Reusable Rockets – the Future of Spaceflight?
On 14 January 2017, SpaceX will attempt a 'return to flight' in their push to make reusable rockets the future of spaceflight.
The possibilities of self-landing, reusable rockets are one of the most exciting modern developments in space travel. If you listen to the leaders of private spaceflight companies, we are at the dawn of the interplanetary age. They estimate that within ten or twenty years people could be living and working in space, commuting back to Earth daily. They also claim that in less than twenty years anyone will be able to buy a holiday trip to space, for not much more than a family skiing holiday costs now.
If all goes according to plan, this month will mark the next big step towards that goal. As early as 14 January 2017 private company SpaceX will launch ten new satellites on top of their Falcon 9 rocket. The satellites are owned by Iridium Communications and will be part of Iridium’s constellation of 81 communications satellites in a low earth orbit. SpaceX has already confirmed that at least 70 of these satellites will be launched by SpaceX. A fairly routine launch then. But this month’s launch is important because it marks SpaceX’s return to flight after its last rocket exploded in a huge fireball on the launch pad last September 2016. If SpaceX wants to restore faith in their technology, then this launch will have to be perfect.
By far the most expensive part of space travel is the rocket and all the fuel that it takes to launch astronauts, equipment, and technology into space. Once the rocket has served its purpose, it falls back to the Earth and either plunges into the sea or burns up completely in Earth’s atmosphere.
This is wasteful, but for decades it’s been the best option that we’ve had. If the rocket could be recycled and launched again, it’s been estimated that total launch costs could be reduced by about 30%.
Space shuttles and the history of reusable spacecraft
The last efforts to make space travel reusable and more cost efficient were the shuttle programmes in the United States and Soviet Union, known as the Space Shuttle and the Buran respectively. NASA’s five Space Shuttles are the best known; Columbus, Challenger, Discovery, Atlantis, and Endeavour were seen as the next big step in making space travel more affordable. The theory was similar to the self-landing rockets, in that each of the Space Shuttles could fly up to a low-earth orbit, drop off their payload, and then return to Earth, landing safely on a runway. The only part of the Shuttle that would have to be replaced was its large external fuel tank. The Soviet Union’s Buran shuttle looked remarkably like NASA’s Space Shuttle. It only flew one unmanned mission before the Soviet Union collapsed and the project was cancelled.
Sadly none of the shuttle programmes were as effective as the developers had hoped. The cost of flying and repairing the shuttles dominated NASA’s whole budget. Part of the extra cost came from the heat-resistant tiles that protected the Shuttle as it re-entered Earth’s atmosphere. After each landing, each of the Shuttle’s 35,000 tiles had to be individually checked for damage and replaced if need be. As each tile was specifically designed for a certain location on the shuttle, this made any replacements even more tedious.
The Soviet’s Buran shuttle is said to have been much more cost effective than the NASA shuttles, but after only one flight, it’s hard to know for sure.
On 23 November 2015 Blue Origin demonstrated the first successful flight and landing of a reusable rocket with the launch of its New Shepard spacecraft. The rocket reached a maximum altitude of just over 100 kilometres, detached from its payload. Instead of crashing back down to Earth, the New Shepard rocket was guided towards a landing pad where its engines were re-ignited, slowing it down to a hover above the ground, before finally completing a ‘soft landing’, completely intact. Examination of the rocket afterwards showed that it was perfectly ready to fly again. This made it the first ever reusable spacecraft to cross the Kármán line (the official altitude where space begins, used by NASA) and land safely back onto the ground.
Since then Blue Origin has successfully launched and re-landed the same New Shepard rocket four times.
But now SpaceX arguably has the more advanced programme, landing five reusable Falcon 9 rockets this year alone, sometimes on floating platforms in the sea. The most impressive of these launches was earlier this year, on 14 August 2016. The Falcon 9 launched a Japanese communications satellite into a particularly difficult elliptical orbit, which meant that the re-entry speeds and temperatures were even more extreme during the rocket’s descent back to Earth. Despite these harsh conditions the rocket successfully landed on SpaceX’s floating platform in the middle of the Atlantic Ocean.
Sadly, less than a month later on 1 September 2016 all SpaceX Falcon 9 launches immediately ground to a halt following the huge explosion of one of the rockets on the launch pad while pre-launch testing was taking place. The rocket and the 200 million US dollar payload were completely destroyed in the blast and for several weeks it was unknown exactly what had gone so wrong, casting serious doubts on the reliability of the Falcon 9 rockets. It was eventually confirmed that the explosion was due to a faulty interaction between the liquid helium bottles, carbon composites, and solidification of the liquid oxygen propellant.
With the launch planned for this Sunday, investors and commercial interests will undoubtedly be holding their breath, hoping that this sort of disaster does not re-occur.
When aeroplanes were first developed, it was private development and investment that drove flight prices down and down, first making planes affordable for the rich, and then readily available for everyone. The same thing may now be happening for space travel. Industrial competition is making the technology more efficient, driving down the prices, until eventually it may be readily available for the world. As it is, you can already pay a deposit to reserve your spot on a ‘Space Holiday’ with companies such as Virgin Galactic. While still very expensive, it proves that regular space tourism is on the horizon.
About the Author: Scott Davis is a current physics student and president of the Physics Society at the University of Leicester. He also works as a Science Interpreter at the National Space Centre.