My love affair with Mars goes back decades, when I'd hang out with members of the Mars Underground, a small group of University of Boulder science alumni who ate, talked and slept Mars. Then came the excitement of annual Mars Society meetings, the name of which says it all. More recently, I've been speaking and writing on the dream of humans landing on, exploring and, inevitably, terraforming (creating an Earth-like environment) the planet. Seems Elon Musk has been swallowing the same pills I used to, since he's proposing to have a self-sufficient colony of a million Earthlings living on Mars by 2050, transported there by a thousand-strong fleet of SpaceX Starships. If only.
Over the last few years, slowly but surely, reality has overtaken the dream. At this point, I can't see a manned mission to Mars happening anytime in the next 50 years. As for colonization, it's centuries from now, if ever. Terraforming? We're looking at a timescale measured in, not hundreds, but thousands of years. Here's what I'm basing my pessimistic assessment on:
Getting there: The only practical way ("Hohmann transfer orbit") to get to Mars is to take advantage of regular launch windows, which occur every 26 months. It will still take nine months each way, and a return trip — launch to touchdown back on Earth — will take 34 months, with 16 months spent on Mars itself.
The difficulties are enormous. For instance, radiation: No humans have spent an extended period outside of the womb of Earth's protective magnetic field, which (along with our thick atmosphere) protects us from the worst of the sun's UV rays and from energetic gamma radiation from beyond our solar system, aka cosmic rays.
Then there's the nine months, each way, of weightlessness, which International Space Station astronauts have to deal with; our bodies evolved to pump blood and water around in a 1-G environment. When weightless, bodily fluids flow to the head and upper body. The brain sits higher in the skull and eyes flatten, causing vision problems. Even with two or more hours of hard exercise everyday, bones still atrophy and ISS crews take months to recover their previous fitness after returning to Earth.
The Biosphere 2 experiment showed just how psychologically fraught a trip to Mars could be. In the early 1990s, four men and four women, all highly motivated and chosen for their ability to adapt and to get on with others, spent two years in the Biosphere 2 enclosure. Their experience was, to put it mildly, disastrous. They barely made it, exiting in two dissonant groups (think Lord of the Flies) who wouldn't speak to each other. And they were living in a luxury environment compared to the crew quarters of any proposed Mars vessels.
Landing: Only 40 percent of attempted landings on Mars have been successful. The EDL (entry-descent-landing) challenge is enormous, especially when compared with landing on the moon, where you just need a reliable retrorocket. For Mars, you're hitting the planet's thin (less than 1 percent that of Earth) atmosphere at around Mach 2, enough to burn you up but not enough to slow you down efficiently. We've used combinations of airbags, a "skyhook" crane, retrorockets and parachutes, all of which involve hundreds of perfectly timed sequences. If any one of these fails, the crew wouldn't survive.
Living on Mars: Where to start? Radiation on Mars is about the same as in space. In Mars' thin atmosphere and without a magnetic field to deflect ionizing radiation, any life on Mars would be fried. There's talk of finding caves or building dirt-covered shelters, but anyone on the surface will be in immediate danger. (I don't think living like troglodytes for a year or so is on the agenda.)
More challenges next week.
Barry Evans (he/him, barryevans9@yahoo.com) believes that the very worst day on Earth (nuclear war, global warming, pandemic ...) would be better than the very best day on Mars.