HST repair mission "What if" poll

[mrmorris]

<font color="yellow">"What palnet were you calculating orbital velocity for?"</font><br /><br />That would be the planet where one puts 7670 <b>meters</b>/sec into their favorite conversion site, and uses the converstion factor for <b>kilometers</b>/sec to feet/sec. <img src="/images/icons/smile.gif" /><br /><br /><font color="yellow">"...total OMS Delta V capability of the Orbiter is around 312 m/sec."</font><br /><br />I got the dv figure from the Endeavor entry in Astronautix. This may be related to the question I asked a few minutes ago in the ISS reboost thread about whether the RCS and OMS propellant/oxidizer is shared. If not, the Astronautix figure may be combining the two. If they <b>are</b> shared -- Astronautix may simply be wrong.

 

[mrmorris]

<font color="yellow">"I don't buy it."</font><br /><br />It's not for sale. There is no CM to be used. Fantasy Lifeboat season is ended as far as I'm concerned.

 

[gunsandrockets]

"Astronautix is a great site however in this case it appaears that they are combining the Fwd RCS, Aft RCS and OMS total delta v capability plus the Payload Bay OMS kit which was never built to get the 700 m/sec. figure."<br /><br />I was tripped up myself one time by using astronautix.com to find the amount of propellant in the Shuttle OMS. But astronautix.com isn't the only aerospace web reference site mistakenly showing double the true amount of propellant...<br /><br />http://www.braeunig.us/space/<br /><br />...you had told me the Shuttle only had 10 tonnes of propellant and I wondered how these two sites could be so wrong. So I went digging for the information from NASA web references myself and I came up with a theory to explain the errors.<br /><br />I easily found detailed NASA information on the Shuttle OMS, everything except the total amount of propellant carried! I had to calculate the mass myself based on the tanks volume and propellant density, which confirmed your figure of 10 tonnes.<br /><br />I think error can creep in because so much of the OMS is twinned: the twin OMS pods, the twin propellant tanks. I bet the mistake comes from mistakenly doubling the double. The too high delta V figure for the Shuttle in the astronautix.com information was in turn probably based on the wrong OMS propellant calculation.<br /><br />And because astronautix.com is considered so authoritative and used so much, the same mistaken information get repeated all over the internet.

 

[gunsandrockets]

mr morris is in no position to be snarky considering he misread what you wrote in the first place, and that once upon a time it was he who first brought up the Apollo capsule based escape system! Check out the link for details on this proposed escape system for the Space Shuttle...<br /><br />http://www.astronautix.com/craft/aponcept.htm

 

[gunsandrockets]

"Even in the "decayed" orbit the Orbiter can barely reach Hubble."<br /><br />Huh? That makes no sense to me. If a Shuttle orginally launched the Hubble in 1990...<br /><br />http://pds.jpl.nasa.gov/planets/welcome/hubble.htm<br /><br />...why would a Shuttle today 'barely reach Hubble' during a repair mission when the repair Shuttle isn't burdened with the mass of carrying a HST? <br /><br />

 

[gunsandrockets]

"quite dicey. You'd need to use the shuttle OMS to get the shuttle *close* to re-entry, but not all the way there because the CM would still be in the payload pay. Getting it out of the bay would be a reasonably lengthy operation. Someone would have to be in the shuttle to use the RMS to pull the CM out of the payload bay -- then EVA over to the CM. The CM's RCS would then have to have enough dv to complete the DO burn. I still doubt that enough dv would be available, but it's certainly closer."<br /><br />That's silly. The OMS could do a complete deorbit burn and still give the escape capsule 40 minutes to get clear of the Shuttle payload bay before the Shuttle orbit would intersect the atmosphere. Who cares if the Shuttle burns up over the ocean so long as the crew survives?

 

[gunsandrockets]

"The CM could be carried into orbit if you reduced the payload capability of the Orbiter. However you could not do a HST [repair] mission and carry the CM as well."<br /><br />Really? The HST was 11 tonnes and the CM less than 6 tonnes. Please explain.

 

[gunsandrockets]

"Now how do we design a re-entry lifeboat in the little time between now and the servicing mission."<br /><br />Considering the overlap between the CEV development and the remaining life of the Shuttle, in theory the CEV capsule could do the lifeboat job. Except the capsule is 5m in diameter and the largest item the Shuttle payload bay could accomodate is only 4.5m in diameter! Just one more reason why I think NASA should have required a maximum of 4.5m diameter for the CEV capsule, aside from the weight issues.

 

[mrmorris]

<font color="yellow">"...once upon a time it was he who first brought up the Apollo capsule based escape system!"</font><br /><br />Where exactly did I do that?

 

[mrmorris]

<font color="yellow">"but decided to let MMorris do that...... "</font><br /><br />Nope -- I still consider this to be a moot point -- there isn't a CM to be used. However, I will post part of a blog on of the landing of STS-121 for the forty minutes following the DO burn:<br /><br /><i>8:10 a.m. - Deorbit burn has been completed. During the burn Discovery was flying upside down and backwards. The shuttle is now committed to landing today. <br /><br />8:16 a.m. - The orbiter is beginning to feel the effects of the atmosphere. The crew was just given the go to begin dumping the excess propellants from the shuttle's forward maneuvering thrusters. <br /><br />8:22 a.m. - Shuttle Discovery is about 400,000 feet high and 52 minutes from touchdown at Kennedy Space Center. In about 20 minutes the ship will encounter the period of re-entry known as "entry interface." At this point, Discovery will be 80 miles in altitude and 5,000 miles from the runway. <br /><br />8:33 a.m. - Discovery is ten minutes from the start of entry interface. At that point, the ship and its crew will begin to experience increasing drag and friction as the shuttle races into the ever-thickening atmosphere. <br /><br />8:43 a.m. - As Discovery begins entry interface the orbiter is about 31 minutes from touchdown at Kennedy Space Center. At this time the orbiter's protective tiles are being exposed to extreme heat as Discovery enters the top fringes of the atmosphere. Discovery is now 4,600 miles to the runway, traveling at approximately mach 24.8. <br /><br />8:50 a.m. - Discovery has three good APUs and is heading toward the Yucatan Peninsula, on its way home to Florida. Speed is Mach 24.3. Mission control is considering a possible last minute redirect to Runway 15 due to some showers popping up around the Kennedy landing field. </i><br /><br />Perhaps the fact that the shuttle starts hitting atmophere six minutes after the completion of the DO burn has something to do with why the CM-based escape boat

 

[gunsandrockets]

way back in your old Falcon V/Gemini thread

 

[gunsandrockets]

"Because the 6 ton CM in the Orbiter payload bay means you offload the parts you planned to replace on the Hubble so why go to Hubble ?."<br /><br />Are you saying the repair parts mass more than 5 tonnes? How much mass is the repair mission carrying?<br /><br />Not only is the Shuttle for the Hubble repair mission not burdened with the 11 tonne bulk of the original 1990 Shuttle Hubble launch mission, the repair mission is also using the super lightweight External Tank which is 3 tonnes lighter than the tank used by the launch mission. So the repair mission starts off with a 14 tonne mass advantange (before adding the mass for repair parts or anything else carried up to the Hubble orbit).<br /><br />http://en.wikipedia.org/wiki/Shuttle_External_Tank#Super_Lightweight_Tank<br /><br />

 

[mrmorris]

<font color="yellow">"...once upon a time it was he who first brought up the Apollo capsule based escape system!" </font><br /><br /><font color="orange">"Where exactly did I do that? "</font><br /><br /><font color="yellow">"way back in your old Falcon V/Gemini thread"</font><br /><br />If you can point out in that thread where I suggested using an Apollo CM as an escape system for an orbiter -- I hereby pronounce you King of the World.<br /><br />If, however, what's in that thread is me proposing using concepts from the Apollo CM MODAP study as a basis for a modern space-station taxi lofted by Falcon V/IX <b>and</b> requiring a set of strap-on de-orbit boosters to provide the dv to return to atmosphere, I pronounce you the Lord of Bovine Byproducts. <br /><br />You can have three guesses which of the two is the case.

 

[montmein69]

>Are you saying the repair parts mass more than 5 tonnes?<br /> />How much mass is the repair mission carrying?<br /><br />Is the payload mass the main reason for the de-orbitation module not to be part of this mission ?<br /><br />A new mission (using Ares an Orion ? in 2025) to enable a safety "death" for HST is very expensive .... and I don't understand why the de-orbitation module is not a part of the 2008 servicing mission.<br /><br />On the other hand the real future (I mean JWST) is the true challenge for the astronomical observation and its launch is not on the timetable.<br /><br />Who can explain this decision ? <div class="Discussion_UserSignature"> </div>

 

[gunsandrockets]

"...8:10 a.m. - Deorbit burn has been completed. During the burn Discovery was flying upside down and backwards. The shuttle is now committed to landing today..."<br /><br />"...8:43 a.m. - As Discovery begins entry interface the orbiter is about 31 minutes from touchdown at Kennedy Space Center. At this time the orbiter's protective tiles are being exposed to extreme heat as Discovery enters the top fringes of the atmosphere. Discovery is now 4,600 miles to the runway, traveling at approximately mach 24.8."<br /><br />Entry Interface...top fringes of the atmosphere...very interesting. So instead of 40 minutes for an escape capsule to clear the shuttle bay after OMS burn it only has 33 minutes. Well you sure showed me! Thanxs for the correction. <br /><br />

 

[gunsandrockets]

"...The RCS on the CM was designed just for re-entry maneuvering and had only 257 kg-sec of impulse. This isn't enough to get home from a 700km orbit..." When in reality the post you refered to was talking about the Shuttle OMS for deorbit, not the CM. <br /><br /><br />"...Perhaps the fact that the shuttle starts hitting atmophere six minutes after the completion of the DO burn..." When in reality the text you refered to shows the figure is 33 minutes.<br /><br />So now mrmorris, the master of misreading, has this to say...<br /><br />"If you [can't] point out in that thread where I suggested using an Apollo CM as an escape system for an orbiter... I pronounce you the Lord of Bovine Byproducts."<br /><br />Let me spell out in greater detail for you exactly what I meant in my post where I came to the defense of Leovinous from your snark attack.<br /><br />When Leonivous brought up the idea of a CM escape capsule, the first response you had was to jump down his throat with a strawman attack on the Leovinous idea. This is in spite of the fact that you were already well aware of the old plan for a CM-based escape capsule for the Shuttle. So rather than post usefull background information which Leovinous probably had no idea existed, your first instinct was to attack instead. That's bad form.<br /><br />That was what I meant in refering to your once upon a time posting of the CM escape capsule. Clear now? Or do you have another straw-man ready to knock over?

 

[mrmorris]

<font color="yellow">"So instead of 40 minutes for an escape capsule to clear the shuttle bay after OMS burn it only has 33 minutes"</font><br /><br />At DO +33m, the tiles are glowing. They're glowing because they hit atmospheric effects at DO+6m as the blog indicated. You're not separating vehicles anytime after the DO burn because the shuttle begins decellerating more and more rapidly due to the thickening atmosphere. You *cannot* even open the payload doors at that time because of there aerodynamic effects this would have on the shuttle -- almost certainly it would tumble. If the vehicles are going to separate - they have to do so before hitting any atmospheric effects.

 

[mrmorris]

<font color="yellow">"This is in spite of the fact that you were already well aware of the old plan for a CM-based escape capsule for the Shuttle. "</font><br /><br />No -- I wasn't. I use Astronautix a good bit... but I haven't (yet) memorized every proposed configuration of the Gemini and Apollo spacecaft there.<br /><br /><font color="yellow">"Clear now?"</font><br /><br />Indeed it's clear that you're going to set up whatever personal worldview is required, however fantastic, in order to avoid admitting an error.<br /><br /><b>The Shuttle doesn't reboost the ISS</b><br /><br /><i>Oh -- it does? And it can be proven? Well then -- it doesn't reboost it *much*. HA! See, I was correct.</i><br /><br /><b>There's 40 minutes after the DO burn...</b><br /><br /><i>Oh -- it's not 40 minutes? Well 33 minutes until the tiles are glowing red hot is 4/5ths of that. Seems like enough time -- let's use that figure. HA! See, I was correct.</i><br /><br /><b>mrmorris proposed an escape capsule himself so cannot be snarky</b><br /><br /><i>Oh... he didn't? Well -- one is proposed on Astronautix, and mrmorris *must* have known about it since he uses that site sometimes. That's essentially the same thing as proposing it himself. HA! See, I was correct.</i><br /><br /><br />I suggest seeking professional help.

 

[gunsandrockets]

"At DO +33m, the tiles are glowing. They're glowing because they hit atmospheric effects at DO+6m as the blog indicated. You're not separating vehicles anytime after the DO burn because the shuttle begins decellerating more and more rapidly due to the thickening atmosphere. You *cannot* even open the payload doors at that time because of there aerodynamic effects this would have on the shuttle -- almost certainly it would tumble. If the vehicles are going to separate - they have to do so before hitting any atmospheric effects."<br /><br /><br />Isn't is odd then how the Shuttle doesn't tumble immediately at the end of the deorbit burn considering the Shuttle is flying tail forward? Amazing. Amazing how far off the cliff are you willing to drive your error despite how easy it is to find information on Shuttle reentry via google.<br /><br /><br />Try even paying attention to your own source. Go on, reread it. See how high the Shuttle velocity still is at the point of Entry Interface? Even though the OMS burn was 33 minutes earlier? That's because atmospheric drag is negligable until reaching the Entry Interface. That's probably why NASA calls it the Entry Interface!<br /><br />Excerpt from one NASA document ... "It typically takes an orbiter 25 to 30 minutes from the deorbit burn to descend low enough to begin feeling the effects of the Earth's atmosphere. Columbia followed that standard and reached that point, called Entry Interface, about 28 minutes after deorbit burn."<br /><br />In fact the aerodynamic forces are so low on the Shuttle that it isn't until about 220 seconds after the Entry Interface that any Shuttle aerosurfaces even begin to work. When the aerodynamic forces have increased to 10 pounds per square foot (or when Shuttle deceleration has increased to 0.176 G's) is when the ailerons first become effective. The elevators don't become effective until the force reaches 20 pounds per square foot.<br /><br />Peak heating of the Shuttle isn't reached until mo

 

[nacnud]

<font color="yellow">Isn't is odd then how the Shuttle doesn't tumble immediately at the end of the deorbit burn considering the Shuttle is flying tail forward? Amazing. Amazing how far off the cliff are you willing to drive your error despite how easy it is to find information on Shuttle reentry via google.<br /><br /><font color="white">Just out of interest Shuttle starts turning as soon as the APUs are brought on line as it is the exhaust from these that push the Shuttle round.</font></font>

 

[gunsandrockets]

"I suggest seeking professional help."<br /><br />Look up the term -- projection.

 

[gunsandrockets]

" I don't understand why the de-orbitation module is not a part of the 2008 servicing mission...Who can explain this decision ?"<br /><br />From this link...<br /><br />http://www.spaceflightnow.com/shuttle/sts125/061031approval/<br /><br />see this excerpt...<br /><br />"In addition, the spacewalkers will ... install a fixture that will permit the eventual attachment of a small rocket module to drop it safely out of orbit when it is no longer operational."<br /><br />I guess that when the time comes for deorbit of the Hubble this fixture will allow an automated mission to easily attach a rocket module. <br /><br />

 

[Leovinus]

My guess is that such a de-orbit module would be robotically attached. No need to send a manned mission to do that. <div class="Discussion_UserSignature"> </div>