The chance that I live and work off Earth before I die.

That is by 2071. Nobody knows how long I get, so the dial lets you change that assumption and watch the odds move.

How long do I get? the W in the equation

If I live about as long as a man my age is expected to: roughly to 2071. This is the default, and the number I hold myself to.

39%I fly to space at least once

1.6%A Belt exists at all: people living past Mars

0.9%I'm out there working when it does

A Belter?

In the TV series The Expanse, Belters are the people who live and work in the asteroid belt, far from Earth. Stubborn, underestimated, at home where nobody thought people could be. I want to be one of them. This site works out, in public, how likely that is.

Who is asking

I'm John. I'm 40, I'm training to teach survival in the Air Force, and I'd like to leave the planet before I die. This is a scoreboard on my own long shot. Every year I re-check every link below, publish what changed, and let anyone argue with a number.

Why so low

Seven things all have to go right.

Each link below is a real thing that has to happen. Any broken link breaks the chain. That is the whole equation: multiply seven maybes together and you get a small number, even when no single link looks hopeless.

Odds shown by 2071
change the dial above to see them move

01L · Launch Getting to orbit has to get cheap. A fully reusable heavy rocket flying often, launch under $200 a kilogram, fuel transferred in orbit. 14% chance this link holds 02E · Energy There has to be power out there. A reactor running on the surface of the Moon. Solar gets thin past Mars. 66% chance this link holds 03D · Drive Ships fast enough to make the trip routine. Nuclear propulsion in regular use, and a permanent crewed site somewhere past the Moon. 9.4% chance this link holds 04B · Biology Bodies that hold up. Living off Earth long term by some route, radiation dose halved, life support that recycles for a year. 18% chance this link holds 05M · Motive A reason for people to go. Something made off Earth and sold at a profit, and a hundred people paid to work up there. 6.8% chance this link holds 06R · Regime Governments that don’t wreck it. Programs that outlive elections and recessions. Resource rights the big powers recognise. 36% chance this link holds 07A · Access A seat for me. A job whose holders rotate off Earth, reached through the training and choices I make now. 9.6% chance this link holds

Right now the weakest link is a reason to go, at 6.8%. The links lean on each other, so these are not independent dice; the honest math, with every one of the 60 smaller steps behind these seven, is on the numbers page. There is also an eighth thing I track and never multiply in. It is there too.

In the notation of the numbers page: P(Belter)= W × L × E × D × B × M × R × A with C beside it, never multiplied in

What would move it

Cheap launch and bodies that tolerate low gravity. Nearly everything else leans on those two. When either one moves, the number at the top moves with it.

What I can do about it

Only the last link is mine. I can choose the training I take and the jobs I chase, and the tree tells me which choices raise the odds. That is the real reason this exists.

Think I'm wrong?

Good. Every link has a page, a definition of what counts, and a number you can argue with. Changes get a line in the public changelog.

Argue with a link

Numbers from the run of 2026-09-19, 20,000 play-throughs of the tree per scenario. First pass, 2026-09-19. Under review by outside models before publication (roadmap step 27); every number may move. How the numbers are computed. What has changed.