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Next round of U.S. optical spy satellites to start launching in 2018
by
Star One
on 02 May, 2015 14:28
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#1
by
Billium
on 02 May, 2015 15:36
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The Solar Probe mission is also supposed to launch on a Delta IV Heavy in 2018. 2 in 1 year for Delta IV Heavy, is that a record? Will the year Delta IV retires be the year the highest number of Delta IV cores are launched? It's a shame they won't keep the line active for another year or two.
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#2
by
baldusi
on 02 May, 2015 17:25
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I might do a different speculation. They they might use SEP to counteract atmospheric drag and fly lower orbits. The heavier and the more propellant parts are a SFN speculation and no hard data.
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#3
by
kevin-rf
on 02 May, 2015 23:58
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A wag, but SEP requires power, meaning larger panels that will result in higher drag.
I wonder at what altitude with SEP you reach a point of diminishing returns with the larger panels.
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#4
by
baldusi
on 03 May, 2015 00:32
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A wag, but SEP requires power, meaning larger panels that will result in higher drag.
I wonder at what altitude with SEP you reach a point of diminishing returns with the larger panels.
If they are sort of SSO the panels are always showing its thinner side. If somehow they keep using the elliptic orbits, the drag will be at perigee, which will first affect the apogee. Thus, they can thrust during transfer and put the panels on aerodynamic configuration (i.e. thinner side fore of the orbit) when going down.
But the GOCE demonstrated ridiculously low altitudes that can be held for a long time with SEP.
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#5
by
kevin-rf
on 03 May, 2015 02:14
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Groce always displayed it's thinner side. That drag will not work if it is a stubby hubble pointing down. Also, you will want perigee to occur during the day lit side of the orbit. That means apogee will be on the dark side. Depending on the geometry and season, apogee may be in shadow.
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#6
by
gosnold
on 03 May, 2015 09:03
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Groce always displayed it's thinner side. That drag will not work if it is a stubby hubble pointing down. Also, you will want perigee to occur during the day lit side of the orbit. That means apogee will be on the dark side. Depending on the geometry and season, apogee may be in shadow.
You can use a folding mirror and use a KH-9 configuration, and then you can point the telescope body forward and look down at the same time. Add some batteries to thrust at apogee and you are set.
Since it will launch on a Delta IV H, it could also be that it is a much lighter satellite on a much higher orbit. That would give a somewhat persistent capability.
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#7
by
kevin-rf
on 04 May, 2015 13:37
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Except everything revealed so far about the KH-11 does not indicate a folding mirror, more a stubby hubble configuration. Also, the donated optics from the failed FIA-I program did not include a folding mirror. FIA-I's optics where based on other evidence the same size (2.4m) as the KH-11.
Also, from an optics stand point, the fast f number of the FIA-I optics indicate a wide field of view, that does not play nice with folding mirrors. The folding mirror needs to be larger than the primary.
While this is a new program, it is being built by the people who built the KH-11. I would suspect it lacks a folding mirror. A more interesting question would be, will it be another 2.4m optic. They seem to really like the size.
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#8
by
gosnold
on 04 May, 2015 18:40
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Good points. Anyway, it does not make sense to launch a low-flying SEP sat with a delta IV Heavy. It would need to weigh twice as much as Hubble. That's why I think a move to higher orbits is more likely.
Another option is the NRO wants to be able to change plane from one orbit to the next to be able to overfly a target directly in a crisis situation. That means hydrazine, because SEP would be too low thrust.
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#9
by
Space Ghost 1962
on 04 May, 2015 19:13
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You can also use off center optical systems.
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#10
by
kevin-rf
on 04 May, 2015 20:04
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$$$, oh wait, NRO... never mind
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#11
by
gosnold
on 07 May, 2015 19:01
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#12
by
kevin-rf
on 11 May, 2015 16:25
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This older article was pointed out to me:
http://spacenews.com/us-intelligence-official-drops-hint-about-next-gen-spy-sat-capability/Basically 2.4m objective and an incremental evolution of the current system.
A new generation of electro-optical imaging satellites to be built by Lockheed Martin pending congressional approval will have an aperturesize of 2.4 meters, a senior U.S.intelligence official said.
James R. Clapper, undersecretary of defense for intelligence, disclosed the aperture size — or diameter of the satellite’s primary imaging mirror — of the Next-Generation Optical satellite system Oct.19 during a keynote address here at the Geoint 2009 Symposium.
Lockheed Martin Space Systems of Sunnyvale, Calif., is doing preacquisition work on the Next-Generation Optical System, and the National Reconnaissance Office (NRO), which buys and operates the nation’s spy satellites, expects to award the company the full-scale development contract in late 2011. The two-satellite system will be an evolutionary upgrade of the satellites Lockheed Martin has been building for decades.
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#13
by
Star One
on 11 May, 2015 17:20
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So upgraded variants of the KH-11 then.
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#14
by
kevin-rf
on 11 May, 2015 23:46
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The evidence does seem to be leaning in that direction.
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#15
by
Zed_Noir
on 12 May, 2015 02:22
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Wonder why they limited the new contract to just 2 birds? Maybe an interim gap filler until they figure what future optical surveillance needs are?
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#16
by
Semmel
on 12 May, 2015 08:34
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A monolithic mirror of 4m-class would fit inside the fairing. What makes you think NRO will settle for anything less than that?
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#17
by
Star One
on 12 May, 2015 08:47
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The evidence does seem to be leaning in that direction.
Why not I suppose, they seemingly do the job from what we can tell from the outside so this is probably the lowest risk solution & an appealing option after what happened with FIA-O.
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#18
by
kevin-rf
on 12 May, 2015 09:43
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A monolithic mirror of 4m-class would fit inside the fairing. What makes you think NRO will settle for anything less than that?
History, The Undersectretary for defense saying the next gen. will be 2.4m, the donated mirrors from FIA-I being 2.4m, Hubble being 2.4m, the KH-11 being 2.4m, the 2.4m tooling exists. They really seem to like 2.4m. Based on what has been published they will be sticking with it for at least the next two satellites. Remember these satellites last about 15 years, they historically have kept 4 in orbit, two where built and launched after FIA-I was canceled, with the two new satellites on order this will be the system until the mid 2020's.
It would will be insteresting to see what they do after that.
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#19
by
baldusi
on 12 May, 2015 17:31
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A monolithic mirror of 4m-class would fit inside the fairing. What makes you think NRO will settle for anything less than that?
If you used a bared primary, like the one on the Herschel Space Observatory, you'd be able to squeeze the same 3.5m primary under a 5m fairing (4.6 effective dynamic diameter). Herschel was something like 4.5m total diameter. AIUI, if you go for something Hubble like, you are sort of restricted to 2.4m primary if you fit under a 5m fairing.
And if you decided to use something bigger, say a 6.5m fairing, which ULA has proposed for a DIVH, you wouldn't be able to transport it, unless you subcontracted an Airbus Beluga, which would be more than obvious if you were working for the DoD. So, unless NRO decides to pay for a lot of new infrastructure, I don't see anything bigger than 2.4m monolithic flying anytime soon.
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#20
by
RonM
on 12 May, 2015 17:44
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A monolithic mirror of 4m-class would fit inside the fairing. What makes you think NRO will settle for anything less than that?
History, The Undersectretary for defense saying the next gen. will be 2.4m, the donated mirrors from FIA-I being 2.4m, Hubble being 2.4m, the KH-11 being 2.4m, the 2.4m tooling exists. They really seem to like 2.4m. Based on what has been published they will be sticking with it for at least the next two satellites. Remember these satellites last about 15 years, they historically have kept 4 in orbit, two where built and launched after FIA-I was canceled, with the two new satellites on order this will be the system until the mid 2020's.
It would will be insteresting to see what they do after that.
2.4m might be the optimal size. Since optical spy satellites have to deal with looking through the atmosphere, larger mirrors may not be worth the effort.
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#21
by
gosnold
on 12 May, 2015 20:43
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Larger mirrors at higher altitude gives you more frequent revisits. But to transition to a new constellation with different orbits, you need to launch most of the new constellation before the old one is retired, or else you can lose coverage. Keeping the same kind of sat on the same kind of orbit makes the transitions to the new generation much easier.
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#22
by
Burninate
on 14 May, 2015 05:46
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Good points. Anyway, it does not make sense to launch a low-flying SEP sat with a delta IV Heavy. It would need to weigh twice as much as Hubble. That's why I think a move to higher orbits is more likely.
Another option is the NRO wants to be able to change plane from one orbit to the next to be able to overfly a target directly in a crisis situation. That means hydrazine, because SEP would be too low thrust.
Hydrazine can't do significant rapid plane changes in practice, because the amount of propellant required grows to many times the mass of the satellite very quickly. They would prefer to fly a larger constellation, or have their satellite last ten times as long in orbit, to actually using rapid-response plane change & phase change capability a few times per satellite.
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#23
by
gosnold
on 14 May, 2015 10:19
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Good points. Anyway, it does not make sense to launch a low-flying SEP sat with a delta IV Heavy. It would need to weigh twice as much as Hubble. That's why I think a move to higher orbits is more likely.
Another option is the NRO wants to be able to change plane from one orbit to the next to be able to overfly a target directly in a crisis situation. That means hydrazine, because SEP would be too low thrust.
Hydrazine can't do significant rapid plane changes in practice, because the amount of propellant required grows to many times the mass of the satellite very quickly. They would prefer to fly a larger constellation, or have their satellite last ten times as long in orbit, to actually using rapid-response plane change & phase change capability a few times per satellite.
You are right the plane change could only be used a dozen times or less per satellite. So with a constellation of 4 you would get around 40 plane changes to overfly time-sensitive targets over 15 years. It seems cheaper to me to stock up on hydrazine than to launch more satellites, assuming you can use SEP to compensate drag.
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#24
by
gosnold
on 14 May, 2015 10:44
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Speaking of constellation architectures, here is an interesting paper by Airbus on LEO/MEO/GEO architectures for earth Observation.
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#25
by
Burninate
on 14 May, 2015 10:47
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Good points. Anyway, it does not make sense to launch a low-flying SEP sat with a delta IV Heavy. It would need to weigh twice as much as Hubble. That's why I think a move to higher orbits is more likely.
Another option is the NRO wants to be able to change plane from one orbit to the next to be able to overfly a target directly in a crisis situation. That means hydrazine, because SEP would be too low thrust.
Hydrazine can't do significant rapid plane changes in practice, because the amount of propellant required grows to many times the mass of the satellite very quickly. They would prefer to fly a larger constellation, or have their satellite last ten times as long in orbit, to actually using rapid-response plane change & phase change capability a few times per satellite.
You are right the plane change could only be used a dozen times or less per satellite. So with a constellation of 4 you would get around 40 plane changes to overfly time-sensitive targets over 15 years. It seems cheaper to me to stock up on hydrazine than to launch more satellites, assuming you can use SEP to compensate drag.
What do you base those estimates on?
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#26
by
gosnold
on 14 May, 2015 11:21
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Good points. Anyway, it does not make sense to launch a low-flying SEP sat with a delta IV Heavy. It would need to weigh twice as much as Hubble. That's why I think a move to higher orbits is more likely.
Another option is the NRO wants to be able to change plane from one orbit to the next to be able to overfly a target directly in a crisis situation. That means hydrazine, because SEP would be too low thrust.
Hydrazine can't do significant rapid plane changes in practice, because the amount of propellant required grows to many times the mass of the satellite very quickly. They would prefer to fly a larger constellation, or have their satellite last ten times as long in orbit, to actually using rapid-response plane change & phase change capability a few times per satellite.
You are right the plane change could only be used a dozen times or less per satellite. So with a constellation of 4 you would get around 40 plane changes to overfly time-sensitive targets over 15 years. It seems cheaper to me to stock up on hydrazine than to launch more satellites, assuming you can use SEP to compensate drag.
What do you base those estimates on?
The earth rotates 22.5° between each pass of a LEO satellite. So to overfly a target by plane change, you need to rotate your plane by half that at most, so 11.3°. On average, you don't need to use the maximum plane change, so you need 5.6° change. That's for one satellite.
If you have a constellation of 4 sats, you can set up their ground tracks so they are spaced equally, so you need 1/4th of the plane change capability of one sat.
So one of the 4 sats of your constellation needs to change plane 1.4° (on average) to be able to directly overfly a target within 24 hours.
Thats a delta-v of sin(1.4°)x8 km/s=200 m/s
If your satellite is half hydrazine, your delta-v is ln(2)*230s / 9.8m/s^2 =1500 m/s
So each sat can do around 8 plane changes. If you have 4 of them, that's 32 plane changes over the lifetime of the constellation (15 years for a typical satellite).
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#27
by
Targeteer
on 18 May, 2015 19:22
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Interesting analysis from Ted Molzcan on the subject that expands on his comments used in the story that spawned the thread. I won't post the text from Seesat-L after being "corrected" for doing it recently
Past and future KH-11 orbits
http://www.satobs.org/seesat/May-2015/0096.html
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#28
by
kevin-rf
on 18 May, 2015 19:43
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Very nice read, thanks for sharing.
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#29
by
zubenelgenubi
on 18 May, 2015 20:19
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Interesting analysis from Ted Molzcan on the subject that expands on his comments used in the story that spawned the thread. I won't post the text from Seesat-L after being "corrected" for doing it recently
Past and future KH-11 orbits
http://www.satobs.org/seesat/May-2015/0096.html
The information in the article noted in the OP (from a certain web site to be referenced in this forum as little as possible) is really augmented by Ted M's post. I really wish the article had gone into this greater explanatory detail; I don't know why the author did not.
(One of the main reasons I "lurked" NSF for a few years before joining L2, is for the synthesis of sources provided in the various topic threads, with an enviable signal-to-noise ratio therein.
Also--the direct commentary by the many learned veteran spaceflight experts.
And the grade-A articles.
There are other spaceflight web sites that I rarely use anymore--they just don't measure up!)
Regards,
Zubenelgenubi
EDIT Dec 3, 2019:
NROL-71/USA 290 launch thread
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#30
by
Star One
on 18 May, 2015 21:34
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Interesting analysis from Ted Molzcan on the subject that expands on his comments used in the story that spawned the thread. I won't post the text from Seesat-L after being "corrected" for doing it recently
Past and future KH-11 orbits
http://www.satobs.org/seesat/May-2015/0096.html
Thanks for the info. I posted that as well but it was removed & I couldn't figure out why.
