It is one of the most complex space missions ever contemplated. A flotilla of unmanned probes and robot rovers will be flown to Mars to gather rock samples which will then be blasted back to Earth for study for signs of life.
This is Nasa’s Mars Sample Return and it would involve the first-ever space launch from another planet, as well as the first-ever rendezvous in orbit around another planet.
But this massively ambitious mission is in trouble. Its costs have spiralled dramatically and an independent review panel – set up by the space agency – has just warned that the mission’s original $4.4bn price tag is likely to soar to $8-11bn. A swath of other Nasa missions could be cancelled as a result.
“The Mars Sample Return was established with unrealistic budget expectations,” says the panel’s report. “There is currently no credible, congruent technical, nor properly margined schedule, cost and technical baselines that can be accomplished with the likely available funding.” In fact, there is “near zero probability” of Nasa’s plan succeeding on its current budget, the board concluded.
To the fury of a number of space scientists, the mission’s spiralling costs are already playing a part in the postponement of other Nasa-funded projects. These include Veritas, a mission to study Venus to discover why this searingly hot planet lost its potential to be a habitable world.
Another victim has been the Geospace Dynamics Constellation mission for studying the upper atmosphere. “You are cutting the artery, the lifeblood of our science,” plasma physicist Allison Jaynes of Iowa University told the journal Science. “All of Nasa science is taking a hit because of the Mars Sample Return burden.”
The mission will rely on the robot rover Perseverance, which is currently trundling across the red planet collecting samples of Martian rock. These are placed in titanium tubes, each the size of a hot dog, and stored. In a few years, the agency envisages putting a lander, currently developed by Lockheed Martin, on Mars.
Perseverance would place its stockpile of containers into this lander which would then be sent back into space and placed in orbit around Mars while a third craft – an Earth return orbiter, built by the European Space Agency (Esa) – would pick up the tubes of rock and ferry them back to Earth. A small probe would parachute the samples down to waiting scientists, possibly by 2033 at the earliest, says Nasa.
Unfortunately, the space agency initially underestimated the size of the spacecraft that would be needed to take the samples off the surface of Mars. In addition, it failed to realise the highly complex steps that would have to be taken to prevent Earthly bacteria or viruses from contaminating Martian soil samples, while also guarding against possible Martian lifeforms infecting Earth.
Inflation and supply shortages are also reported to have triggered cost increases.
As a result, several leading scientists have called for the mission to be scrapped, although many others say it should be saved.
The latter group point to the example of the James Webb space telescope which only narrowly survived a series of cancellation calls after its price tag soared from $1bn to $10bn, triggering the postponement of other space missions. However, the telescope is now returning breathtaking images of distant stars and galaxies and is transforming our knowledge of deep space.
The Mars Sample Return has a similar, transformative potential, said Professor Lewis Dartnell of Westminster University. “At present, we have to seek evidence of past life on Mars by attempting to shrink an entire laboratory to a miniaturised size so it can be fitted with wheels and cameras to trundle across Mars in the hope it can find signs of life.
“The Mars Sample Return will change all that by making Martian rock available to the most sophisticated analytical laboratories on Earth. That will give us the best possible chance of finding evidence that there was once life on Mars.”
This point was backed by Professor Caroline Smith of the Natural History Museum, London. “We are not going to open one of these samples and find a dinosaur bone there. We are only going to find signs of past primitive life by putting them through a host of physical and chemical tests which, in many cases, can only be done with huge, building-sized instruments like the UK’s Diamond Light Source.
“Only when we have done all these tests will we be able to say there is clear evidence a sample contains the remains of once living things.”
Scientists now believe Mars was a warm, watery world 4 billion years ago and possessed ideal conditions for the appearance of life. However, the planet later lost its magnetic field, as well as its water and atmosphere, and was battered by intense ultraviolet radiation. Life would have found it difficult to survive.
“Nevertheless, it is important to find out if living things did evolve there in the past, just as it is crucial to discover if they now exist elsewhere in the solar system,” said Professor Andrew Coates, of University College London.
“At present, we know there are seas of water, rich in organics, on Europa, a moon of Jupiter, and on Enceladus, a moon of Saturn.
“Life could have evolved there and we need to investigate these worlds as well – for if we find life is present on these distant moons, and once existed on Mars in the past, we will have very firm evidence that life is ubiquitous across the universe.”
