The problem with money and Mars is that the estimated money for a Mars mission seems to quickly spiral out of control. NASA estimated the cost per person during the Bush administration to be about $100 billion per seat. However, Elon Musk wants to take people to Mars for the cost of a house, and that is approximately $500,000. Here is the grand plan.
Reducing the cost per person
The key players
This is a key concept and there has been considerable progress on this front. A few private companies have tried to land their rockets, such as Blue Origin and SpaceX. Both have been successful.
SpaceX now boasts of having landed their first stage seven times (at the point of updating) out of twelve attempts. They have accomplished this feat both on the land and in the sea. They have landed the first stage and used the same one to deliver supplies again. Their next target is to land and launch within 24 hours.
Their official plan for the future:
Colonizing Mars (thanks Prof Hubbard for creating this from my talk). Major changes to the plan coming soon. https://t.co/s59qMHUj5O
— Elon Musk (@elonmusk) June 17, 2017
Blue Origin, funded by Jeff Bezos, has also accomplished this feat.
As of 2016, they have accomplished the feat 4 times. However, it would be unfair to compare them to SpaceX, considering that SpaceX’s rockets go higher than Blue Origin’s do, deliver payload to the ISS, and use the process of supersonic retro propulsion to land, as opposed to Blue Origin’s parachute.
You may well point out that the much-hyped Space Shuttle was also reusable. However, it required extreme refurbishment, often lasting 6 months to be able to fly again. Additionally, it was only partially reusable. The Space Shuttle main engines and the Orbital Maneuvering System engines, as well as the two solid rocket boosters, were reused after several months of refitting work for each launch. However, the external tank was discarded after each flight. And it obviously was not meant to even go further than Low Earth Orbit. (LEO)
How it will reduce costs
To demonstrate this point, I would like to take the example of the aviation industry. Airplanes are entirely reusable, and therefore a trip to the USA from India costs just a thousand dollars. The point to be made here is that if that the airplane was not reusable, then the same trip would cost the same amount of money it took to build the plane in the first place, which is in excess of a 100 million dollars. Keep in mind that the majority of the launch cost comes from building the rocket, which flies only once. The cost of manufacturing a Falcon 9 is surprisingly equivalent to the cost of manufacturing a Boeing 747. Similarly, if perfectly reusable rockets were to exist, then the factor by which cost per flight would reduce would be roughly equal to the number of times it was reused. If a rocket was used twice, the price would be halved. If it was used 10 times, then the cost would be reduced by a factor of 10. But Elon Musk likes to go grand. Eventually, he wants to build the ITS (Interplanetary Transport System) rocket (pictured above) such that it can be used at least a 100 times with a few repairs, reducing the cost by a factor of a 100.
“If one can figure out how to effectively reuse rockets just like airplanes, the cost of access to space will be reduced by as much as a factor of a hundred. A fully reusable vehicle has never been done before. That really is the fundamental breakthrough needed to revolutionize access to space.”
Taking a lot of people
First off, this is not happening anytime soon. Or anytime during the early stages of Mars exploration. It will happen only after:
- We are comfortable with launching rockets to Mars
- We are comfortable with reusing those rockets
- We have established a base on Mars
- There is interest in the common masses to go to Mars
After reaching that point, however, with a clear intention of establishing a self-sustaining colony on Mars, we will have to take a lot of people with every launch.This is because Mars and Earth often wind up far away, due to their orbits, and therefore a real launch window opens up only every 26 months. Elon Musk’s envisioned ITS (Interplanetary Transport System), or the rocket we have been talking about, should be able to take a 100 people, which reduces the cost by a factor of 20. As we get more comfortable with this technology, we would send an even larger fleet of numerous rockets. That again is far, far into the future.
Reducing the cost per kilogram of payload
We also need to look the cost per kilogram of payload launched. This will help us maximize the payload we can take. Maximizing payload is important because you get to go only once every 26 months and when you go you want to take as much equipment as you can. Current launch prices to LEO are about $10k/kg, though SpaceX quotes about $4,600/kg, provided you buy a lot of kilograms. Generally speaking, a rocket can get about 1/4 to 1/3 of its LEO mass to Mars, though landing it is not a precise science and would depend greatly on the size of your payload. SpaceX quotes the Falcon Heavy for $135m can get 13,200kg to Mars (i.e. a loaded Dragon), though it isn’t clear if that’s payload on the surface. Realistically, a Falcon Heavy could deliver at most 3 or 4 tons of cargo to Mars. That implies a cost of $10.2k/kg including the spacecraft, or $45k/kg for the payload. Note that if you can reuse the vehicle 10 times, that price drops to about $5k/kg, which is Elon’s estimated cost. Note that while the ITS can be used only once per launch window (at most), the big booster can be used many more times than that.
What will happen
SpaceX plans to send a vehicle designed exclusively for the launch and short-term holding of propellants to LEO (Low Earth Orbit) for re-filling propellants in the spaceship. This tanker that will launch from Earth will then dock with the spaceship and transfer 380 metric tons of fuel. This process would repeat itself five times over, giving the rocket enough fuel to make the long trip to Mars.
This is remarkably cool, considering that this is not an artist’s impression. This was created using SpaceX CAD models, and this is exactly what will happen.
How this reduces costs
To escape from Earth into space, an object needs to achieve what is called escape velocity. Escape velocity is the velocity required to escape the realm of Earth’s gravity. Escape velocity is incredibly high, at 11.2 km/s. To put that into perspective, it is thirty-three times the speed of sound. Reaching such high velocities requires a lot of fuel. A lot of fuel means a lot of space to store the fuel. A lot of space to store the fuel means that there would mean lesser space to store other payloads, which proportionally increases costs per kilogram of payload sent to Mars. By not storing all the fuel at once, but refueling it in orbit, we maximize the payload, which effectively reduces the cost/kg.
Note: This was not originally a part of Robert Zubrin’s Mars Direct plan, but he said that if it was possible, then it would be cool.
Choosing the right propellant
So there are only three main choices for the fuel. A few parameters decide if a rocket fuel is suitable for a Mars mission, which includes:
- Vehicle size
- Cost of propellant
- Mars propellant production
- Propellant transfer
This was well demonstrated in Musk’s presentation at the Space Congress in Mexico, at 14:26.
Let me summarize what he said:
- Helps keep the vehicle size small
- Very expensive
- Difficult to make on Mars due to lack of oil
- Difficult to keep from boiling due to low boiling point
- “Energy” cost of producing hydrogen on Mars is high
He thus settled on using a combination of CH4 and O2 ,also known as deep cryo-methalox as a rocket propellant.
Propellant production on Mars
Storing all the fuel for a two-way trip obviously takes twice the space it takes to store all the fuel for a one-way trip. More fuel reduces the space for other payloads, which increases the cost per kilogram of payload. Therefore, Robert Zubrin, in his Mars Direct plan, proposed a radical solution.
He envisions that a chemical reactor will begin creating rocket fuel (methane) and water as soon as it lands on Mars in one of the pre-supply missions. The reactor will carry out a reaction known as the Sabatier reaction to produce the methane.
CO2 + 4H2 → CH4 + 2H2O
Now, remember, this works because the Martian atmosphere contains approximately 95% carbon dioxide, and can, therefore, be obtained very easily. The hydrogen required is only about 5% of the total propellant weight and can, therefore, be easily imported from Earth.
Next, comes the question of the hydrogen. Where do we get the hydrogen from after the imported stock runs out, without which the process becomes unsustainable? Well, we electrolyze the water produced from the above Sabatier reaction.
2H2O → 2H2 + O2
The oxygen thus produced is stored, and can be as rocket fuel.The hydrogen is put back to facilitate the Sabatier reaction. Oxygen and methane thus produced are stored as rocket propellant for the trip back. After six months of this and other processes, the 6 tons of liquid hydrogen originally sent becomes 108 tons. That’s an eighteen-fold increase.
An added benefit of the methane/oxygen combo is that it can be stored at cold temperatures. The ability to produce methane at really cold temperature makes it a really efficient fuel.
This is an important part of in-situ resource utilization (ISRU), which is exactly what is sounds like. It quite literally is defined as the harnessing of resources naturally found at the exploration site (in situ), that replace materials that would otherwise be brought from Earth. And that is what we have just demonstrated above.
Part 2.1.3- The funding
This part remains unclear, as yet, but Musk predicts that the money will have to be a mixture of private and government investments. He also looks towards crowdfunding,and the money SpaceX makes in the launch business as potential revenue sources. I would envision something like an International Mars Science Foundation, as depicted in the MARS series on National Geographic, some kind of a multi-national, multi-company consortium contributing money and resources to the cause. SpaceX is planning to have a crewed mission to the ISS as soon as 2018.
The Mars One funding model is a little weird if you will. This is what their website actually says:
“To most investors in Mars One Ventures however, a positive return on their investment is more important than the actual mission success. A viable business case that projects a solid return on investment even if the Mars mission wouldn’t progress as scheduled, is therefore essential to successfully attract investments.”
While appreciating their unparalleled transparency, the funding model is not feasible, and I predict that the Mars mission that actually gets off the ground, will have a significantly different funding plan.
Musk hopes to get money mainly from launching satellites, and launching cargo and astronauts to the ISS, which is what SpaceX is currently doing. He also pins his hopes on some kind of a crowdfunding campaign. Come to think of it, it’s actually a good idea.