Elon Musk is setting dates: He intends to send one of his Optimus humaniform robots to Mars aboard SpaceX's Starship in 2026, to be followed by humans "no later than" 2031. If he can pull this off, it's a big deal for a number of reasons. 

Elon Musk has confirmed that SpaceX’s Starship will head to Mars at the end of 2026. The ship will be carrying Optimus, Tesla’s humanoid robot. The tech billionaire said that if all goes well, humans could be on the red planet by 2029, although he admitted that 2031 is more likely.

The X account for Optimus replied to Musk’s announcement with just two words: "Hold on."

Musk announced the plan on his X account.

Starship departs for Mars at the end of next year, carrying Optimus.

If those landings go well, then human landings may start as soon as 2029, although 2031 is more likely. https://t.co/JRBB95sgNN

— Elon Musk (@elonmusk) March 15, 2025

Optimus, the android explorer, replied, no doubt assisted by a human:

Hold on

— Tesla Optimus (@Tesla_Optimus) March 15, 2025

This, of course, presents enormous technical challenges. Also, there are major biological challenges if Musk intends to send humans to Mars. But SpaceX has already surmounted many technical challenges.

"Starship is the world’s most powerful launch vehicle ever developed, capable of carrying up to 150 metric tonnes fully reusable and 250 metric tonnes expendable," SpaceX writes on its website. In US tons, that is up to 165 tons of fully reusable and up to 275 tons expendable.

Aside from providing the lift capacity, there are other issues. Shipping a robot to Mars isn't anything new; NASA has already done that, although the Optimus robot, being a humaniform robot, or android, puts a new aesthetic angle on the whole thing. But sending humans to Mars - that's a whole new kettle of spacefaring fish.

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Shipping humans to Mars will be the greatest technological flex mankind has pulled off to date. Not only do these people need to have food and water for the entire trip, including any time spent on the Red Planet, but they will have to be shielded from hard radiation, again including time spent on Mars. The red planet has no magnetic field, as Earth does, to deflect solar radiation and cosmic rays, which presents a serious health hazard.

A permanent human colony on Mars, which Elon Musk has also said he would like to make happen, is an even greater challenge, with all of the factors above, added to the fact that the Martian soil may not support plant growth for food without extensive addition of nitrogen and fertilizers, which would have to be shipped to Mars. Also, the fourth planet has only 38 percent of Earth's gravity; any human colony there, after a couple of generations, would consist of people that probably look very different than the people remaining on Earth - taller, with longer limb bones, and less muscle mass. In fact, second or third-generation Martians would likely be unable to ever visit the home planet, as Earth's gravity might kill them.

We shouldn't underestimate Elon Musk and his organization's ability to overcome technical obstacles. The biological obstacles, though, that's a different story.

This seems appropriate.