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Space Shuttle Challenger
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11-01-2008 11:17pm#1
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Nope. Unless you want to have a geostationnary position you can orbit in any direction you like. There are even satelittes which are in a pole orbit, i.e. north-south-north orbit. Orbiting is all about gravity, which is completely independent of the planet's rotation.
Well, that's not true. The space shuttle, like the vast majority of objects launched into orbit, is always launched towards the east, corresponding to the direction of the earths rotation. This is extremely important.
The angular velocity of any point on the surface of the earth increases from 0 MPH at the axial pole to over 1000 MPH (West to East) at the equator. Any vehicle heading for orbit need to reach orbital velocity (which varies depending on the height of orbit you require).
For the shuttle this is approximately 185 mile up, which in the greater scheme of things, is just outside the atmosphere. The orbital velocity for this altitude is between 17000 and 18000 mph - and it takes a huge amount of fuel to acheive this. However the space shuttle would need substantially more fuel (and therefore size and weight) were it not for two combined factors - the lowest available lattitude for launch, and the launch being in and easterly direction.
The surface of the earth at the Kennedy space centre is moving at 914.3 MPH to the east. Launching to this direction adds this speed to the shuttle (launcing to the north or south adds nothing, launching to the west is the worst possible scenario - the rotation speed is subtracted; it might not even make it to orbit!). So the shuttle and most other objects always launch to the east.
The US opted to keep the launch site on US mainland, so this launch site, surrounded by sea and therefore away from populated ares, is their lowest practical lattitude. The shuttle does vary it's orbit profile, but it's always a relatively insignificant variation from the flat east orbit.
Acheiving polar orbits or other high-incidence orbits requires huge amounts of propellant to be expended per kilo of payload. It is done, mostly for Earth imaging (both for science and military), GPS and polar region communications etc, but it's hugely expensive even compared to normal satellite launches, and certainly too expensive to be done with something like a shuttle orbiter.
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Zirconia, your launch trajectory map shows that a launch may pass close to Ireland. Would the rocket trail still be visible by the time the shuttle gets to Ireland? I personally doubt it, but maybe you can clear things up with figures and the like?
No, in the (extremely unlikley) event that the shuttle launch trajectory crossed Ireland, there would be no exhaust plume anyway. The solid rocket boosters are separated after less than 150 miles of downrange travel, and the external tank separation is just before 900 miles of downrange travel - and as all the fuel for the space shuttle main engines is in the external tank, they obviously are shut down by this point, and the shuttle is already outside the atmosphere.
Most launches are in daylight, so all you would see is blue sky, the orbiter is to high and distant by this point. If it was a night launch, you might see a point of light but is would depend on the critical angle between you, the orbiter and the sun at that moment. It's pretty much the same viewing critera as per normal viewing of the shuttle during its orbits at that point really.
By the way on your original point, the shuttle was originally intended to be used for polar launches (mainly through exclusively military controlled missions) from Vandenberg AFB, but when the shuttle program was realised, the whole loss of payload due to fuel requirements killed that off, and they military went back to conventional launch vehicles for polar orbits.
Another interesting point is that Shannon airport was originally listed at the beginning of the program as one of several abort landing sites should the shuttle malfunction during the launch phase (the diagram I posted earlier is an illustration of the trans-oceanic launch abort landing options). As far as I am aware, they don't use it as an option any more.
This is a long exposure of a shuttle night launch to the east, with the launch tower to the lower left. You can see from this photo how the shuttle begins to circularise its trajectory; arching over immediately after clearing the tower. The photo gives the illusion that it is decending to the east, but in reality is is actually gaining altitude continously in this scene.
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