Traders on prediction market platform Kalshi see only an 18% chance the Elon Musk-led company gets to Earth's neighbor by 2030.

Today could be one of the biggest days in stock market history. After 24 years of anticipation, the SpaceX IPO finally debuted on Friday.

SpaceX's bold Mars vision faces scientific doubts. Experts highlight engineering challenges and human biology unknowns. Colonizing Mars presents immense hurdles. Musk's ambitious…