If you think flying to Hawaii or Australia is a long trip, look at the out-of-this-world vision being discussed by Boeing and a smaller company called SpaceX: They envision civilian flights to Mars as soon as next decade or two. The billionaire founder of SpaceX, Elon Musk, recently told International Astronautical Congress delegates in Mexico about ambitious, costly plans to colonize Mars. Now the chief executive of Boeing announces that his company also plans to shuttle paying passengers to the planet.

Musk promotes a science fiction-like image of a self-sustaining city on Mars and people going there via SpaceX rockets with 100 seats each. The first "Interplanetary Transport System" rocket could launch as soon as 2024 if the plans – and undetermined financing – come together smoothly, Musk says. His company is financing preliminary development and counts on some kind of government partnership eventually, plus payments from companies that will be "anchor tenants" of a Mars colony. Passenger tickets might cost $500,000 apiece at first, and drop to about a third of that later on, speculates Musk, who earlier developed the Tesla electric car.

NASA, the U.S. space agency, last month said its goals include manned missions to orbit Mars in the 2030s and a landing in the 2040s via a Space Launch System rocket that Boeing is starting to build as a government contractor. Dennis Muilenburg, the Seattle firm's top leader, spoke this month at a Chicago conference about a not-so-distant time when humans can travel easily to Mars and even other planets – which he describes as "space tourism." Boeing, a longtime NASA partner, built the first stage for the Saturn V, a rocket that took American astronauts to the moon six times from 1969 to 1972.

Boeing executive says: "I'm convinced that the first person to step foot on Mars will arrive there riding on a Boeing rocket." – Dennis Muilenberg, chief executive

SpaceX founder says: "As we show this is possible, that this dream is real, I think the [financial] support will snowball over time." – Elon Musk

Tech journalist says: "The hottest topic in space exploration today is Mars. . . . There appears to be serious momentum from serious players about mounting missions to Mars." – Bill Roberson of Digital Trends website