Russian Manned Space Vehicle May Land With Rockets

The Narrative Fallacy writes "Russia's next-generation manned space vehicle may be equipped with thrusters to perform a precision landing on its return to Earth. Previous manned missions have landed on Earth using a parachute or, in the case of space shuttles, a pair of wings. Combined with retractable landing legs and a re-usable thermal protection system, the new system promises to enable not only a safe return to Earth, but also the possibility of performing multiple space missions with the same crew capsule. The spacecraft will fire its engines at an altitude of just 600-800m, as the capsule is streaking toward Earth after re-entering the atmosphere at the end of its mission. After a vertical descent, the precision landing would be initiated at the altitude of 30m above the surface. Last July, Korolev-based RKK Energia released the first drawings of a multi-purpose transport ship, known as the Advanced Crew Transportation System (ACTS), which, at the time, Russia had hoped to develop in co-operation with Europe. 'It was explained to us how it was supposed to work and, I think, from the technical point of view, there is no doubt that this concept would work,' says Christian Bank, the leading designer of manned space systems at EADS-Astrium in Bremen, Germany. However, the design of the spacecraft's crew capsule had raised eyebrows in some quarters, as it lacked a parachute — instead sporting a cluster of 12 soft-landing rockets, burning solid propellant. Inside Russia, the idea apparently has many detractors. During the formal defense of the project, one high-ranking official skeptical of the rocket-cushioned approach to landing reportedly used an unprintable expletive to describe what was going to happen to crew members unlucky enough to encounter a rocket engine failure a few seconds before touchdown."

Comments

Seems Pretty Inefficient

[Kozar_The_Malignant]

It seems pretty inefficient to carry the fuel mass for the retro rocket braking all the way up out of the gravity well into orbit and then back down into the gravity well so you can use it in the last kilometer of the flight. There doesn't seem any way to stop at a gas station on the way down, but maybe they are planning on lifting the fuel to orbit on non-reusable tankers, which also seems inefficient. In something like this, inefficient equates to really fucking expensive.

Re:Seems Pretty Inefficient

[evanbd]

Your choices are rockets, parachutes, wings and landing gear, or a variety of weird and exotic options (like deploying helicopter blades; see the Roton concepts). There are a variety of reasons to prefer rockets to parachutes (and vice versa). The rockets are likely somewhat heavier than the parachutes and their deployment system, but I suspect the weight difference is small enough that the decision would likely be made on the basis of operational advantages (like being able to do a landing on solid ground instead of the ocean easily).

The American space program seems to be of the opinion that everything should be as light weight and efficient as possible, without regard to other criteria. The Russians, on the other hand, have a long history of being willing to build larger, heavier, less efficient rockets in order to make operations easier. Personally, I think the Russian approach is better -- the correct figure of merit to optimize is not liftoff weight, but cost. If you can develop, build, and/or operate more cheaply by spending more weight on the problem, that's a win in my book.

Re:High-G landing?

[Waffle Iron]

Capsules don't just plummet vertically through the atmosphere. They spend most of the reentry going almost horizontally bleeding off speed. Most of them also angle the heat shield so that they get a good deal of lift, and they "fly" for a more gentle reentry.

In any case, a capsule must slow down to less than hypersonic speeds before deploying a parachute. Otherwise the parachute would burn up and/or be ripped to shreds.

Once a capsule is going slowly enough to put out a chute, it doesn't have all that much kinetic energy. Small retrorockets would be sufficient to stop it instead.