For as long as there have been telescopes, there has been fascination with Mars and its tantalising similarities to Earth. Although it has been a very long time since anyone seriously believed in Martians or feared a HG Wells-style war of worlds, the orbiters and landers that have probed the Red Planet since the 1960s have left open the most fascinating question of all, is there – or if not was there ever – life on Mars?

As enticing as answering that question might be, however, it has been more than 40 years since the last Apollo mission to the relatively close Moon. NASA’s follow-up George W Bush-era Constellation programme was ultimately axed by the succeeding Obama administration – apparently because it was deemed unaffordable. Constellation had the goal of returning to the Moon by 2020.

So, it would seem reasonable to surmise that sending astronauts to Mars is not on the proverbial radar.

However, as NASA chief scientist Ellen Stofan recently explained to a full house at the Royal Aeronautical Society, there are reasons to believe that human explorers could resolve our questions about Mars the way robots never could – and there is indeed a plan to land on the Red Planet in 2035.

Moreover, says Stofan, this global exploration roadmap is not just a NASA scheme. All the world’s spacefaring nations together have built this common vision of why humans should visit Mars – and what preparatory work needs to be done to get them there and back safely. Whatever co-ordination may be needed – and however much money – Stofan stresses that above all, international collaboration is the key to such an ambitious endeavour. Nobody – not even NASA – can do it alone.

Echus Chasma

Mars Express imaged Echus Chasma, one of the planet's water source regions; the cliff is 4,000m high


Indeed, she says, the roadmap is about “trying to do something very bold over a long time”, so there is a “huge challenge” to get from piecemeal budgets to a long-term, sustained plan.

But at least, under a common plan, the world’s space agencies can work independently or together to fill in some remaining gaps in our understanding of the science and technology needed for a human Mars mission.

Also, fortunately, the broad scientific programme guiding NASA and its peers aligns with the needs and objectives of reaching Mars. Headline goals include better understanding the effects of operating in zero-g environments. For example, Stofan notes, some viruses appear to be more virulent without gravity.

Getting to Mars also benefits from and contributes to our efforts to better understand our own planet and the solar system.

That is, Stofan says, a “huge breadth of science” – and her job is to connect it all. Connecting it all to Mars are the common factors scientists believe are needed to sustain life. Two of these – organic (containing carbon) chemicals and energy (from sunlight, geologic activity or gravitational forces) are commonplace. The third, liquid water, is “the hard part”.

Saturn’s moon Enceladus and Jupiter’s satellite Europa have both energy and possibly organics, so they are candidates for life and even targets for future robotic missions. However, Mars is the most promising – data from seven landings, Stofan says, has led scientists to believe Mars at some point in its history had “sustaining conditions” for life.

So, for the scientific community the prime focus is to put a human on the surface to do the science that will, hopefully, tell us whether Mars ever actually did sustain life – or even harbours some today. While orbital observation and robotic exploration of the surface – ranging from NASA’s Viking missions in the 1970s to the Curiosity rover operating in Mars’ Gale crater since summer 2012 – have revealed a great deal about the planet, Stofan believes direct human interaction is “the only way we’re going to move forward”.

Stofan is as delighted as any scientist by the available data. That said, she is also a geologist by training and hence intimately familiar with the scientific value of putting expert eyes – and hands – on the terrain. To that end, she is keenly aware of the limitations of robotic equipment.

NASA’s Pathfinder mission covered a few metres a day. The Spirit and Opportunity rovers went further, but even Curiosity – a car-sized machine – can only manage about 1km a day. A human scientist could travel much farther.

Plus, Stofan adds, the analysis equipment carried by these rovers – however sophisticated – is “woefully” short of what is really needed to analyse Martian rocks and dust. NASA still hopes that Curiosity will find organic molecules on the surface, but the reality is that the sensitive mass spectrometers needed for the job are huge, and any rover-borne machines we can send to Mars are a compromise.

Bringing samples back home would be better, but that would be a very expensive mission. So, says Stofan, what is needed is to send scientists – and a laboratory – to Mars. And, she emphasises: “We’re not sending astronauts to Mars. We’re sending scientists to Mars.”

Finally, there is another reason why the plan – at least from an American perspective – has got to be aimed at sending human missions, not just robots. The simple American political reality, she says, is that human spaceflight enjoys popular support.


While spacecraft currently orbiting Mars, on the surface, on the way or in the works (see box) are gathering data on the huge technical challenge of entry-landing-descent in Mars’ thin atmosphere, and on the radiation conditions there, a lot of science still needs to happen in what Stofan calls a “stepwise” plan for reaching Mars.

Currently we are still in what she calls the “Earth-reliant” stage. Here, the International Space Station is a laboratory for understanding the effect on the human body of living and working in space. Microgravity raises medical problems with vision, circulation, muscle and bone wastage, among other issues (see box).

Radiation is also a big problem in space travel. Exposure exacerbates bone density loss and can cause cancer and cognitive issues, so another critical step will be learning how to shield against radiation. Metal does not work, as solar energy energises it, and while water looks like the best answer, the engineering challenge is significant.

In all, says Stofan, “there is a huge amount of scientific work to do to be ready to move beyond this Earth-treliant phase”.

Subsequently, starting in the early 2020s – when NASA’s Space Launch System rockets and NASA-European Space Agency Orion crew vehicle is flying (see box) – comes what Stofan calls the “proving ground phase”. This period sees operations in the space between Earth and the Moon’s orbit, to test our ability to live and work beyond Earth reliance, while still having the “safety valve” of being able to come back in a day or two – not the eight or nine months it would take to reach or return from Mars.

Finally, in the period preceding a 2035 mission, would be the “Mars-ready phase”. Here, says Stofan, we need to understand practical problems like managing surface dust picked up by boots and space suits, which caused a lot of problems for Apollo astronauts and equipment. Also critically, the teams need to understand entry, descent and landing – getting humans to the Martian surface will take a vehicle 10-50 times the mass of Curiosity.


Apart from sustaining an international effort focused on Mars will be the challenge of linking three categories of programmes that have traditionally been managed separately in NASA: human exploration, science and technology development. One example is the proposed asteroid redirect mission, which aims to bring an asteroid to the space between Earth and the Moon. There it would stay for hundreds of years, accessible for humans to work, test techniques and retrieve samples.

The science part is to identify a target. The technology part is to work out how to redirect it – robotic capture and ion propulsion are being looked at. Then, the human exploration element would see astronauts working on and around an asteroid the way they would work on Mars, but – as per the proving-ground plan – doing it near enough to Earth to be able to get home if needed.

The first steps are imminent. In 2021, the first crewed flight is planned of the vehicle that would carry astronauts beyond low-Earth orbit and ultimately, with the addition of a habitation module, to Mars. NASA’s Space Launch System rocket – the biggest ever built – will carry astronauts around the Moon, for the first time since 1972, in the Orion multipurpose crew vehicle.

Lockheed Martin is developing the crew capsule, while Airbus Defence & Space is to deliver the attached service module – based on its Automated Transfer Vehicle robotic resupply ship, which has been key to keeping the ISS supplied. On the eve of last month’s Berlin air show the European Space Agency approved the design, so Airbus is confident it will pass the critical design review by the end of 2015, in anticipation of delivering the first example to Lockheed Martin in time for a 2017 uncrewed test flight (see box).

The asteroid redirect manoeuvre is tentatively planned for 2023.

From an engineering perspective, says Stofan, the two “tentpoles” that need erecting to reach Mars are radiation protection and entry-descent-landing. Neither is straightforward, but she believes the goal of 2035 is realistic. “I think this is an achievable goal, to have something on the surface in this timeframe,” she says.

NASA chief Charles Bolden said as much one week later at the Berlin air show. Participating in a panel discussion on international co-operation (see box) with Jean-Jacques Dordain and Johann-Dietrich Wörner, his ESA and German aerospace agency (DLR) counterparts, and Evert Dudok, who heads the communications, intelligence and security business at Airbus Defence & Space, Bolden made the point that NASA’s decision to bring ESA into the Orion programme was the first time his agency has ever brought a foreign partner on to “the critical path” for a major piece of hardware.

That ESA alliance, he says, is collaboration “with intent”. And, added Bolden: “We are as close [to Mars] today as we have ever been.”

Orion heat shield

Orion's 5m-diametre heat shield is the world's largest



Whether being closer than ever is very close at all remains an open question, however. Stofan’s conviction that the engineering challenges can be overcome is infectious and, as the ISS experience shows, international collaboration can be made to work – even to the detailed extent of dividing tasks between agencies and, increasingly, private contractors. But the very terrestrial matter of money is another issue.

Barack Obama moved into the White House in 2009 with an economy in crisis, so it is hardly surprising that heavy spending on long-term but hardly essential plans like Moon missions came under scrutiny. Indeed, one feature of his first year in office was the so-called Augustine Commission review of human spaceflight programmes, and among its conclusions was that Constellation was so far behind schedule and over budget as to be essentially unachievable.

Obama axed the programme in early 2010, before setting out a new space policy. Out were Constellation’s Ares launch vehicles and Moon lander. In were the Orion crew vehicle, what has become the SLS heavy rocket, a 2020s asteroid mission and a mid-2030s humans-to-Mars mission.

A generous reading of this shift in priorities is that by doing away with the interim step of returning astronauts to the Moon, it sets out a more affordable path to the widely held long-term objective of Mars. A more sanguine reading might be that it keeps some US space industry workers in jobs to build Orion and SLS – while maintaining funding for the ISS, which provides a stage for the politically important theatre of US astronauts waving the flag in space. Other, more expensive aspects of the plan were punted into the next decade, when they can be realised – or not – as budgets allow.

Budgets, of course, are a huge sticking point. Whatever a Mars mission would actually cost – and when pressed to speculate following her Royal Aeronautical Society presentation, Stofan declined – it is hard to see where the money would actually come from. As of its 15thanniversary in late 2013, the ISS had consumed $150 billion of US, European, Russian, Canadian and Japanese money, so the cost of reaching Mars – notwithstanding the value realised so far from ISS investments – must reasonably be in the hundreds of billions of dollars.

NASA’s total annual budget is some $17 billion, and it has non-Mars, non-human spaceflight priorities ranging from Earth observation to aeronautics. NASA’s partner agencies are less well funded.

Where hundreds of billions are going to come from is as mysterious as life on Mars itself.

Stofan, however, does not see money as the huge stumbling block it would appear to be – because just as the plan for getting to Mars comes in phases, so does the spending. From now until the early 2020s, what might be called the ISS spending phase predominates. But, she says, after the ISS is finished that money will be freed up for other parts of the programme.

Ultimately, she adds, as things stand today “we’re in a better position than we were at the time of Apollo”. When President Kennedy set America on the course to reach the Moon by the end of the decade, NASA and its partners had barely eight years – and spaceflight technology was in its infancy. Today, she says, we have the “luxury” of far more time, and lots experience in low-Earth orbit.

Since we are “already on the path”, she says, we can talk about reaching Mars “without a herculean budget” because – unlike during Apollo – we do not have to invent everything we need.

Source: Flight International