Mars: the next space race
Image credit: Space X
It’s decades since men first walked on the Moon, but now a new space race is on the horizon. Who will be first to transport humans to Mars?
They were optimistic days in the wake of the Moon landings. In the early 1970s, informed observers were confident that a manned mission to Mars would occur sometime in the 1980s. They believed it because Nasa had gone from flying astronaut Alan Shepard to the edge of space – without making it fully to orbit – in May 1961, to landing Armstrong and Aldrin on the Moon in July 1969.
It took just over eight years from a tentative 15-minute suborbital hop that included five minutes of microgravity to a world-shattering event that marks the first time humankind set foot on another planetary body. The Apollo programme was funded and enabled by Cold War politics in a technology race against the Soviet Union, but once the race was won there was no politically justifiable reason to send government astronauts to Mars. The final three missions of the Apollo programme were cancelled.
Human Mars exploration became a distant dream as Nasa turned to more pragmatic, low-Earth-orbit-based manned programmes such as the Space Shuttle and the International Space Station before making cuts to those in favour of unmanned exploration. In recent years, however, private space enterprises have returned to the dream of visiting and even inhabiting the red planet.
Elon Musk’s Space Exploration Technologies Corp (SpaceX) announced plans to colonise Mars at the International Astronautical Congress (IAC) in late September (E&T Nov 2016 p18-19).
Musk is not alone. It was clear from a second IAC presentation, by Lockheed Martin, that there is more than one potential engineering solution to placing humans on the surface of Mars – parallel tracks to Mars, if you will. Indeed, it is worth noting that Boeing and Orbital ATK announced similar plans to Lockheed’s in the run-up to the US presidential election in the hope of driving a new wave of optimism for manned space exploration.
Despite the rise of the privately run ‘NewSpace’ enterprises, it’s important to note that the majority of space exploration missions – outside the launching of satellites for telecoms, meteorology and navigation – are still designed, managed and funded by government space agencies such as Nasa.
That agency’s hopes of sending astronauts to Mars are based on the development of the Space Launch System (SLS) derived from Space Shuttle propulsion technologies: the liquid propellant engines of its core stage will use modified shuttle engines and its two strap-on solid rocket boosters are essentially longer versions of the shuttle SRBs.
The basic design of the SLS is conservative. In space technology this is demonstrably a good thing: brand new rockets do not have the best reliability record. And adapting existing systems saves money on development. No surprise then that many are disappointed by the glacial pace of the SLS programme, which was announced in 2011 and will not see its inaugural launch until late 2018 at the earliest, with a manned launch planned for late 2021. Why, they ask, could we go from zero to the Moon in eight years in the 1960s, but take 10 years of the 21st century to develop an SLS based on 1970s shuttle technology?
The spacecraft the SLS is designed to carry, the Orion Multi-Purpose Crew Vehicle (MPCV), is a conical capsule rather than a winged spaceplane and in many ways marks a return to the Apollo era. The Orion capsule has been characterised as ‘Apollo on steroids’, though of course the technology inside is very much 21st-century and, as ‘multipurpose’ implies, it is designed for more than a single mission-type.
The 2021 flight, designated Exploration Mission 2 (EM-2), would involve sending a crew of four on a lunar fly-by. The only other SLS-Orion mission planned to any level of detail is a flight to an asteroid in 2026, but detractors in Congress and beyond are already questioning the reasons for such a mission.
A mission to Mars is currently languishing in the ‘wish-list’ category and even the most aggressive estimates don’t see this happening before 2035. Some optimism may have returned but it is still a long way from the rush of the 1960s.
There have been a number of failures to launch. In 1989, for example, US President George HW Bush announced the Space Exploration Initiative (SEI) that would send astronauts back to the Moon – “but this time to stay” – and culminate in “a journey into tomorrow – a journey to another planet – a manned mission to Mars”.
Manned space exploration proponents began to argue whether it would be more efficient to go to Mars directly, or whether it was better to test out technologies and systems on an interim lunar mission. After all, the Moon is a matter of a few days’ flight. A journey to Mars would easily take nine months with little hope of staging a rescue mission if the astronauts got into trouble. A study by Martin Marietta, since absorbed into Lockheed Martin, criticised SEI and argued for a “Mars Direct” programme that would avoid wasting time and money on what some referred to as “Apollo redux”.
By 2004, with no discernible progress in either Moon or Mars missions, President George W Bush announced his “new vision” for Nasa, calling on the agency to “gain a new foothold on the Moon and to prepare for new journeys to the worlds beyond our own”. But since then astronauts have travelled no further than 400km into space to the International Space Station (ISS).
The prospect of private investment rather than reliance on government initiatives may mean the new wave of Mars missions has a better start, although the plans have different approaches.
The 2016 IAC could go down as a turning point in the road to Mars, because it provided a platform for two opposing visions of potential engineering development – one from industry leviathan Lockheed Martin and another from NewSpace upstart SpaceX.
In keeping with its position as a longstanding space technology contractor, Lockheed Martin’s plan, known as Mars Base Camp, uses the same basis in the SLS as Nasa’s own proposal. SpaceX, by contrast, proposes a so-far-unnamed vehicle with a payload capacity four times that of the Apollo-Saturn V, but based on a new ‘Raptor’ engine using a relatively new propellant combination of methane and liquid oxygen.
Whereas the SLS core stage has four engines derived from those used on the Space Shuttle, Musk’s new rocket would feature no fewer than 42 Raptor engines. His argument is that the Falcon Heavy – due to make its first launch in late 2017 – has 27 engines. So it’s not a huge increase in motor count. The cluster design allows several engines to fail without compromising the mission.
Supply is not an issue, according to Musk. SpaceX is currently producing Falcon engines at a rate of “almost 300 per year, so we understand how to make rocket engines in volume”, he says.
Another significant difference is that, in common with most rockets, the SLS is expendable. Musk’s rocket is reusable: having delivered the ‘colonial transporter’ to low-Earth-orbit, the booster returns to the spaceport to launch the propellant tanker, which is designed for several journeys. Among his other aims, Musk is seeking the holy grail of the rocket engineer – full reusability – not just because it’s cool but because his plans demand it.
Although it has a conventional design, the SLS will be built using state-of-the-art techniques such as friction stir welding, which according to its manufacturer Boeing produces welds that are “considerably stronger and virtually defect-free”. By contrast, Musk’s has a carbon-fibre primary structure which includes the propellant tanks. He characterised this as “a fairly significant technical challenge”, but the big reveal an hour into his IAC presentation was an image of a development model of a carbon-fibre tank around 12m in diameter that dwarfed the five people placed for scale in front of it. The enormous tank had passed its initial leak-test with cryogens, Musk claimed.
As for the human payloads of the respective rockets, there is almost no comparison to be made: the SLS will launch a crew of four, whereas Musk is talking about “a hundred people and their luggage” as a starting point. Whether or not this is practical remains to be seen, but one thing is certain: reliability of the launch vehicle would have to surpass industry norms to ensure that passengers would be willing to fly. In effect, the system will be expected to mirror the reliability of commercial passenger aircraft, which regularly carry more than a hundred passengers.
Lockheed’s Mars Base Camp concept is, according to the company, “built on a strong foundation of today’s technologies, making it safe, affordable and achievable”. During the company’s IAC presentation, its presenters confirmed that there is “no magic in this architecture. All the capability exists today.”
In terms of the hardware it needs, Lockheed’s spacecraft resemble many previous concepts: two Orion capsules for initial exploration of the Martian moons and subsequent Earth re-entry; a number of laboratory/habitat modules based on ISS technology; solar arrays for power; and a cryogenic upper stage, like the existing Centaur, for the boost from here to Mars.
But it differs from Musk’s ambition in another key way. The aim of the concept is to place “humans in Mars orbit in about a decade... and prepare for a human Mars landing”. It’s not actually a mission to Mars. When it comes to the landing phase, Lockheed Martin imagines a shuttle-like “reusable single-stage lander”, but that is very much at the PowerPoint stage today.
SpaceX already has a prototype for a future Mars lander. Its initial incarnation, known as Red Dragon, is expected to make a first unmanned flight-test in 2018 or 2019. The capsule is based on the existing Dragon capsule, used to transport cargo to the ISS, and the Dragon 2 being developed under Nasa contract to transport crews later this decade.
One would not expect SpaceX to adopt any standard method for Mars entry, descent and landing – such as parachutes, airbags or even the ‘skycrane’ solution used for Nasa’s Curiosity lander – and one would not be disappointed. To land gently on the planet’s surface, SpaceX plans to use the technique of “supersonic retropropulsion”, which involves firing a rocket system to decelerate from orbital velocities and descend through a tenuous atmosphere that offers limited resistance to parachutes. It may look like a ‘Thunderbirds solution’, but it’s elegant in its simplicity.
That said, the European Space Agency’s failure to land its Schiaparelli probe on Mars in October 2016, because its thrusters shut down prematurely, shows that Mars exploration is difficult. Historically, more than a third of Mars missions have failed.
It’s 40 years since the US Viking probes landed successfully on Mars – the first to do so – and it’s been a long wait to see the first people on Mars. There is more than one engineering solution in the offing, but the jury is still out on whose technology is best placed to head to the red planet.
The one-way option
Elon Musk does not have a monopoly on Mars colonisation or settlement. Mars One, a private programme to “establish a permanent human settlement on Mars” began the search for volunteer astronauts in 2012 and now boasts 100 candidates it calls ‘The Mars 100’ apparently willing to make a one-way trip to the red planet.
The original plan was to conduct a first launch in the mid-2020s, though important details regarding rockets and spacecraft were absent. This has recently slipped to 2031 at the earliest. Unmanned orbiter, lander and rover precursor missions are planned for 2022, 2024 and 2026 respectively. According to an announcement in December 2016, the delays will give the venture time to raise financing for the mission.
Mars One became a publicly-traded company on the Frankfurt Stock Exchange in December, via a merger with InFin Innovative Finance AG, a Swiss company involved in mobile payment technologies. The newly formed Mars One Ventures plans to raise €10m to fund continued work on the effort, including its astronaut selection process. “Mars One can only implement the mission to Mars if we can afford it,” says Bas Lansdorp, chief executive and co-founder of Mars One, “and we need investments to get going.”