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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."
Watch the touch down too! I rewrote the nose wheel steering GN&C module in '89 and the stuff that makes landings "perfect" in '91. They were blowing tires with rough landings. Since then, the touch downs are PERFECT and smooooooooooth.
Hi JV, KM, DC, BW, AR, LP, SM, JY, PP, and the rest of the old GN&C team!
At first I thought those were March X and was going to congratulate NASA on conquering time travel.
I'm not sure minimizing drag is the goal when you start your landing approach at Mach 22.
Drag is a good thing on reentry, where you are slowing down as fast as the heat shield will let you. The shuttle acts a glider only for the very last part, and hence doesn't need to be a very good one. It may look like a plane but it really spends more time acting like a rocket.
I'd tell a UDP joke, but you may not get it. I'd tell a TCP joke, but I'd have to keep repeating it until you got it.
What should I look for, about 500 miles straight-line distance along the path from the runway?
Last time I had this chance, I think I saw a plane cross the sky, but it seemed too slow.
All my liberal friends think I'm a conservative, all my conservative friends think I'm a liberal.
You know what? That's a great idea. Likewise, I always thought that I need to reduce the friction that the brake pads constantly apply on my car's wheels. I've heard that any kind of oily substance might help, but synthetic motor oils are preferred because they withstand higher temperatures. Imagine the fuel economy (after that subtle modification, I'll only need to refuel the vehicle only once during its lifetime).
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You know what else has really bad aerodynamics and catches all kinds of drag in the atmosphere? Meteorites.
And your mama.
Drag is a good thing on reentry, where you are slowing down as fast as the heat shield will let you.
Why slow down as fast as possible? It's not like the shuttle couldn't spend a few hours gradually slowing down at a safe altitude.
Or is there a reason they want it to come in as fast as possible?
Its supposed to catch as much air as possible, thats how it slows down from Mach 22 to 250 knots in 35 minutes.
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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."
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You want to lose as much of the speed as possible in the initial stages of reentry, high in the atmosphere; before you hit the dense parts. In those higher areas the lift to keep you up there longer could only be produced basically almost at orbital speeds...while what you want to do is slow down.
Shuttle actually "flies" in a quite un-aerodynamic position through large part of reentry preciselly to maximise drag.
One that hath name thou can not otter
but what about your momma?
Depends on her surface area to mass ration ;-)
SB
It's old. The more humans I meet, the more I like my cats. At least they are honest.
Your mama
a) is dumber
b) has a significantly higher volume and mass than our reentry vehicles, and essentially wears quite small amounts of drag
c) enters the atmosphere extremely fat
All in all, often still carrying lots of weight because she's so dense. Where she loses a large part of her mass to ablation, often shatters. We don't want to do that with your momma.
I've seen reentry across Austin (and not the time it broke up smarty pants). Have you ever seen the ISS or a satellite crossing the sky? It looked kinda like that. The shuttle was a bright dot streaking across the horizon very fast, a good 3 times faster than a commercial plane, and left a contrail that hung in the air for a while. Contrail is a misnomer since it stands for condensation trail. What it really is leaving is a trail of ionized gas and ablated material off the orbiter. A minute later I heard a faint sonic double boom.
At the distance you are at, it will be lower, meaning you will have less range you can see it over, so I'd imagine it will still appear to be going very fast (and it will be fast). I think it should be just above supersonic, so you should hear the boom. I doubt it will still be leaving a contrail. I don't think you'll be able to miss it.
Yep here it is, orbital calculator. Punch in your zip code and tell it to show you pass 222 of the shuttle. It will give a set of times. (in eastern standard time)
My set peaks at 10 deg above the horizon, so ya, probably not going to happen. Maybe if I went out in the country, but it'd be so far away, that's a shame. I'd like to say "maybe next time", but that's not likely... :(
I work for the Department of Redundancy Department.
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.
See that "Preview" button?
mach 22 = 45 014 740.2 furlongs per fortnight 250 knots = 773 323.789 furlongs per fortnight :)
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Just watched the shuttle pass over Seattle without re-entry on orbit 222, closely followed by ISS. Next pass will be well past sunrise (6:57).
The landing has been postponed until Tuesday (at least) due to rain. Check SpaceWeather for updates.
And drag doesn't matter till the vehicle drops below Mach 2 or so. Also the Shuttle has to carry stuff and have those big engines sticking out the back. I'd say its pretty aerodynamic given its shape. If I were the grandparent poster, I might be asking if a better lifting body could be developed, so that the Shuttle approaches landing a bit slower (ie, at a slower speed and better glide ratio). Given that no one has yet crashed a Shuttle, I don't think this is a serious issue, but you never know, they haven't landed that many Shuttles (it could be comparable in frequency to the failure modes like SRB or heat shield failures, but just not have happened yet).