Nasa rover perseverance
This illustration provided by NASA shows the Perseverance rover, bottom, landing on Mars. Hundreds of critical events must execute perfectly and exactly on time for the rover to land safely on Feb. 18, 2021. Image Credit: AP

Dubai: After seven months in space, Nasa’s mission to Mars to find out if there was ever life on the Red Planet will touch down on Thursday night if it survives ‘seven minutes of terror’ while landing.

It is a mission that costs nearly $3 billion and has been planned for decades.

NASA's Perseverance rover will search for telltale signs of microbes that might have existed there billions of years ago, when conditions were warmer and wetter than they are today. Over the course of several years, it will attempt to collect 30 rock and soil samples in sealed tubes, to be eventually sent back to Earth sometime in the 2030s for lab analysis.

The landing of the six-wheeled vehicle would mark the third visit to Mars in just over a week. Two spacecraft from the UAE and China swung into orbit around the planet on successive days last week.

All three missions lifted off in July to take advantage of the close alignment of Earth and Mars, travelling some 480 million kilometres in nearly seven months.

Here’s a look at what we know about the latest mission.

What is Perseverance?

Perseverance is the largest and most sophisticated vehicle ever sent to Mars. About the size of an SUV, it weighs a ton, is equipped with a seven foot (two meter) long robotic arm, has 19 cameras, two microphones, and a suite of cutting-edge instruments to assist in its scientific goals.

Nasa rover perseverance
In this illustration made available by NASA, the Mars 2020 Perseverance rover studies a Mars rock outrcrop. Image Credit: AP

Building on discoveries of nearly 20 US outings to Mars dating back to Mariner 4's 1965 flyby, Perseverance may set the stage for scientists to conclusively show whether life has existed beyond Earth, while paving the way for eventual human missions

Is the landing really ‘seven minutes of terror’?

The risky landing procedure has scuppered nearly 50 per cent of all missions to the planet. The spacecraft will careen into the Martian atmosphere at 20,000 kmph, protected by its heat shield.

It will then deploy a supersonic parachute the size of a Little League field, before firing up an eight-engined jetpack to slow its descent even further, and then eventually lower the rover carefully to the ground on a set of cables, Reuters reported.

Graphic Nasa Mars
Image Credit: Graphic News

Safe arrival hinges on a self-guided sequence of events unfolding with flawless precision within seven minutes - the time it should take the rover to get from the top of the Martian atmosphere to the floor of Jezero Crater.

The spacecraft is expected to pierce Mars' atmosphere at 19,300 kmph and angled to produce slight aerodynamic lift while jet thrusters adjust its trajectory.

What is the Jezero Crater?
Scientists believe that about 3.5 billion years ago, the Jezero Crater, where Perseverance is expected to land, was home to a river that flowed into a lake, depositing sediment in a fan-shaped delta. Perseverance is tasked with determining whether it was actually inhabited. It will begin drilling its first samples in summer, and its engineers have planned for it to traverse first the delta, then the ancient lake shore, and finally the edges of the crater, AFP reported

Perseverance's top speed of 0.16 kmph is sluggish by Earth standards but faster than any of its predecessors, and along the way it will deploy new instruments to scan for organic matter, map chemical composition, and zap rocks with a laser to study the vapour.

How bad can the landing be?

Mars has proved a treacherous place: In the span of less than three months in 1999, a US spacecraft was destroyed upon entering orbit because engineers mixed up metric and English units, and an American lander crashed on Mars after its engines cut out prematurely.

How soon will we find out about the landing?

It takes 11 1/2 minutes for a signal that would confirm success to reach Earth. By the time that signal reaches mission managers some 204 million km away at the Jet Propulsion Laboratory (JPL) near Los Angeles, Perseverance will already have landed on the Red Planet - hopefully in one piece.

What is the mission planning to accomplish?

The nuclear battery-powered rover will embark on the primary objective of its two-year mission - engaging a complex suite of instruments in the search for signs of microbial life that may have flourished on Mars billions of years ago.

$2.7billion

is the cost of Nasa's latest mission to Mars

Advanced power tools will drill samples from Martian rock and seal them into cigar-sized tubes for eventual return to Earth for further analysis - the first such specimens ever collected by humankind from the surface of another planet.

Two future missions to retrieve those samples and fly them back to Earth are in the planning stages by NASA, in collaboration with the European Space Agency.

What else will it do?

Perseverance also incorporates several pioneering features not directly related to astrobiology.

Among them is a small drone helicopter, Ingenuity, that will test surface-to-surface powered flight on another world for the first time. If successful, the 1.8-kg drone could pave the way for low-altitude aerial surveillance of Mars during later missions.

Another experiment is a device to extract pure oxygen from carbon dioxide in the Martian atmosphere, a tool that could prove invaluable for future human life support on Mars and for producing rocket propellant to fly astronauts home.

Have other rovers rolled on Mars?
Perseverance is only the fifth ever to hopefully set its wheels down on Mars. The feat was first accomplished in 1997 and all of them have been American. That will probably soon change: China's Tianwen-1 spacecraft entered Martian orbit last week and is expected to touch down with a stationary lander and a rover in May.

Is flying a helicopter on Mars possible?

NASA has been exploring the surface of Mars with rovers for about 25 years, but no one has flown an aircraft on a planet other than Earth before.

The Martian atmosphere is only about 1 per cent the density of what we're used to on Earth. That means that the air is really thin, and piloting the 1.8kg drone on the surface of Mars will be like trying to fly at about 30km of altitude on Earth. That's almost three times as high as airplanes usually fly.

Nasa Perseverance rover mars
In this illustration made available by NASA, the Perseverance rover casts off its spacecraft's cruise stage, minutes before entering the Martian atmosphere. Image Credit: AP

Ingenuity will also have to survive very cold temperatures of -90 degrees Celsius and recharge its batteries using solar panels.

First, the scientists will see whether Ingenuity can fly straight up and hover a few feet above the ground before touching back down safely. Next they will test its ability to take short horizontal flights. Finally, if everything else goes according to plan, Ingenuity will try to fly about the length of a football field and return to its home base on the rover.

It can take as long as 45 minutes for instructions to travel from Earth to Mars, which means the scientists won't be controlling the helicopter with a joystick. Instead everything the helicopter does will be programmed in advance by a computer.

What are the hurdles?

The mission's first hurdle after a 472 million km flight from Earth is delivering the rover intact to the floor of Jezero Crater, a 45-km-wide expanse that scientists believe may harbor a rich trove of fossilized microorganisms.

The descent sequence begins as Perseverance, encased in a protective shell, pierces the Martian atmosphere at 19,300 km per hour, nearly 16 times the speed of sound on Earth.

Jezero crater Mars
This image made available by NASA depicts a possible area through which the Mars 2020 Perseverance rover could traverse across Jezero Crater. Image Credit: AP

After a parachute deployment to slow its plunge, the descent capsule's heat shield is set to fall away to release a jet-propelled "sky crane" hovercraft with the rover attached to its belly.

Once the parachute is jettisoned, the sky crane's jet thrusters are set to immediately fire, slowing its descent to walking speed as it nears the crater floor and self-navigates to a smooth landing site, steering clear of boulders, cliffs and sand dunes.

Hovering over the surface, the sky crane is due to lower Perseverance on nylon tethers, sever the chords when the rover's wheels reach the surface, then fly off to crash a safe distance away.

Isn’t another probe already on Mars?

When the Perseverance rover sets down on Mars on Thursday, another NASA spacecraft already there will be listening for the thump-thump that will result when the newcomer arrives.

The hope is that these thumps will create enough shaking to be detected by InSight, a stationary NASA probe that arrived in 2018 to listen for marsquakes with an exquisitely sensitive seismometer, NYT reports. The InSight lander sits more than 3,200km to the east of where Perseverance is to land.

Perseverance is to be lowered to the surface from a hovering crane, bumping to the ground gently at slower than 3.2km/hr.

Scientists will also be sifting through InSight's seismic data for signs of the impacts of two 77 kg blocks of tungsten metal that helped keep Perseverance in a stable, balanced spin during its trip from Earth. At an altitude of 1,450km above Mars, they will be jettisoned as junk, and without parachutes or retrorockets to slow them down, they will then slam into the surface at some 14,500kmph.

- With inputs from agencies