by Prasad Ganti
Space X recently launched its flagship rocket Falcon 9 to send cargo to the International Space Station. It was almost a routine launch, barely indistinguishable from the others except for one feature. The first stage of the rocket was flying for the second time. In essence it was being reused. This reuse planted a significant milestone in the history of space launches.
Space is a vastly complex business and very expensive too. Mainly due to the single use of the rocket which launches a spacecraft. In a multi stage rocket used to launch any significant payload, the first stage drops back to the Earth after giving a big initial boost to the payload. Typically, that dropping was into an Ocean or a Sea where it became debris. Space X in an effort to reuse the first stage, tried to take baby steps towards recovering and refurbishing the first stage.
After all, nobody uses a bus or a train or a plane or a horse for one trip only. But getting to the multi-use was not easy. The rockets which powered the spacecraft to the Moon in the 1960s and 1970s were all single use. An attempt was made to build a reusable space vehicle. The result was the Space Shuttle. It took off strapped to a rocket, and came back and landed like an airplane. It needed extensive refurbishment before launching again. Each of the hundreds of heat protecting tiles underneath the Shuttle had to be carefully inspected and replaced. Eventually, the economics did not work in its favor. Much like the supersonic Concorde airplane which does not run anymore. The Space Shuttle also got relegated to the museums like the Concorde.
Space X designed its first stage to come back and touch down gently either on a floating barge or on land. Success followed after initial stumbles. One of those recovered first stages was refurbished and used for the latest launch. That completed the cycle of recovering, refurbishing, and relaunching. This cycle is expected to be repeated over and over again to reduce the cost of future space launches.
The way Space X recovers the first stage is by leaving some fuel unburnt. After separation from the main rocket, the leftover fuel in the first stage is used to reignite the engines on the rocket in a series of burns, to help the vehicle reenter the Earth’s atmosphere and then slow down for landing. This technique is known as supersonic retro propulsion.
Now that the concept of recycling the first stage has been proven, SpaceX’s new goal is to begin reusing rockets within 24 hours of landing, with just an inspection and refueling like for many of the passenger and cargo jets.
Space X is not the only game in the town. Blue Origin, owned by Amazon Chief Jeff Bezos. Although Blue Origin rockets have not gone into space yet, but it did get to the edge of the space. And reused its New Shepard suborbital rocket five times last year. In the bargain, Blue Origin won the prestigious Collier Trophy. Collier Trophy is given for the greatest achievement in aeronautics or astronautics in America, with respect to improving the performance, efficiency, and safety of air or space vehicles. It is a healthy competition between the private space companies – Space X, Blue Origin, Orbital Sciences etc.
What happened to aviation a few decades back is now happening for space launches. Boeing 707 ushered in the jet age. Then Boeing 747 made cheap intercontinental travel possible. In the coming years, space is going to get its A380 and Boeing 787 Dreamliner. It is exciting times to be living in.
Amateur Astronomers Association of Princeton 