After the UAE’s Hope and China’s Tianwen-1’s successful venture to Martian orbit on February 10 and 11 respectively, NASA’s Perseverance is attempting to land on the surface of Mars on February 18. The mission is quite challenging and risky, with more than half of the missions to Mars failed so far.
“Landing on Mars is hard,” NASA said. “Only about 40% of the missions ever sent to Mars – by any space agency – have been successful.”
Perseverance, launched back on July 30, 2020, aims to look for signs of ancient life and gather Martian rock and soil samples. The rover is expected to remain in the Red Planet for at least one Mars year which is about 687 Earth days.
How does Perseverance rover land on Mars?
Perseverance will follow an entry, descent and landing process, shortly known as “EDL” to perform the landing on the Martian surface. The process is similar to NASA’s previous Mars mission, Curiosity, which reached the Red Planet in 2012. According to NASA, EDL “is the shortest and most intense phase of the Mars 2020 mission”.
When the probe, with an approximate speed of 20,000 kilometers per hour, reaches the top of the atmosphere on Mars, the EDL process starts. The process lasts for about seven minutes until the rover lands on the surface and is stationary. The maneuver between all this is very testing with every small move demanding perfection. NASA also describes this period of the mission as “seven minutes of terror”.
“To safely go from those speeds down to zero, in that short amount of time, while hitting a narrow target on the surface, requires ‘slamming on the brakes’ in a very careful, creative and challenging way,” NASA said.
The EDL procedure is completely autonomous since the manual mode is not practical as there is a gap of more than 11 minutes to receive a signal back from the probe during the landing.
Perseverance consists of small thrusters that will fire to maintain a stable position of the spacecraft. The heat shield helps to reduce the speed of the probe to under 1,600 kilometers per hour. A supersonic parachute is programmed to deploy about 4 minutes after entry, at an altitude of about 11 kilometers.
The heat shield will get separated away from the spacecraft about 20 seconds after parachute deployment. The rover will use its special camera to map the landing surface and choose the safest spot for landing.
The parachute can slow the spacecraft to about 320 kilometers per hour only. For the safe touchdown, the spacecraft will get rid of the parachute and proceed down towards the surface using rockets.
“Directly above the rover, inside the backshell, is the rocket-powered descent stage. Think of it as a kind of jetpack with eight engines pointed down at the ground. Once it’s about 6,900 feet (2,100 meters) above the surface, the rover separates from the backshell, and fires up the descent stage engines,” NASA said in its EDL explanation.
For the landing, Perseverance executes a skycrane maneuver after the speed reduces to 2.7 kilometers per hour. NASA had used this maneuver in its previous Curiosity mission too.
“With about 12 seconds before touchdown, at about 66 feet (20 meters) above the surface, the descent stage lowers the rover on a set of cables about 21 feet (6.4 meters) long. Meanwhile, the rover unstows its mobility system, locking its legs and wheels into landing position,” NASA said.
Instantly after the rover touches the surface, it cuts the cables connecting it to the descent stage to fly off away from Perseverance.
Where is NASA’s Perseverance rover going to land on Mars and why?
NASA chooses Jezero Crater as the landing site of SUV-sized Perseverance rover.
Jezero Crater is an ancient dried-up lake on Mars. Scientists believe the Red Planet had rivers and lakes, billions of years ago. Thus, they assume, on locations like Jezero Crater, microorganisms might have lived and still may hold some imprints.
“More than 3.5 billion years ago, a river there flowed into a body of water about the size of Lake Tahoe, depositing sediments in a fan shape known as a delta,” NASA wrote in an article. “The Perseverance science team believes this ancient river delta and lake deposits could have collected and preserved organic molecules and other potential signs of microbial life.”
Perseverance consists of highly advanced instruments such as SHERLOC (Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals) and PIXL (Planetary Instrument for X-ray Lithochemistry) which will help to study Mars in more depth. SHERLOC detects organic matter and minerals and PIXL surveys the chemical composition of rocks and sediments.
The rover has cameras that can zoom in on rock texture from far away and study their composition, and RIMFAX (Radar Imager for Mars’ Subsurface Experiment) to examine geological features below the Martian surface using radar waves.
NASA aims to collect about 40 samples that could contain signs of ancient microorganisms and store them in sample tubes to transport back to Earth in the future. Perseverance is also gathering important information about Mars’ geology and climate.
“Understanding Mars’ past climate conditions and reading the geological history embedded in its rocks will give scientists a richer sense of what the planet was like in its distant past,” NASA said. “Studying the Red Planet’s geology and climate could also give us a sense of why Earth and Mars – despite some early similarities – ended up so different.”