NASA’s first test of its next-generation heat shield is postponed to at least November 9 | Engadget

Frictions exerted during atmosphere re-entry are enough to turn spacecraft into comets of glowing slag if not properly mitigated — but otherwise. The Space Shuttle, when it was still operational, was designed to hit the very edges of Earth’s atmosphere on its journey (~17,000 MPH) and then ride a wave of superheated plasma – created because the frictional forces are so great, that they literally rip the surrounding air apart at the molecular level – all the way down into the atmosphere until aerodynamic surfaces regain their effectiveness.

“Using atmospheric drag is the most mass-efficient way to slow a spacecraft,” . To survive these intense 3000 degree F temperatures, the shuttle would melt and delaminate, carrying extra heat with it, but for tomorrow’s reusable spacecraft, NASA has better things in mind.

NASA has set a launch window for November 9 for the LOFTID mission. It will fly alongside a new NOAA “polar weather satellite.” After the satellite separates from the Atlas rocket upper stage, LOFTID will deploy and inflate before re-entering low Earth orbit.

“One of the biggest differences is that before the suborbital tests we got to about 5,600 miles per hour or 2.5 kilometers per second, which is already difficult,” Steve Hughes, LOFTID aeroshell director at NASA’s Langley Research Center. “But with LOFTID we will arrive at almost 18,000 miles per hour or 8 kilometers per second. That’s about three times as fast, but that means nine times more energy.”

The LOFTID heat shield offers four layers of protection against all that energy. The outermost layer is ceramic and silicon carbide yarns woven into fabric on the same industrial weavers that make denim. The second and third layers are two types of insulation, they are there to protect the fourth layer – the actual inflatable parts. Everything is stacked in a series of concentric rings – themselves made of a woven polymer ten times stronger than steel – that help control the shield’s expansion.

NASA has been developing Hypersonic Inflatable Aerodynamic Decelerator (HIAD) technology for more than a decade. LOFTID (Low-Earth Orbit Flight Test of an Inflatable Decelerator) is the latest iteration of this technology, a new type of heat shield that potentially avoids many of the problems NASA is having with the current generation of rigid aeroshells. These hard shields have a strict limit on their size, dictated by the diameter of the missile’s envelope. Soft aeroshells do not have this limitation and can be extended well beyond the edge of the shell, allowing NASA to protect larger and heavier payloads when they enter the atmosphere.

This is particularly important for our future solar system exploration plans, since the other problem with current heat shields is that they only work in Earth’s atmosphere. You’re attempting to land something the size of the space shuttle on the surface of Mars, and this exercise ends with your spacecraft making a very long swath across the red planet — or a very short crater, if you’re particularly unlucky. The Martian atmosphere just isn’t thick enough to create enough friction against modern-sized heat shields to safely slow the shuttle’s descent. So NASA is testing an inflatable one.

At the beginning of the descent, LOFTID will be traveling at more than 25 times the speed of sound. NASA hopes LOFTID will end up crawling along at a relatively weak 609 MPH. Throughout the flight, the data recorder on board the test shield transmits the most relevant sensor and video data, while storing as much as possible on board in an ejectable recorder. If all goes according to plan, the LOFTID shield will slow sufficiently to deploy a landing chute before landing in the Pacific Ocean before being retrieved by the ULA.