Mars – Colonising and terraforming

I just finished reading Dr Robert Zubrin’s The Case for Mars (TCFM), which I bought from the man himself when he was last in Adelaide. Dr Zubrin is the president of the US Mars Society, a group which advocates sending a manned mission to Mars. Zubrin creates a rather compelling case for why we should send such a mission and how we could do it. The book is somewhat anti-NASA with the author expressing his frustration that we could get to the Moon in the 1960’s, yet can’t get back today, let alone get to Mars. There is a recurring theme that we are doing less with more than our space faring predecessors. I’ll cover several key ideas of the book, including the plan to get to Mars, then how to colonise and terraform the red planet, and add my own ideas.

Mars - Image from commons.wikimedia.org.
Mars – Image from commons.wikimedia.org.

Zubrin’s plan to put humans on Mars is dubbed the Mars Direct Plan. A bit of background: due to the rate at which Earth and Mars orbit relative to each other, the ideal launch window for a mission to Mars opens up once every 2 years. For a mission with reasonable propulsion capability, it should take around 6 months to get there. One of the biggest complaints about sending a human mission to Mars is the fact that it would be too hard to bring all the fuel you need to launch back to Earth from Mars’ surface. So – going to Mars would be a death sentence, so to speak – a little off-putting for some. The Mars Direct mission utilises in-situ propellant generation, creating a fuel from Mars’ atmosphere via a series of chemical reactions using a feedstock of a small quantity of fuel brought from Earth. This means that we don’t have to bring the fuel with us, and we can return humans to Earth.

We start by sending an unmanned Earth Return Vehicle (ERV) to Mars with in-situ propellant generation capabilities. This travels for 6 months then lands. It spends the next 18 months generating fuel. By this time, we are about ready for the next launch window. We remotely test the ERV to make sure it’s good to go for return, then send the first human mission and another ERV. The second ERV can act as a spare if the first doesn’t work, but more importantly can repeat the same process to prepare for the next human mission in 2 years.

I could go on at length about the numerous technical aspects. You can either trust me that Zubrin does a good job at covering all the bases or you can read the book yourself! But note that this plan doesn’t necessarily involve futuristic technology. A lot of the infrastructure required (including the in-situ propellant generation) exists now.

One idea proposed to encourage Mars exploration is dubbed the ‘Gingrich Approach’. This involves creating a series of challenges, each with its own cash prize, culminating in the ultimate prize of ‘Be the first to send a crew to Mars and return the crew members safely to Earth‘ with a reward of $20 billion US, plus $1 million per person for each day spent on the Martian surface, up to a maximum bonus of $5 billion. Not bad! I’d certainly put my hand up to spend 18 months on Mars for $1 million a day! Similar competitions exist, such as the Google Lunar xPrize. The idea is to create a financial incentive for private entities to explore Mars and develop the technology required. This would likely be a cleaner, more efficient way than directly funding the mission through a space agency. The country in question (in this case USA) would offer the prize at tax-payer expense, but the benefits to jobs and the economy would be huge, not to mention furthering science, and if no one succeeds, the tax-payer doesn’t cough up a cent.

One idea that came out of TCFM was to ‘sell’ blocks of land on Mars (of which there is 144 million square kilometres), just as tracts of land in Kentucky were sold for large sums of money a hundred years before settlers arrived. This would encourage the exploration of Mars as investors push for development of the planet in the hope that the value of their Martian territory increases in value as miners look to lease the land and property developers look to purchase it in the future. This would require the creation of some international body whereby all countries agree on the legality and authority of individuals owning parts of Mars. Why not go one step further and use the money raised to just fund a Mars mission? Zubrin thinks it should only cost $4-6 million for a private entity. At a value of just $20 an acre (around 4,000 square metres), Mars would be worth $700 billion. Or you could, I don’t know, solve a whole bunch of problems. Whatever. While we’re at it lets start selling off other planets, moons, asteroids, stars… We could have a whole swatch of money from cashed up investors to do with what we like. Cash which probably would not have been spent anyway.

The concept of terraforming Mars is certainly plausible enough. Essentially, the theory is that there is carbon dioxide and other gas locked in the polar ice caps and beneath the surface in permafrost. The aim is to heat up a small area of an ice cap using one of several methods (my favourite is a giant mirror near Mars to reflect and focus sunlight – read TCFM for more details!), which releases some of the gas, thickening the atmosphere and trapping in more heat. Eventually enough gas is released that this triggers a ‘runaway’ effect which finishes melting the rest of the ice itself over a time scale of decades to centuries, eventually making the atmospheric pressure high enough to wander about without a full space suit. The air still won’t be breathable though, so then we’d have to introduce plants to turn some of the carbon dioxide into oxygen.

While I confess I don’t fully grasp some of the atmospheric and climate system modelling covered in TCFM, we have certainly achieved a version of ‘terraforming’ by accident here on Earth over the course of the industrial revolution, raising the carbon dioxide concentration from 280 to 400 parts per million (0.028-0.04%) and increasing surface temperature. Imagine what we could do when we actually try to achieve such changes. This brings me to an important question: should we terraform another planet?

It’s a difficult one to answer, and I don’t pretend to know the answer, but there are a lot of clever people working on this sort of thing, and I’m sure I’ll write a blog entry devoted to terraforming in the future.

Regarding the simpler case of accidentally transporting Earth-based microbes to Mars and ‘contaminating’ the planet, Zubrin raises the interesting point that unsterilized Earth originating material is already raining down on Mars, possibly seeded with organisms, just as Mars rock rains down on Earth (at the rate of around 500 kg per year) as the result of material flung into space from asteroid impacts and large volcanic eruptions. Following on from this is the realisation that perhaps life on Earth originated on Mars.

Zubrin appeals to our humanity in that we as humans have a need to explore the next frontier, and Mars is just that.

One world will be just too small a domain to allow the preservation and continued generation of the diversity needed not just to keep life interesting, but to assure the survival of the human race.

I wonder… does Zubrin refer to the innate human need to expand and consume more resources? If that is truly necessary for human survival as a species, we will eventually consume our entire Solar system in the not too distant future. Rocky planets, asteroids and gas giants alike will one by one fall to humanity’s conquest. Is it impossible for us as a species to be sustainable? Zubrin seems to think that humanity is not doomed because the universe is vast, its resources are infinite, and technology is advancing at an ever increasing rate. I’ll leave you all with that thought, and some of my favourite quotes from the The Case for Mars.

To summarize in Star Trek terminology, what a piloted Mars mission needs are two “Scottys” and two “Spocks”. No “Kirks,” “Sulus,” or “McCoys” are needed

Just as the example of nineteenth-century America changed the way the common man was regarded and treated in Europe, so the impact of progressive Martian social conditions may be felt on Earth as well as on Mars.”

Until next time.

Anyone interested in reading more about or joining the Mars Society can do so here: www.marssociety.org

Making history with Pluto

Last night I watched the live stream from NASA TV of the New Horizons team and onlookers as a space probe reached Pluto for the first ever time. There were no images at the time, as the radio signals take over 5 hours to reach Earth from Pluto. Also, as I found out last night, to reduce the risk of equipment failure New Horizons can only send data back to Earth when it is not doing science and taking photos. The antenna itself to return data to Earth does not move, and so it must be pointed at Earth by turning the probe itself, and therefore the science instruments away from Pluto. Despite this, the atmosphere was incredible, with many crying for joy.

The first images have come in, and courtesy of the xkcd web-comic we have our first geological interpretation of Pluto.

In all seriousness, I’d like to turn your attention to the so-called heart of Pluto. This incredibly large patch of Pluto’s surface appears almost completely devoid of surface features. Scientists are already speculating that this is due to ongoing geological processes at work under the surface. For this to be the case, Pluto must remain quite geologically active today – rather unusual for such a small planetary body! If the surface had not been recently active, this area should be riddled with craters from asteroid and comet impacts like the rest of the surface.

One possible explanation that comes to mind is in the form of the Lunar mare, the large, dark basaltic planes on the Moon formed by volcanic eruptions. These eruptions are thought to be the result of asteroid impacts that had enough force to induce widespread volcanism on the surface. These areas are relatively smooth as the young volcanism covers any trace of impacts.

The heart has roughly the right shape to have been caused by several such events, but it is unusual that the region is a lighter colour than the rest of the dwarf planet. This could possibly be the result of a more felsic magmatism? Or I could be way off. Comment your thoughts below!

Until next time.

Pluto, measuring gravity with probe swarms and more!

A lot of exciting space science news coming in this weekend! Lets start with this project brief from Johns Hopkins University.

The proposal is to use a series of orbiting probes and a mothership to measure the gravity field of an asteroid or comet, and use this information to model the internal structure. Modelling the interior of small planetary bodies is something that we haven’t achieved yet as a species, simply because most of our exploration tools focus on large scale and surface features. We haven’t been able to put a drill hole into the centre of an asteroid yet!

Scientists are turning to remote sensing techniques like gravity, ground penetrating radar and radio tomography (think penetrating an asteroid with lightwaves of different frequencies and measuring the signal returning signal bouncing off different internal structures) to cheaply gather data on an asteroid’s interior.

In the above proposal the mothership will precisely monitor the position of the orbiters as they rotate the asteroid. Even a small change in orbit will reveal changes in density which can be caused by heavier or lighter material and empty spaces within. The combined data will be used to build a picture of the asteroid’s interior. This technique is already shown to be feasible through a series of simulations.

The benefits of such a project include the mothership being able to perform other experiments simultaneously, even leaving room to send a lander to the surface.

My only concern is in accurately tracking the position of the orbiters with respect to the asteroids surface. On Earth we need 4 GPS satellites to provide accurate location coordinates.

In other news, an incredible new photo reveals signs of geological features on Pluto, making a geophysicist like myself giddy with excitement. Even with a resolution of 27 kilometres, breathtaking new features can already be made out.

I think my reaction can be neatly summarised by this photo of science team members.

While it is unlikely that Pluto is still geologically active due to its small size, it seems apparent that it underwent a series of events leaving clues on its surface to its past.

As New Horizons principal investigator Alan Stern said, “After nine and a half years in flight, Pluto is well worth the wait.”

Different materials reflect various wavelengths of light in different proportions. As a result, each material has its own characteristic spectral signature.

Even with the most advanced telescopes, the light from distant planets beyond our solar system constitute a single pixel. This makes it hard to look for life, as the light signature from a planet gives us only the average of the near side of the planet.

Researchers from the University of Washington and the Virtual Planetary Laboratory published a paper in May in Astrobiology. They have found that if an organism with nonphotosynthetic pigments (which use light for things other than energy) cover enough of a planet’s surface, their influence on the spectral signature could be strong enough to be detected by a new generation of telescopes currently in development.

This possibility has been overlooked in previous searches for life, and while there are some difficulties with this method, it certainly broadens our ability to detect life at great distances.

A link to the original paper can be found here.

Until next time.

New Horizons – Journey to Pluto

After 9 years, only 5 days remain until New Horizons performs its flyby of Pluto!

Time to brush up on our (my) knowledge of this ex-planet.

“Did you know that until very recently, the best images we had of Pluto were just a few pixels in size? That’s right: those pictures you have in your head of what Pluto looks like are mere artists’ impressions.”

No!

During New Horizons’ close encounter we will see imagery revealing details as small as 50 metres across. For a sneak peak at what’s in store, check out this photo New Horizons took as it passed Jupiter.

Jupiter and Io taken by New Horizons in 2007 - image sourced from abc.net.au.
Jupiter and Io taken by New Horizons in 2007 – image sourced from commons.wikimedia.org.

New Horizons will pass as close as 12,500 km from Pluto, taking high resolution imagery as it floats by. It will take as long as 16 months to return 1 day worth of photos to Earth due to the probes’ low bandwidth!

I’m excited to see what insight we can get into the geology of Pluto with these images. Given how little we know about it, the little data we get from the imagery and New Horizons’ other equipment will surely yield some incredible discoveries!

Unfortunately, after Pluto, New Horizons is destined for a lonely journey through the Kuiper Belt, an icy ring of debris beyond Neptune. While there are millions of objects in this belt, they are few and far between, leaving New Horizons very unlikely to come into contact with one.

From there it will be on to the Oort cloud, and finally,  interstellar space.

For a more detailed summary of Pluto, check out this article by ABC News.

Until next time.

Rosetta and 67P

67P/Churyumov-Gerasimenko, named after its founders by the same names, is rapidly approaching its closest point in orbit to the Sun. At almost 38 km/s to be precise.

Comet 67P/Churyumov-Gerasimenko
Comet 67P/Churyumov-Gerasimenko. Image from wikimedia.commons.org.

Last November, the Rosetta spacecraft’s lander, Philae, became the man-made object to perform a soft landing on a comet.

And what a landing it was! Philae was unsuccessful at anchoring itself to the surface of the comet with its landing harpoons and bounced twice before coming to a halt in a dark zone. This was a problem as the lander couldn’t charge its batteries as well as planned using solar panels, and went into hibernation 3 days after touchdown.

Although Philae made contact at a very low speed, the low gravity on the comet (around one ten-thousandth that of Earth), meant that a small bounce was disastrous.

One proposed theory for the greater than expected ‘bounce factor’ is that the surface of 67P was elastic, with a hard crust under a metre thick overlying an elastic material (S. Ernst pers. comms.). This made me think of the recent announcement that the mysterious ‘craters’ on the surface are created when porous rocky material which has lost its water-ice due to outgassing. Eventually this porous rock can no longer hold its own weight, even in the low gravity of the comet (suggesting high porosity indeed… and a very high current or previous water content for the comet overall!), and it collapses, creating a sinkhole-like feature.

Perhaps the proposed ‘spongy material’ causing Philae to bounce is the same porous rock that is causing these sinkholes?

If so, is the whole surface of the comet poised on the brink of collapse with high porosity? Or did Philae get unlucky and land on a soon to be sinkhole?

These are the questions that excite me about space science. Part of my PhD will involve developing new and novel ways to test various models for the structure of asteroids and comets. Currently I’m looking at seismics and ground penetrating radar, but endless possibilities abound!

Until next time.

Edit: This article suggesting that 67P could be home to microbial life refers to an organic rich crust which is being constantly replenished. The presence of this crust and the replenishment of water (by outgassing from the deeper ice?) would support the above hypothesis!

Second edit: The Skeptics Guide to the Universe has stated that the original scientific research the above article was based on doesn’t actually make any claim to the existence of life on the comet. It just goes to show that one should always read the original science before commenting, as science journalism does get it wrong from time to time!