SpaceX has been announcing very ambitious goals such as starting to send manned missions to Mars in order to (eventually) create a colony, and recently there has been a substantial release of more technical details about this plan (see links at the the end). As quoted in Spaceflight Now's article SpaceX’s Elon Musk announces vision for colonizing Mars:
SpaceX plans to launch its first mission to Mars, a robotic test flight with a modified Dragon capsule, as soon as May 2018. After that “Red Dragon” flight, Musk said SpaceX’s goal is to send at least one spacecraft to Mars during every interplanetary launch opportunity, which come every 26 months or so.
The concept detailed Tuesday features a huge rocket standing 400 feet (122 meters) tall, and a fleet of passenger-carrying spaceships and refueling tankers.
Musk’s long-term vision is to build a self-sustaining civilization on Mars, complete with “iron foundries and pizza joints.” Eventually, it might have a million residents or more.
“When will we reach that million person threshold? It’s probably between 20 and 50 total Mars rendezvouses,” Musk said, counting Mars launch windows occurring every other year. “It’s probably anywhere from 40 to 100 years to fully achieve a self-sustaining civilization on Mars.”
He counts those numbers from the time of the first crewed flight, which might some as soon as the 2020s.
“We aspire to launch in late 2024 with an arrival in early 2025,” Musk told reporters after his presentation at the International Astronautical Congress in Guadalajara, Mexico. “That’s optimistic, so I would describe that as an aspiration and within the realm of possibility, but a lot of things need to go right. That said, I don’t think it would be significantly beyond that if it did go later.” (emphasis added)
This seems really soon. Has technology advanced enough for this type of mission to be fulfilled - transporting astronauts all the way to Mars, and (presumably) returning them safely home again? And what about the radiation problem in the trip?
Question: Based on the more detailed information available by SpaceX recently, what are the most difficult challenges that SpaceX faces accomplishing this goal by 2025, or not "significantly beyond that"? Are there any obvious technology or logistic "show-stoppers" that could make this goal convincingly untenable?
More about the plan can be found on the SpaceX page http://www.spacex.com/mars and a link to a PDF of Elon Musk's position paper Making Humans a Multi-Planetary Species can be found at http://online.liebertpub.com/doi/full/10.1089/space.2017.29009.emu