A bold step towards man on Mars
NASA’s technological triumph of landing the Curiosity rover on the Red Planet is a testament to human ingenuity.
‘Far better it is to dare mighty things, to win glorious triumphs, to risk failure, than to live in the grey twilight that knows neither victory nor defeat.’
This slight paraphrasing of Theodore Roosevelt at the NASA press conference on Sunday night would have sounded honourable if the Mars Science Laboratory, dubbed Curiosity, had failed like so many Mars missions before it. Fewer than half of all missions successfully reach the Red Planet in working order.
But Curiosity had just landed successfully on target and on schedule, sending back its first images – of its own wheel and its own shadow – within minutes. An event well worth getting out of bed before 6am (UK time) to watch – albeit via the internet, as UK broadcasters didn’t deem it worthy of live coverage. In my Edinburgh Fringe flat, an admittedly technophile crowd was almost as jubilant as the NASA engineers we were watching.
NASA has every right to celebrate. They’ve put a one-ton mobile lab on a planet so far away that communications travelling at light speed take 13.8 minutes to reach us. So by the time Mission Control at NASA’s Jet Propulsion Laboratory got the first signals that things were going according to plan, what was dubbed the ‘seven minutes of terror’ – from when Curiosity entered the Martian atmosphere to its landing on the surface – were long over.
Because of the long time lag – up to 20 minutes, depending on the relative orbits of Earth and Mars – any robot exploring Mars needs a degree of autonomy. Curiosity, the size of a small car, is equipped with multiple cameras and guidance systems enabling it to tackle the rocky Martian landscape without a human driver. Teams of scientists and engineers on Earth will receive one Martian day’s – or sol’s – results via one of the three spacecraft currently orbiting Mars, and be able to plan the next sol’s work, beaming orders for Curiosity across millions of miles.
Curiosity is primarily a science mission, equipped with 10 different instruments to investigate the Martian environment. Its landing area, in Gale crater, located just south of the Martian equator, was chosen because orbiting missions spotted evidence of past water flowing there, and for its layers of sedimentary rocks. Like rock strata on Earth, that means it contains a geological snapshot of the planet’s history. By analysing the minerals in the rock layers, NASA hopes to find out what Mars was like in the past, and whether life could have existed there.
Returning samples from Mars to Earth for analysis is still years in the future, so instead NASA has sent a mini-lab to Mars to analyse samples of soil and rock. They hope to spot tell-tale signs that life might be present, or might once have played a part in changing the planet’s chemistry. The rover’s equipment also includes the Mars Hand Lens Imager (MAHLI) – a robot version of a geologist’s magnifying glass – and something NASA endearingly calls its ‘rock-zapping laser’. By melting the surface of a rock into plasma from up to seven metres away, Curiosity will be able to analyse the spectrum of emitted light and identify the chemicals it has vapourised.
But this mission is also about building up a picture of Mars today, including the weather (mostly windy, cold and dusty) and the radiation. Unlike Earth, which is protected by a strong magnetic field and a relatively dense atmosphere, the surface of Mars is effectively sterilised by radiation from the sun and the rest of the cosmos.
Though NASA is sometimes coy about the human aspect of ‘habitability’, understanding and tackling the radiation problem is key to getting humans on to Mars. So the Radiation Assessment Detector instrument (RAD) is the only part of the mission partly funded by the human exploration wing of NASA. It was also running throughout the eight-month trip from Earth, as protecting astronauts from radiation en route will be equally vital.
But the entire engineering challenge of getting such a large, complex machine on to Mars is, to some extent, a practice run for getting people there in one piece.
‘Today, the wheels of Curiosity have begun to blaze the trail for human footprints on Mars’, said NASA administrator Charles Bolden. Given the high failure-rate of previous missions, proving that astronauts could land safely is no small challenge. The complexity of Curiosity’s EDL (entry, descent, landing) procedure makes this landing a technological triumph.
First, the Cruise Stage, which had powered, protected and steered the rover through space for 254 days, had to separate before the EDL procedure began. Then a complex series of manoeuvres changed the balance of the aeroshell so it could both present its heat shield to the friction that would slow its descent and ‘fly’ aerodynamically through the thin Martian atmosphere, guided by automated thrusters. Then a 51-foot-diameter parachute slowed the descent still more, before the heat shield, the back of the aeroshell and the parachute itself were jettisoned.
Finally, the descent stage – the so-called ‘Skycrane’ – used thrusters to slow the speed of the fall to less than 2mph and lowered Curiosity gently to the ground on nylon cords from a height of around 20 metres.
All this had to be done with no intervention from Earth, and many thought there were too many things that could go wrong. But it seems that NASA’s hubris has paid off.
Scientifically speaking, this is only the beginning. Although Curiosity’s working life is planned to be two years, the team hopes it will work on for far longer – like its humbler predecessor, Opportunity, which is still exploring after eight years. And although much of the analysis will be done in situ, that’s just data gathering – making sense of the results will take still longer. The question of past or present life on Mars remains open and won’t be answered by Curiosity.
But the question of how we get people on to Mars is one small step closer to being answered, thanks to the international team that landed a one-ton robot safely. And that is good news for the human project of exploring our universe. ‘Curiosity is the central, defining human attribute’, as Adam Steltzner, who led the EDL team, put it when answering a journalist’s question about the rover’s name.
Last November, I was one of the lucky people in Florida who watched an Atlas rocket build a column of white smoke beneath itself and thunder into the blue sky. A cloud slipped in front of it, and it was gone – and so was Curiosity, which had already vanished into the distance. Even then, the idea that it wouldn’t come back, that it was on its way to a planet I know only as a bright reddish dot in the night, was extraordinary. Now, to think that it has been delivered across 154million miles and is already sending back images of that distant planet is quite wonderful.
Personally, I won’t be satisfied until living people are walking on Mars. But to have sent our eyes, our hands and our minds in robot form with such audacity is a bold step in the right direction.
Timandra Harkness is currently performing Humans v Nature: Engineering FTW at the Edinburgh Festival Fringe. With robots.
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