NASA’s Low-Earth Orbit Flight Test of an Inflatable Decelerator, or LOFTID, was launched, deployed and retrieved on November 10. LOFTID is a type of heat shield being tested for atmospheric re-entry that could be used to help put people on Mars.
One of the most complicated aspects of space travel is atmospheric re-entry. This is important both when astronauts return to Earth and when shuttles go to other destinations with atmospheres, like Mars.
Space shuttles re-enter Earth’s atmosphere at up to around 7 kilometres a second, or nearly 30,000 kilometres an hour! At these speeds, a mixture of huge amounts of friction (air resistance from the molecules in the atmosphere) and shockwaves generated by travelling almost 30 times the speed of sound, generates a lot of heat. The surface of re-entering shuttles can reach nearly 1,500°C.
But it is this friction which helps slow the spacecraft down enough for a safe landing.
To protect astronauts, equipment and any other payload on a shuttle, a key challenge for engineers and physicists is to slow down re-entering craft and shield it from these extreme conditions.
On Earth, while causing high temperatures through friction, our thick atmosphere is great for slowing spacecraft. Mars, however, has a very thin atmosphere – too thin to decelerate spacecraft quickly enough using conventional heat shields. Current technologies restrict payloads for Mars missions to about 1.5 tonnes.
Theoretically, a larger heat shield which would experience more friction would solve this problem. But current rigid aeroshells are constrained in size by the size of our rockets.
To get around this problem, NASA engineers have developed LOFTID – a flying saucer-shaped inflatable aeroshell with a flexible heat shield.
For entry from low-Earth orbit, NASA’s test launch of LOFTID successfully demonstrated a 6-metre inflatable decelerator re-entry.
“Everybody’s just relieved and excited,” Greg Swanson, the instrumentation lead for LOFTID, told the NASA Television broadcast.
Following the successful launch and re-entry of LOFTID and its data capsule, NASA scientists will have to analyse the results of the $93US million project for the next phase of development.
Dr Neil Cheatwood, principal investigator for LOFTID, told the New York Times that a heat shield of around 9 metres in diameter would be required to take humans to Mars.