In previous posts I’ve talked a little about the challenges of landing on other planets. A planet’s unique composition and gravity have a major effect on a spacecraft’s entry into and descent through the atmosphere, as well as its landing on the surface – more simply, the spacecraft’s EDL. One central problem associated with interplanetary missions that has always fascinated me is the problem of testing EDL systems without being able to simulate the target planet’s environment. (Pictured, an artist’s concept of the Mars Pathfinder mission’s terminal descent and landing.)
Take Mars for example. The planet’s atmosphere is one percent as thick as the Earth’s and Martian gravity is one-third that felt on Earth. It’s impossible to simulate these conditions. Individual systems can be tested separately in approximate environments, but the only time the whole system will go through the stages of EDL is when it arrives at Mars.
In looking up results from Martian EDL systems tests, I kept turning up information on parachutes. I’ve never thought any aspect of spaceflight was simple, but I also never thought parachutes were very interesting. Turns out they are. For the moment, I’m going to limit myself to Mars landings and the Mars Science Laboratory (MSL) in particular. Set to launch in November 2011, MSL will use the brilliant yet frighteningly complex Sky Crane landing system to deliver the rover Curiosity to the surface.
But if the Sky Crane is going to have a chance to do its job, the whole MSL payload is going to have to enter the atmosphere and slow to a speed where its retrorockets can take over. That is the job of its parachute. Continue reading “Preparing Planetary Parachutes”
In a previous post, I looked at the Rogallo paraglider wing landing system and its failed development as part of NASA’s Gemini program. I also mentioned that the landing system didn’t disappear right away. After its cancellation from Gemini, NASA attempted to salvage its research and incorporate the landing system in Apollo and its follow-up programs. The US Air Force also expressed interest in including the Rogallo wing into its own space program. Regardless of the extra attention, it would seem that the paraglider was doomed to never leave the ground. (Left, a model Gemini capsule with Rogallo wing in a wind tunnel test. 1961.) Continue reading “Rogallo After Gemini”
Landing methods and the Gemini program are two of my favourite topics, and I’ve previously posted about landing methods in Gemini. The Mercury program demonstrated sufficient reason to move away from splashdowns, and the second generation Gemini manned spaceflight program gave NASA an opportunity to do so – it was the first to actively pursue a pilot-controlled land landing system. NASA reviewed multiple proposals before selecting the Rogallo paraglider wing. (Left, a model Gemini spacecraft with a Rogallo wing. 1963.)
Beginning with its initial development in 1961, the Rogallo wing had a long and interesting history within NASA. For the moment, I will limit myself to its inclusion in Gemini, putting the system’s research and development timeline against the Gemini program as a whole. This will begin to unravel why, in spite of NASA’s best efforts, all Gemini missions ended in splashdown. Continue reading “Losing Rogallo from Gemini”
In previous posts about Mars and the difficulties of landing on other planets, I’ve mentioned that the red planet is a veritable graveyard for unmanned spacecraft – two-thirds of all Mars-bound missions have failed. In some cases, engineers are able to figure out why. The key is telemetry and a thorough understanding of the spacecraft. With the right tools, the failures act as lessons, illuminating unknown challenges so mistakes aren’t repeated. But the data doesn’t always come back, leaving engineers with little to go on if a mission fails. The worst-case scenario, and not an altogether uncommon occurrence, is the total loss of communication with a spacecraft with no indication of what went wrong. (Left, an artist’s rendition on the ESA’s Beagle 2 as it enters the Martian Atmosphere.)
Two missions in the last 12 years have failed rather spectacularly: NASA’s Mars Polar Lander (MPL) and the European Space Agency’s (ESA) Beagle 2. Their failures were in very different circumstances, however, and a comparison of events illustrates the importance of pre-launch testing and constant telemetry for the success of a mission. These two cases also demonstrate the amount of work needed to successfully land a spacecraft, especially when the target is millions of miles away. Continue reading “A Tale of Two Landers”
Regular readers of Vintage Space are doubtless aware that I have a tendency to link newer posts to older ones. This reflects the interrelation of all the topics I have (and will) discuss in this blog. I find this era of history to be complex (as most big historical eras are) with aspects that can be treated independently, but need to be contextualized by one another.
And so I thought I would begin mapping Vintage Space, building a sort of narrative roadmap that will give the more casual reader a better idea of where in the history of space and spaceflight each individual episode belongs. This is in no way a complete chronology, but rather a framework for my content. (Pictured, the sun rise above the gulf of Mexico as seen from orbit by Apollo 7. 1968.) Continue reading “Mapping Vintage Space”
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. Continue reading “Planetary Landings, Another New Frontier”
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. Continue reading “Not Exactly Rocket Science”