Nasa’s nail-biting moment
NASA’s Mars rover Perseverance hurtled into the final stretch of its seven-month journey from Earth en route to a nail-biting landing attempt yesterday on an ancient, alien lake bed, where scientists hope to find signs of fossilised microbial life.
Perseverance, the most advanced astrobiology lab ever flown to another world, was headed for a self-guided touchdown inside a vast, rocky basin called Jezero Crater.
Engineers at Nasa’s Jet Propulsion Laboratory (JPL) near Los Angeles hoped to receive confirmation of the landing, and possibly a first image from the rover, shortly after its arrival, which was set for 8.55pm GMT (10.55pm in SA). Those transmissions were to be relayed to Earth from one of several satellites already in orbit around Mars.
What makes Jezero Crater’s terrain – deeply etched by long-vanished flows of liquid water – so tantalising to scientists also makes it especially treacherous as a landing site.
“It’s full of the stuff that scientists want to see but stuff that I don’t want to land on,” Al Chen, head of JPL’s descent and landing team, said. Getting Perseverance to its destination in one piece after its journey of 471 million kilometres, he added, was far from assured.
The multi-stage spacecraft, streaking into the Martian atmosphere at 19 000km/h, had to perfectly and swiftly execute a complex series of self-guided manoeuvres to slow its descent, avoid myriad surface hazards and plant itself gently upright on all six wheels.
The seemingly far-fetched sequence was to include a perilous parachute deployment at supersonic speed and a rocket-powered “sky crane” designed to detach from the entry capsule, fly to a safe landing spot and lower the rover on tethers, before zipping off to crash a safe distance away.
The entire process was set to unfold in a heart-pounding interval Nasa’s engineers half-jokingly refer to as the “seven minutes of terror”.
Because it takes radio waves 11 minutes to travel one way between Mars and Earth, the SUV-sized rover would have already reached the Martian surface – intact or not – by the time its atmospheric entry signal was received at mission control.
Nasa scientists describe Perseverance as the most ambitious of nearly 20 US missions to Mars dating back to a 1965 Mariner fly-by.
Larger and packed with more instruments than the four Mars rovers preceding it, the latest mobile robotic probe would build on previous discoveries that the fourth planet from the sun was once warmer, wetter and possibly hospitable to life.
The primary objective of Perseverance’s two-year, $2.7 billion (R39bn) endeavour is to search for signs of microbes that may have flourished on Mars some 3 billion years ago, about the time life was emerging on Earth.
Scientists hope to find biosignatures embedded in samples of ancient sediments that Perseverance is designed to extract from Martian rock for analysis back on Earth – the first such specimens ever collected by humanity from another planet.
Two future missions are planned to retrieve the samples and return them to Nasa in the next decade.
Perseverance’s payload also includes demonstration projects that could help pave the way for eventual human exploration of Mars, including a device to convert the carbon dioxide in Mars’ atmosphere into pure oxygen.
The box-shaped tool is the first built to extract a natural resource of direct use to humans from an extraterrestrial environment, according to Lori Glaze, director of Nasa’s planetary science division. It would prove invaluable for future life support on Mars and for producing rocket propellant to fly astronauts home.
Another experimental prototype carried by Perseverance is a miniature helicopter designed to test the first powered, controlled flight of an aircraft on another planet.
Last week, separate probes launched by the United Arab Emirates and China reached Mars orbit.