to survive the ‘seven minutes of terror’. The phrase was used in a legendary video produced by NASA in 2012 to describe the incredible technical challenges faced during a Mars landing. The soft landing on Mars of a vehicle weighing just over a tonne, in a dried-up crater lake not far from the steep slopes of an ancient river delta, is an engineering feat – particularly given that the martian atmosphere is too thin to use conventional descent and landing methods.
The landing capsule containing the rover entered the upper atmospheric layers at a very high speed – approximately 19,500 kilometres per hour. Within just seven minutes, this speed had to be reduced to zero, and it had to be done autonomously. The control room could not intervene because the signal transit time between Mars and Earth on that day was 11 minutes and 22 seconds. When the signal was received in the control room that entry into the atmosphere had begun, the rover had in fact already landed. Whether it had landed in one piece, however, remained uncertain.
The tension on the evening of 18 February was palpable. Unfortunately, the pandemic prevents any kind of normalcy, including for our shared jitters and jubilation. We were among neither my Mastcam-Z science team nor our colleagues in the large lecture hall at DLR’s Berlin site – which is usually the case on similar occasions. Instead, I sat at a safe distance from my colleague, Mars geologist Daniela Tirsch, in our Regional Planetary Image Facility (RPIF) in front of the large screen, where I followed the events while a film crew from ZDF looked over our shoulders. Meanwhile, our colleague Ernst Hauber sat with the Bayerischer Rundfunk during the filming of a special programme recorded live for ARD Alpha and shared the events with the viewers. Earlier, my colleague Frank Preusker and I had informed the viewers of the live stream of the Berlin Planetarium Foundation (Stiftung Planetarium Berlin) about Perseverance and DLR's participation in the mission. The decisive seven minutes were broadcast live on zdf.de, and you can see our joy and relief both in the Heute Journal and in the update after midnight.
Landing on Mars is always a challenge. Many past landing attempts have failed. NASA itself has actually only had one failed attempt – the Mars Polar Lander (1999) – and otherwise eight clean landings prior to Perseverance. Over the course of these missions, each landing has improved on the previous one.
That evening, once again, everything went well. Shortly after the receiving the 'touchdown confirmed' announcement, the first image arrived in the control room. What an incredible feeling! After more than seven years of work on the mission, the right front wheel of the rover was finally on red soil. The image was acquired by one of the Hazard Avoidance Cameras (HazCam) mounted at the front and rear of the rover deck. The image is blurred because it was taken through the dust cover, which is still in front of the lens. But for me it was the most beautiful image I had seen in a long time.
After a glass of champagne with a few people from the DLR Mastcam-Z and DLR Communications teams, we headed off to the first meeting of the Mars 2020 science team. At 05:00 CET, seven hours after landing, still in the middle of the night and having slept barely two hours, I was in front of my laptop once again. Approximately 200 colleagues from Europe and the US had gathered virtually. Everyone was enthusiastic but also tense in anticipation and aware that our work had begun. The entire team had been preparing for this since 2017, through a series of realistic scenarios. Following a perfect performance by the engineers at JPL, the landing was now complete. Without them, all that is to come would not be possible. Now we face our own challenges.
We took a few minutes to celebrate this special moment. NASA's project managers paid tribute to the entire NASA team that got the rover to Mars. I may be repeating myself, but it cannot be repeated enough – what precision! The final orbit correction manoeuvre two days prior to landing was... cancelled. After more than 400 million kilometres of cruising through space, Mars 2020 was exactly on course. The targeted entry point in the Martian atmosphere had been reached with pinpoint accuracy – prompting a round of applause from the team. Quotes were exchanged. My favourite comes from the scientific director of Mastcam-Z, Jim Bell from Arizona State University, who has been 'cruising' scientifically across the Solar System and on Mars for a couple of decades:
"We have an unknown distance yet to run, an unknown river to explore. What falls there are, we know not; what rocks beset the channel, we know not... With some eagerness, and some anxiety, and some misgiving, we enter the canyon below, and are carried along by the swift water."
The quote originates from John Wesley Powell, who led the famous first expedition to explore the Grand Canyon in the Arizona highlands in 1869.
Now that we had arrived, we began to marvel together at the first images that the Mars Reconnaissance Orbiter, MAVEN and the ESA-Roscosmos ExoMars Trace Gas Orbiter satellites around Mars were receiving bit by bit from the rover and transmitting to Earth. There was another round of applause for the colleagues responsible for planning these first images. The HiRISE instrument captured the rover in its landing capsule under its parachute, hovering over Jezero Crater, from a distance of 700 kilometres. The camera mounted on the sky crane delivered a sensational image of the rover being lowered on nylon cords, just before touchdown. Goosebumps.
"They can park!"
We were then able to, for the first time, take a look at a section of the surface of Jezero Crater from the rover's perspective. The images from the HazCam instrument revealed only a small portion of the surface, but we could already make out rocky bedrock, loose soil, dunes, light and dark rocks, boulders and even the horizon in the distance. In the months prior, we had studied this area intensively using high-resolution images and spectroscopic data supplied by research satellites orbiting Mars.
The approximate landing site and the position of the rover are already known quite accurately. The landing site lies just a few metres from the centre of the calculated target landing ellipse – the JPL engineers did a terrific job. A British colleague quipped: “They can park!”. We compared what we saw with what we knew from the orbiter data. The first scientific discussions about possible geological interpretations began immediately. Among other things, there was intense discussion about the texture of the rocks in the immediate vicinity of the rover. The images show several small holes in the rocks, which could have been created through sedimentary or volcanic processes. There will be much discussion in the coming days – the first few images are already enough to fill team meetings with presentations about the possible geological interpretations for phenomena at the site.
A lot happened in the days following the landing. The rover is being brought into operation system by system, instrument by instrument. The other cameras on the rover are providing even better images with higher resolutions from different perspectives. The comparison with mapping data acquired from orbit (including data from the HiRISE instrument on the Mars Reconnaissance Orbiter and the digital terrain models calculated using DLR's HRSC instrument on ESA's Mars Express spacecraft) and with images taken by the rover's cameras during the landing enables us to more precisely localise the landing site. In addition to prominent features of the terrain such as rock formations and the several-hundred-metre-high rim of Jezero Crater, the rover itself and the landing sites of the parachute, the heat shield and the sky crane stage can all be seen in the images. This allows the mapping team to tell exactly where the rover is and in which direction it is facing.
On Sunday 22 February, the rover's mast, which was safely stowed on the rover deck during the flight to Mars, was finally extended. This has allowed the first images to be taken with the navigation cameras and – finally! – also with Mastcam-Z, the experiment in which I am involved. From two metres above the surface, we received the first 360-degree panorama of the landing site in colour.
So, there it is now, on the floor of Jezero Crater, with views of the slopes of the front of the river delta to the northwest and west. Images and data acquired by the rover’s instruments and systems are transmitted daily from the rover to the various spacecraft in Mars orbit and relayed to Earth using their communication antennas. There, the signals are received by the 70-metre antennas of NASA's Deep Space Network or ESA's own network of ground stations and relayed to the control centre in Pasadena, California, where they are finally delivered to the science and engineering teams.
It will take a few more days for all systems and instruments to be checked and operational, and there is still a lot to be done on the ground before Perseverance moves its first metre. The science team now consists of over 400 hundred people, and we can all hardly wait. The excitement continues!