The endowment for the human exploration of space would seek to raise private capital to build a reusable infrastructure in space to facilitate the human exploration and exploitation of space resources. To achieve this goal, an endowment of one billion dollars or more would be required. However, rather than invest the entire endowment in space exploration, the endowment would be invested in traditional diversified equities, like the S&P 500 index fund, to earn 8% or more annual return (adjusted for inflation). 30% of annual returns, averaged over a five year term to smooth out market fluctuations, would be re-invested in the endowment, and 70% would be used to fund operations. This would yield an initial stable revenue stream of $56 million annually, which would grow over time. In this way the endowment would grow to over $3.1 billion over about 50 years, assuming an 8% rate of return, adjusted for inflation.
The first goal of the endowment would be to obtain a supply of water in space. Water is perhaps the most valuable resource in space. It is required to support life systems. It can also be used to produce traditional chemical rocket propellant, as LOX and liquid hydrogen. Water also is an excellent natural radiation shield. Finally, some high impulse propulsion systems, such as VASIMR or NERVA, can use either hydrogen or even water as a propellant.
There are some indications that water may be found on the moon, which would be a tremendous asset. Water certainly exists on comets, but because of the typical orbital configuration of a comet it is difficult to obtain. Water can be found in significant quantities on Mars. Although the escape velocity of Mars makes extracting water from Mars is a lot easier than getting it from earth, delivering large amounts of water into low mars orbit is still a significant challenge.
However, one exciting possibility is that water may be found on Deimos. Deimos has shown outgassing which is most likely from water, and in fact Deimos may be the expended nucleus of an ancient comet. Either way, there is a very good chance that large amounts of water may exist on Deimos in a form which can be readily extracted, and the escape velocity of Deimos is negligible.
Therefore, the first target of the endowment would be to find and extract water from Deimos. Of course, this assumes that there is in fact usable water on Deimos, which is a very big if. However, for the purpose of this analysis, let as assume this is true. If the endowment were to be funded today, the annual budget would of course be $56 million. In fact, the total budget for the first 9 years would be around $555 million. This should be enough to develop an exploration module capable of orbiting Deimos, creating a hydrology map, and maybe even sending a very small lander or even an impactor to directly measure a candidate deposit of water on the surface.
There are also a couple of additional assumptions. One is that the endowment would use commercially available launch services. A next generation launch vehicle, such as the Beal BA-2, should be capable of delivering a 17,000 kg payload to LEO for around $3,000 per kg, or a total launch cost of about $50 million. While this represents a significant cost improvement over current commercially available launch systems, it is probably a realistic figure. Today payloads can be delivered to LEO for as little as $4,000 per kg, using the Russian Proton, so $3,000 per kg is probably an achievable goal, and is may close to the practical limit. In fact, this illustrates one of the most important obstacles to the human exploration of space, the high cost of delivering material to LEO.
It takes about 9500 m/s of delta V to deliver a payload to LEO. This must be done at very high thrust, so that the cost in terms of energy and propellant to do this is staggering, approaching the limit of what is technologically feasible. This is the whole point of developing resources in space. If it costs at least $3,000 per kg to deliver material to LEO, the inherent value of any useful material already in space is at least the same $3,000 per kg, which represents the cost of delivering that material to LEO. This is why, for example, water is such a valuable resource in space. It is very useful, but it would cost $3,000 per kg to deliver it to LEO from earth. The same is true of iron and other metals, which are readily available from m-type asteroids. The materials are useful, and the cost of delivering them to LEO form earth would be at least $3,000 per kg.
Another important long term goal of the endowment would be to develop a reusable transportation infrastructure in space. You would want to have very high efficiency, high specific impulse propulsion for moving cargo across interplanetary distances. You would also want high efficiency and high thrust transportation to transport humans across interplanetary distances. Fortunately, there are existing propulsion technologies either under development or already developed which meet these criteria.
For fast human transportation, nuclear thermal rockets, such as NERVA, developed in the 1960�s, provide both high thrust and high specific impulse. NERVA rockets can develop high thrust at up to 800 seconds of specific impulse (ISP), which is more than enough to get to mars and back. For example, about 5 km/s of delta V would be required to go from LEO to Deimos, maybe less if you use aerobraking at mars. At 800 seconds of ISP, this would require less than 50% of the vehicle mass in propellant, assuming you can replenish your propellant at Deimos. A higher energy, fast transfer orbit from Earth to Mars would require only slightly more delta V and would be achievable using NERVA propulsion. Another advantage of a NERVA engine is that it can be modified to supply supplemental electric power during the cruise phase, using the NERVA fission core as the core of a nuclear reactor.
If less thrust is required, higher efficiency nuclear electric propulsion could be used. VASIMR and other variations of a magneto-plasma or Lorentz force propulsion can develop 5,000 seconds of ISP or more, and can theoretically use almost anything as a propellant. Although they usually use molecular hydrogen for propellant, they could also use water, and water is much easier to store and transport. Hydrogen must be kept at cryogenic temperatures to avoid boiling, water does not. Electric propulsion can be powered by solar arrays or by a nuclear power source. Another interesting alternative is a solar sail, which can provide thrust almost comparable to a nuclear electric propulsion system, is very simple, and requires no propellant at all. Still, nuclear electric propulsion provides significantly more thrust and may be a more practical solution beyond the orbit of Mars.
All these factors taken into consideration, the first mission of the endowment would be to develop a reusable transportation spacecraft, a sort of a nuclear electric space tug, to deliver a small probe to Deimos, and then wait at Deimos to be refueled in the future. Assuming 8500 kg for the space tug, 3000 kg for the probe, and 5500 kg propellant, that should be enough for the tug to deliver the probe to Deimos and still have enough propellant to return to earth if desired. At a total budget of about $550 million, including $50 million to launch the 17,000 kg payload to LEO, the first mission would launch in 2014, if the endowment started in 2006. While $550 million might seem like a small budget for such an ambitious mission, since the mission would be privately funded, significant cost savings my be possible. Even if $550 million IS an unreasonable budget, any mission could be accomplished given enough time. Just continue to stretch out the funding over enough years to complete the mission. However, for the purpose of this analysis, we will assume the mission could be accomplished for $550 million, using private funding.
The next mission, assuming the probe is successful in identifying local reserves of water on Deimos which could be extracted, would be send a small automated drilling and processing plant to begin extracting water. By this time, the endowment should be producing a $70 million surplus budget annually. Reusing the same design to build a second tug, mission #2 would cost only $450 million and should launch in 2020. The extraction facility would require a powered landing on Deimos, with a total mass of 6500 kg, leaving only 2000 kg for propellant, enough to get to Deimos but not return. However, we are now producing propellant locally on Deimos, so the tug can be re-supplied in situ. Also, the second mission would be landed on Deimos using a reusable lander which could later be outfitted to shuttle water from Deimos surface into Deimos orbit. Fortunately, the esacpe velocity on Deimos is negligible.
The third mission, in 2025, would now try to bring some of the valuable resources from Deimos back to LEO. With the endowment's annual surplus budget now exceeding $80 million, the total mission budget for the third mission would be about $400 million. The third mission would include another space tug, a reusable lander for Deimos, a backup nuclear reactor, and fuel processor to split the water into hydrogen and oxygen to be used for fuel for the two Deimos lander / shuttles.
The fourth mission, in 2030, would finally make the return of water to LEO practical by supplying a fourth space tug and several modular fuel tanks, double walled for storing either cryo fuels like LOX or liquid hyrdrogen, or even liquid water. With a dry mass of 500kg each, they can serve either as propellant tanks for the 4 space tugs, or as cargo vessels. The fourth mission would include the fourth tug, 2000 kg propellant, and 13 storage tanks, each with a capacity of 5,000 kg of liquid propellant. Once at Deimos, the other three tugs could dock with the fourth and exchange tanks. Each tug would carry 3 tanks, and the remaining tank would be shuttled to the surface of Deimos for additional storage on the surface.
Mars and Earth are in a proper alignment for an optimal hohman transfer orbit at approximately 18 month intervals. Assuming the augmented fuel and water processing faciliaty on Deimos is capable of keeping up with the demand, if one tug were dispatched from Deimos with full cargo of 15,000 kg of water every 18 months, that would be a transfer rate of 10,000 kg per year from Deimos into LEO. Note that the ropellant used by the tugs for each full transfer would be less than 4,000 kg, since the tug is using VASIMR propulsion operating at 5,000 ISP, so the net excess cargo delivered to LEO would be around 6,500 kg per year. As soon as each tug arrived back in LEO, it would transfer its cargo to whatever projects need it, or simply leave it in orbit, and immediately return to Deimos. 4 tugs should be enough to create a continuous supply chain, so there would always be a tug waiting in orbit at Deimos to pick up material from the extraction facility as needed. At this point, propellant in LEO is no longer an issue. 6,500 kg per year is a lot of propellant, enough that a lower ISP but higher thrust transfer from Earth to Mars is possible.
The next mission, in 2034, would deliver a third nuclear reactor and human habitat module to Deimos, and also deliver supplemental tankage into LEO to store fuel for future missions. A tug returning from Deimos could easily pick up the extra cargo in LEO and deliver it to Deimos, where a Deimos shuttle / lander could deliver the habitat to the surface near the fuel extraction facility. All this assumes routine robotic rendezvous and docking between spacecraft, something which in recent years has been developed as part of the supply effort for the ISS. The habitat and reactor could mass as much as 10,000 kg and still easily be delivered to Deimos by the tug and safely landed on the surface using a Deimos shuttle / lander.
By 2034, the annual surplus budget will be in excess of $100 million. The next 4 missions, spread over the next 12 years, would result in the first manned mission beyond the moon. With a combined budget of $1.5 billion, funded entirely by surplus revenue from the endowment over 12 years, the endowment would develop and build 2 NERVA powered fast human transport vessels, and supplemental tankage in LEO to store fuel and water from Deimos.
The next launch in 2038 would deliver a large tankage facility to LEO, probably to be docked with ISS, although it could certainly be delivered to an independent orbit. The tankange facility would be able to store 150 cubic meters (150,000 kg equivalent) of propellant, either as liquid water, or stored cryogenically as liquid hydrogen or oxygen, and would include a solar array to develop power to keep cryo fuels cooled or even to process water into hydrogen and oxygen if required.
In 2041, the first NERVA powered fast human transport would be launched unmanned. Fueled in LEO, it would proceed to Deimos without a crew to be used as an emergency return vehicle. With a dry mass of 17,000 kg, the transport would include a hybrid NERVA engine / nuclear reactor, hydrogen fuel cells for backup power when the NERVA rocket motor is being used, 3,000 kg of water to be used as radiation shielding for the habitation module, also supplied in LEO. With shielding, it would require 10,000 kg of propellant to reach Deimos, on a one way trip. Of course, it would be easily refueled at Deimos, and wait in orbit, fully fueled and ready to return to earth in case of some disaster.
Finally, in 2044, the second NERVA powered fast transport would be launched, fueled, and wait in orbit, until the final mission would deliver the crew in 2045. The crew could be launched using a reliable Soyuz launch vehicle, or whatever means are available in 2045.
Using a fast semi-hohman transfer orbit, the crew should arrive on Deimos in a few months. Once on Deimos, the crew would inhabit the existing habitation module, launched in 2034, and maintian the now aging equipment on Deimos. They would have a small machine shop and necessary raw material and spare parts to make minor repairs. IF the geology is suitable, they could mine out ice caves deep beneath the surface on Deimos, deep enough that the could hold pressure. Although cold, an ice cave can be heated up to 0 C, and with some supplemental insulation could be made almost comfortable. Being deep underground would provide protection from space and radiation, and could be used for storage or a variety of purposes. Each crew would be exchanged every 18 months, as the orbital characteristics allow, but the Deimos base would be occupied continuously from 2045 on. Eventually, they would be able to grow some of their own food, using water and possible regolith form Deimos, combined with human organic waste, to make soil. At first, there would be 3 redundant nuclear reactors to supply power, and there would always be an emergency return vehicle in orbit in case of catastrophy.
The next major milestone would nto be the surface of Mars, although it would be tantalizingly close, but instead would be a nearby m-type asteroid, perhaps Hertha, which is a large m-type asteroid in a nearly circular low inclination orbit just beyond the orbit of mars
Between 2045 and 2054, $1.5 billion would be invested in supporting the Deimos base and launching a mission to Hertha. By 2054, the endowment would be funded at over $3 billion in assets, generating $174 million annually in supplemental revenue, and still growing. Missions between 2045 and 2054 would launch a third and fourth fast transport to support the mission to Hertha, as well as two larger, 17,00 kg space tugs, capable of developing more power and transporting larger payloads. Additionally, a 17,000 kg habitat on Hertha would be similar to the original habitat developed for Deimos. Additionally, Hertha would have 34,000 kg of heavy mining equipment for mining iron and other metals, a large megawatt class nuclear reactor, and refining equipment capable of refining metals mined from Hertha into usable raw materials.
However, to refine iron into steel requires carbon. While carbon may be available on Hertha, as CO2 ice, or even on Deimos, it is certainly available on Mars. After 2054, the conquest of Mars would begin. Another habitat module, heavy landers capable of delivering equipment and supplies to the Mars surface, a reactor capable of refining water into rocket fuel so that the landers can return to orbit, and an atmospheric processor capable of extracting CO2 and Nitrogen, which would eventually be required to grow food, directly from the atmosphere.
Perhaps by 2070 a nearly self sufficient infrastructure would exist in space, capable of producing raw materials in abundance, probably supplying their own food, certainly capable of supplying air and water, all beyond the 9500 m/s barrier of LEO. By that time the endowment would have an annual budget of more than $250 million and would be capitalized at over $4.5 billion. The $3000 per kg cost of launching material into LEO would be conquered forever, all for an initial endowment of just $1 billion, a mere fraction of the multi billion dollar Mars missions proposed by NASA and other government agencies.
Instead of approaching a manned mission to Mars as a single mission, a precursor to establishing a permanent human presence in space, if we build a permanent, reusable infrastructure first, the overall cost is much lower. In fact, you can send a manned mission to Mars and establish a permanent base there for a lower overall investment than a single mission to go to Mars and return to Earth, if you are willing to spend the time and money, spread the investment over decades, and be committed, not to a single mission, but to the permanent and inevitable human conquest of space.
External space exploration web links