Here's how much it now costs for American astronauts to ride in Russia's spaceship

Soyuz russia roscosmos spaceship nasaNASAA three-module Soyuz spacecraft.

Tonight three people who have spent 172 days in orbit above the Earth will attempt to return home.

But they won’t be riding a US spacecraft.

NASA retired its space shuttle fleet in mid-2011. Meanwhile, commercial carriers like SpaceX and Boeing are still building, testing, and certifying their spaceships, respectively called Dragon and CST-100 Starliner.

Only one spaceship can launch people more than 200 miles above Earth, dock them to the International Space Station (ISS), and bring them back: a Russian spacecraft called the Soyuz, which first launched in 1966 and means “union” in Russian.

Russia’s space agency, Roscosmos, has upgraded the three-module Soyuz design several times over the decades yet has changed its core layout very little.

What it charges other space agencies per seat, however, has dramatically spiked in recent years.

Below is a chart that shows what Russia has historically charged NASA per Soyuz spot since 2006, plus what it plans to charge in the near future, according to a new report that NASA’s Office of Inspector General (OIG) released on Thursday, Sept. 1, 2016:

Chart showing how much Russia is charging NASA per seat for launching US astronauts.Skye Gould/Business InsiderHow much NASA is paying Russia for each US astronaut seat aboard a Soyuz spacecraft from 2006 through 2018.

The cheapest Soyuz seats ever were for NASA was $21.8 million in 2007 and 2008.

As soon as the space agency permanently grounded its space shuttles, though, Russia sharply raised the cost per seat. And it shows no signs of stopping while NASA, JAXA, and the European Space Agency wait for other options.

By 2018, NASA and its partners will have to pay roughly $81 million per person to ride a Soyuz to the ISS and back again — a cost increase of 372% in 10 years. (The total cost to NASA over 12 years will be about $3.37 billion.)

What will $81 million get you on a Soyuz?

One of the safest trips to space, yet cramped between avionics and bags of cargo — for anywhere from 6 hours to 2 days:

Soyuz astronauts cosmonauts russia roscosmos spaceship esa nasaESA/NASAAstronauts and a cosmonaut buckled into a cramped Soyuz descent module make for a very tight fit..

Companies like Space Adventures have also purchased Soyuz seats in the past, sending mega-millionaires like video game developer Richard Garriott up to the ISS.

But the outfitter’s next mission is far more ambitious: It intends to recreate the Apollo 8 mission of 1968 and launch a lucky passenger (and two cosmonaut accomplices) around the moon.

At $150 million per lunar-trip seat, it’s starting to sound like a bargain.

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