SpaceX installed 29 Raptor engines overnight on Booster 4, being built now at Boca Chica. Staff were reportedly moved to Boca Chica from other SpaceX sites to speed up the process. (Teslerati) This is an extraordinary pace. Musk is clearly determined to get Starship into orbit as soon as possible. His problem is that even a few months' slippage will cause the whole program to be retarded by more than 2 years, because Earth and Mars are only in 'orbital sync', or 'in opposition' as astronomers refer to it, every 26 months. These are the points when Mars and Earth are closest. If SpaceX misses the 'orbital sync' at the end of 2022, the next one will only take place in early 2025.
The original plan, back in September 2017, when Musk announced the Starship (then called BFR) program to a mostly disbelieving public, was to send 4 cargo BFRs in late 2022 and 2 crewed BFRs in early 2025. As an aside, SpaceX will have gone from announcing the BFR in September 2017 to the first orbital flight (prolly August/September 2021) in just 4 years, during which the company pivoted from carbon fibre composite to steel, which must have set them back by many months.
The switch from carbon fibre to stainless steel reduced the capital cost per Starship perhaps 60-fold. So, SpaceX could send 20, 30 or even 60 times as many Starships to Mars for the same cost as the total of 6 it planned to send in 2017. Scale will be important, perhaps crucial. The new settlers will need food for 26 months (until the next expedition from Earth) just in case something goes wrong with the food greenhouses, plus wind turbines, solar panels, NASA's nuclear power plants, rovers, medicines, etc.. Sending more crew allows for more specialities. 500 crew instead of 100 means that, for example, there can be a surgeon as well as a doctor.
But what about timing? Can the original dates of end-'22 (Cargo) and early-'25 be realised? Musk has been tight-lipped about that. I suspect it will be essential that uncrewed landings on Mars take place to check whether Starship's 'belly-flop' landing technique works as well there as it does here on Earth. And since the 'orbital sync' window is shorter than the journey time there, it won't be enough to launch cargo versions at the beginning of, say, a 3 month window and send crewed ships at the end of the window, because the cargo ships would not yet have reached Mars. So if a crewed expedition to Mars is to take place in 2025, it will be essential to send a test mission in 2022. And those test ships might as well carry cargo. At SpaceX's construction speed, which will likely be speeded up,
My new timetable then is something like this:
Q4 2021: first orbital launch of the full stack (Starship and Super Heavy)
Q3 2022: launch of test/cargo fleet. They will probably be launched at 2- or 3-day intervals so that later ships can 'learn' from the successes and failures of earlier ships.
2023: 'Dear Moon' circumlunar expedition.
H1 2024: Artemis 3. NASA's plan to land astronauts on the Moon for a permanent base. This involves various frills such as an orbiting lunar space station, which may change if Starship works. SpaceX has the contract for the moon lander, which is in fact a modified Starship which could do the whole journey from Earth, so ....
Q4 2024: first crewed expedition to Mars.
Q1 2025: first humans on Mars
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