How Fast Can NASA Shuttles Really Travel in Space?

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Discussion Overview

The discussion revolves around the speed capabilities of NASA shuttles in space, exploring the limitations imposed by physics, fuel requirements, and the implications of traveling at high speeds, particularly near the speed of light. Participants examine both theoretical and practical aspects of space travel, including mass, fuel efficiency, and gravitational influences.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants suggest that once in space, vehicles can accelerate without limits, but others clarify that mass and the laws of physics still apply, impacting acceleration and speed.
  • One participant emphasizes that fuel is a critical limitation for shuttles, as they cannot carry enough fuel to achieve significant speeds beyond low Earth orbit.
  • Another participant proposes a hypothetical scenario where a shuttle with unlimited fuel could approach the speed of light, but acknowledges that occupants would not experience any effects of acceleration.
  • Concerns are raised about the implications of approaching light speed, including the increase in mass and the time dilation effects experienced during such travel.
  • Participants discuss the design of rockets, highlighting that multiple stages can reduce mass and improve efficiency, with comparisons made to the Apollo missions.
  • There is a debate regarding the efficiency of liquid hydrogen as a fuel, with differing opinions on its advantages and disadvantages in terms of density and storage requirements.

Areas of Agreement / Disagreement

Participants express a range of views on the capabilities and limitations of NASA shuttles, with no consensus reached on the implications of speed in space or the efficiency of various fuels. The discussion remains unresolved regarding the best approaches to understanding these concepts.

Contextual Notes

Participants note that the actual weight of a spacecraft in low Earth orbit is nearly the same as on the surface, and that fuel requirements for both launch and travel are significant factors in determining speed capabilities. There are also unresolved discussions about the implications of traveling at relativistic speeds.

  • #31
rbj said:
it doesn't hit the speed of light. even with all the fuel in the universe.

when i had said that i had meant when the shuttle gets to the speed of light then what would happen to it

Jeff Reid said:
I'm not sure what fuel is used to slow down the shuttle for reentry. The small maneuvering thrusters use a fuel that doesn't have the storage issues of hyrodgen and oxygen, but it's toxic.

To slow down i know they use the rudder and i am pretty sure they use the slats, flaps and spoiler. When planes are landing they use all of those except for the rudder

Shuttle rudder
 
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  • #32
The Shuttle first has to enter the atmosphere. The aero surfaces don't do anything while the Shuttle is on-orbit. The Shuttle has to do a "de-orbit burn" directed against the orbital velocity vector. The burn changes the eccentricity of the Shuttle's orbit such that the perigee is below the top of the atmosphere. Half an orbit or so later, the Shuttle enters the atmosphere.

Once it does enter the atmosphere, it is the body of the Shuttle that slows the Shuttle down, not the aero control surfaces. That is why the bottom of the Shuttle is covered with tile. Those aero control surfaces exist to keep the Shuttle on the right angle of attack and in the right attitude.
 
  • #33
As D_H points out, the shuttle uses aerobraking, not aerodynamics to slow down - the very same aerobraking that all the Apollo capsules used - and they didn't have any wings or rudder.

At 25 times the speed of sound you don't want to be sticking anything out. The wings and rudder only come into play once the shuttle slows below the speed of sound.
 
  • #34
noagname said:
To slow down i know they use the rudder and i am pretty sure they use the slats, flaps and spoiler.
Shuttle rudder
The shuttle doesn't have flaps, but it does have speed brakes in the vertical stabilizer as seen in the picture. The speed brakes aren't used until the shuttle is well below sub-sonic speed. Wiki includes information about what occurs between re-entry and landing.

http://en.wikipedia.org/wiki/Space_Shuttle

Many (most) delta wing type aircraft don't have flaps, since delta wings can be flown at about double the angle of attack of a normal wing to allow for slower speed flight such as landing. The Concorde is a typical delta wing design, without flaps (the rear control surfaces are elevons).

http://www.concordesst.com/wing.html
 
  • #35
NASA has a "Landing 101" web page that describes shuttle landing from 4 hours prior to deorbit burn to wheelstop. http://www.nasa.gov/mission_pages/shuttle/launch/landing101.html

Note that (1) the aerosurfaces become active as soon as they have some air to work against, and (2) the Shuttle doesn't go subsonic until it is 25 miles shy of the landing site. Practically all of the descent is supersonic.

noagname said:
when i had said that i had meant when the shuttle gets to the speed of light then what would happen to it

The Shuttle goes Mach 25 or so (25 times the speed of sound). The speed of light is Mach 880991. Science fiction movies do not portray reality, and are particular guilty of veering from science to fiction when it comes to spacecraft . Spacecraft, unlike aircraft, do not need to bank to turn and cannot turn on a dime. Spacecraft are not at all like jet fighters. If you want a good analogy, think of a fully-loaded 18 wheeler on ice with a VW engine and no brakes.
 
  • #36
D H said:
If you want a good analogy, think of a fully-loaded 18 wheeler on ice with a VW engine and no brakes.
I love it!
 
  • #37
ok ok
i am young and i am into airplanes not shuttles
i guess i just drifted into a no fly zone.
and nice analogy
 
  • #38
rbj said:
it doesn't hit the speed of light. even with all the fuel in the universe.

noagname said:
when i had said that i had meant when the shuttle gets to the speed of light then what would happen to it

the shuttle doesn't get to the speed of light. so how can your question be answered? there is no meaning to a question of "what are the consequences when something impossible happens?"
 
  • #39
D H said:
Spacecraft are not at all like jet fighters. If you want a good analogy, think of a fully-loaded 18 wheeler on ice with a VW engine and no brakes.

OMG I'm still laughing! The only caveat being that while controlling direction and velocity can be brutal, with thrusters and gyro's and no air there is a vast amount more freedom of attitude control.
 

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