14 DAY TRIAL // As more and more activities are carried out outside the spacecrafts that provide transportation and shelter for the astronauts, their safety proves more of a concern for scientists. Perhaps, in the not-so-distant future, EVAs (extra-vehicular activities) will require longer spacewalks and actions that must be performed farther away from the space vehicles. All these EVAs, as well as the astronauts' safety and physical integrity, rely on constant communication. But since it is known that sound and outer space are not two concepts that fit very well in the same equation, a new distress beacon had to be developed.
Unlike light, the sound vibrations need a medium made of denser molecules in order to travel (just like ocean waves need water), since they move by propagating along molecules' bumping into each other in a domino effect. Common conception has it that the outer space has no molecules that can carry the sound along (meaning that the SF movies that got you used to loud explosion effects in space couldn't be further from scientific truth). But this is not entirely valid, as the massive gas clouds provide enough atoms for the phenomenon to happen. So, sound actually is transmitted through space, but on such a low level that we are not able to hear it at all.
Perhaps powerful audio enhancing devices could amplify the sound enough to make it detectable. But until those are available, the increasing numbers of EVAs (23 in 2007, almost two per month) have to be supported somehow in case of any failure that would endanger the lives of their astronauts. Currently, they are provided plenty of air inside their suits in order for the sound of their speech to make it to the microphones in the helmets. The sound is then carried further in the form of radio waves and reconverted into sound upon reception.
If, for some reason, the process goes wrong, the newly-developed distress beacon provides visual alert signals through its LED lights that are visible from a range of 800 meters (about half a mile) away. It will also consist of monitoring sensors that will track the astronauts' heartbeats and breathing rates. According to Sarah Harris from the Harvey Mudd College in California, who works with the experts from California's Aerospace Corporation in El Segundo, "The astronaut might even flash them to send messages in Morse code."