November 30, 2019 • Evelyn J. Arevalo
Elon Musk envisions a future where humans are multi-planetary species. His ambitious goal is building a sustainable city on Mars before the year 2050. Musk mentioned that one of the long-term plans for SpaceX, his aerospace company, is to develop a system so that rocket flights will be zero net carbon. This could transform spaceflight into a more eco friendly venture --like his electric company, Tesla. Developing an environmentally-friendly rocket would be a huge breakthrough in the space industry. Musk stated:
"Sometimes I get criticism for, ‘why are you using combustion in rockets and you have electric cars’. There isn’t some way to make an electric rocket. I wish there was. But in the long-term, you can use solar power to extract CO2 from the atmosphere, combine it with water, and produce fuel and oxygen for the rocket."
In reality, SpaceX rockets contribute significantly less emissions than all the commercial airlines combined. The Falcon 9 Merlin engines use about ~156,000 kg of rocket kerosene (RP-1) during a single launch, versus a commercial airplane like a Boeing 737-800 uses approximately ~20,800 kg of Jet-A kerosene and flies every single day, several times per day. According to the International Air Transport Association, there over a hundred thousand commercial airplane flights a day, unlike rocket launches that do not occur every single day. In a single year, the airplane industry flies about 50 billion times per year, significantly contributing to carbon emissions.
SpaceX has definitely been working hard towards the development of a new kind of engine in rocketry. Their new rocket engine, the Raptor, uses a unique kind of propellant that will eventually make spaceflight more eco-friendly, by working along a carbon capture system.
Their new craft, Starship, that is under its early stage of development will utilize Raptor engines. The first prototypes are currently under construction at SpaceX's facilities in Texas and Florida. SpaceX plans to replace their current rockets, the Falcon 9 and Falcon Heavy, with this new craft one day.
Starship will be a massive vehicle consisting of a spaceship that attaches atop a rocket booster named Super Heavy.
Starship will be capable of carrying 100 passengers and tons of cargo to the Moon and Mars, solely powered by it's 6 Raptor Engines. The Super Heavy rocket is only needed to get Starship out of Earth's atmosphere, powered by 37 Raptor engines. This rocket will be reusable, capable of flying into space, then back, landing vertically at a spaceport pad on Earth in order to be reused again.
Raptor engines are a new kind of rocket engine developed and manufactured by SpaceX. Unlike any other rocket engines used today, Raptors are powered by a combination of liquid methane and liquid oxygen in a full flow staged combustion cycle. As cryogenic methane and liquid oxygen (LOX) react, in turn, water vapor (H2O) and carbon dioxide (CO2) are released upon combustion reaction. - Here's the plot twist - Musk said that SpaceX "is already developing high efficiency CO2 capture with H2O to form liquid CH4 (methane) & O2." So basically, the plan is to recycle carbon emissions by capturing them to utilize in fuel production. This would make Starship carbon neutral and rocket launches would become more environmentally-friendly flights!
Correct, pure electric. Wish orbital rockets could be so too, but there’s no escaping Newton’s Third Law. SpaceX is already developing high efficiency CO2 capture with H2O to form liquid CH4 (methane) & O2. Critical for propellant production at Mars Base Alpha.— Elon Musk (@elonmusk) June 10, 2018
Regarding this carbon (CO2) capturing process, someone asked Musk via Twitter: What "about carbon-capture-for-rocket-fuel that you hinted at before? I’ve always been interested in the ISRU side." (ISRU is the acronym for In-Situ Resource Utilization, which in the space sector it is the process of using resources found at the exploration location.) Musk responded:
"Sure. Have to do it on Mars from beginning. Will ultimately do that on Earth too, so rocket flights will be zero net carbon long-term."
Sure. Have to do it on Mars from beginning. Will ultimately do that on Earth too, so rocket flights will be zero net carbon long-term.— Elon Musk (@elonmusk) September 21, 2019
Propellant for Starship's Raptor engines could also be made on Mars upon arrival by capturing carbon dioxide from the planet's atmosphere and sub-surface ice water, to make liquid oxygen and methane. SpaceX teams could use electrolysis to split water into oxygen and hydrogen, and use the Sabatier process to transform carbon dioxide and hydrogen into water and methane. The Sabatier process involves the reaction of hydrogen with carbon dioxide at very high temperatures of about 300–400 °C and pressures in the presence of a nickel catalyst to produce methane and water.
Future Martians will be tasked with building a propellant plant to refuel and return to Earth. All of this process will be powered by solar energy, Musk mentioned that the plant would need somewhere between 1 to 10 megawatts of energy.
Depends on total system efficiency & how long the propellant plant can run to refill Starship, so 1 to 10MW as a rough guess— Elon Musk (@elonmusk) October 12, 2019
SpaceX also plans to develop an Earth-to-Earth version of Starship, that could one day make long distance flights in under 30 minutes! That is way quicker than any airplane trip today! That's why the technology developed for Mars' carbon capture, could one day be used on Earth to make fuel for more eco-friendly, city-to-city flights. [Read: SpaceX plans to fly you anywhere on Earth in under an hour using Starship]
The SpaceX carbon capture system along with the Raptor engine will completely revolutionize the spaceflight industry, making Starship the first carbon neutral rocket!