NASA just announced which companies are going to supply the International Space Station through 2024 -- and there's a surprising addition

On Thursday, NASA announced the awardees of its second round of Commercial Resupply Services (CRS2) contracts, which will cover cargo deliveries to and from the International Space Station (ISS) from 2017 through 2024.

Compared to the CRS1 contracts, this second round includes three awardees instead of two. The winners are: Orbital ATK, SpaceX, and new kid on the block Sierra Nevada.

These contracts are a lucrative agreement wherein NASA pays commercial spaceflight companies to fly unmanned cargo deliveries to, and sometimes from, the ISS.

The mission are critical to the relevance of the ISS as an international science laboratory. Without these missions, NASA would have no way of delivering or returning science experiments to and from space.

The biggest difference between the CRS1 and CRS2 contracts is that NASA chose to award three companies this round instead of two.

NASA officials said the reason for adding a third was to maximise the agency’s flexibility.

“This offers really great flexibility for us to execute the ISS program,” Kirk Shireman, who is ISS program manager, said during a press event on Thursday. “By choosing the various companies, we have more options for various types of missions.”

Moreover, three companies beats two since both Orbital ATK and SpaceX were temporarily grounded, or unable to fulfil their CRS1 contracts on time, after rocket explosions in 2014 and 2015, respectively. Both companies have since gotten back on their feet and are well on their way toward continuing their contracts with NASA.

NASA did not announce how much money they’re awarding each company, instead saying that it will depend on the types of missions they contract in the future. Shireman did, however, say that NASA’s maximum budget for the contracts is a hefty $14 billion, but added that the agency doesn’t expect to spend all of that on CRS2.

“The total cost paid will depend on which mission types are ordered,” Shireman said.

For an idea of what the companies might see, the CRS1 contracts provided Orbital with $1.9 billion and SpaceX with $1.6 billion.

Under the contract’s guidelines, each company will be commissioned for at least six trips to the ISS. One advantage that Sierra Nevada brings to the table is the ability to return cargo from space back to Earth.

Before, SpaceX was the only contracted company that could do that, but Sierra Nevada’s Dream Chaser spacecraft can land on a runway after returning from space, similar to how NASA’s Space Shuttles landed.

This is great for science experiments that focus on the biological impact of low-gravity, ISS Chief Scientist Julie Robinson said.

With a spacecraft like Dream Chaser, scientists will be able to get their data three to six hours after it has left space, which will give them the chance to witness how quickly the genes in plants and animals adapt to gravity on Earth compared to in space, explained Robinson.

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