November 29, 2020

I, Science

The science magazine of Imperial College

As the upper atmosphere gets privatised, NASA aims for the further reaches of the solar system ...


I’m imagining what it would be like to be stuck in here for eight months, hurtling relentlessly into the darkness, and I’m only on the central line. An exclusive event in a library salon of the Royal Institution, the juxtaposition of Georgian grandeur with the ghostly, projected image of Mars had seemed like a window into the fanciful mind of a gentleman eccentric; but what was delivered made the endeavour seem startlingly simple. NASA would put astronauts on Mars by 2035, and this was how.

The evening began with NASA chief scientist Ellen Stofan, three time winner of the cleverest woman on Earth award. For such an auspicious figure, her manner was approachable, enthusiastic, even playful, despite being visibly drained by an exhaustively intense series of public appearances on her brief stay in London (ours was one of the lost).

She launched into a mission statement for NASA in the next few decades. They are no longer interested it seems in the toe-hold in space that is dominion over our near Earth orbit and the International Space Station, seeing that there is little more to learn from expensive incursions into what is essentially the upper atmosphere. Instead the space between the Earth and the Moon will become proving grounds for new technologies, with the ISS acting as a staging post. Nor is there much else to learn from repeated returns to the Moon, seeing how despite being vital for the existence of life on Earth, it is in itself a lifeless, barren rock.  NASA will go as far as privatising near Earth orbit as a means of saving money, with corporations such as Spacex having already sent missions to recover crews from the ISS and supplies into orbit.

Instead, NASA will focus on the exploration of our own solar system for the purposes of seeking usable resources in space, and ultimately, for the existence of extraterrestrial life. In the last year the number of 3500 candidate planets that exist in the Goldilocks Zone as determined by Kepler, the zone deemed ‘just right’ for the conditions required for the possible existence of life, has been identified as only a small fraction of potentially tens of billions of such planets orbiting some of the two hundred billion stars of our own galaxy.

A probe passing through the jets of liquid water and ice ejected from the geysers of Saturn’s moon Enceladus detected a combination of complex hydrocarbons, water and a source of energy (volcanic activity) thought to provide the basic capability for the formation of simple life. Such proto-Earth environments may give us an invaluable insight into the origin of life on our own planet, even in the absence of its own complex organisms.

Titan is Stofan’s real muse. Saturn’s largest moon, Titan has a thick atmosphere of methane and carbon dioxide. It has lakes, rivers and rain, but not of water; of liquid methane. It has been assumed because of our experience of life on Earth that the existence of life requires liquid water as an organic solvent, however some argue that methane would work equally well. In this environment, some have even proposed that other gases could be used as electron carriers in the transport chains of metabolic processes.

NASA astrobiologist Chris McKay proposes that hydrogen, present in Titan’s atmosphere would work equally well, and has even found, consistent with the possibility of life existing on the shores of Titan’s methane lakes, a profound decline in the chemocline of hydrogen in the atmosphere close to the surface. Something seems to be consuming it. Because of the size of methane molecules, coupled with the solubility of other hyrdocarbons in the liquid, he further proposes that we reassess our understanding of the scale of simple organism. To efficiently respire, single cell-like organism may have to be significantly larger than those on Earth, even visible to the naked eye, to posses sufficient surface area to survive in this harsh environment.

Next to speak was Jim Adams, Deputy Chief Technologist at NASA. A fascinating man possessed of a child-like exuberance, clearly thought that his was simply the best job in the world. On the evidence he presented, I am inclined to agree.

The first step in a Mars landing will be the rover scheduled for Mars landing in 2020, which will be the first mission with in situ resource utilisation. It will test the possibility of producing fuel from the resources available on the Martian surface. Meanwhile, astronauts will train for a Mars mission by landing on, and subsequently exploring a mid-sized asteroid, which because of the velocity and spin of the object through space is technically almost impossible. One idea is to capture a 10m asteroid in what is essentially a huge bag, with a mechanical winch, which would allow the asteroid to be towed into stable orbit. As Adams puts it, to “Snag it, bag it, drag it” into retrograde lunar orbit. Over a million asteroids have been mapped that are of suitable scale. Larger objects, particularly those which are possible disaster scale asteroids (>1km), 97% have been mapped and are known not to be on a collision course.

The Dawn Mission, currently en route to Ceres utilises the Vesta ion propulsion system. Ion propulsion provides a low-level of constant thrust that is 100% efficient but very slow to accelerate; it is in Adams’ words a demonstration of ‘the power of patience’. Because of the dangers of long-term exposure to radiation outside the protection of the ionosphere, this slow but efficient propulsion system would be considered perfect for the transportation of cargo rather than people. Simultaneously, there are many other problems with humans living for extended periods in microgravity. Bone demineralisation and muscular atrophy, which are currently counteracted on the ISS only by several hours of exercise every day are the main dangers. Getting the astronauts to Mars as quickly as possible obviously minimises these risks, as well as the psychological issues associated with long-term space flights. There has consequently been talk of re-initiating the quest for propulsion through a fission reactor.

One of the biggest challenges of a Mars landing compared to a moon landing is the need to decelerate incredibly rapidly, from around 17000km/s – 0 within seven minutes. This amount of deceleration is similar to the re-entry into Earth’s atmosphere and is an extremely difficult technical challenge. Even if the entry vehicle is able to enter the Martian atmosphere and land, the craft must be able to exit again, from a massive body with atmosphere thick enough to evoke an enormous amount of resistance. These are technical challenges beyond our current capability.

Another technical challenge comes in the form of communication. Even ‘piggybacking’ communication frequencies on lasers to improve their fidelity provides a challenge. From the distance of the moon, the accuracy of transmission to a single point of the Earth is achievable, but from the distance of Mars, the wobble of the laser, even the tiniest vibration would be enough to makes the beam move around from its intended receiver by at least the entire diameter of the Earth in each direction. Stabilisation of the beam would then be paramount.

Colonisation will require the establishment of a power source, generating about 40-70kW. Indeed designs for landing a fission reactor on Mars have begun, with designs using carbon or ceramic casings tested.  A place of habitation will also be required. One idea is to inflate a greenhouse type habitation pod that would be flexible enough to withstand the hurricanes of tempestuous Martian weather. Another is to find an old lava tube, and establish an atmosphere and raise the temperature to render it suitable for habitation.

Why is a Mars mission necessary, and why do we need to send astronauts to the surface? Sending humans to Mars will be a global enterprise, unifying science, exploration and technology. Robotic exploration of Mars is a slow process. Seven years of rover science could be done in about a week of human activity. The mission specialists in fact prefer the use of the term pioneering, as all we know of our neighboring planet will be overshadowed by even a couple of days on the surface. Indeed, it is debated by some if establishing a base of operations on Mars will, necessarily, be a one way trip.

In the end all that marred the event was its duration. At the end of ten public relations events in 48 hours, our hosts were feeling the burn, and it showed a little in the delivery of their talk, which seemed to cut short at 40 minutes. It was a fascinating, enlightening event of existential brilliance, which is why I’m standing here on the tube trying to write notes and all I can think about is floating round this carriage on my way to Mars. I’ll sign off this article as did Jim Adams in our Q&A session by posing you a question, space is cold, it’s endless, it has no air. You’re travelling so fast that if you hit a rock the size of a pea it could tear a hole in your ship the size of a doorway. The place you’re going is a barren world, where water and perhaps even life has existed and since eradicated, where there are hundreds of degrees difference in temperature between night and day and where enormous hurricanes rage for years at a time. There’s no guarantee that your equipment will work as it should once you get there, which means there’s no guarantee you can ever get home. “So, if you got the chance, would you go to Mars?” Answers on a post card please.

The talk ‘NASA’s exploration programme: Path to Mars’ took place on 15 May 2014 at the Royal Institution. You can view the full talk below.