Mark Adler has worked as an engineer and program manager at NASA’s Jet Propulsion Laboratory in Southern California for more than 20 years, mostly on missions to Mars. He now heads a new project with a mouthful of a name — the Low-Density Supersonic Decelerator, known in the acronym-strewn world of NASA as LDSD.

Its purpose is simple: to slow a heavy object hurtling toward the surface of Mars at four times the speed of sound. If humans ever set foot there — or, for that matter, land anything heavier than the Curiosity rover — something like the LDSD must exist. However, building it, testing it and successfully deploying it is anything but simple.

“Mars is actually a tricky place to land,” said Philip Christensen, a geologist at Arizona State University who studies the Red Planet. The thin atmosphere can’t provide substantial drag, yet it creates enough friction to burn up objects that enter it.

Four years into the project, Adler has grown intimately familiar with the challenges of pushing the technological envelope. He experienced a significant one this month.

Abnormal wind patterns stymied plans to conduct the first full-scale LDSD test in Hawaii.

“We rolled the dice and didn’t win,” Adler said.

Resurrected from the notebooks of early aerospace engineers, the LDSD differs from existing technology in that it takes a two-pronged approach to not crashing into Mars.

Like the system that delivered Curiosity, it will still deploy a parachute (one significantly bigger and stronger), but only after an inflatable doughnut expands around the vehicle. This air bag will increase its area by at least 60 percent, creating more drag and slowing it down from spaceflight velocities of Mach 4 to more modest speeds of Mach 2.5, when the chute can safely be released. Only then can the rest of the landing sequence begin.

The idea for inflatable decelerators emerged in the 1960s, when scientists on the Viking mission knew little about the Martian atmosphere and what it might take to land there.

They soon realized they could get by with just a parachute. But when NASA launched the Curiosity rover in 2011, engineers finally reached the limits of that system.

“If we want to go bigger, bolder and more capable, we need something new,” said Ian Clark, who specializes in designing entry, descent and landing systems like the LDSD.

If it works, the new vehicle will be able to ferry loads weighing up to 3 metric tons to the surface of Mars — twice the capacity of the Curiosity mission.

Onthe remote Pacific Missile Range Facility on Kauai, Hawaii,NASA scientists hope to test the system in something approximating its intended environment.

The test will reveal not only whether LDSD has a future on Mars, but whether the blue skies over Hawaii make a suitable testing ground.