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#1040
by
brahmanknight
on 31 May, 2008 22:16
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Thanks for the answers, Jorge and Mark. It seems it is about as difficult/far fetched as I thought it was.
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#1041
by
brahmanknight
on 31 May, 2008 22:19
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What you probably saw was the plasma around the back of the orbiter. The engines turn off before ET separation.
Listen for the 'MECO" call. That is when the SSMEs have ceased operation.
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#1042
by
astrobrian
on 31 May, 2008 22:23
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Shuttle QnA thread is where this should have been posted
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#1043
by
michaellefebvre
on 31 May, 2008 22:25
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sorry just joined , will do next time
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#1044
by
astrobrian
on 31 May, 2008 22:27
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no problem , welcome to the show
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#1045
by
Danny Dot
on 01 Jun, 2008 01:57
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I just watched a shuttle launch and am puzzled about something.
When the external tank is droped it appears that the shuttles main engines continue to run.
I would assume that the shuttle still need velocity to orbit.
If it were to cut engines at the same time as it drops the tank, it would fall out of orbit like the tank does.
My question is, where does the fuel for the engines come from if
it has droped the external tank?
thks
The needed velocity to achieve orbit comes from the Orbital Maneuvering System Engines, OMS Engines.
Danny Deger
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#1046
by
usn_skwerl
on 02 Jun, 2008 14:32
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With the FOD produced by this launch (124), as well as the pad debris kicked up by either 123 or 122 (I forget which), I'm wondering if this is from all the launches over the last 40-some years at LC-39, and is NASA concerned about it becoming more of an issue with the rest of STS flights?
If this is due to the extremes the pads face every time the candles are lit, are the pad engineers going to repair only as necessary, especially for Ares, or will the pads be repaired as needed, or ovehauled to handle Ares I and V?
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#1047
by
AndrewSTS
on 02 Jun, 2008 14:58
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How do they know in advance when they are going to be in a specific period of ratty comm?
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#1048
by
Jim
on 02 Jun, 2008 15:04
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How do they know in advance when they are going to be in a specific period of ratty comm?
Antenna look angles and vehicle obstructions
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#1049
by
AndrewSTS
on 02 Jun, 2008 15:21
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Thanks Jim!
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#1050
by
madmardy
on 02 Jun, 2008 20:06
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I just watched a shuttle launch and am puzzled about something.
When the external tank is droped it appears that the shuttles main engines continue to run.
I would assume that the shuttle still need velocity to orbit.
If it were to cut engines at the same time as it drops the tank, it would fall out of orbit like the tank does.
My question is, where does the fuel for the engines come from if
it has droped the external tank?
thks
Just going to add some more detail to this one.
The main Engines cut out some moments before the External tank separates (MECO) and the stack coasts for a short while until ET Sep
At the time of ET Sep the orbiter fires its -Z RCS (downward facing) thrusters so infact the tank does not fall away from the orbiter, the orbiter actually lifts off the tank. At this point both the Tank and the orbiter are on a ballistic trajectory and both WILL enter the atmosphere.
Half an orbit later the orbiter then fires it OMS engines (OMS 2 Burn)
this circularises the orbit for the orbiter and keeps it up there, obviously the tank does not and consequently re enters.
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#1051
by
DaveS
on 02 Jun, 2008 21:36
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Half an orbit later the orbiter then fires it OMS engines (OMS 2 Burn)
this circularises the orbit for the orbiter and keeps it up there, obviously the tank does not and consequently re enters.
Half an orbit? Not quite! Half an orbit is where the perigee(lowest point of the trajectory) is located! It's more a quarter of an orbit.
An orbit is counted as when the vehicle passes a specific point of the orbit(in the STS case it's the longitude of KSC).
And for the OMS-2 burn to have the desired effect on the orbit, you need to burn close to apogee(the highest point of the trajectory).
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#1052
by
Jim
on 02 Jun, 2008 22:13
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An orbit is counted as when the vehicle passes a specific point of the orbit(in the STS case it's the longitude of KSC).
That is the definition of a revolution. Orbit is defined by the ascending node
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#1053
by
nacnud
on 03 Jun, 2008 00:11
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That is the definition of a revolution. Orbit is defined by the ascending node
That's crossing the equator heading north to crossing the equator heading north again, right?
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#1054
by
pr1268
on 03 Jun, 2008 01:52
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At this point both the Tank and the orbiter are on a ballistic trajectory and both WILL enter the atmosphere.
Half an orbit later the orbiter then fires it OMS engines (OMS 2 Burn)
this circularises the orbit for the orbiter and keeps it up there, obviously the tank does not and consequently re enters.
Just curious, how far away from each other are the Orbiter and ET when OMS-2 happens?
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#1055
by
ChrisGebhardt
on 03 Jun, 2008 03:23
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That's crossing the equator heading north to crossing the equator heading north again, right?
Yes.
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#1056
by
Zephon907
on 03 Jun, 2008 06:13
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When looking at NASA's Orbital Tracking website-
http://spaceflight.nasa.gov/realdata/tracking/there is a red, lopsided circle which encompasses the image representing the spacecraft. It's not the areas on earth from which the spacecraft can be seen is it? I don't think so because, while the circle often includes the area I live in, a sighting possibility is not always listed for that particular orbit. What does it represent?
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#1057
by
maxx
on 03 Jun, 2008 09:43
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When looking at NASA's Orbital Tracking website- http://spaceflight.nasa.gov/realdata/tracking/
there is a red, lopsided circle which encompasses the image representing the spacecraft. It's not the areas on earth from which the spacecraft can be seen is it? I don't think so because, while the circle often includes the area I live in, a sighting possibility is not always listed for that particular orbit. What does it represent?
My uneducated guess is that it's indeed a "sighting possibility" but doesn't include the altitude nor the earth curvature. Depending on your altitude this circle can be smaller and stretch depending on the latitude, which can explain why you "miss" some sighting opportunities...
I've compared with Orbitron and the visibility "circle"
roughly have the same diameter, but Orbitron takes the earth curvature into account, so it's a circle only around the equator. [edit]Need more cofee, the java applet also takes into account the earth curvature...[/edit]
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#1058
by
mark147
on 03 Jun, 2008 09:45
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It does represent that but you'll only have a sighting if the spacecraft is in sunlight but the surface is in darkness.
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#1059
by
kneecaps
on 03 Jun, 2008 11:25
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My uneducated guess is that it's indeed a "sighting possibility" but doesn't include the altitude nor the earth curvature. Depending on your altitude this circle can be smaller and stretch depending on the latitude, which can explain why you "miss" some sighting opportunities...
I've compared with Orbitron and the visibility "circle" roughly have the same diameter, but Orbitron takes the earth curvature into account, so it's a circle only around the equator. [edit]Need more cofee, the java applet also takes into account the earth curvature...[/edit]
Simply put. The circles around vehicles in views like this are 'Line of Sight'....don't forget..line of sight often means Radio comms from a ground station...so its useful not just for determining visual sightings.
no problem , welcome to the show