2024 Science, Technology and Environment

Neil Cheatwood, Stephen Hughes

Envisioned and led the development of a new inflatable heat shield for planetary entry, descent and landing that will enable spacecraft to deliver bigger payloads to distant planets, including during a future human mission to Mars.

One of the greater challenges of sending payloads to Mars and other planets is the possibility that the heat will become very intense and pose a threat to the spacecraft and crew members during atmospheric reentry. 

NASA Langley Research Center engineers Neil Cheatwood and Stephen Hughes have been instrumental in developing a new heat shield for planetary entry that is inflatable, can be hard packed into a small volume for launch and then deployed as a spacecraft reenters the atmosphere for stable deceleration.  

The heat shield, known as the Hypersonic Inflatable Aerodynamic Decelerator, or HIAD, is the only proven entry system that will enable a human mission to Mars, currently planned for 2039. The technology significantly increases the payload a Mars mission could land on the surface from 1.5 metric tons—the size of a well-equipped golf cart—to between 20 and 40 metric tons—a fully furnished ranch house with a car. 

“Developing the HIAD technology and demonstrating to the world that it works really put a new type of spacecraft in NASA’s tool belt to be able to be used for missions. This is the only technology that we know could safely land humans on Mars,” said Jeff Herath, deputy director for space technology and exploration at the NASA Langley Research Center. 

HIAD’s origins and a deflating reception 

Hughes conceived of the concept for the HIAD after being asked to review a similar, but more problematic, proposal devised by Russia. In 2003, after drawing the concept on a napkin during a conference, he pitched an updated version to Cheatwood, who backed the idea.  

But the rest of the scientific community didn’t.  

According to Hughes, others thought the idea was “comical” and doubted that an inflatable shield could withstand the heat, speed and pressure of entering an atmosphere. Initial funding was slow, with Cheatwood securing amounts as low as $762 and hunting for small chunks of leftover money in NASA’s budget to kickstart production, an effort he equated to “digging through the couch cushions.” 

Ready for liftoff  

Eventually, in 2007, Cheatwood and Hughes amassed enough support to launch the Inflatable Re-entry Vehicle Experiment, the first of three suborbital flight tests demonstrating the viability of HIAD, including aerodynamic stability in all flight regimes. 

Successful tests led to more funding, but the effort was disrupted after Orbital Sciences’ Antares rocket exploded on the launchpad in 2014.  

Their perseverance, and Cheatwood’s staunch advocacy for the technology, eventually drew the interest of the United Launch Alliance, a space launch company that offered to partner on the Low-Earth Orbit Flight Test of an Inflatable Decelerator, or LOFTID, to prove HIAD’s feasibility for returning from orbit.  

The test was successfully completed in 2022, with Hughes on hand to discover the returned payload in near-pristine condition. 

What started as a small team of believers led to more than 100 people working on LOFTID. The successful flight test is paving the way for other companies to use these heat shields to return materials from space and has the potential to foster a more environmentally friendly space industry by recovering launch vehicle assets or satellites for reuse. 

“The fact that they took this from a seedling idea back in the 1990s, and then demonstrated its effectiveness, gave us confidence that this would be safe for both our missions and our people,” said Dave Young, senior advisor to the Langley Research Center director.  

According to Herath, Cheatwood was the “evangelist” for the work, helped secure the funding, and built partnerships with private industry and academia, while Hughes led the design and technical aspects of the project.  

Both take pride in building a team that is helping NASA reach new milestones in space exploration.  

“It’s satisfying to have witnessed the project go from being viewed as a parlor trick to a technology that will potentially get us boots on the ground on Mars,” Hughes said.