Why didn't the Space Shuttle bounce back into space as many times as possible so as to lose a lot of kinetic energy up there?If there was a non-rotating skyhook in Earth orbit, what would re-entry be like after dropping from its foot?Why didn't the Space Shuttle have a launch escape system?How many Solid Rocket Boosters were there in the Space Shuttle program?Why didn't NASA use the shuttle to make a profit?While decending from orbit can a blimp glider skip an atmosphere to shed speed?Is getting IN or OUT of orbit easier for the Space Shuttle?Why didn't the space shuttle SRBs have wings and tires?Why didn't the SRBs of the Space Shuttle use carbon instead of aluminium?How many times were there thirteen people inside the ISS? Is it hard on the station?Why didn't the space shuttle use non-foam-shedding external tanks?Why can't you just parachute down right from orbit?
Lock in SQL Server and Oracle
Was it really necessary for the Lunar Module to have 2 stages?
Is it possible to Ready a spell to be cast just before the start of your next turn by having the trigger be an ally's attack?
Has any spacecraft ever had the ability to directly communicate with civilian air traffic control?
Python "triplet" dictionary?
Single Colour Mastermind Problem
How can Republicans who favour free markets, consistently express anger when they don't like the outcome of that choice?
Examples of non trivial equivalence relations , I mean equivalence relations without the expression " same ... as" in their definition?
How deep to place a deadman anchor for a slackline?
Does the EU Common Fisheries Policy cover British Overseas Territories?
What is the difference between `a[bc]d` (brackets) and `ab,cd` (braces)?
Phrase for the opposite of "foolproof"
If Earth is tilted, why is Polaris always above the same spot?
Illegal assignment from SObject to Contact
Stark VS Thanos
Were there two appearances of Stan Lee?
How to set the font color of quantity objects (Version 11.3 vs version 12)?
Is GOCE a satellite or aircraft?
How to determine the actual or "true" resolution of a digital photograph?
Cannot populate data in lightning data table
Toggle Overlays shortcut?
How to figure out whether the data is sample data or population data apart from the client's information?
What is the range of this combined function?
Pressure to defend the relevance of one's area of mathematics
Why didn't the Space Shuttle bounce back into space as many times as possible so as to lose a lot of kinetic energy up there?
If there was a non-rotating skyhook in Earth orbit, what would re-entry be like after dropping from its foot?Why didn't the Space Shuttle have a launch escape system?How many Solid Rocket Boosters were there in the Space Shuttle program?Why didn't NASA use the shuttle to make a profit?While decending from orbit can a blimp glider skip an atmosphere to shed speed?Is getting IN or OUT of orbit easier for the Space Shuttle?Why didn't the space shuttle SRBs have wings and tires?Why didn't the SRBs of the Space Shuttle use carbon instead of aluminium?How many times were there thirteen people inside the ISS? Is it hard on the station?Why didn't the space shuttle use non-foam-shedding external tanks?Why can't you just parachute down right from orbit?
$begingroup$
From this video, I got know that Space Shuttle did reentry around 5000 miles away from landing site. It's angle of attack is maintained around 40 degrees during re-entry. If it is more than that, it bounces back to space.
Why don't we let the Shuttle bounce back into space many times as possible and skim a lot of atmosphere so that it loose lot of kinetic energy over there? I think bounce back causes intermittent heating so heat shield tiles get a lot of time of radiate heat out.
space-shuttle reentry
edited Apr 24 at 23:03
MackTuesday
1033
asked Apr 24 at 1:59
SRDSRD
443129
$endgroup$
add a comment |
$begingroup$
From this video, I got know that Space Shuttle did reentry around 5000 miles away from landing site. It's angle of attack is maintained around 40 degrees during re-entry. If it is more than that, it bounces back to space.
Why don't we let the Shuttle bounce back into space many times as possible and skim a lot of atmosphere so that it loose lot of kinetic energy over there? I think bounce back causes intermittent heating so heat shield tiles get a lot of time of radiate heat out.
space-shuttle reentry
edited Apr 24 at 23:03
MackTuesday
1033
asked Apr 24 at 1:59
SRDSRD
443129
$endgroup$
$begingroup$
To be clear, it's not AoA which prevents the shuttle from skipping; it's banking - pointing the lift vector sideways instead of up. An increase in AoA from 40° would most likely reduce the chance of skipping.
$endgroup$
– Bret Copeland
Apr 24 at 7:11
21
$begingroup$
5000 nautical miles away. The answer is in the video but easy to miss; he notes very quickly, and only once, that slowing too much: you'll drop out the sky like a rock (which is the penultimate concern at all times only to 'rapid unplanned disassembly'). It's bad enough that it's already a flying brick.
$endgroup$
– Mazura
Apr 24 at 10:04
$begingroup$
Hi SRD I think BretCopeland's answer does a better job addressing the question than mine; I wonder if you would consider accepting that one instead of mine?
$endgroup$
– uhoh
Apr 25 at 20:39
add a comment |
$begingroup$
From this video, I got know that Space Shuttle did reentry around 5000 miles away from landing site. It's angle of attack is maintained around 40 degrees during re-entry. If it is more than that, it bounces back to space.
Why don't we let the Shuttle bounce back into space many times as possible and skim a lot of atmosphere so that it loose lot of kinetic energy over there? I think bounce back causes intermittent heating so heat shield tiles get a lot of time of radiate heat out.
space-shuttle reentry
edited Apr 24 at 23:03
MackTuesday
1033
asked Apr 24 at 1:59
SRDSRD
443129
$endgroup$
From this video, I got know that Space Shuttle did reentry around 5000 miles away from landing site. It's angle of attack is maintained around 40 degrees during re-entry. If it is more than that, it bounces back to space.
Why don't we let the Shuttle bounce back into space many times as possible and skim a lot of atmosphere so that it loose lot of kinetic energy over there? I think bounce back causes intermittent heating so heat shield tiles get a lot of time of radiate heat out.
space-shuttle reentry
space-shuttle reentry
edited Apr 24 at 23:03
MackTuesday
1033
asked Apr 24 at 1:59
SRDSRD
443129
edited Apr 24 at 23:03
MackTuesday
1033
asked Apr 24 at 1:59
SRDSRD
443129
edited Apr 24 at 23:03
MackTuesday
1033
edited Apr 24 at 23:03
MackTuesday
1033
edited Apr 24 at 23:03
MackTuesday
1033
1033
asked Apr 24 at 1:59
SRDSRD
443129
asked Apr 24 at 1:59
SRDSRD
443129
asked Apr 24 at 1:59
SRDSRD
443129
443129
$begingroup$
To be clear, it's not AoA which prevents the shuttle from skipping; it's banking - pointing the lift vector sideways instead of up. An increase in AoA from 40° would most likely reduce the chance of skipping.
$endgroup$
– Bret Copeland
Apr 24 at 7:11
21
$begingroup$
5000 nautical miles away. The answer is in the video but easy to miss; he notes very quickly, and only once, that slowing too much: you'll drop out the sky like a rock (which is the penultimate concern at all times only to 'rapid unplanned disassembly'). It's bad enough that it's already a flying brick.
$endgroup$
– Mazura
Apr 24 at 10:04
$begingroup$
Hi SRD I think BretCopeland's answer does a better job addressing the question than mine; I wonder if you would consider accepting that one instead of mine?
$endgroup$
– uhoh
Apr 25 at 20:39
add a comment |
$begingroup$
To be clear, it's not AoA which prevents the shuttle from skipping; it's banking - pointing the lift vector sideways instead of up. An increase in AoA from 40° would most likely reduce the chance of skipping.
$endgroup$
– Bret Copeland
Apr 24 at 7:11
21
$begingroup$
5000 nautical miles away. The answer is in the video but easy to miss; he notes very quickly, and only once, that slowing too much: you'll drop out the sky like a rock (which is the penultimate concern at all times only to 'rapid unplanned disassembly'). It's bad enough that it's already a flying brick.
$endgroup$
– Mazura
Apr 24 at 10:04
$begingroup$
Hi SRD I think BretCopeland's answer does a better job addressing the question than mine; I wonder if you would consider accepting that one instead of mine?
$endgroup$
– uhoh
Apr 25 at 20:39
$begingroup$
To be clear, it's not AoA which prevents the shuttle from skipping; it's banking - pointing the lift vector sideways instead of up. An increase in AoA from 40° would most likely reduce the chance of skipping.
$endgroup$
– Bret Copeland
Apr 24 at 7:11
$begingroup$
To be clear, it's not AoA which prevents the shuttle from skipping; it's banking - pointing the lift vector sideways instead of up. An increase in AoA from 40° would most likely reduce the chance of skipping.
$endgroup$
– Bret Copeland
Apr 24 at 7:11
21
21
$begingroup$
5000 nautical miles away. The answer is in the video but easy to miss; he notes very quickly, and only once, that slowing too much: you'll drop out the sky like a rock (which is the penultimate concern at all times only to 'rapid unplanned disassembly'). It's bad enough that it's already a flying brick.
$endgroup$
– Mazura
Apr 24 at 10:04
$begingroup$
5000 nautical miles away. The answer is in the video but easy to miss; he notes very quickly, and only once, that slowing too much: you'll drop out the sky like a rock (which is the penultimate concern at all times only to 'rapid unplanned disassembly'). It's bad enough that it's already a flying brick.
$endgroup$
– Mazura
Apr 24 at 10:04
$begingroup$
Hi SRD I think BretCopeland's answer does a better job addressing the question than mine; I wonder if you would consider accepting that one instead of mine?
$endgroup$
– uhoh
Apr 25 at 20:39
$begingroup$
Hi SRD I think BretCopeland's answer does a better job addressing the question than mine; I wonder if you would consider accepting that one instead of mine?
$endgroup$
– uhoh
Apr 25 at 20:39
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
I think bounce back causes intermittent heating so heat shield tiles get a lot of time of radiate heat out.
Your thinking is reasonable as far as it goes...
But once you lose too much velocity and become deeply sub-orbital, you will sink like a rock into thicker atmosphere.
Within five minutes you'll either be toast from heating or jelly from pulling 15-20 gees.
In this answer I did a calculation for a different spacecraft (a Dragon capsule) with lift to drag between 0 and 0.3 and the scenario was always the same. Being significantly slower results in falling too deeply to quickly, and the higher density results in huge heat production and unsurvivably large accelerations.
answered Apr 24 at 2:37
uhohuhoh
41.7k19160524
$endgroup$
1
$begingroup$
@MontyHarder thank you for that. For some reason those two wires are permanently crossed.
$endgroup$
– uhoh
Apr 24 at 22:34
5
$begingroup$
And if you want hands on (simulated) experience, there's always KSP. Suborbital approaches are surprisingly tricky, and losing horizontal speed too quickly is a great way to lose all that lift you need not to drop like a rock.
$endgroup$
– Luaan
Apr 25 at 15:03
1
$begingroup$
@Luaan Yup. It's amazing how much horizontal velocity you need in KSP slow enough to pop your chute. For suborbital missions I actually found it's cheaper to go straight up and then use your rocket to slow your descent! (The braking burn needs less delta-v than you would expend getting enough horizontal velocity to survive without the braking burn.)
$endgroup$
– Loren Pechtel
Apr 25 at 19:32
add a comment |
$begingroup$
Skipping reentries aren't unheard of. The Apollo command module performed a single skip when returning from lunar missions. However, there are several reasons why a skipping reentry (especially one involving multiple skips) would be disadvantageous for the shuttle:
- As uhoh points out, a skipping reentry results in losing lateral speed at a very high altitude. In turn, you lose the ability to control your descent rate. By the end of entry you'd practically be in a free-fall which the vehicle would be unlikely to survive due to the heat and/or stress of attempting to pull out of the dive.
- The shuttle's thermal protection system was not designed to withstand long drawn-out reentries. Here's a quote from the "Entry, TAEM, and Approach/Landing Guidance Workbook":
On the flip side of high surface temperatures, there are high backface temperatures. If
you fly at high temperatures for a long time, heat will flow through the tiles to the
aluminum underneath. This can happen if you fly a low drag profile. In fact, backface
temperature is the current low limit to the drag profile. - Several other systems weren't designed for long drawn-out reentries either. The APUs only have the fuel capacity to run for about 110 minutes, which wouldn't be enough to support both launch and an extended reentry. The radiators, which were cold-soaked before entry, may have needed additional capacity to absorb heat build up during entry. The RCS may have needed more reserves.
- Flying a low-drag profile gives you less margin for error. Flying a middle-of-the-road drag profile means you have room to increase or decrease your drag as necessary in order to make the landing site. If your designed flight path is already on the low-end and you end up in a low energy condition, there's not much you can do about it.
- It's not impossible to develop guidance for a skipping reentry, but it is definitely a more difficult problem.
I suspect there are other reasons I haven't thought of.
On the flip side, I can't think of any advantages. The shuttle's reentry was already comparatively gentle (well under 2g's the whole time) and the heat was perfectly managable as-is.
answered Apr 24 at 8:15
Bret CopelandBret Copeland
84958
$endgroup$
$begingroup$
+1 for the limitations due to other systems.
$endgroup$
– Organic Marble
Apr 24 at 13:56
$begingroup$
The APU's a non-issue (it had power for days) but everything else seems right.
$endgroup$
– Joshua
Apr 24 at 15:22
6
$begingroup$
@Joshua no, the APUs had very little fuel reserves. See the Shuttle Crew Operations Manual page 2.1-2: "The hydrazine is stored in a fuel tank with a total capacity of about 350 pounds.... The fuel supply supports the nominal power unit operating time of 90 minutes in a mission or any defined abort mode, such as an abort once around, when the APUs run continuously for approximately 110 minutes. Under operating load conditions, an APU consumes approximately 3 to 3.5 pounds of fuel per minute."
$endgroup$
– Bret Copeland
Apr 24 at 18:22
1
$begingroup$
A slight correction on your first paragraph: Apollo had the option to perform a skip re-entry when coming in from the Moon, but I don't think they ever used it.
$endgroup$
– Mark
Apr 24 at 19:54
1
$begingroup$
@BretCopeland, commentary on the radio transcript for the Apollo 11 re-entry and the Apollo 11 re-entry analysis. Yes, Apollo 11 bounced a bit during re-entry (and it extended the re-entry flight path by running the skip-out software), but it never went back above either the Karman line or the Air Force's 50-mile boundary of space.
$endgroup$
– Mark
Apr 25 at 21:07
|
show 5 more comments
Your Answer
StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "508"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);
else
createEditor();
);
function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);
);
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fspace.stackexchange.com%2fquestions%2f35741%2fwhy-didnt-the-space-shuttle-bounce-back-into-space-as-many-times-as-possible-so%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
I think bounce back causes intermittent heating so heat shield tiles get a lot of time of radiate heat out.
Your thinking is reasonable as far as it goes...
But once you lose too much velocity and become deeply sub-orbital, you will sink like a rock into thicker atmosphere.
Within five minutes you'll either be toast from heating or jelly from pulling 15-20 gees.
In this answer I did a calculation for a different spacecraft (a Dragon capsule) with lift to drag between 0 and 0.3 and the scenario was always the same. Being significantly slower results in falling too deeply to quickly, and the higher density results in huge heat production and unsurvivably large accelerations.
answered Apr 24 at 2:37
uhohuhoh
41.7k19160524
$endgroup$
1
$begingroup$
@MontyHarder thank you for that. For some reason those two wires are permanently crossed.
$endgroup$
– uhoh
Apr 24 at 22:34
5
$begingroup$
And if you want hands on (simulated) experience, there's always KSP. Suborbital approaches are surprisingly tricky, and losing horizontal speed too quickly is a great way to lose all that lift you need not to drop like a rock.
$endgroup$
– Luaan
Apr 25 at 15:03
1
$begingroup$
@Luaan Yup. It's amazing how much horizontal velocity you need in KSP slow enough to pop your chute. For suborbital missions I actually found it's cheaper to go straight up and then use your rocket to slow your descent! (The braking burn needs less delta-v than you would expend getting enough horizontal velocity to survive without the braking burn.)
$endgroup$
– Loren Pechtel
Apr 25 at 19:32
add a comment |
$begingroup$
I think bounce back causes intermittent heating so heat shield tiles get a lot of time of radiate heat out.
Your thinking is reasonable as far as it goes...
But once you lose too much velocity and become deeply sub-orbital, you will sink like a rock into thicker atmosphere.
Within five minutes you'll either be toast from heating or jelly from pulling 15-20 gees.
In this answer I did a calculation for a different spacecraft (a Dragon capsule) with lift to drag between 0 and 0.3 and the scenario was always the same. Being significantly slower results in falling too deeply to quickly, and the higher density results in huge heat production and unsurvivably large accelerations.
answered Apr 24 at 2:37
uhohuhoh
41.7k19160524
$endgroup$
1
$begingroup$
@MontyHarder thank you for that. For some reason those two wires are permanently crossed.
$endgroup$
– uhoh
Apr 24 at 22:34
5
$begingroup$
And if you want hands on (simulated) experience, there's always KSP. Suborbital approaches are surprisingly tricky, and losing horizontal speed too quickly is a great way to lose all that lift you need not to drop like a rock.
$endgroup$
– Luaan
Apr 25 at 15:03
1
$begingroup$
@Luaan Yup. It's amazing how much horizontal velocity you need in KSP slow enough to pop your chute. For suborbital missions I actually found it's cheaper to go straight up and then use your rocket to slow your descent! (The braking burn needs less delta-v than you would expend getting enough horizontal velocity to survive without the braking burn.)
$endgroup$
– Loren Pechtel
Apr 25 at 19:32
add a comment |
$begingroup$
I think bounce back causes intermittent heating so heat shield tiles get a lot of time of radiate heat out.
Your thinking is reasonable as far as it goes...
But once you lose too much velocity and become deeply sub-orbital, you will sink like a rock into thicker atmosphere.
Within five minutes you'll either be toast from heating or jelly from pulling 15-20 gees.
In this answer I did a calculation for a different spacecraft (a Dragon capsule) with lift to drag between 0 and 0.3 and the scenario was always the same. Being significantly slower results in falling too deeply to quickly, and the higher density results in huge heat production and unsurvivably large accelerations.
answered Apr 24 at 2:37
uhohuhoh
41.7k19160524
$endgroup$
I think bounce back causes intermittent heating so heat shield tiles get a lot of time of radiate heat out.
Your thinking is reasonable as far as it goes...
But once you lose too much velocity and become deeply sub-orbital, you will sink like a rock into thicker atmosphere.
Within five minutes you'll either be toast from heating or jelly from pulling 15-20 gees.
In this answer I did a calculation for a different spacecraft (a Dragon capsule) with lift to drag between 0 and 0.3 and the scenario was always the same. Being significantly slower results in falling too deeply to quickly, and the higher density results in huge heat production and unsurvivably large accelerations.
answered Apr 24 at 2:37
uhohuhoh
41.7k19160524
edited Apr 24 at 22:33
answered Apr 24 at 2:37
uhohuhoh
41.7k19160524
answered Apr 24 at 2:37
uhohuhoh
41.7k19160524
answered Apr 24 at 2:37
uhohuhoh
41.7k19160524
41.7k19160524
1
$begingroup$
@MontyHarder thank you for that. For some reason those two wires are permanently crossed.
$endgroup$
– uhoh
Apr 24 at 22:34
5
$begingroup$
And if you want hands on (simulated) experience, there's always KSP. Suborbital approaches are surprisingly tricky, and losing horizontal speed too quickly is a great way to lose all that lift you need not to drop like a rock.
$endgroup$
– Luaan
Apr 25 at 15:03
1
$begingroup$
@Luaan Yup. It's amazing how much horizontal velocity you need in KSP slow enough to pop your chute. For suborbital missions I actually found it's cheaper to go straight up and then use your rocket to slow your descent! (The braking burn needs less delta-v than you would expend getting enough horizontal velocity to survive without the braking burn.)
$endgroup$
– Loren Pechtel
Apr 25 at 19:32
add a comment |
1
$begingroup$
@MontyHarder thank you for that. For some reason those two wires are permanently crossed.
$endgroup$
– uhoh
Apr 24 at 22:34
5
$begingroup$
And if you want hands on (simulated) experience, there's always KSP. Suborbital approaches are surprisingly tricky, and losing horizontal speed too quickly is a great way to lose all that lift you need not to drop like a rock.
$endgroup$
– Luaan
Apr 25 at 15:03
1
$begingroup$
@Luaan Yup. It's amazing how much horizontal velocity you need in KSP slow enough to pop your chute. For suborbital missions I actually found it's cheaper to go straight up and then use your rocket to slow your descent! (The braking burn needs less delta-v than you would expend getting enough horizontal velocity to survive without the braking burn.)
$endgroup$
– Loren Pechtel
Apr 25 at 19:32
1
1
$begingroup$
@MontyHarder thank you for that. For some reason those two wires are permanently crossed.
$endgroup$
– uhoh
Apr 24 at 22:34
$begingroup$
@MontyHarder thank you for that. For some reason those two wires are permanently crossed.
$endgroup$
– uhoh
Apr 24 at 22:34
5
5
$begingroup$
And if you want hands on (simulated) experience, there's always KSP. Suborbital approaches are surprisingly tricky, and losing horizontal speed too quickly is a great way to lose all that lift you need not to drop like a rock.
$endgroup$
– Luaan
Apr 25 at 15:03
$begingroup$
And if you want hands on (simulated) experience, there's always KSP. Suborbital approaches are surprisingly tricky, and losing horizontal speed too quickly is a great way to lose all that lift you need not to drop like a rock.
$endgroup$
– Luaan
Apr 25 at 15:03
1
1
$begingroup$
@Luaan Yup. It's amazing how much horizontal velocity you need in KSP slow enough to pop your chute. For suborbital missions I actually found it's cheaper to go straight up and then use your rocket to slow your descent! (The braking burn needs less delta-v than you would expend getting enough horizontal velocity to survive without the braking burn.)
$endgroup$
– Loren Pechtel
Apr 25 at 19:32
$begingroup$
@Luaan Yup. It's amazing how much horizontal velocity you need in KSP slow enough to pop your chute. For suborbital missions I actually found it's cheaper to go straight up and then use your rocket to slow your descent! (The braking burn needs less delta-v than you would expend getting enough horizontal velocity to survive without the braking burn.)
$endgroup$
– Loren Pechtel
Apr 25 at 19:32
add a comment |
$begingroup$
Skipping reentries aren't unheard of. The Apollo command module performed a single skip when returning from lunar missions. However, there are several reasons why a skipping reentry (especially one involving multiple skips) would be disadvantageous for the shuttle:
- As uhoh points out, a skipping reentry results in losing lateral speed at a very high altitude. In turn, you lose the ability to control your descent rate. By the end of entry you'd practically be in a free-fall which the vehicle would be unlikely to survive due to the heat and/or stress of attempting to pull out of the dive.
- The shuttle's thermal protection system was not designed to withstand long drawn-out reentries. Here's a quote from the "Entry, TAEM, and Approach/Landing Guidance Workbook":
On the flip side of high surface temperatures, there are high backface temperatures. If
you fly at high temperatures for a long time, heat will flow through the tiles to the
aluminum underneath. This can happen if you fly a low drag profile. In fact, backface
temperature is the current low limit to the drag profile. - Several other systems weren't designed for long drawn-out reentries either. The APUs only have the fuel capacity to run for about 110 minutes, which wouldn't be enough to support both launch and an extended reentry. The radiators, which were cold-soaked before entry, may have needed additional capacity to absorb heat build up during entry. The RCS may have needed more reserves.
- Flying a low-drag profile gives you less margin for error. Flying a middle-of-the-road drag profile means you have room to increase or decrease your drag as necessary in order to make the landing site. If your designed flight path is already on the low-end and you end up in a low energy condition, there's not much you can do about it.
- It's not impossible to develop guidance for a skipping reentry, but it is definitely a more difficult problem.
I suspect there are other reasons I haven't thought of.
On the flip side, I can't think of any advantages. The shuttle's reentry was already comparatively gentle (well under 2g's the whole time) and the heat was perfectly managable as-is.
answered Apr 24 at 8:15
Bret CopelandBret Copeland
84958
$endgroup$
$begingroup$
+1 for the limitations due to other systems.
$endgroup$
– Organic Marble
Apr 24 at 13:56
$begingroup$
The APU's a non-issue (it had power for days) but everything else seems right.
$endgroup$
– Joshua
Apr 24 at 15:22
6
$begingroup$
@Joshua no, the APUs had very little fuel reserves. See the Shuttle Crew Operations Manual page 2.1-2: "The hydrazine is stored in a fuel tank with a total capacity of about 350 pounds.... The fuel supply supports the nominal power unit operating time of 90 minutes in a mission or any defined abort mode, such as an abort once around, when the APUs run continuously for approximately 110 minutes. Under operating load conditions, an APU consumes approximately 3 to 3.5 pounds of fuel per minute."
$endgroup$
– Bret Copeland
Apr 24 at 18:22
1
$begingroup$
A slight correction on your first paragraph: Apollo had the option to perform a skip re-entry when coming in from the Moon, but I don't think they ever used it.
$endgroup$
– Mark
Apr 24 at 19:54
1
$begingroup$
@BretCopeland, commentary on the radio transcript for the Apollo 11 re-entry and the Apollo 11 re-entry analysis. Yes, Apollo 11 bounced a bit during re-entry (and it extended the re-entry flight path by running the skip-out software), but it never went back above either the Karman line or the Air Force's 50-mile boundary of space.
$endgroup$
– Mark
Apr 25 at 21:07
|
show 5 more comments
$begingroup$
Skipping reentries aren't unheard of. The Apollo command module performed a single skip when returning from lunar missions. However, there are several reasons why a skipping reentry (especially one involving multiple skips) would be disadvantageous for the shuttle:
- As uhoh points out, a skipping reentry results in losing lateral speed at a very high altitude. In turn, you lose the ability to control your descent rate. By the end of entry you'd practically be in a free-fall which the vehicle would be unlikely to survive due to the heat and/or stress of attempting to pull out of the dive.
- The shuttle's thermal protection system was not designed to withstand long drawn-out reentries. Here's a quote from the "Entry, TAEM, and Approach/Landing Guidance Workbook":
On the flip side of high surface temperatures, there are high backface temperatures. If
you fly at high temperatures for a long time, heat will flow through the tiles to the
aluminum underneath. This can happen if you fly a low drag profile. In fact, backface
temperature is the current low limit to the drag profile. - Several other systems weren't designed for long drawn-out reentries either. The APUs only have the fuel capacity to run for about 110 minutes, which wouldn't be enough to support both launch and an extended reentry. The radiators, which were cold-soaked before entry, may have needed additional capacity to absorb heat build up during entry. The RCS may have needed more reserves.
- Flying a low-drag profile gives you less margin for error. Flying a middle-of-the-road drag profile means you have room to increase or decrease your drag as necessary in order to make the landing site. If your designed flight path is already on the low-end and you end up in a low energy condition, there's not much you can do about it.
- It's not impossible to develop guidance for a skipping reentry, but it is definitely a more difficult problem.
I suspect there are other reasons I haven't thought of.
On the flip side, I can't think of any advantages. The shuttle's reentry was already comparatively gentle (well under 2g's the whole time) and the heat was perfectly managable as-is.
answered Apr 24 at 8:15
Bret CopelandBret Copeland
84958
$endgroup$
$begingroup$
+1 for the limitations due to other systems.
$endgroup$
– Organic Marble
Apr 24 at 13:56
$begingroup$
The APU's a non-issue (it had power for days) but everything else seems right.
$endgroup$
– Joshua
Apr 24 at 15:22
6
$begingroup$
@Joshua no, the APUs had very little fuel reserves. See the Shuttle Crew Operations Manual page 2.1-2: "The hydrazine is stored in a fuel tank with a total capacity of about 350 pounds.... The fuel supply supports the nominal power unit operating time of 90 minutes in a mission or any defined abort mode, such as an abort once around, when the APUs run continuously for approximately 110 minutes. Under operating load conditions, an APU consumes approximately 3 to 3.5 pounds of fuel per minute."
$endgroup$
– Bret Copeland
Apr 24 at 18:22
1
$begingroup$
A slight correction on your first paragraph: Apollo had the option to perform a skip re-entry when coming in from the Moon, but I don't think they ever used it.
$endgroup$
– Mark
Apr 24 at 19:54
1
$begingroup$
@BretCopeland, commentary on the radio transcript for the Apollo 11 re-entry and the Apollo 11 re-entry analysis. Yes, Apollo 11 bounced a bit during re-entry (and it extended the re-entry flight path by running the skip-out software), but it never went back above either the Karman line or the Air Force's 50-mile boundary of space.
$endgroup$
– Mark
Apr 25 at 21:07
|
show 5 more comments
$begingroup$
Skipping reentries aren't unheard of. The Apollo command module performed a single skip when returning from lunar missions. However, there are several reasons why a skipping reentry (especially one involving multiple skips) would be disadvantageous for the shuttle:
- As uhoh points out, a skipping reentry results in losing lateral speed at a very high altitude. In turn, you lose the ability to control your descent rate. By the end of entry you'd practically be in a free-fall which the vehicle would be unlikely to survive due to the heat and/or stress of attempting to pull out of the dive.
- The shuttle's thermal protection system was not designed to withstand long drawn-out reentries. Here's a quote from the "Entry, TAEM, and Approach/Landing Guidance Workbook":
On the flip side of high surface temperatures, there are high backface temperatures. If
you fly at high temperatures for a long time, heat will flow through the tiles to the
aluminum underneath. This can happen if you fly a low drag profile. In fact, backface
temperature is the current low limit to the drag profile. - Several other systems weren't designed for long drawn-out reentries either. The APUs only have the fuel capacity to run for about 110 minutes, which wouldn't be enough to support both launch and an extended reentry. The radiators, which were cold-soaked before entry, may have needed additional capacity to absorb heat build up during entry. The RCS may have needed more reserves.
- Flying a low-drag profile gives you less margin for error. Flying a middle-of-the-road drag profile means you have room to increase or decrease your drag as necessary in order to make the landing site. If your designed flight path is already on the low-end and you end up in a low energy condition, there's not much you can do about it.
- It's not impossible to develop guidance for a skipping reentry, but it is definitely a more difficult problem.
I suspect there are other reasons I haven't thought of.
On the flip side, I can't think of any advantages. The shuttle's reentry was already comparatively gentle (well under 2g's the whole time) and the heat was perfectly managable as-is.
answered Apr 24 at 8:15
Bret CopelandBret Copeland
84958
$endgroup$
Skipping reentries aren't unheard of. The Apollo command module performed a single skip when returning from lunar missions. However, there are several reasons why a skipping reentry (especially one involving multiple skips) would be disadvantageous for the shuttle:
- As uhoh points out, a skipping reentry results in losing lateral speed at a very high altitude. In turn, you lose the ability to control your descent rate. By the end of entry you'd practically be in a free-fall which the vehicle would be unlikely to survive due to the heat and/or stress of attempting to pull out of the dive.
- The shuttle's thermal protection system was not designed to withstand long drawn-out reentries. Here's a quote from the "Entry, TAEM, and Approach/Landing Guidance Workbook":
On the flip side of high surface temperatures, there are high backface temperatures. If
you fly at high temperatures for a long time, heat will flow through the tiles to the
aluminum underneath. This can happen if you fly a low drag profile. In fact, backface
temperature is the current low limit to the drag profile. - Several other systems weren't designed for long drawn-out reentries either. The APUs only have the fuel capacity to run for about 110 minutes, which wouldn't be enough to support both launch and an extended reentry. The radiators, which were cold-soaked before entry, may have needed additional capacity to absorb heat build up during entry. The RCS may have needed more reserves.
- Flying a low-drag profile gives you less margin for error. Flying a middle-of-the-road drag profile means you have room to increase or decrease your drag as necessary in order to make the landing site. If your designed flight path is already on the low-end and you end up in a low energy condition, there's not much you can do about it.
- It's not impossible to develop guidance for a skipping reentry, but it is definitely a more difficult problem.
I suspect there are other reasons I haven't thought of.
On the flip side, I can't think of any advantages. The shuttle's reentry was already comparatively gentle (well under 2g's the whole time) and the heat was perfectly managable as-is.
answered Apr 24 at 8:15
Bret CopelandBret Copeland
84958
edited Apr 24 at 18:25
answered Apr 24 at 8:15
Bret CopelandBret Copeland
84958
answered Apr 24 at 8:15
Bret CopelandBret Copeland
84958
answered Apr 24 at 8:15
Bret CopelandBret Copeland
84958
84958
$begingroup$
+1 for the limitations due to other systems.
$endgroup$
– Organic Marble
Apr 24 at 13:56
$begingroup$
The APU's a non-issue (it had power for days) but everything else seems right.
$endgroup$
– Joshua
Apr 24 at 15:22
6
$begingroup$
@Joshua no, the APUs had very little fuel reserves. See the Shuttle Crew Operations Manual page 2.1-2: "The hydrazine is stored in a fuel tank with a total capacity of about 350 pounds.... The fuel supply supports the nominal power unit operating time of 90 minutes in a mission or any defined abort mode, such as an abort once around, when the APUs run continuously for approximately 110 minutes. Under operating load conditions, an APU consumes approximately 3 to 3.5 pounds of fuel per minute."
$endgroup$
– Bret Copeland
Apr 24 at 18:22
1
$begingroup$
A slight correction on your first paragraph: Apollo had the option to perform a skip re-entry when coming in from the Moon, but I don't think they ever used it.
$endgroup$
– Mark
Apr 24 at 19:54
1
$begingroup$
@BretCopeland, commentary on the radio transcript for the Apollo 11 re-entry and the Apollo 11 re-entry analysis. Yes, Apollo 11 bounced a bit during re-entry (and it extended the re-entry flight path by running the skip-out software), but it never went back above either the Karman line or the Air Force's 50-mile boundary of space.
$endgroup$
– Mark
Apr 25 at 21:07
|
show 5 more comments
$begingroup$
+1 for the limitations due to other systems.
$endgroup$
– Organic Marble
Apr 24 at 13:56
$begingroup$
The APU's a non-issue (it had power for days) but everything else seems right.
$endgroup$
– Joshua
Apr 24 at 15:22
6
$begingroup$
@Joshua no, the APUs had very little fuel reserves. See the Shuttle Crew Operations Manual page 2.1-2: "The hydrazine is stored in a fuel tank with a total capacity of about 350 pounds.... The fuel supply supports the nominal power unit operating time of 90 minutes in a mission or any defined abort mode, such as an abort once around, when the APUs run continuously for approximately 110 minutes. Under operating load conditions, an APU consumes approximately 3 to 3.5 pounds of fuel per minute."
$endgroup$
– Bret Copeland
Apr 24 at 18:22
1
$begingroup$
A slight correction on your first paragraph: Apollo had the option to perform a skip re-entry when coming in from the Moon, but I don't think they ever used it.
$endgroup$
– Mark
Apr 24 at 19:54
1
$begingroup$
@BretCopeland, commentary on the radio transcript for the Apollo 11 re-entry and the Apollo 11 re-entry analysis. Yes, Apollo 11 bounced a bit during re-entry (and it extended the re-entry flight path by running the skip-out software), but it never went back above either the Karman line or the Air Force's 50-mile boundary of space.
$endgroup$
– Mark
Apr 25 at 21:07
$begingroup$
+1 for the limitations due to other systems.
$endgroup$
– Organic Marble
Apr 24 at 13:56
$begingroup$
+1 for the limitations due to other systems.
$endgroup$
– Organic Marble
Apr 24 at 13:56
$begingroup$
The APU's a non-issue (it had power for days) but everything else seems right.
$endgroup$
– Joshua
Apr 24 at 15:22
$begingroup$
The APU's a non-issue (it had power for days) but everything else seems right.
$endgroup$
– Joshua
Apr 24 at 15:22
6
6
$begingroup$
@Joshua no, the APUs had very little fuel reserves. See the Shuttle Crew Operations Manual page 2.1-2: "The hydrazine is stored in a fuel tank with a total capacity of about 350 pounds.... The fuel supply supports the nominal power unit operating time of 90 minutes in a mission or any defined abort mode, such as an abort once around, when the APUs run continuously for approximately 110 minutes. Under operating load conditions, an APU consumes approximately 3 to 3.5 pounds of fuel per minute."
$endgroup$
– Bret Copeland
Apr 24 at 18:22
$begingroup$
@Joshua no, the APUs had very little fuel reserves. See the Shuttle Crew Operations Manual page 2.1-2: "The hydrazine is stored in a fuel tank with a total capacity of about 350 pounds.... The fuel supply supports the nominal power unit operating time of 90 minutes in a mission or any defined abort mode, such as an abort once around, when the APUs run continuously for approximately 110 minutes. Under operating load conditions, an APU consumes approximately 3 to 3.5 pounds of fuel per minute."
$endgroup$
– Bret Copeland
Apr 24 at 18:22
1
1
$begingroup$
A slight correction on your first paragraph: Apollo had the option to perform a skip re-entry when coming in from the Moon, but I don't think they ever used it.
$endgroup$
– Mark
Apr 24 at 19:54
$begingroup$
A slight correction on your first paragraph: Apollo had the option to perform a skip re-entry when coming in from the Moon, but I don't think they ever used it.
$endgroup$
– Mark
Apr 24 at 19:54
1
1
$begingroup$
@BretCopeland, commentary on the radio transcript for the Apollo 11 re-entry and the Apollo 11 re-entry analysis. Yes, Apollo 11 bounced a bit during re-entry (and it extended the re-entry flight path by running the skip-out software), but it never went back above either the Karman line or the Air Force's 50-mile boundary of space.
$endgroup$
– Mark
Apr 25 at 21:07
$begingroup$
@BretCopeland, commentary on the radio transcript for the Apollo 11 re-entry and the Apollo 11 re-entry analysis. Yes, Apollo 11 bounced a bit during re-entry (and it extended the re-entry flight path by running the skip-out software), but it never went back above either the Karman line or the Air Force's 50-mile boundary of space.
$endgroup$
– Mark
Apr 25 at 21:07
|
show 5 more comments
Thanks for contributing an answer to Space Exploration Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fspace.stackexchange.com%2fquestions%2f35741%2fwhy-didnt-the-space-shuttle-bounce-back-into-space-as-many-times-as-possible-so%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
$begingroup$
To be clear, it's not AoA which prevents the shuttle from skipping; it's banking - pointing the lift vector sideways instead of up. An increase in AoA from 40° would most likely reduce the chance of skipping.
$endgroup$
– Bret Copeland
Apr 24 at 7:11
21
$begingroup$
5000 nautical miles away. The answer is in the video but easy to miss; he notes very quickly, and only once, that slowing too much: you'll drop out the sky like a rock (which is the penultimate concern at all times only to 'rapid unplanned disassembly'). It's bad enough that it's already a flying brick.
$endgroup$
– Mazura
Apr 24 at 10:04
$begingroup$
Hi SRD I think BretCopeland's answer does a better job addressing the question than mine; I wonder if you would consider accepting that one instead of mine?
$endgroup$
– uhoh
Apr 25 at 20:39