Shuttle Reentry Over the Continental US

TheOtherChimeraTwin notes that the shuttle Discovery will land at Kennedy Space Center on Monday morning at 8:48 EDT. The craft will make a rare "descending node" overflight of the continental US en route to landing in Florida. Here are maps of the shuttle's path if is lands on orbit 222 as planned, or on the next orbit. Spaceweather.com says: "...it takes the shuttle about 35 minutes to traverse the path shown... Observers in the northwestern USA will see the shuttle shortly after 5 am PDT blazing like a meteoric fireball through the dawn sky. As Discovery makes its way east, it will enter daylight and fade into the bright blue background. If you can't see the shuttle, however, you might be able to hear it. The shuttle produces a sonic double-boom that reaches the ground about a minute and a half after passing overhead."

Comments

Re:So fast, so dangerous

[BitZtream]

Its supposed to catch as much air as possible, thats how it slows down from Mach 22 to 250 knots in 35 minutes.

Not as much "glider" as "brick" ;)

[Moraelin]

1. Well, during re-entry it's not entering nose-first, but belly-first, so the wings basically like air brakes more than like wings. I'm not sure if making it more aerodynamic for flight like an aircraft would actually be an impediment there. It would still have the aerodynamics of a parachute when re-entering belly-first anyway.

2. Well, "glide" is technically accurate, but maybe painting a slightly wrong image for the layman. That thing is losing altitude (falling) at 50m/s (about 110mph or 180 km/h) even in its best glide phase. And it's glide-to-drag ratio is more comparable to a parachute, and I don't mean paraglider, than to an aircraft even at touchdown, during earlier phases let's just say it's got about half as much lift/drag as a squirrel ;)

The angle of descent at touchdown is actually 20 degrees, which doesn't sound like too steep, but it's about 7 times steeper than a commercial airliner landing. By comparison to just about any fixed wing aircraft, it's not akin landing an anvil or the proverbial lead duck ;)

Not saying it's a bad thing, since it does have a _lot_ of altitude and speed to shed, and it's obviously doing a good job at thazt. More like just saying, for the benefit of whoever needs that kind of clarification, that it never actually acts that much like a normal glider, not even on the very last part. Or at least not like a glider you'd want to pilot for fun. All it can do is fall, and quite rapidly at that, just in a more controlled manner. It's a shape to do just one thing: fall down from 340,000m or so (about a million feet) to the ground without going *SPLAT* on touchdown. While techically there is some gliding involved, I think the best description of its role for the layman is more like "rigid parachute" than "glider."

Re:Retrograde Descent?

[Orgasmatron]

It isn't. A retrograde landing at KSC would come in from the Atlantic Ocean.

An orbit requires two things, altitude and transverse velocity. There are no shortcuts for altitude, so we have to do it entirely the hard way, with rockets. On the other hand, everything on the surface of the earth (not counting the poles) has transverse velocity already, because the earth is turning. This gift of velocity is towards the east, and is related to the launch site's latitude, greater at the equator, less at the poles. This is one of the two reasons why we nearly always launch to the east. Anyone know the second reason?

When we launch to the east to take advantage of this gift, we call that a prograde orbit. Launching into a retrograde orbit requires burning fuel for 100% of the required transversal, plus enough to overcome the initial eastward velocity from the launch site.

A southward launch from California can be used for a polar orbit, but I don't think the shuttle has ever actually done it. I think the Air Force insisted that the shuttle be capable of this mission, which would be a single-orbit spy flight over the Soviet Union.