It is called “Mars to Stay” and I hope it will involve a 85-year-yound Italian in 2052 going to Heaven but first stopping for around 30 years on the Red Planet. For the final resting place I select this:
One can only feel sad upon reading Giovanni F Bignami’s op-ed piece about the race to the Moon and what choices to take for the future (“Once in a Blue Moon “, IHT, 18-19 July 2009). Prof Bignami’s argument appears to be about treating space-faring as a purely novelty product, like a fairly curious but ultimately useless item on a late-night TV shopping channel. Something you may be convinced to buy, but just the once.
And even if we have spent less than a week in total time exploring a few square miles of a place as big as the former Soviet Union, Prof Bignami tries to seriously argue that there is no “compelling reason” to go back to the Moon. And that we should embark on the enormous effort to reach Mars instead, presumably for a couple of trips before getting bored with travelling millions of kilometers too.
Here’s a “compelling reason” then: as it is well known, one needs a lot less fuel to travel to Mars from the Moon, than from Earth. Most of the launch cost lies in getting from our planet to low Earth orbit: beyond that, the whole planetary system is within relatively easy reach.
Prof Bignami remarks also that “the notion of mining on the moon would also [be] environmentally offensive“. I for one do not understand how will humans ever be able to “environmentally offend” a surface pummeled for billions of years by asteroids of all sizes, by a perfectly unhindered solar wind, and by cosmic radiations of all sorts. That is the Lunar surface, made of a type that likely covers several billion square kilometers on hundreds of natural satellites in our Solar System alone.
Paradoxically, the astronomical/astronautical community has been unable to support its own cause since the launch of the Sputnik. Nobody has gone anywhere because of effective lobbying by planetary geologists or solar scientists.
Bignami’s op-ed appears to be yet another example of how bizarrely brainy arguments about going to Mars vs returning to the Moon have succeeded so far only in keeping the human race in low Earth orbit, literally going around in circles instead of literally reaching for the stars.
The following text, by Stephen Ashworth FBIS, has been presented at the British Interplanetary Society’s “Ways to Mars” symposium, held on 19 November 2008 at the Society’s London headquarters. Its main points:
– Most of the mass needed for an Earth-Mars transport system consists of propellants and life support materials, and that is already in space, and already in orbits very close to the ones which we need;
– But this near-Earth asteroidal resource is completely invisible to the space agency paradigm of space exploration, because [the paradigm] excludes the construction of permanent human activity in space.
Transport for Areopolis Or: “Implications of the Choice of Economic Paradigm for Strategies of Manned Access to the Moon and Mars” by Stephen Ashworth
When considering human access to Mars, it seems to me that there are two key points which need to be taken into account, but which are often ignored. I shall offer you these two points very shortly.
Designs for manned missions to Mars typically involve assembling in low Earth orbit a spaceship weighing several hundred to over a thousand tonnes.
For example, each Troy spacecraft, which we shall be hearing more about this afternoon, weighs nearly 800 tonnes to carry 6 astronauts. The “space lego” nuclear powered Mars mission uses two ships of 240 tonnes each, thus a total of 480 tonnes in low Earth orbit. [I was wrong — this turns out to come to a total of 955 tonnes.] The “magic” Mars mission requires five Energiya launches, thus probably weighs 4 to 500 tonnes when ready to go.
Meanwhile the official European Space Agency design study for a Mars mission proposed a ship, again for 6 astronauts, which required 20 Energiya launches for every single Mars departure. These launches would build up a ship weighing 1357 tonnes at departure.
The Mars ship in low Earth orbit thus weighs between about 50 tonnes and about 200 tonnes per astronaut on board. Launching such large masses into orbit for the benefit of so few people is one reason why manned Mars exploration is hopelessly uneconomic.
At present-day cargo rates to low Earth orbit of $10 million per tonne, this is a billion dollars per astronaut, plus the cost of the Mars hardware itself. Even at spaceplane rates, which may fall to as low as $10 thousand per tonne, this is still a million dollars per astronaut, plus the cost of the hardware.
At these rates, there will not be many people going to Mars.
Let me show you an Earth-Mars transfer orbit.
Here is an orbit which reaches out from Earth to pass the orbit of Mars. It has about the same size and shape as the orbit of an Earth-Mars cycler, such as the ones being studied by Buzz Aldrin and his collaborators.
It might therefore be the orbit of a future manned Mars vehicle. But that’s not what I drew. What I’m showing you here is the orbit of minor planet 4660 Nereus.
The concept of an interplanetary cycler, which repeatedly encounters Earth and Mars, goes back to the early 1980s. Alan Friedlander and John Niehoff first proposed setting up long-lived space habitats which remain permanently in interplanetary space. These would periodically be used for transporting people between Earth and Mars. Relatively small ferry spacecraft would complete the transport chain between the cycler and a local parking orbit or planetary surface.
In 1985 Buzz Aldrin added the concept of a gravity assist at each planetary flyby. This technique allows a cycler to stay in phase with the relative motion of Earth and Mars. It enables it to offer passage between these planets once every 2.14 years, the Earth-Mars synodic period.
A great number of near-Earth asteroids, such as 4660 Nereus, resemble natural Earth-Mars cyclers. A proportion of them are believed to be carbonaceous chondrites, containing water and other volatiles. Water in space is of incalculable value as a feedstock for propellant manufacture, as a near ideal substance for radiation shielding, and for other life support functions.
I have checked the online listings of near-Earth asteroids published by the Minor Planet Center. Applying quite stringent orbital criteria, I found a total of 56 Amor and Apollo asteroids which behave like natural Earth-Mars cyclers. New ones are being discovered all the time — for example, of those 56, ten were only identified this year.
Now to my two key points.
Firstly: most of the mass needed for an Earth-Mars transport system consists of propellants and life support materials. That mass is already in space, and already in orbits very close to the ones which we will need to reach and return from Mars. It does not need to be launched from Earth. It can be mined in situ.
So why is hardly anybody getting excited about this? Why does it not form the basis of the Constellation programme, or of the recent ESA or Russian design studies, or even the magic, the trojan or the space lego Mars missions?
Because of my second point: the asteroidal resource is completely invisible to the space agency paradigm of space exploration. That mode of planning excludes the possibility of systematic use of natural in-space materials, and it excludes the construction of permanent infrastructure on Earth-Mars cycler orbits. It will not contemplate anything that suggests permanent human activity in space.
I think we can identify two broadly contrasting attitudes to transport infrastructure.
The heroic paradigm is only interested in special missions of heroic exploration. This is the space agency mode of thinking. Its prime goal is national presige, under a fig-leaf of science, spinoff and educational inspiration. Think of the Apollo programme. Further back in history, think of Zheng He’s epic voyage of exploration around 1421, from a China which was about to close in on itself.
In contrast with the heroic paradigm, we can identify the systemic paradigm of transport infrastructure. The prime goals here are permanence, growth, and economic profitability. Think of the Cunard and White Star steamers which connected Britain with the Americas and the Empire from the mid-nineteenth to the mid-twentieth century.
Now obviously, since there is currently nobody on the Moon or Mars, the next people to travel there will of necessity be heroic government explorers. But the question we need to address is this: will their transport system be designed for cancellation, like Apollo, or will it be designed for growth, like Cunard?
What would a systemic manned space transport system look like?
I have identified four key features.
Firstly, it will employ reusable spacecraft — an obvious enough point.
Secondly, it will not be content with a single route — say, between Kennedy spaceport on Earth and a single base at Utopia Planitia on Mars. It will rather seek to foster a network of different routes among a number of different transport nodes. Those nodes may include an increasing number of space hotels, factories and laboratories, and lunar and martian bases.
Note particularly that the use of transport nodes allows in-space refuelling. This capability was regarded by early spaceflight theorists such as Hermann Oberth and Guido von Pirquet as essential if lunar and martian flights were to become achievable using chemical fuels.
Thirdly, a systemic space transport system will diversity its sources of propellants and life support materials, exploiting the transport nodes for in-space refuelling.
Fourthly, it will not be content with a pillar architecture, but will develop a pyramidal one. In a pillar architecture, one unique space station is succeeded by one unique Moon base, and that in turn by one unique Mars base. In a pyramid architecture, by contrast, it is growth in the use of space stations that supports the first Moon base, and growth in the use of Moon bases that supports the first Mars base.
Thus in impressionistic figures, if there are ten people on Mars, then we should expect to see at the same time at least a hundred people on the Moon, and at least a thousand on board stations in Earth orbit at any one time.
So we can now design a Mars transport system along the following principles:
— The long-haul journey is accomplished on modular interplanetary cycler stations, which are upgrades of stations in regular use as Earth-Moon cyclers, which are themselves upgrades of stations in regular use in low Earth orbit as hotels, factories and so on;
— The transport chain between Earth and the interplanetary cyclers is closed by short-range ferries, which are upgrades of ferries in regular use to connect with the Earth-Moon cyclers, which are themselves upgrades of ferries in regular use between Earth’s surface and low Earth orbit;
— The bulk of the development work that goes into the first Mars mission is carried out by commercial companies in pursuit of profitable business in space tourism, manufacturing and energy;
— As a result of growth in traffic in the Earth-Moon system, an in-space refuelling system based on near-Earth asteroidal water will become economically viable, vastly decreasing launch costs from Earth.
There may still be a heroic attempt to get to Mars in isolation from the development of such a space economy. If we are lucky, it will be like Apollo, and will be cancelled after the first few landings. If we are unlucky, it will be like the X-33 or Hermès spaceplanes, or like the Soviet Moon-landing programme, and be cancelled before its first landing.
Either way, it will not produce much progress towards sustainable human access to Mars. That can only be achieved by a systemic transport system, not a heroic one.
To conclude, I would remind you of my two key points:
— Most of the mass needed for an Earth-Mars transport system consists of propellants and life support materials, and that is already in space, and already in orbits very close to the ones which we need;
— But this near-Earth asteroidal resource is completely invisible to the space agency paradigm of space exploration, because it excludes the construction of permanent human activity in space.
Is it possible to estimate the most likely values for climate (temperature) sensitivity to CO2 concentrations by studying the atmosphere of the planet Mars?
If it is, the results suggest even a +1C/doubling of CO2 concentration may be too large a value.
First the constants in the calculations (values from Wikipedia unless linked elsewhere):
CO2 molar mass: 44.0095
For Earth’s atmosphere molar mass: 28.97
mass: 5.148 * 10^18 kg
CO2 concentration: 385ppmv
pre-industrial CO2 concentration: 278ppmv
Greenhouse effect: +33C
Contribution by CO2 to Greenhouse effect: 9% (+2.97C)
For Mars’s atmosphere molar mass: 4.33
mass: 2.5 * 10^16 kg
CO2 concentration: 953,200ppmv
Greenhouse effect: +5C (only due to CO2)
What is then the mass ratio of CO2 between Mars and Earth?
In Earth’s atmosphere: 385ppm volume –> 585ppm mass –> 3.01 * 10^15 kg In Mars’s atmosphere: 953,200ppm volume –> 967,925ppm mass –> 2.42 * 10^16 kg
CO2 (Mars) = 8.04 * CO2 (Earth) (by mass)
Let’s imagine now to increase CO2 (Earth) by 8.04 times by mass, equating what’s in the Martian atmosphere.
In that case, quick computations show terrestrial atmospheric CO2 concentration would increase to 4,680ppm mass, that is 3,081ppm volume: 8 times the current values, and 11 times the estimated pre-industrial concentration.
What would be the effect on Earth of such an increase? If we follow RealClimate’s and the IPCC’s estimation of a 3C/doubling sensitivity, the result is a whopping +12C compared to today’s, i.e. +14.97C in total.
If, instead, we stick to the estimation that, on its own, a doubling of CO2 should bring around +1C of temperature, the result is +4C compared to today’s. And that would provide a grand total for the CO2-related greenhouse effect of +6.97C
Compare now the figures of +14.97C and +6.97C with what is considered to be the same effect on Mars: +5C.
The above appears to indicate that a plausible value for climate sensitivity is in the region of +0.5C/doubling CO2 concentration.