Spacex Chief tech officer Tom Mueller discussed the next-gen Falcon 9, called the "Block 5," which will have a reusable thermal protection that won't burn up the heat shielding. It will also have retractable legs that will only come out during landing. The Falcon 9 Block 5 will have a 24-hour turnaround and be much cheaper and is expected to be flying by the end of 2017.

With a cheaper design comes a few tradeoffs. The Block 5 has a single Merlin engine on it, although it's a fairly sophisticated version of the engine. It uses some of the same tech — like the guidance computer — from the Falcon 9 (which has 9 Merlin engines), though. Mueller says the Block 5 has a significantly lower cost but the performance is "marginal."

The Falcon 9 Block 5 is expected to be far more reusable than the Block 3. Shotwell said a Block 5 booster could relaunch " a dozen or so times." The Block 3, by comparison, has an estimated life of two or three missions.