Page content and layout © 1996-2002 Michael Grabois and Astra Enterprises.Last updated: August 13, 2002
Compilation copyright © 1997-2002 by Michael R. Grabois. This document may be freely redistributed in various electronic media (including, but not limited to, e-mail, Usenet, and the World Wide Web) in its complete and unmodified form. It may not be reproduced for profit in commercial outlets (such as, but not limited to, CD-ROMs and books) without prior written consent from the author. Other use requires written permission of the author. Except as where noted in the individual answer, all material was written by the compiler of this document. Standard disclaimer: this is in no way officially endorsed by NASA or any of its contractor companies.
Please submit all corrections, additions, and suggestions to WizardImps@hotmail.com.
Steven Pietrobon posts two wonderful documents at the beginning of each month: the Unofficial Space Shuttle Manifest and the Unofficial Space Shuttle Launch Guide (some of which was written by Ken Hollis).
The Launch Guide tells you everything you ever wanted to know about getting around at KSC: This file contains information on how to get a launch or landing pass, and if you can't get one, where to view the shuttle for launch or landing. The file also contains hints for first-time attendees, where to stay in the Cocoa Beach area, the distances to the pads from the various viewing sites, Shuttle frequencies, HAM frequencies for listening to and watching NASA select, hints on photographing launches, where to watch SSME test firings, how to get accredited as a Press Personage, internet sites to get additional NASA information, how to get the latest two line element sets, and information for teachers on how to access NASA information. Whew! This guide can't be recommended highly enough.
You can also find more info on car passes at
For more on launches at KSC, go to
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[The following answer and translation are provided by Ken Jenks, from Jon Leech's FAQ, then paraphrased and abridged:]
The quick and easy answer is that the shuttle rolls to pick up the correct inclination for the mission and orient the vehicle for a heads-down ride to orbit. Getting a bit more complex, we roll the Shuttle around so that the wind hits the wings at a slightly negative angle which alleviates structural loading. The new attitude (after the roll) also allows a number of different things to happen, from increasing payload, orbital altitude, or inclination, to allowing better communication and orientation.
This all begs the question, "Why isn't the launch pad oriented to give this nice attitude to begin with? Why does the Shuttle need to roll to achieve that attitude?" The answer is that the pads were leftovers from the Apollo days. The access tower and other support and service structure are all oriented basically the same way they were for the Saturn V's.
For an expanded answer, see:
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[With inputs from Henry Spencer and Andy Foster]
When the engines were originally designed, they were supposed to put out a certain thrust level (rated thrust), which was called 100%. After some engine upgrades, the engines were running at 104% of rated thrust. They left it this way rather than go back and re-scale all the numbers so that the new value was equal to 100% instead of 104%. Additionally, in some abort scenarios (RTLS, for example) the engines can throttle all the way up to 109%, though this is reserved for emergency use. There is an effort underway to certify the engines to run at 106% in nominal situations (vs. 104%).
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For a due east (28.5 degrees inclination) rendezvous launch, the potential window is about an hour. There is an amount of propellant that is allotted for out-of-plane maneuvering; that is, moving out of the launch plane and into the plane that the target is in. The further away from the inplane time you move, the more propellant is required. If we move earlier from the inplane time, eventually you get to a point where that much plane change requires all of the allotted propellant. That turns out to be a maximum of 63 minutes. On the other hand, if you move in the other direction, past the inplane time, it still costs more propellant, but here you run into the case where if you launch more than 9 minutes after the inplane time, you'll drop the external tank on Hawaii. So the maximum launch window for a due east flight is about 72 minutes.
There are some different considerations for an ISS rendezvous.
In general, the further away from the inplane time (the time at which ISS's inertial plane passes over the launch site) you go, the more propellant it costs to steer out of plane and into the correct plane. And the curve gets steeper the further away you go. For example, it costs the same amount of propellant for the first 2.5 minutes away from the inplane time as for the next 1 minute after that. So that's 7 minutes, 3.5 on each side of inplane.
The phase angle (angle between the shuttle, center of the earth, and ISS) and the difference in rate at which each vehicle revolves around the earth will determine when they rendezvous. The shuttle can change its revolution rate depending on altitude: higher orbit means slower catch-up rate. For a phase angle less than 360 degrees, the rendezvous will be on Flight Day 3. This is considered "pane 1" of the launch window.
But if we add 360 degrees to the phase angle, that gives us a completely new launch pane, for a rendezvous on Flight Day 4. The two panes don't exactly overlap; there's a few minutes offset between the start of pane 1 and the start of pane 2. So the overlap gives you about a ten minute launch window. This is pretty much transparent to anyone who's watching on TV.
If we have a ten minute window, for example, the first 3 minutes might be FD3, the next 4 minutes either FD3 or FD4, and the last 3 minutes FD4. We'd probably use the first 7 minutes of FD3 and the last 3 minutes of FD4.
For more information:
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The shuttle has two ways of getting into orbit once the main engines have stopped: by doing two OMS burns or just one.
In the early days of the shuttle program, insertion into orbit was called "Standard Insertion" (or maybe this was a backwards coining once the second method came about). In this scenario, the shuttle hits Main Engine Cut-Off at an orbit of around 85 x 20 nautical miles. Obviously this is too low for an orbit, so right after MECO, when they're at apogee (the highest point in the orbit), they do an OMS burn that raises the perigee (the lowest point in the orbit, at the opposite side of the orbit) to a safe altitude of about 160 nautical miles. Then they do another burn later that raises the low part of the orbit (now 85 miles) up to circularize at 160.
Later, the "Direct Insertion" method was devised. Instead of having two OMS burns, the main engines would cut off when the shuttle's apogee was at the desired altitude. So for a regular mission now, the orbit would be about 160 x 45 nautical miles, and only one more burn would be required to raise the low part of the orbit.
Among the big differences between Standard Insertion (SI) and Direct Insertion (DI) are timeline (fewer burns), better placement of the external tank (in the Pacific instead of Indian Ocean), and propellant (DI is more fuel efficient).
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[written by Jon Leech for the Really Big FAQ, section 10]
Studies indicate that they in reality have only a minute impact, both in absolute terms and relative to other chemical sources. The remainder of this item is a response from the author of the quoted study, Charles Jackman.
The following are the estimated sources of stratospheric chlorine:
Industrial sources: 300,000,000 kilograms/year Natural sources: 75,000,000 kilograms/year Shuttle sources: 725,000 kilograms/year
The shuttle source assumes 9 space shuttles and 6 Titan rockets are launched yearly. Thus the launches would add less than 0.25% to the total stratospheric chlorine sources.
The effect on ozone is minimal: global yearly average total ozone would be decreased by 0.0065%. This is much less than total ozone variability associated with volcanic activity and solar flares... The launch schedule of the Space Shuttle and Titan rockets would need to be increased by over a factor of a hundred in order to have about the same effect on ozone as our increases in industrial halocarbons do at the present time.
For an expanded answer, see:
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[written by Dwayne Allen Day]
About $400-500 million. This is just the cost of the 8 or so missions per year divided into the total cost of the program per year. Adding another mission to the ones already planned costs about $100 million or so. If you work in the development costs, then the cost of each shuttle mission can be as high as $1.5 billion, but this number keeps going down as more and more shuttles are launched and the development costs are amortized over more total flights.
For an expanded answer, see:
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[written by Jeff Findley, Dwayne Allen Day, Justin Wigg, Steve Wachowski]
The quick answer is that the Air Force really wanted to divorce itself from the Shuttle. They closed it down because of "safety issues", when the real reason was that they had had enough and was going back to ELV's. Most of the safety issues had been resolved by late 1986 when it was mothballed--or were resolvable. But the Air Force (read: NRO) had decided that it wanted to get off the space shuttle much earlier and Challenger simply gave them the ammunition they needed to succeed with their arguments.
However, SLC-6 has not been dismantled completely. A lot of the hardware is still there. Slick Six in fact was kept in mothballs for a while (for the third time) after the USAF secretary announced it had been placed in "operational caretaker" status in July 1986. Any shuttle notions were dropped after money was cut for Lockheed's fix for the hydrogen entrapment problem.
SLC-6 was placed in "mothballs" status in 1986, essentially condemned in 1988, and partially dismantled in 1997 or so. The complex was kept in mothballs until Lockheed's Athena booster set up launch operations from one of the Shuttle SRB sections of the launch pad, and when Lockheed decided to launch their EELV from there, they tore down the launch pad itself.
For more information, see:
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Please submit all corrections, additions, and suggestions to WizardImps@hotmail.com.
Page content and layout © 1996-2002 Michael Grabois and Astra Enterprises.
Last updated: August 13, 2002