Slinging a fast-moving probe into orbit around a faraway planet is hard enough; landing a hefty, astronaut-carrying spacecraft on an alien surface is beyond difficult.

But doing just that -- on Mars -- is exactly what NASA hopes to do in the coming decade. To do so successfully, NASA engineers are considering employing an inflatable spacecraft that resembles the rainbow-colored, donut-like stacking rings that small children play with.

Researchers believe a lightweight inflatable structure -- the current prototype is dubbed the Hypersonic Inflatable Aerodynamic Decelerator (HIAD) -- could be deployed in order to slow the spacecraft's as it descends through the thin Martian air.

"We have been eating, sleeping, dreaming this technology -- in my case for six years," NASA scientist Anthony Calomino said last year at a project meeting.

"In a real spacecraft, a connected stack of donut rings would be inflated before entering a planet's atmosphere to slow the vehicle for landing," NASA explained in a blog update last summer. "The stacked-cone concept would allow NASA to land heavier payloads to the surface of the planet than is currently possible, and could eventually be used to deliver crews."

Slowing an alien descent with inflatables would save missions from carrying extra fuel to put on the brakes by using reverse rocket propulsion.

But one the challenges is building the inflatable technology out of materials that can withstand high temperatures caused by the friction of atmospheric reentry.

"This idea has actually been around since the 1960s," said Neil Cheatwood, the senior engineer at Langley Research Center in Hampton, Virginia. "But now we have materials that can withstand higher temperatures. We've made great strides with this technology."

Researchers plan to build and test a real life prototype consisting of a titanium frame and an underlining of carbon fire skin. It would be inflated with nitrogen.