From SpaceX we get the following statement:
“Aspirationally, we want to get Starship to orbit within a year. We definitely want to land it on the Moon before 2022. We want to […] stage cargo there to make sure that there are resources for the folks that ultimately land on the Moon by 2024, if things go well, so that’s the aspirational time frame.”
That is quite aspirational. People have mixed feelings about Elon Musk, who tends to dream big but not always deliver. But sometimes he does, and SpaceX has perhaps been his most successful endeavor. His goal is to make commercial spaceflight practical and reduce the cost of getting into space. His primary mechanism for that is the development of the reusable rocket, which SpaceX has perfected. By now you have probably seen video of SpaceX rockets landing vertically. To me that accomplishment wins Musk an eternal place in the pantheon of awesome people.
A the very least that has earned him the right to be taken seriously when he states his next big goal for space. SpaceX has developed the Falcon 9 followed by the Falcon Heavy, both of which have been flying successfully with many recoveries of the rocket boosters, as they were designed. They have also developed the Dragon capsule, which has successfully autonomously docked with the ISS, and is able to deliver and return cargo. The first crewed mission is scheduled to go up in 2020, and that will hopefully end our dependence on Russia for lifts to the space station.
Meanwhile NASA is developing its Orion spacecraft system, with the first crewed flight of its new capsule slated for 2022. NASA originally planned to return to the Moon by 2028, but the Trump administration arbitrarily asked them to move that up to 2024. NASA is dutifully complying, but many are skeptical they will be able to achieve that accelerated timeline.
On top of all this SpaceX is developing an entirely new spacecraft, called Starship. This is a completely independent system, so it will not use any of the major components from the Falcon, Falcon Heavy, or Dragon capsule (although it does use the same raptor engines). Starship is a two-stage system – there is the Starship spacecraft and the Super heavy rocket, collectively referred to as Starship. The Super heavy rocket will get the spacecraft into Earth orbit and then return and land to be reused. The Starship spacecraft will then be able to travel into higher Earth orbit, return to Earth for fast long-distance travel, or travel to the Moon, Mars, or other deep space destinations.
The top third of Starship is for crew or cargo, with various possible configurations. The lower two-thirds are for fuel. The craft will be able to land intact on the Moon or Mars and then lift off again for return to Earth, and ultimate reuse. The Starship is what SpaceX plans to take to the Moon by 2022.
I was surprised when I heard that the Starship will be built mainly out of steel alloy. More advance carbon fiber materials are lighter for the weight, but they are much more expensive. Again – one of Musk’s goals is to make getting into space as cheap as possible. Musk also touts the fact that steel alloys could withstand much higher operational temperatures than carbon fiber. Carbon fiber taps out at about 200 C while steel can go to 870 C (depending on the alloy).
As a side note, everyone (including Musk) refers to the material as “stainless steel” but I wonder if that will be literally true. Stainless steel is a steel alloy with, by definition, a minimum of 11% chromium. Chromium as an alloy makes the steel corrosion resistant (and shiny) and can increase its hardness, but also makes it more brittle. Jet engines, for example, use superalloys of steel with mostly nickel. I would be interested to learn what the ultimate alloy used in the Starship construction is.
As a cool side effect of this choice, the Starship looks like a retro-futuristic rocket from a science fiction movie in the 1950s.
One side of Starship will also be covered in glass tiles for atmospheric reentry. Musk says they are also planning on a new design for heat control, transpirational cooling. This involves two layers of steel with either water or fuel between them. The liquid heats up and then evaporates through micropores in the outer steel layer.
Sounds like SpaceX still has a lot to work out, and we do not have an actual Starship built yet. By calling their timeline “aspirational” they are also clearly hedging their bets. But even if they run over by several years, and this goes for NASA as well, it seems very likely that humans will be stepping on the Moon again sometime in the 2020s. The next decade will not only likely mark NASA’s return to the Moon, but the beginning of private commercial flights to the Moon.