Planetary Landings, Another New Frontier

Frequent visitors to Vintage Space are doubtless aware that I am fascinated with the problem of landing from space. Faced with this unknown, the US and Soviet Union developed very different methods, parachute-controlled descent and splashdown and Earth-landing via parachutes, retrorockets, and pilot ejection respectively. (Pictured, the view from Viking 1, the first successful robotic landing on Mars. 1976.)

Part of what interests me in studying landings is the lack of attention paid to this critical mission phase in favour of the more exciting launches. But there is one area were landings are not only a major focus but a vital aspect of a mission: robotic planetary exploration. Without a successful landing, there could be no robotic mission.

Like manned return from space, planetary landings have developed and become increasingly sophisticated over time.  The more scientists and engineers know about a planet, the better chance they have of successfully touching down on its surface. After all, each body in the solar system has different characteristics and presents difference challenged to the entry, descent, and landing (EDL) stage.

Advertisement

Spaceflight: Risky Business

One of the things that fascinates me about NASA’s early manned programs is the risks the organization took to achieve its goals. The Apollo Program is a great example: NASA had a goal, a time frame in which to achieve its goal, and a real need to succeed. The risks could be justified in the name of a successful end-of-decade lunar landing. But the organization also had the money needed to achieve such a technological feat – roughly 4 percent of the GDP in the mid-1960s instead of the less than 1 percent it has now. (Pictured, engineers and astronauts begin troubleshooting in the minutes after an explosion rocked Apollo 13. 1970.)

Still, it wasn’t just having enough money to run the tests needed to get the results. NASA made bold, daring decisions in the 60s. Since the end of Apollo, however, NASA has become more conservative in its approach to both manned spaceflight and unmanned planetary exploration.

Not Exactly Rocket Science

A while ago, I talked about NASA’s invention of landing methods for the Mercury program – what to do when finding a solution for an entirely unknown problem. Tied into the question of landing methods for NASA’s first manned program was the design of the capsule. The basic constraints were laid out fairly early on in the program. Mercury would use a ballistic design proposed by Langley engineer Maxime Faget and splashdown in the ocean. This was the simplest method. In returning from space, NASA was content to let gravity do most of the work. (Pictured, Mercury model makers Richard Altimus and Arthur Lohse with model finisher John Wilson. 1960.)

With the basic capsule design set, there remained smaller design questions needing answers. What ballistic design would fare best against the heat of reentry? Throughout the descent stage, would one ballistic shape have better inherent stability than another or would the astronaut have to control the capsule’s attitude all the way down? Once the capsule was in the ocean, would it float? If the astronaut had to get out of the capsule, would it still float with a hatch open? In the 1950s, NASA sought answers to these questions in an age before computer programs could immediately generate answers. And so they did the next best thing. They tested model capsules, each shape designated by a letter, and picked the best design through trial and error.

Bringing Down a New Bird: Landing Gemini

I’ve previously discussed NASA’s invention of a landing system for the Mercury program – with little time and almost no prior experience, engineers determined that splashdowns were the simplest and least risky method to bring an astronaut home. But, as I’ve also previously discussed, splashdowns were far from an ideal landing method; inherently dangerous to both astronaut and capsule alike. (Left, a half-scale Rogallo wing mated to a half-scale Gemini spacecraft. NASA Archives.)

NASA’s second-generation Gemini program opened the door for a change in landing methods. Though incepted in early 1962, work on the program began late in 1961 when the end-of-decade lunar landing goal was seemingly far away. Gemini, then, had a more open schedule at the outset, allowing engineers to undertake some major design changes. One of the first aspects of Mercury to go was splashdown. The original goals for Gemini stated that a pilot-controlled land landing was paramount. So the program began seeking an answer to the question of how to invent a land landing system.