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#300
by
edkyle99
on 04 May, 2010 18:21
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... Maybe there's some form of shield in the payload bay designed to deploy and reduce the signature of the vehicle. If nobody spots the X-37B in orbit, I'd give that theory more credence. But I suspect that it's going to be found.
Can we think about that announced second burn of the Centaur? Since it got an identifier, it's in orbit -- somewhere, or at least it was for awhile after the burn.
If the announced time is accurate, doesn't that mean that the burn occurred near the first southbound equator crossing?
And isn't that the point where a plane change is most efficient in lowering orbital inclination?
Even a 25 deg inclination orbit would be magnificently unobservable from major unfriendly tracking facilities, not to mention Europe and NZ -based ground observers, n'est-ce pas??
A problem with that idea is that Vandenberg AFB, where X-37B is supposed to land, is at 34.772 deg North.
- Ed Kyle
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#301
by
JimO
on 04 May, 2010 18:33
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That's why you like crossrange. Also, crossrange is needed for landing from polar orbit because a given ground track may be too far east or west of the airfield.
I don't think the bird is at 25, but I'm trying to keep our imaguinations warmed up.
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#302
by
edkyle99
on 04 May, 2010 19:32
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That's why you like crossrange. Also, crossrange is needed for landing from polar orbit because a given ground track may be too far east or west of the airfield.
I don't think the bird is at 25, but I'm trying to keep our imaguinations warmed up.
I would expect a low-as-possible crossrange approach on an inaugural mission. Still, "maneuver" was part of the original name for this program, so plane and altitude change demonstrations seem likely. Did we get the flight azimuth for AV-012?
- Ed Kyle
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#303
by
Blackstar
on 05 May, 2010 03:23
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The other issue is activation time. For a lot of sensitive instruments, outgassing time and other calibration activities can take weeks, or longer, before useful functions are achieved.
That's something I've never gotten a good description of. Just a few random bits of data:
-DMSP weather satellites take up to 30 days for full activation
-DSP satellites take up to 60 days for full activation
-some large military satellites reportedly take 60-120 days for full activation
-the Chandra X-ray telescope didn't open its cover for a month because of outgassing
But I've seen pictures returned from new commercial remote sensing satellites only a few days after launch.
Now, of course, there's probably a curve to all of this stuff--many of these satellites can probably start returning data only a few days after getting into orbit, but it may take weeks for them to be fully calibrated so that they can return their best data. And scientific satellites, which are much more sensitive, might take months to be calibrated. But "rapid response" has some limitations.
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#304
by
yinzer
on 05 May, 2010 05:21
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Now, of course, there's probably a curve to all of this stuff--many of these satellites can probably start returning data only a few days after getting into orbit, but it may take weeks for them to be fully calibrated so that they can return their best data. And scientific satellites, which are much more sensitive, might take months to be calibrated. But "rapid response" has some limitations.
If it's going to take you one month to call up a launch vehicle for your satellite already built and sitting in a clean room, it's not worth spending a lot of effort to bring the on-orbit activation time from a week to a day. That doesn't mean it's not possible.
Likewise, if it's going to take you four years to design and build your science payload, it's not worth spending the effort to get the instrument checkout and calibration time down below two weeks.
There are a bunch of chicken and egg issues surrounding rapid response, and without a pressing need no one wants to spend the money to solve them all. The best hope for progress is to chip away at the issues with technology demonstration missions, but then you have to deal with people asking "why are you trying to solve problem X when you still have problems W, Y, and Z?"
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#305
by
Blackstar
on 05 May, 2010 21:49
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Very good points. It may be possible to design a sensor for more rapid availability. But this may also depend upon a lot of other things. For instance, how much does the spacecraft outgas and do you have to reduce that in order to make the sensor available sooner?
And of course, this is all going to affect cost. So it may be possible to design sensors to go into the payload bay of a rapid response spacecraft (assuming that X-37B is such), but that could end up costing a lot of money.
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#306
by
Robotbeat
on 05 May, 2010 21:52
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Very good points. It may be possible to design a sensor for more rapid availability. But this may also depend upon a lot of other things. For instance, how much does the spacecraft outgas and do you have to reduce that in order to make the sensor available sooner?
And of course, this is all going to affect cost. So it may be possible to design sensors to go into the payload bay of a rapid response spacecraft (assuming that X-37B is such), but that could end up costing a lot of money.
There's a ton of literature on the responsive space trade-space:
http://www.responsivespace.com/index.asp
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#307
by
yinzer
on 06 May, 2010 01:24
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Very good points. It may be possible to design a sensor for more rapid availability. But this may also depend upon a lot of other things. For instance, how much does the spacecraft outgas and do you have to reduce that in order to make the sensor available sooner?
And of course, this is all going to affect cost. So it may be possible to design sensors to go into the payload bay of a rapid response spacecraft (assuming that X-37B is such), but that could end up costing a lot of money.
Or it might not; it's hard to tell. Maybe you just have to bake your spacecraft in a vacuum chamber for a month then store it in a nitrogen-filled container as part of the manufacturing process.
A significant part of my job deals with automating complex tasks that have traditionally been performed by highly skilled workers. Doing the automation work is usually very difficult and time consuming, but once it's done the recurring effort to perform the tasks goes down to effectively zero.
The question becomes how complicated is the task you're trying to automate, how many times do you have to do it, and what kind of time pressure does it have to be done under.
Spacecraft operations is probably on the bad end of the spectrum for all of these attributes - complicated, done infrequently, and not typically under time pressure - but not impossibly so.
It's still a bit odd that no one has reported spotting the X-37B yet. Is anyone on SeeSat-L in Hawaii?
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#308
by
Danderman
on 06 May, 2010 01:32
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... Maybe there's some form of shield in the payload bay designed to deploy and reduce the signature of the vehicle. If nobody spots the X-37B in orbit, I'd give that theory more credence. But I suspect that it's going to be found.
Can we think about that announced second burn of the Centaur? Since it got an identifier, it's in orbit -- somewhere, or at least it was for awhile after the burn.
If the announced time is accurate, doesn't that mean that the burn occurred near the first southbound equator crossing?
And isn't that the point where a plane change is most efficient in lowering orbital inclination?
Even a 25 deg inclination orbit would be magnificently unobservable from major unfriendly tracking facilities, not to mention Europe and NZ -based ground observers, n'est-ce pas??
This doesn't really explain why no one has seen the Centaur. There must be someone looking for it who is farther south than 25 degrees.
A better explanation is that the Centaur was de-orbited, and the X-37 is testing to see if its blackened TPS makes it invisible.
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#309
by
TimL
on 06 May, 2010 01:38
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Assuming a 28-32 degree orbit and between 400-500km has put it in the southern hemisphere at sunrise/sunset windows. Should start becoming visible pre-sunrise in the USA around May 15th hopefully mid elevation southern sky.
I'll be watching
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#310
by
Antares
on 06 May, 2010 03:46
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Somewhere around reply #240, there was talk that the Centaur went escape. If so, no one's going to see it for several years.
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#311
by
yg1968
on 17 May, 2010 17:10
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One U.S. Air Force Research Laboratory (AFRL) concept for future applications depicts a reusable Concorde-sized hypersonic transport equipped with four X-51 type scramjet engines. Carried on its back in the concept is a USAF X-37 type unmanned spaceplane like that currently undergoing tests in space after launch from Cape Canaveral on an Atlas 5.
http://spaceflightnow.com/news/n1005/16waverider/
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#312
by
Robotbeat
on 17 May, 2010 17:33
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One U.S. Air Force Research Laboratory (AFRL) concept for future applications depicts a reusable Concorde-sized hypersonic transport equipped with four X-51 type scramjet engines. Carried on its back in the concept is a USAF X-37 type unmanned spaceplane like that currently undergoing tests in space after launch from Cape Canaveral on an Atlas 5.
http://spaceflightnow.com/news/n1005/16waverider/
That was what I was thinking of, as well, when I saw both the reusable flyback rocket booster concept and the x-37b. Doesn't mean it will work, but still interesting. The X-37B (or whatever the upper stage would be called) will probably need far more delta-v capability, though... Closer to 5km/s than the current 1.7 km/s (probably less than that, actually), so would likely be quite different indeed from the X-37b.
Would be nice to have a return to the Faget-style Shuttle concept which fell victim to too many requirements and not enough money.
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#313
by
nooneofconsequence
on 18 May, 2010 00:59
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That was what I was thinking of, as well, when I saw both the reusable flyback rocket booster concept and the x-37b.
Rocketback AF booster concept is more like a reusable Atlas V first stage.
Possible you might be able to cluster them.
Nothing like RASCAL which is implied by the article.
X-37 dV isn't meant for substituting for a second stage but for on-orbit maneuvering.
add:
Oh, and BTW if you are wondering about any
observations of it on-orbit.
No such luck
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#314
by
jgoldader
on 18 May, 2010 13:24
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Oh, and BTW if you are wondering about any observations of it on-orbit.
No such luck
At some point, do we start to assume it's due to some sort of low-obs techniques being used? Or are there just too few seasoned observers beneath a low-inclination orbit to allow for observations?
I really hope we get to learn how the story ends! It would be great to hear of a successful landing, even if the date/time are kept vague.
Jeff
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#315
by
edkyle99
on 18 May, 2010 18:12
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#316
by
nooneofconsequence
on 18 May, 2010 19:17
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#317
by
Antares
on 19 May, 2010 02:10
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What's his latitude?
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#318
by
yg1968
on 19 May, 2010 21:13
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#319
by
edkyle99
on 19 May, 2010 23:53
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What's his latitude?
He reports this observation to have been at:
44.6062 N
75.6910 W
- Ed Kyle
