Curiosity - an amazing success
NASA has scored an amazing success by getting its latest exploration vehicle Curiosity down on to the surface of Mars. The landing system is without any doubt one of the most incredible pieces of engineering ever designed, and at almost every stage even the smallest failure would have meant catastrophe. After all, it’s hard enough to get off the Earth into orbit. Once you've done that, getting to Mars presents further huge challenges. But then,deploying a re-entry capsule, then a parachute, followed by an elaborate rocket powered jet pack which flies off and self-destructs after letting a thing the size of a car down to the ground on a piece of string is almost unbelievable. It all looks like something Rube Goldberg or Heath Robinson would have rejected as being too ridiculous. However, it’s worked – and Curiosity is getting ready to start exploring the Red Planet in earnest.
Seven minutes of terror
However, Curiosity isn’t the first vehicle to have a wacky method of getting to its destination. Here’s a handful of other unconventional touchdowns, some real, some failed, and some definitely staying on the drawing board.
The Brodie rig
This rickety, spindly and frankly terrifying-looking piece of kit was actually used very successfully in World War Two by US forces in the Pacific. It enabled a small plane to “land” in remote and often forested islands without a runway being needed at all. In essence, the Brodie device was a very long wire strung between two tall masts, and could be installed in only a few hours instead of the weeks needed to build an airfield. Planes equipped with a hook device on the top of their fuselage could fly at and then snag the wire like a climber clipping on to a rope. They would then remain suspended, hanging above the tops of trees, or above a treacherous ravine, until needed for another attack or reconnaissance mission. Then they’d accelerate down the wire and un-clip just before its end, flying off on their next mission. Pilots needed bravery of the highest order to use the rig (particularly for the first time, or when used at sea) – but it proved its worth as the Marines rapidly advanced in the Far East throughout 1945.
The development in 1980 of this weird hybrid stemmed directly from the failed Operation Eagle Claw, the US government’s failed attempt to rescue hostages from the US embassy in Teheran. That plan had used several helicopters and conventional transports, and had gone horribly wrong, with several servicemen being killed. It would ultimately cost Jimmy Carter the presidency. To try to regain the initiative, the Department of Defense ordered the immediate development of new hardware to have another go. The platform they chose was the C-130 Hercules, the powerful military workhorse that used since the 1950s. The “Conventional Sport” modification meant equipping the C-130 with 30 powerful rocket motors, enabling it to stop almost instantly in mid-air, land in little more than its own length, and take off again. The idea was that the plane would land and take off from within a soccer stadium. The planes’ wings required massive strengthening, and it also needed a means of restraining the passengers, who would be subject to enormous g-forces as the rockets fired. Despite the changes, the CS C-130 was spectacularly unsuccessful on testing, with one wing breaking off and the rest of the plane catching fire. The programme was unsurprisingly cancelled shortly after the release of the hostages in November of that year, following Ronald Reagan’s winning the White House.
Whole plane parachutes
Since the dawn of flight, people have suggested giving passengers emergency parachutes. However, there are many pretty obvious drawbacks with this idea, not least of which would be actually getting untrained and terrified people to leap out of a plane which might be at 30,000 feet and nose-diving at over 600 mph. However, parachutes capable of ensuring the safe landing of an entire plane are in operation. These aren’t capable of bringing a jumbo jet down in one piece - that would take about 11 or 12 parachutes, each one the size of a football field. There are systems, however, which can mean the difference between life and death. Cirrus Aircraft's CAPS system, for example, which is essentially a large rocket-propelled parachute fired vertically out of the top of the plane if there's an engine failure, has been used successfully 32 times since 2002. Some ultralight manufacturers use similar systems which, like CAPS, is made by BRS Aerospace. The manufacturers do generally make it clear that using these systems is very much the last resort.
A previous Martian landing also required a novel approach, although not as complex as Curiosity. Spirit, the famous rover which explored the planet starting in 2003, used a heat shield, parachute and rockets. These allowed the vehicle to descend to within a few tens of meters of the planet’s surface. At this point, large airbags on the outside of the craft rapidly inflated. The wire holding Spirit to the parachute was then released, and the little rover (which looked a bit like Disney’s WALL-E) bounced across the dry Martian landscape like an enormous, $400 million beach ball for hundreds of meters before coming to rest unharmed. Spirit successfully explored for almost seven years, sending back vital data and providing a greater understanding of conditions on Mars than ever before, before being declared dead in 2010.
A somewhat theoretical one to finish: how about a landing on the sun? While not much more than science fiction at the moment, a craft made of tantalum hafnium carbide might be able to cruise above the solar surface, basking in the balmy 4600C temperatures, and exploring solar flares, prominences and sunspots. It would perhaps need to have protected itself with a plasma field (perhaps produced by intensely powerful electromagnets) to penetrate the corona, which is a slightly more challenging 2,000,000C. It would also have to have some means of dealing with the sun’s vast gravitational and magnetic fields so as to avoid being squashed like a bug. This landing is somewhat beyond our current technology. But who knows, if something as unlikely sounding as the Brodie rig can work, who knows? How about it, NASA?