LOFTID sparks interest in the innovative inflatable heat shield technology

Getting to orbit requires an advanced vessel to correctly accelerate a payload to speeds of thousands of kilometers per hour. When returning to the Earth’s surface, a spacecraft inevitably comes into contact with the various layers of the atmosphere. Atmospheric drag is an efficient way of deceleration, so spacecraft that need to survive this phase, have a specific component called “heat shield”.

It’s made of carefully studied materials that can absorb or keep most of the heat coming from atmospheric reentry away from sensitive components. The friction caused by those incredible speeds decelerates the spacecraft while generating a great amount of heat. Any material or part that comes into contact with high-temperature gas also experiences a vertiginous increase in temperature.

NASA Johnson S68-55292 (August 1968) --- A North American Rockwell Corporation artist's concept depicting the Apollo Command Module (CM), oriented in a blunt-end-forward attitude, re-entering Earth's atmosphere after returning from a lunar landing mission. Note the change in color caused by the extremely high temperatures encountered upon re-entry — *Artist’s impression of an Apollo Command Module reentering the Earth’s atmosphere. Credits: NASA Johnson*

Conventional heat shields are composed of ablative materials, that gradually chip away while keeping heat away. They can also be made of various special tiles that absorb most of the heat and then release it gradually with time. Both types have limitations concerning their size.

A new technology that is making its way into the aerospace sector is inflatable heat shields. Initially hidden inside a small container, they inflate just before reentry and can be many times larger than a normal heat shield.

The LOFTID demo

A first-of-a-kind experiment was successfully designed and executed by NASA and ULA in November of 2022. Its designation was Low Earth Orbit Flight Test of an Inflatable Decelerator, or LOFTID for short.

The joint ULA-NASA demonstrator was 6 meters in diameter when completely extended. A flexible membrane acted as a heat shield, while an inflatable structure made it deploy in a precise cone shape out from the spacecraft. This particular shape allowed it to form a shockwave that could deflect the flow of hot gas and plasma.

GIF showing the LOFTID spacecraft reentry, a streak of bright plasma can be seen — *LOFTID reentry footage showing the plasma trails. Credits: NASA Langley*

LOFTID reached orbit as a secondary payload for a ULA Atlas V launch on November 10, 2022. The Hypersonic Inflatable Aerodynamic Decelerator (HIAD) of LOFTID was successfully proven to work. In a report published on November 17, 2023, Joe Del Corso, LOFTID’s project manager at NASA Langley defined the test as “Just Flawless”.

A moment of celebration for the many people at Langley Research Center, who worked on the LOFTID project. — *The LOFTID team celebrates a successful reentry. Credits: NASA Langley*

The shield had no visible damage and successfully decelerated from 29,000 km/h to just 130 km/h. The spacecraft then deployed parachutes and splashed down in the Pacific Ocean. Therefore research on this technology was deemed ready to advance to its next phase: larger size.

Future Developments

Given the success of the demo, NASA awarded $25 million in funds to ULA to joint-develop a larger-scale platform. The joint demonstration will test a new aeroshell, now 10 meters across. Clearly, this will translate into a huge engineering effort to scale up the technology, but the benefits are enormous.

ULA itself aims to use a large aeroshell to enable a safe reentry of the engine section of their Vulcan rocket. This would reduce the cost of launch since the engines could be reused after some refurbishment.

According to Space News, Joe Del Corso said during a meeting on November 30 that the teams at NASA/ULA are already nearing a preliminary design review.

Informative panel comparing the LOFTID test with the proposed ULA heat shield for Vulcan engine reuse — *Details on the ULA aeroshell. Credits: ULA*

There are also smaller companies that have contacted NASA to develop their version of the inflatable heat shield. That’s the case for Outpost, which aims to offer a service for commercial customers.

But there appear to be “bigger names” in the industry involved. Reportedly, Blue Origin has paid NASA to acquire the Scientifically Calibrated In-Flight Imagery from the LOFTID demo. And other undisclosed companies are even exploring options for shields 18 to 20 meters across.

As demonstrated by LOFTID, the inflatable heatshields technology is an extremely valid concept that could revolutionize how and what payloads we can land on any planet with an atmosphere, not just Earth. One could think of landing huge crew habitats on Mars or reusing the second stages of rockets after atmospheric reentry. The possibilities are vast and this could be the opening of a whole new approach in space exploration.