Mars is within reach

From our Expert Voices conversation on travel to Mars.

To make a Mars mission a reality, we will lean on four main capabilities:

1. Controlled hypersonic flight of slender-body vehicles. SpaceX has successfully brought back the first stage of their Falcon 9 rockets, testing on both a droneship at sea and a landing pad near their launch site.
2. Supersonic retro-propulsion. For large objects, parachutes and other familiar landing systems won't work on the Martian surface. We'll need a new landing propulsion in which a rocket engine descending at supersonic speeds is ignited in order to slow down for landing.
3. Full and rapid reusability of rockets and spacecraft. Aircraft-like operations will be essential in keeping down costs.
4. Refueling in orbit and on planetary surfaces. We'll need to "live off the land" as much as possible. That means, for example, turning Mars' atmosphere into rocket fuel and launching fuel tankers into space to refuel a primary ship.

SpaceX has already demonstrated the first and second of these capabilities and efforts on the third are progressing. The refueling challenges are trickiest—they will require complicated on-orbit and on-surface operations that involve engineering and procedures yet to be developed.

What's next: While the timeline and capabilities are certainly ambitious, the U.S. aerospace industry has demonstrated it is ready to lead us into this exciting future.

Other voices in the conversation:

• Francis Cucinotta, radiation researcher, University of Nevada, Las Vegas: There are too many unknown health risks to go to Mars soon
• Kate Greene, writer and former physicist: It's not just rocket science