In the 1950s, Hollywood cranked out many so-called 'B-movies', featuring aliens from other planets attacking the earth. Some of the most memorable were War of the Worlds, based on the story by H.G. Wells, and Invaders from Mars, a surrealistic story of an invasion by creatures from Mars who came to earth in a flying saucer. Now, in what may be an example of life imitating art, these films may be on the verge of becoming reality, but with a twist. Instead of the Earth being attacked by flying saucers from Mars, Mars may soon be attacked by flying saucers from the planet Earth.
Maybe attacked is too strong a word. When sending a spacecraft to Mars or any other planetary body, the first thing that must be done is accelerate to a speed of at least 25,000 miles per hour, so it can escape the gravity of the Earth. But equally important is slowing it down when it reaches its destination; otherwise, it would just be smashed into a million pieces. This can also be done with rockets, but rockets need fuel, so scientists at NASA are searching for more economical ways to do so. One way that is currently being developed looks remarkably like a flying saucer (see photo), but is actually more like a balloon (sorry, Roswell fans). As part of Low Density Supersonic (LDSD) project, which is being run by the Jet Propulsion Laboratory, this device will use atmospheric drag to help slow down a spacecraft so that parachutes or rockets can be used to lower it to the surface. This has actually already been done with the Galileo spacecraft that was sent to explore Jupiter, so scientists know that it's feasible. Even though the atmosphere of Mars is far thinner than the atmosphere of Jupiter (thinner even than the earth's atmosphere at the summit of Mount Everest), it is still thick enough to help slow down the spacecraft.
Testing of the LDSD is due to begin in Hawaii in June of this year, and if all goes well, it may be used on unmanned missions to Mars as early as 2018, and eventually, for manned missions as well. As for what the martians, if there are any, will think of this, one can only hope that there is no martian Orson Welles to scare them as the people of planet Earth were scared by that famous radio broadcast of 1938.