We’ve already seen Elon Musk roll out the design for his Mars spaceship, but we’re still waiting for NASA to show off the ship future astronauts will take to the Red Planet (oh, and the concept art above is circa 1989, for the record).

The space agency has contracted with six different firms to develop potential deep-space habitats as part of the NextSTEP program, which is essentially a bridge to an eventual deep-space craft. The goal will be to put one of these habitats in space near the moon, and let it serve as a destination for astronauts to visit while NASA tests out all the tech they want to use to get to Mars (and beyond). If the final design works out, NASA could use it as a framework for a habitat on its eventual deep-space craft.

The six companies developing the habitats include Boeing, Lockheed Martin, Bigelow Aerospace, Orbital ATK, Sierra Nevada Corporation and NanoRacks. According to Ars Technica, the companies will get $65 million to refine their designs and build a ground-based prototype for testing. Construction on flight hardware for the winning design is slated to kick off in 2018. The goal would be to actually launch it by the mid-2020s, where it could be used to help train future astronauts and test out equipment for deeper missions.

The NextSTEP program is just that, a next step, as NASA tries to figure out how it will actually get humans to Mars. If all goes as planned it could be a very big step, too.

Check out the six designs below and let us know who you’re pulling for: