Science and Technology

What on Mars for?

M. Ramesh | Updated on: Feb 28, 2021
image caption

With the rover Perseverance touching down safely on the red planet, a peek into its local itinerary

M Ramesh

Now that the US rover, the car-sized robotic vehicle Perseverance, stands on the rocks and regolith of the Jezero crater of Mars, a little north of the planet’s equator, things are all set to move — literally.

Right now, NASA scientists are busy making sure everything is alright to get Perseverance started. Once that’s done, the rover will rove over the rocky planet.

Now, there are several points of intrigue around the ‘Mars 2020 mission’. We know that a giant, the Atlas V rocket (of United Launch Alliance), roared into the heavens from Cape Canaveral, Florida, on July 30, 2020. It’s nose, carrying the Perseverance, took nearly seven months to reach the neighbourhood of Mars.

Unlike the early rovers such as Sojourner (1997) and the twins Spirit and Opportunity (2004), and like Curiosity (2012), Perseverance did not land on airbags — it’s too heavy for that. Instead, it was lowered to the ground by a sky-crane system, which is a jetpack with six mini rockets, to slow the descent until the rover was detached from its underbelly and lowered by cables.

When the spacecraft entered the Martian atmosphere, it was shooting at 5.8 km per second; the touchdown speed was a gentle 0.7 metres a second.

What of the jetpack? After dropping Perseverance, it flew off and crash-landed some distance away.

Well, then, Perseverance will be driven around. Questions are how and for what?

You can’t remote-drive the vehicle from here. When Earth and Mars come closest to each other, it takes 4 minutes for a signal to get across; at the farthest, it takes 20. So, Perseverance gets its instructions for the day early morning. Then it is on its own. This includes flying the helicopter (drone) Ingenuity, to test flying in the Martian atmosphere (which is a hundredth of ours in density.)

Unlike satellites, Perseverance does not have a solar array to power it. Instead, it has a ‘radioisotope thermoelectric generator’, which converts heat from the decay of Plutonium-238 into electricity. Perseverance (and Curiosity) can therefore work even during nights.

With Perseverance, NASA wants to find evidence of early life on Mars. Not fossilised dinosaurs; only tiny microbes. That’s why they landed in that crater, which was a lake 3.5 billion years ago — the most likely site to have held any life.

Okay, you find bio-signatures of ancient life, so you know there was life on Mars billions of years ago. So what? The mission does not stop with a ‘yes’ or ‘no’— it goes deeper.

Down here, we have lots of fossils that are hundreds of millions of years old, but none that are billions of years old. So, we get no peek into the deep origins of life. Here is where rock samples from Mars, which had water and liveable temperatures, come into play. The fossilised microbes can be put under microscopes to see how things were 3.5 billion years ago. To guess your future, you must know your past.

So, when is Perseverance flying back home with the samples? Well, never. The poor thing is doomed to lie in the Martian desolation along with the carcasses of Sojourner, Opportunity, Spirit and Curiosity (which is still alive).

Perseverance will take ‘cores’ — crayon-sized samples — from below the surface and put them into tubes. (These, by the way, are very special tubes. In order that you don’t carry microbes from the Earth and later think you’ve got them from Mars, paranoid scientists kept the glass tubes heated to 150 degrees C for 26 hours, before loading them onto Perseverance.)

Once the 40 tubes are filled with cores, Perseverance will drop (‘cache’) them on the Martian surface. With that its main job is over. It might continue to wander around and take snaps.

Sometime in 2026, NASA will land another spacecraft on Mars, which will pick up the sample tubes and place them in a basketball-shaped container located inside a ‘Mars ascent rocket’.

The rocket will soar, and spit the container into a Martian orbit. The container will mindlessly revolve around the planet, until another NASA spacecraft swallows it and brings it back to earth — in 2031.

What India should do

Chaitanya Giri, a Gateway House space expert who has worked on comet landings, observes that for the US, Mars exploration is more than just learning science. Its “meta-strategy” is to make Mars a human colony. Accordingly, it is encouraging other countries — such as the UAE — to get on to the Mars bandwagon. This is an opportunity for India. Indian start-ups will plug themselves into the US’s ‘Mars ecosystem’, Giri told Quantum .

Published on February 28, 2021

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