THE PLAN FOR SUSTAINABLE SPACE DEVELOPMENT
- a proposal for America’s space program during the current administration -

COST EFFECTIVE
SpaceX is planning on launching its Falcon Heavy in early November 2017. It is important to note that the Falcon Heavy is the best near-term rocket for lunar development for several reasons. The most significant reason is that the Falcon Heavy is largely a collection of three Falcon 9 rockets stuck together. And the Falcon 9 is the world's most cost-effective rocket, is launching the most frequently, has the largest launch manifest, and is demonstrating reusability of its first stage. The good news is that, regardless of how often the Falcon Heavy launches, its cost is largely determined by the cost of its Falcon 9 components. In other words, the Falcon Heavy will always be as inexpensive (and even more so) than the Falcon 9.

However, the Falcon Heavy will only be half as capable as the Saturn V which took us to the Moon. And its upper stage doesn't use cryogenic propellant and so isn't particularly efficient going beyong low Earth orbit (LEO). So, how can it effectively work as a Moon rocket?

BEYOND Low Earth Orbit (LEO)
The secret is to use the Falcon Heavy for where it is best -- from Earth to LEO. Then, replace it's upper stage and fairing with a lunar lander, cargo module, and propellant drop tank. At separation from the central stage, the cryogenic engines of the lunar land would fire while using the propellant from the drop tank. Once headed on trans-lunar injection, the drop tank would be separated (could be used as a depot) and then the full-fueled lander would be able to use its engines once again to slow down just before landing on the Moon. This approach would maximize the amount of payload sent to the Moon. Specifically, it calculates to 10 metric tons to the lunar surface. This is an excellent amount of telerobotic hardware to start with.

But another way to make the Falcon Heavy a useful Moon rocket would be to start by using it to send lunar lander on a one-way mission to the Moon so that all of the mass of the return propellant could be used to deliver more telerobotic hardware. Initially, the goal would be an attempt to harvest and process lunar polar ice to refuel the lander just by using telerobots alone. It may be possible to achieve this goal with even just the first Falcon Heavy Moon launch. If not, then follow-on Falcon Heavy launches would deliver more Ice harvesters, spare parts, etc in a continuing effort to harvest ice for propellant and so initiate a transportation system between the Earth and Moon and back. As a final back-up two Falcon Heavies could be launched and their payloads docked to provide return propellant and when crew arrive, they could work with the telerobotic hardware until lunar-derived propellant was being produced. But this is a worse-case scenario. Most likely sufficient propellant would be produced with the first telerobotic lunar mission.

Click here for a greater explanation of the lander and here for more about the telerobots.

REUSABILITY
Much of the space advocacy community is excited about what SpaceX is doing starting with their demonstration of reusability. As of this writing, SpaceX has successfully retrieved 16 of its first stages either by drone ship or ground pad. Reusability has the potential to dramatically reduce the cost of access to space in a manner analogous to how different a transcontinental jet flight would cost if one were able to refuel the plane as we do now versus having to throw it away after each flight. However, the Falcon 9 is not currently fully reusabile. It retrieves just its first stage and not its upper stage.

But, if a lunar lander were to replace the upper stage and if the lunar lander were to remain in space to be refueled on the Moon and reused, then instantly, all parts of the transportation system would be reusable thereby dramatically reducing the cost of sending cargo or people to the Moon.

Consider the situation where a few (e.g. four) Falcon Heavies launch a few lunar landers. If those landers could be refueled from lunar ice, and each of the landers flew six or seven times, then the landers would rack up between 25 and 30 flights. This is a good amount of flight history necessary to human-rate the landers. Therefore, just a few launches would be necessary in order to human-rate the landers.

COMPARED TO NASA'S SPACE LAUNCH SYSTEM (SLS)
The Falcon Heavy will have 90% of the LEO capability of the government's SLS Block 1 but only about 50% of the capability of the SLS Block 2. As discussed above, the Falcon Heavy will be sufficiently capable for lunar development over the long run. However, the SLS is also intended to go to Mars. Even with the full 130 tonne capability, it would take at least five or more SLS launches for each Mars mission. Trying to do the same thing with many more Falcon Heavies would be stretching things. So, unless a better alternate architecture can be conceived, the US should continue with the SLS for its journey to Mars.

The SLS will always cost more per kilogram to LEO than the Falcon Heavy. For this reason and since the Falcon Heavy is sufficiently capable for the Moon, the Plan for Sustainable Space Development states that the SLS should not be used for lunar development but should be reserved for those missions that need its level of capability -- namely, for crew-scale missions to Mars.