Sunday, June 6, 2010

Spaced out

Long post alert: This is what happens when a space buff starts rambling!

Come November, the Space Shuttle will leave on its final journey into Earth's orbit. During the stone age of space exploration, the earliest space modules used a small spherical or conical capsule mounted atop a powerful multi-stage rocket to get people into space. That was how the Mercury, Vostok, Gemini, Soyuz and Apollo programmes worked, and how the Russians and Chinese send and retrieve their cosmonauts and taikonauts from space to this day. The Space Shuttle was the first and only major deviation from this tried and tested method. Instead of using a capsule that could be used only once, the Space Shuttle had an orbiter that could be reused. Instead of using parachutes to land a capsule into the Kazakh steppes or the Pacific Ocean, the orbiter landed on a normal runway like a glorified glider. Instead of using a multiple staged rocket, the shuttle used 3 separate rockets. The main engines on the orbiter were fed fuel from a giant orange fuel tank, and two huge solid-fuelled booster rockets on either side of the tank gave extra thrust during take off, and subsequently jettison from the shuttle and return to Earth to be reused.

Space Shuttle Orbiter (from here)

There were obvious benefits to this new system: The orbiter and booster rockets can be reused multiple times, the payload bay of the shuttle can carry a Spacelab - to carry out experiments in zero gravity - or satellites to be launched by the shuttle. The robotic arm on board can be used to capture and repair satellites and space stations. The shuttle could carry 12 astronauts, as opposed to the 3 or 4 that a capsule could carry.

There were not so obvious drawbacks as well. The booster rockets were solid-fuelled, which meant that they could be relied on more than liquid fuelled rockets to fire, but once they did fire, there's nothing much you can do to control it, a fact that was made brutally clear with the explosion that destroyed the shuttle Challenger in 1986. The main safety feature of the capsule era, the escape rocket, was also missing from the shuttle. The capsule is positioned on the very top of a large rocket, and a small rocket would be attached on top of the capsule. If anything went wrong during lift-off and the astronauts wanted to bail out, they would detach the capsule from the last stage of the rocket and fire the escape rocket, which would blast them off out of harm's way.

Escape rocket from Mercury era (from here)

But the main problem with the shuttle, and the one that eventually lead to its retirement, is the cost. It costs much more to launch a shuttle than it does to launch a traditional capsule-atop-rocket spacecraft. This is why the Russians, even during the tough economic times after the Soviet Union collapsed, were able to launch their Soyuz capsules, while even the world's leading economy couldn't keep launching their shuttles. Don't get me wrong here, the shuttles carried out more missions during this period than the Russians could even dream of, but it was eventually realised that the reusability of the shuttle was not going to pay back for the cost that it took to blast one of these things off into orbit.

SpaceShipOne (from here)

And while NASA is looking to return to its roots by getting rid of the shuttle and going back to old capsule technology, space enthusiasts like Burt Rutan are building next generation reusable space shuttles (Like SpaceShipOne, which won the Ansari X-Prize) that are so cheap to launch that they can even carry space tourists. The commercial space industry is bound to grow from the niche satellite market that it is in right now and move onto bigger things like space tourism and even settlements on other planets and moons (including Luna, our own). Costs will continue to come down, and more powerful rockets and propulsion systems are bound to emerge.

A golden age in space exploration occurred in the 50s, 60s and 70s due to Cold War competition between the US and the Soviets. As competition between various space companies grows, we're bound to see a similar golden age in the future too. But I can't help but wonder if the Space Shuttle was a costly misstep in human evolution into a space faring race.