Naperlous. Thanks for the clarification and technical details. I think the airbag can bring down the air frictional force considerably. At the same time the way of parachute can be affected by other natural sources like Rain, Strom etc.
I've often wondered how these capsules maintain their orientation during reentry. Is the shape aerodynamically stable such that the shield self orients the correct way? (Doesn't look like it would be, but...) Or, are there some sort of steering/ or stabalizing surfaces, or thrusters, which maintain orientation? Anyone know?
My understanding is that like the shuttle, heat shield orientation is critical to survival of the craft as it reenters, at literally blazing speed.
A trend that seems to be emerging in spacecraft is "decoupling" the cargo and passengers. 20/20 hindsight, but part of the Shuttle's complexity and low launch reliability may have been due to launching crew and cargo together. The safety and system requirements necessary on a manned launch bring unncessary cost, design complexity, and reliability "hits" to a cargo launch. Most of the recent ISS support missions are cargo or people only.
The Boeing capsule fits this trend, which again is just my speculation / observation.
The advantage of the vertical flight model is that it requires less energy. There is a fundamental amount of energy required to reach orbit. It can be divided into a horizontal (orbital velocity) component and a vertical (gravitational potential) component. The problem with the horizontal model of space flight is that it adds air friction to that. The vertical model minimizes the air friction by taking the shortest path out of the air, then dealing with the horizontal energy needed. Finding the best path to orbit can thus be thought of as an energy minimization problem.
Zippy, you are correct. This is the cheapest way to do it in our current situation. As jhankwitz speculates it is the money (and consequently politics, etc.). I worked on the Space Station in the 1980s. I had colleagues who had worked on it a decade prior. It didn't launch until a decade after. The design is not significantly different from the early concept. We also had experience with Spacelab and MIR. That is one of the most frustrating aspects of the space program. It takes forever to get anything done. During the space race, when we had a goal with a date, we had three capsule designs in less than a decade. Considering our design tools today, the current pace is VERY SLOW...
D.Sherman, I think the 'aerospace plane' goes back even a little further than the X-20 "Dyna-Soar", although it also started roughly the same time. My history is probably a little suspect, but I think that level spaceflight was in the works since the beginning of the X project planes (although it was obvious that the initial goal was breaking Mach I). My knowledge is primarily from reading "The Right Stuff", Yeager's biography, and a handfull of articles and book references so it may be full of holes... and I was born after we landed on the moon ('71) so I don't have first hand knowledge.
My understanding is that the space program, since its inception, was split into two major flight model factions... level (horizontal) space flight and vertical space flight. There were advantages to each... level flight was a more controlled, conventional flight whereas vertical flight may have been considered more of a 'down and dirty' approach... Imagine which model the early astronauts (test pilots) preferred. Level flight presents problems at higher atmospheres, as aerodymanics plays less of a role, and environmental oxygen becomes less available combustion engines become more difficult to operate... I think Kennedy's creation of NASA and the Space Race forced us into the vertical flight model because it was 'simpler' (less problems to overcome) and faster because we started out behind in the race.
The X-planes were the of the level-flight model, and I think the X-15 was showing some of the first major successes in level flight. I've always wondered why the level flight model was abandoned (for the most part)... The SpaceShipOne launch vehicle (WhiteKnightOne) and high altitude planes (e.g. SR-71) make me believe that its feasible and has probably been continued to be tested if not publicly.
Why it's taken so long, I'm sure, is a drawn out tale of politics, budgets, technological and fiscal (mis)management, and changes in the public's patriotism, pride, and priorities.
I'm with Beth; this takes me way back to my childhood, watching the news and I Dream of Jeannie (and at least two episodes of Gilligan's Island). The capsule is such an iconic image that it's strange how quickly it faded from our cultural awareness (which, after the shuttle, really is going backwards).
I was just at Udvar-Hazy (Air and Space Annex) by Dulles Airport, and you don't appreciate how small they are until you are standing next to them. Or for that matter, how big the Shuttle was until you walk under it. A must visit destination if you are in the DC area.
But, it does follow the KISS principal (i.e. my size comments above), so I'm excited that perhaps our excile from space will be short lived.
Since NASA has been dependent on the Russians to get personnel to and from the Space Station ever since the retirement of the Space Shuttle, I just assumed this ws the cheapest and least risky way to regain that capability.
Very good questions. This technology has been in use since the 60s. The USSR has be hard-ground landing since day one. The only visible change is the addition of a porthole to enable riders to see outside. My question would be, who's funding this program, and who's receiving the money. Follow the money and you'll likely get some answers.
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