There have been a lot of articles in the news about either returning to the Moon or going to Mars of late. I think they are great. Either destination is fine as long as we build the infrastructure that will make spaceflight affordable to everyone in the process.
My reasons for this are simple; whichever program we choose, I don’t want it to be canceled after a handful of missions due to excessive cost like the Apollo program was. If we make spaceflight really affordable the program will continue and people will find a way to make money in space. Once that happens we will be on our way towards building a spacefaring civilization and there will be no turning back.
Returning to the Moon or going to Mars without building the infrastructure to make spaceflight affordable will only result in another canceled program and another 40 to 50-year wait before we try again. The reason for this is simple. Currently, it costs over $12,000 per pound to go to the International Space Station. You can check this yourself by going to the SpaceX website and looking up the cost of flying the Falcon 9 launch vehicle. It is $62 million per flight. If you look up the amount of useful payload that it can deliver to the International Space Station, the answer is 5,000 pounds. $62 million divided by 5,000 equals $12,400 per pound.
Another example is the Space Launch System, NASA’s new heavy-lift rocket that is currently in the process of being developed. The Block 1 version of this rocket is supposed to be able to lift 150,000 pounds into low Earth orbit. The cost per flight is estimated to be $1.86 billion. That also comes out to $12,400 per pound.
The Saturn V rocket that was used to go to the Moon in the 1960s would launch 3 astronauts and 140,000 kilograms into low Earth orbit for each Moon mission. That is a little over 300,000 pounds or 100,000 pounds per astronaut. 100,000 times 12,400 equals $1.24 billion per astronaut in today’s dollars to go to the Moon. You can be sure that sending an astronaut to Mars will cost more than that. Even if the reusable first stage rocket technology that is being developed by SpaceX and Blue Origin is able to reduce the cost of getting into Earth orbit by half, the cost per astronaut for going to either the Moon or Mars will still be in excess of $600 million per person. That is a lot of money. So much money that no one has been able to come up with a commercial activity in space that can make enough money to justify the expense of manned spaceflight.
As much as I want to see us build a spacefaring civilization, it just isn’t going to happen with launch costs this high. Anyone who tells you otherwise is either living in a fantasy world or expects to make money on it via government contracts.
So what can we do?
There are 3 things we need to do to make spaceflight affordable if we want to build a spacefaring civilization.
First, build a combination launch system that includes either an air-launched reusable first stage rocket for flying to the lower end of a non-rotating Skyhook or build a 600 MPH ground accelerator for launching a reusable first stage rocket to a non-rotating Skyhook.
Second, build a reusable spacecraft for launching from the upper end of the Skyhook for going either to the Moon or to Mars, as well as single stage reusable lander for the Moon or Mars.
Third, build outpost space stations with local sources of propellant for refueling those spacecraft and landers.
It doesn’t all have to be built at once. It can be built a piece at a time with jointly funded government/industry programs. SpaceX and Blue Origin are working on reusable rockets. Vulcan Inc. is developing the Stratolaunch carrier aircraft for air-launching launch vehicles. Bigelow Aerospace is developing inflatable space stations. NASA is building the Orion spacecraft for cis-lunar spaceflight and possibly for going to Mars. And finally, the US Air Force is developing a Maglev test track that could be used to accelerate a launch vehicle up to 600 MPH.
What else do we need?
Vulcan Inc. needs to develop a horizontal landing reusable first stage launch vehicle for its Stratolaunch carrier aircraft, and either NASA or Bigelow Aerospace needs to add a 200-kilometer long tether to the International Space Station or to a Bigelow space station along the lines of the one shown in this video.
Air-launching and the 200-kilometer long Skyhook will reduce the cost to orbit to 1/3 of what it is today, from $12,000 per pound to $4,000 per pound. Making the air-launched first stage reusable should reduce the cost to $2,000 per pound. Increase the length of the Skyhook to 380 kilometers and the cost will drop to $1,500 per pound. Continue making the Skyhook longer and the price drops even more. Once the Skyhook is long enough that the upper end is moving at close to escape velocity it becomes possible to place an Orion spacecraft on a free-return orbit to the Moon without the need for an expendable upper stage. Add a single stage reusable lunar lander and an outpost space station in lunar orbit and now we have an affordable transportation system for going to the Moon.
Before the Space Shuttle was retired we had the beginnings of a space tourism industry with people like Dennis Tito flying to the International Space Station. The cost for such a flight was $20 million. An air-launched reusable first stage launch vehicle flying to the lower end of a 380-kilometer long Skyhook equipped space station would cost 1/8th of that, or approximately $2.5 million. Obviously, there will be more people wanting to go into space at that price than for what Dennis Tito paid. Increased demand for flights will justify additional investment in the Skyhook to make it longer as a longer Skyhook will decrease the price even more. Every time the price goes down the demand for flights will increase. The increased demand will lead to further increases in the length of the Skyhook. Eventually, it will reduce the cost of a ride to orbit to $20,000 per person. That is what I call affordable to everyone spaceflight.
As the number of people in orbit increases, it will eventually become economically worthwhile to develop an off-planet source of consumables such as water and oxygen. No matter how affordable the combination launch system becomes, it will always be more affordable to get basics such as water, oxygen, and shielding materials from either the Moon or an asteroid due to the lower energy requirements for going to those places. Once we have access to those materials, building farm modules for growing food in space will also become worthwhile.
Having a NASA program for returning to the Moon or going to Mars will speed up the development of the combination launch system due to the increased demand for flights. This will speed up the pace of development in commercial manned spaceflight as well as reduce the cost of the NASA program. It is a win-win combination that will propel us into the solar system and kickstart the building of a spacefaring civilization.
We are that close to making it all happen.