Forgot your password?
typodupeerror
NASA Science

Shuttle Reentry Over the Continental US 139

Posted by kdawson
from the boom-boom dept.
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."
This discussion has been archived. No new comments can be posted.

Shuttle Reentry Over the Continental US

Comments Filter:
  • by Anonymous Coward on Sunday April 18, 2010 @07:32PM (#31890978)

    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!

    • by PopeRatzo (965947) * on Sunday April 18, 2010 @08:40PM (#31891428) Homepage Journal

      I rewrote the nose wheel steering GN&C module in '89 and the stuff that makes landings "perfect" in '91.

      Big deal. I just killed Zeus in God of War III.

    • The weather [weather.gov] looks a bit grim for a KSC landing.
      • by Tiger4 (840741)

        The weather [weather.gov] at Edwards for the following three days is only a little better. Its either Edwards on Monday, or Canaveral on Tuesday.

        • by e9th (652576)
          Even White Sands looks iffy. [weather.gov] Guess it'll be another day or so before deorbit. Disappointing, but nothing new.
          • Dear god/NOAA/NASA please have a landing in white sands with >2 hours of warning. Not only would my bosses let me off to drive down and see it they would probably car-pool a company van....
  • Mach _ (Score:5, Funny)

    by 0100010001010011 (652467) on Sunday April 18, 2010 @07:32PM (#31890980)

    At first I thought those were March X and was going to congratulate NASA on conquering time travel.

    • Dude, without your comment I’d STILL think ‘why did he say 35 minutes, when the image shows it taking days to fly that distance? And why would it fly so slow and away from the space center anyway?”

      By the way: I am a time traveler too!
      Right now I am at 02:29:15.
      And now I am at 02:29:28! Whoohooo!
      Now wait a minute, and I’ll jump a whole minute into future! ;)

  • The shuttle comes in like a bat out of hell, but I wonder if there couldn't be a more aerodynamic shape it could use to reduce the friction from the atmosphere. The shuttle is like a giant wing catching as much air as possible. It doesn't seem to be the best design to minimize drag...

    • by Jaime2 (824950) on Sunday April 18, 2010 @07:37PM (#31891012)
      I'm not sure minimizing drag is the goal when you start your landing approach at Mach 22.
      • by fredrik70 (161208)

        would be a great contender for fastest thing on land, just need to extend the landing strip a little bit!

      • Re: (Score:3, Interesting)

        by khallow (566160)
        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
    • by MasterPatricko (1414887) on Sunday April 18, 2010 @07:44PM (#31891048) Homepage
      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.
      • Re: (Score:2, Interesting)

        by BadAnalogyGuy (945258)

        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?

        • Re: (Score:3, Interesting)

          by sznupi (719324)

          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.

          • There is another reason, too. The shuttle was designed as a _military_ craft. They don't want it being an easy target on reentry, so it comes in fast and over the continental US. If it were to come in slow, or over the ocean, it would be a target.

        • by pnewhook (788591)

          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.

          If you reduce your angle of descent too much, yes the instantaneous amount of heat buildup will be less, but you will be doing this over a much greater period of time. This will cumulate and fail the heat shields. So your entry needs to be a balance between too much friction to fail the shields, and too much total buildup over the entire glide path. These are the basic restrictions on angle of entry.

          • by ckaminski (82854)
            The laws of conservation of energy would disagree with you. The amount of energy required to decelerate the shuttle is finite, hence the total energy absorbed by the shielding is finite. It's not long-duration temperatures they shields have to withstand - they do that already, being non-ablative - it's the instantaneous heat. They are only rated to certain temperatures. They could take 4 hours to decelerate if the physics of deorbiting allowed it, but get a 6000 degree temperature spike, and poof, no mo
            • by pnewhook (788591)

              It's not long-duration temperatures they shields have to withstand - they do that already, being non-ablative - it's the instantaneous heat.

              It's both. For long duration heating the heat has a chance go through the entire thickness of the heat shield and destroy what the shield was trying to protect. A shorter descent gives a higher surface temperature but it doesn't have time to heat the material underneath.

              Heat shields work this way. They do not violate the conservation of energy.

      • by Moraelin (679338) on Sunday April 18, 2010 @08:15PM (#31891256) Journal

        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."

      • It may look like a plane but it really spends more time acting like a rock.

        FTFY

      • I believe I'm going to have to throw a giggity on that one--or at least a "that's what she said".

    • Re: (Score:2, Funny)

      by tzot (834456)

      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).

      • by BadAnalogyGuy (945258) <BadAnalogyGuy@gmail.com> on Sunday April 18, 2010 @07:53PM (#31891108)

        You know what else has really bad aerodynamics and catches all kinds of drag in the atmosphere? Meteorites.

        And your mama.

        • by sznupi (719324)

          Meteorites

          a) are speedier

          b) have significantly lower volume to mass ratio than our reentry vehicles (hence what you propose, essentially - quite small amounts of drag per the unit of energy carried (which is also higher generally thanks to a)))

          c) enter the atmosphere typically at much more steep angle

          All in all, often still carrying lots of energy when hitting denser atmosphere. Where they lose large part of their mass to ablation, often shatter. We don't want to do that with our vehicles.

          • Re: (Score:3, Funny)

            by /dev/trash (182850)

            but what about your momma?

            • Re: (Score:3, Funny)

              by shadowbearer (554144)

                Depends on her surface area to mass ration ;-)

              SB

              • by game kid (805301)

                Depends on her surface area to mass ration

                Indeed, all those rations have taken a toll on her curves. :(

            • 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.

              • by vandelais (164490)

                You wanta play the dozens, well the dozens is a game. When ablation hits your momma it's a goddamn shame.

        •   Compared to the shuttle, meteorites are practically drag free. They don't glide at all.

          SB

    • Re: (Score:3, Informative)

      by BitZtream (692029)

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

    • Re: (Score:1, Informative)

      by Anonymous Coward

      Orbital mechanics determines the speed required to be in orbit. It is fairly simple physics and about 17,000 MPH for all objects.

      Landing implies a ZERO speed relative to the rotation of the Earth at the landing sight.

      You need to get the vehicle from 17,000 MPH to zero. There are many ways to accomplish that, but many less if you want to reuse the vehicle and want the people inside not to fry or wait for the last second to "stop." Within these limitations and thousands of others for weight, payload sizes,

      • by pnewhook (788591)

        Orbital mechanics determines the speed required to be in orbit. It is fairly simple physics and about 17,000 MPH for all objects.

        Thats for LEO yes, but different altitude orbits require different speeds.

    • How would it slow down without friction? You don’t want it to have no friction with air, or it will land like a meteorite, causing a hole too deep to get their pulverized remains dug out again afterwards. ;)

    • That's because it's end goal is to land on the runway, not embed itself a few hundred feet into it.

    • by LtGordon (1421725)

      The shuttle is like a giant wing catching as much air as possible. It doesn't seem to be the best design to minimize drag...

      I know, right? And don't get me started on the drag coefficient of those parachutes. It's like they're trying to slow themselves down.

    • by anegg (1390659)
      I thought the parent post was in the ironic mode - doesn't anyone get jokes anymore?
    • I wonder if there couldn't be a more aerodynamic shape it could use to reduce the friction from the atmosphere.

      Every additional pound of wing is one less pound of payload. The shuttle comes in dead-stick and has no capability to come around for another pass. So enough wing to get it to the runway is all the wing it should have.

      As it is (if what I heard from someone in the industry back in the day is correct) the shuttle has FAR too much wing for the mission profiles on which it has been used.

      The shuttle w

  • by bondsbw (888959) on Sunday April 18, 2010 @07:47PM (#31891064)

    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.

    • 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.

      Considering the age of those things I don't think it will be hard. Just look for a ball of flame and chunks falling out of the sky.

    • Re: (Score:3, Interesting)

      by BitZtream (692029)

      Click the link in the summary ... it draws you a pretty picture. If you live within 500 miles of the runway, ask your neighbor, every Floridian has probably seen at least one reentry.

      • by bondsbw (888959)

        I'm in west Alabama, so I don't know many people who really know what it should look like.

        I'm not looking for a ground track or even a sky track, which are at that page... I'm more wondering if I should be looking for a fast streak across the sky (or perhaps as slow as a passenger jet), would it be orange or just look like a plane, about how high would it be (as high as a passenger jet, or maybe lower), would it have a smoke trail, etc. Just visual cues that would let me know that what I'm seeing is the sh

    • 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.

      I saw it from the Bay Area once when it was landing at Edwards, which is a pretty similar distance. Look for a fast, bright, colored object that would probably be interpreted as a sign of the apocalypse a couple hundred years ago. It won't be subtle.

    • 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
      • by ckaminski (82854)
        How many of the tiles on the orbiter are ablative? IIRC, none of them are.
        • by colinnwn (677715)
          Not ablative in the traditional sense of that is how the TPS works. Bad choice of words on my part. It is foreign particulates dislodging from the body of the shuttle and unintended flaking of the heat shield, combined with impurities in the atmosphere being heated up, that helps make the smoke contrail.
    • by wtmoose (639328)
      Saw it once in Austin late 2001. It pretty much looked like a contrail made out of fire. It moved slowly, but eventually spanned the entire sky. For a few moments I thought it was a plane bombing (this was right after 9/11). If it passes overhead, you can't miss it.
  • Looking at the map, it's going to be flying right about over my head. I know what I'm going to be doing tomorrow morning.
  • Shuttle sonic booms were a perk for me living in LA, whenever it landed at Vandenburg. Those in the path, set your alarms!
    • Shuttle sonic booms were a perk for me living in LA, whenever it landed at Vandenburg.

      Edwards. It never landed at Vandenburg,
    • by RoboRay (735839)

      Vandenberg was proposed as an alternate launch site for polar orbiting flights, as it allowed overwater launches to the south. No such launches ever occurred, however. I don't believe Vandenberg was ever considered as a landing site.

  •   I hope the map in the link wasn't meant to be accurate. They misplaced Pierre, SD by quite a ways east of where it is - that's closer to Mitchell, SD :-)

      Still, if it's going to pass over Pierre, it should be visible from where I'm at, if I can get up early enough to climb one of the hills here and still make it to work an hour later...

    SB

  • This is a really neat idea since it might give NASA some much-needed good publicity. That, or it will let those in the midwest/southeast get one last good look at it i the sky before it's in museum.
  • If geography allowed it and it made orbital sense to fly over a populated area during every landing, do you think the general population might be more aware and interested in space travel?

    If I had an orbital vehicle streaking across the sky every month or so, I would certainly be very aware of the pace of space travel and keep it in my head for longer then I do now.

    • by v1 (525388)

      I think I'd almost consider it a perk of being an American to see the shuttle cruising in overhead for a landing. "THIS is an example of your tax dollars doing rad things". It's a sight everyone should get to have. I've never seen the shuttle, but I live in Iowa, (central unfortunately, not southwest) so I don't think I am going to get to see it. But I'm going to depart for some research now to see if I have a shot.

    • Re: (Score:3, Informative)

      by v1 (525388)

      Yep here it is, orbital calculator [nasa.gov]. 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... :(

  • Anyone have a clue why the shuttle would be making a retrograde descent?
    • by cruff (171569)

      It isn't. Look up Orbital Node [wikipedia.org] on Wikipedia for a description about what descending node means.

    • Because it's not.
    • by Orgasmatron (8103) on Sunday April 18, 2010 @11:03PM (#31892236)

      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.

      • Re: (Score:1, Informative)

        by Anonymous Coward

        Adding to this, what I'm not sure the OP well above realizes is... well, a couple of things.

        1) Technically, ALL descents start while the vessel is facing retrograde. ;) (Sorry, just being a jerk.)
        2) Orbital planes can take many shapes on a mercator projection of a map, from a flat line (at the equator) to a sine wave, to what appears to be a pair of tangental lines (north-to-south). This particular plane is an abnormally radical "sine wave" when looking at a mercator map projection, and technically is comin

  • Can anyone say how close to the path one needs to be in order to see/hear anything?

    • by Ranzear (1082021)
      Being within 860 miles puts it 8 degrees above the horizon. This is where Seattle will catch it on the first possible attempt, but if it goes to the second attempt it will be much more overhead at a 50 degree angle.
  • Any larger maps? Will it be visible from the Seattle area on the first pass?

  • by PiSkyHi (1049584) on Monday April 19, 2010 @08:06AM (#31894440)
    Pinned to its a tail, a sign reading "Please Donate! NASA"
  • Negative on 222 (Score:3, Informative)

    by Lost Race (681080) on Monday April 19, 2010 @08:42AM (#31894638)
    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).
  • by TheOtherChimeraTwin (697085) on Monday April 19, 2010 @09:11AM (#31894856)
    The landing has been postponed until Tuesday (at least) due to rain. Check SpaceWeather [spaceweather.com] for updates.
  • by ral (93840)
    Landing postponed until tomorrow [nasa.gov] due to weather at the landing site.
  • So we're now looking at orbits 237 or 238, I assume?

    Here's a great calculator from NASA to determine where to look in the sky and at what time, based on your location:

    http://spaceflight.nasa.gov/realdata/sightings/SSapplications/Post/JavaSSOP/JavaSSOP.html [nasa.gov]

    Here in central IL USA, it looks like:

    orbit 237: it'll be at a distance of 136 miles at an elevation of 15deg (not bad!) 06:17 local time.
    orbit 238: a bust for where I live, never gets more than 2deg elevation.

"Everything should be made as simple as possible, but not simpler." -- Albert Einstein

Working...