The International Space Station has been continuously occupied by spacefarers from countries around the world for the last two decades, but it's time among the cosmos won't last forever.

Even now, NASA is laying the groundwork for plans to safely deorbit and land the low-Earth orbit space station, the largest of its kind ever built.

Private companies have until Feb. 12 to submit design proposals for "a new or modified spacecraft using a large amount of propellant" that in the years ahead, will be tasked with docking with the space station and safely crashing it into an ocean. NASA plans to award the contract in June for the vehicle, which will be deployed upon the space station's impending retirement in 2030.

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What is the International Space Station?

Designed and operated thanks to a global partnership of space agencies, the International Space Station has been home to crews of astronauts, cosmonauts and plenty of others since November 2000, NASA says.

More than 260 spacefarers from 20 countries have visited to the International Space Station, including 163 from the United States alone, according to the U.S. space agency.

Crew members who live and conduct scientific experiment aboard the space station orbit Earth 16 times a day. The orbital outpost is larger than a six-bedroom house with six sleeping quarters, two bathrooms, a gym, and a 360-degree view bay window, according to NASA.

Since 1998, more than 260 spacewalks have been conducted at the International Space Station, including a rare all-female spacewalk in November.

In September, a U.S. military astronaut named Frank Rubio was stationed aboard the space outpost when he made history as the American with longest consecutive spaceflight. Rubio spent a U.S. record of 371 days in space after the capsule meant to ferry him back to Earth, a Russian Soyuz, sprang a coolant leak in 2022, which doubled his stay.

The current Expedition 70 crew began their stint in late-September and are scheduled to land in spring. While aboard the station, the seven astronauts and cosmonauts have been conducting a variety scientific experiments and studying an array of microgravity phenomena.

What is the timeline for ending the International Space Station?

Decommissioning the aging cosmic outpost is the shared responsibility of the five space agencies that have operated it since 1998: the United States, Russia, Europe, Japan, and Canada.

All of those nations have committed to supporting the International Space Station operations through 2030 with the exception of Russia, which has agreed to keep going only until 2028, according to NASA.

How will NASA land the space station?

NASA examined several options for decommissioning the International Space Station, including disassembling it while in orbit, boosting it to a higher orbit and allowing it to decay naturally before randomly re-entering Earth's atmosphere.

Many of those options presented "significant logistical and financial challenges" for a space station as large as an American football field, NASA said.

Its modules and truss structure were not designed to be easily disassembled in space, while allowing for an unplanned atmospheric re-entry posed too much of a threat to populated areas. Further, objects that are retired to the safer high "graveyard" orbits are typically smaller satellites, not massive outposts, NASA said.

Such considerations were why the space agency decided that a controlled, targeted re-entry ending in a crash landing into a remote ocean was the safest route.

Whichever private aerospace company is selected by NASA will build a deorbiting craft capable of performing a "propulsive maneuver" to line up the re-entry path into the desired uninhabited waters.

Many of the space station's modules and hardware are expected to burn up, melt away or vaporize upon re-entry. The denser and heat-resistant components that may survive the plunge will splash down into the ocean, where they are expected to harmlessly sink to the ocean floor, according to NASA.

What comes after the ISS?

In the months and years ahead, the United States will shift its focus to commercial operations and contracted missions.

That includes funding and enabling private industry to develop commercially-owned-and-operated space stations, NASA says.

"It is NASA’s goal to be one of many customers in a robust commercial marketplace in low Earth orbit where in-orbit destinations as well as cargo and crew transportation, are available as services to the agency," NASA said in an explanation of its transition plan.

Partnering more often with private industry will hopefully free up NASA to focus on building spacecraft and rockets for deep space missions, including human missions to the moon and Mars.

Artemis moon mission delayed another year

As part of its ongoing Artemis program, the agency had hopes of sending a group of spacefarers on a 10-day trip circumnavigating the moon as early as November. However, the target date for Atemis II was pushed back last week to no earlier than 2025 "to allow teams to work through challenges associated with first-time developments, operations, and integration," NASA said in a statement.

The mission would pave the way for Artemis III, when another group of astronauts will venture to land on the lunar surface itself. That mission, which has experienced setbacks, was also delayed until no earlier than 2026.

The announcement came on the heels of the news that the first American attempt to land a commercial spacecraft on the lunar surface would likely be unsuccessful. NASA spent tens of millions of dollars for a spot for its scientific cargo on Pittsburgh-based Astrobotic's Peregrine spacecraft, which faltered on its journey to the moon when it encountered an issue with its propulsion system.

Eric Lagatta covers breaking and trending news for USA TODAY. Reach him at [email protected]