The F-15 ASAT story

I have added an article "The F-15 ASAT story" to my web site.

* Go to my web site http://www.svengrahn.pp.se
* Click on "What's new?"
* Select entry for 16 January 2005

Many thanks to Gregory Karambelas!

Best Wishes

Sven Grahn

Sven Grahn wrote:

I have added an article "The F-15 ASAT story" to my web site.





This is odd...the test target satellites are inflatable spheres that
have heat generators inside of them, and you point out that the
intercept is basically head-on. The spheres are inflated shortly before
the intercept is attempted... this sounds a lot more like a test of
something designed to intercept incoming ICBM warheads than satellites.
ICBM warheads could well be housed inside of inflatable sphere's (IIRC,
the British Chevaline system may have used this technique) so that they
would appear to be identical to the inflatable decoys on radar until the
covering burnt off during reentry (the decoys would also decelerate
faster on hitting the outer edge of the atmosphere) prior to the
covering burning off, the incoming encased warhead would look like a
heated sphere as it began its descent...much like these target
satellites. If the object of the intercept was to do a realistic test of
hitting a satellite in its natural orbital environment, shouldn't the
heating of its surface have been primarily due to solar irradiation? I
assume that was the case in regards to the P78-1 target satellite*.
About the only other Soviet satellites that would generate significant
heat while on-orbit would be the nuclear powered Soviet RORSATs... were
they the targets being simulated?

*You may want to mention that many scientists were angry about the
destruction of P78-1 at the time, as it was still doing useful work.

Pat

"Pat Flannery" skrev i meddelandet
...


Well, yes, but the balloon made it possible to detect where the interceptor
hit before destroying the telemetry link. A hot gas kept the thing inflated.
I am not sure what the ITV's outside tempertaure would be, one needs the
alpha/epsilon value for that, but a solar panel on a standard satellite gets
quite hot.

Sven

Pat Flannery wrote:
This is odd...the test target satellites are inflatable spheres that
have heat generators inside of them, and you point out that the
intercept is basically head-on. The spheres are inflated shortly before
the intercept is attempted... this sounds a lot more like a test of
something designed to intercept incoming ICBM warheads than satellites.

Nope. It's a way to make something the general size and thermal
properties of bird in orbit without having to launch something of the
same general size... but much larger.

Furthermore, birds in orbit will be heated by the sun, while warheads
will not reliably be so heated.

ICBM warheads could well be housed inside of inflatable sphere's (IIRC,
the British Chevaline system may have used this technique) so that they
would appear to be identical to the inflatable decoys on radar until the
covering burnt off during reentry (the decoys would also decelerate
faster on hitting the outer edge of the atmosphere) prior to the
covering burning off, the incoming encased warhead would look like a
heated sphere as it began its descent...much like these target
satellites.

These targets were considerably above the altitude at which an ICBM
warhead or decoy would display significant heating from re-entry
forces.

If the object of the intercept was to do a realistic test of hitting a satellite
in its natural orbital environment, shouldn't the heating of its surface have
been primarily due to solar irradiation?

Which means a large target... That will decay that much faster. Sven
discusses just this at the end of the essay.

*You may want to mention that many scientists were angry about the
destruction of P78-1 at the time, as it was still doing useful work.

More correctly, the hitchhiker experiment was still doing useful work.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

Derek Lyons wrote:


Furthermore, birds in orbit will be heated by the sun, while warheads
will not reliably be so heated.



Yeah, but the inflated ball will also be heated by the sun...so what's
the need for the internal heater, and how exactly hot does it get? It
gets inflated over Hawaii and comes over the intercept point inside of
twenty minutes. If you want to simulate a satellite, why not let it
orbit once or twice while you track it, then send up the Celestial Eagle
after it? That would be a lot more accurate simulation of a satellite
intercept unless the intention is to hit a just-orbited Soviet satellite
on its first orbit after being launched.
The sphere isn't all that much greater in size than the instrument core
it inflates around, and seems to be there to give a consistant-sized
radar target despite tumbling as well as support the breakable wire kill
vehicle impact position sensor.
The whole F-15 launched satellite interceptor system came and went so
fast that if you' would have missed it if you blinked, and it had the
feel of something that was being used to make the Soviet Union nervous
and bring it to the bargaining table...considering that it obviously
worked, why wasn't it deployed? It wasn't terribly expensive, and the
F-15 launch gave it great flexibility in regards to targeting options on
satellites at various orbital inclinations.



These targets were considerably above the altitude at which an ICBM
warhead or decoy would display significant heating from re-entry
forces.



That's certainly true, but how well does the varying altitude of the
elliptical orbit of the targets match part of the ballistic trajectory
of a ICBM? The warheads and decoys are supposed to separate from the
carrier bus fairly early on in its trajectory towards its target.



If the object of the intercept was to do a realistic test of hitting a satellite
in its natural orbital environment, shouldn't the heating of its surface have
been primarily due to solar irradiation?



Which means a large target... That will decay that much faster. Sven
discusses just this at the end of the essay.



True, it will decay faster when inflated- but this still sounds like a
ASAT and ABM test being done at the same time to me; the Kinetic Kill
Vehicle is basically the same as the Brilliant Pebbles type interceptor
that the Reagan administration proposed for large scale orbital
deployment under the SDI program.



*You may want to mention that many scientists were angry about the
destruction of P78-1 at the time, as it was still doing useful work.



More correctly, the hitchhiker experiment was still doing useful work.



They were still torqued when it got nailed. Especially due to the fact
that they didn't know it was a target until after it was intercepted.

Pat

In article ,
Pat Flannery wrote:
The whole F-15 launched satellite interceptor system came and went so
fast that if you' would have missed it if you blinked, and it had the
feel of something that was being used to make the Soviet Union nervous
and bring it to the bargaining table...

There's a piece in the December issue of Spaceflight by Dwayne Day, in
which he makes the interesting point that a good fraction of the US ASAT
activity may have been motivated more by deterring Soviet use of *their*
ASAT systems than by any perceived urgent requirement for antisatellite
capability per se.

considering that it obviously worked, why wasn't it deployed?

Basically, sustained Congressional hostility.

It wasn't terribly expensive, and the
F-15 launch gave it great flexibility in regards to targeting options on
satellites at various orbital inclinations.

Indeed, if you wanted a practical antisatellite weapon, it was obviously
an excellent choice.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

Henry Spencer wrote:

There's a piece in the December issue of Spaceflight by Dwayne Day, in
which he makes the interesting point that a good fraction of the US ASAT
activity may have been motivated more by deterring Soviet use of *their*
ASAT systems than by any perceived urgent requirement for antisatellite
capability per se.

That sure seemed to be the case at the time. The Soviets were doing some
ASAT tests, and all of the sudden the F-15 ASAT system seems to pop out
of nowhere do some tests, and then vanish. Of course, just about
everything about historical U.S. ASAT efforts is still somewhat shrouded
in mystery- I was amazed when Encyclopedia Astronautica had the article
about SAINT; the device was far more sophisticated in design than I ever
suspected: http://www.astronautix.com/craft/saint.htm
especially given its timeframe (1958-1962)
Of course, those Polyot satellites that the Soviets got into the ASAT
game with were also some pretty impressive pieces of design. I read
somewhere that the Polyot program was just about the only thing that
Chelomei ever did that impressed Korolev.





considering that it obviously worked, why wasn't it deployed?



Basically, sustained Congressional hostility.



Which makes it interesting in regards to my joint ASAT/ABM test
speculation; if you want to do ABM kill vehicle tests without having to
get the funding for them, then a test against a object that may well
resemble a balloon-encased warhead as well as a target satellite, and
that is in an elliptical orbit that may well simulate a section of a
ICBM's flight trajectory is a great way to kill two birds with one stone.

Pat

Sven Grahn wrote:
I have added an article "The F-15 ASAT story" to my web site.

* Go to my web site http://www.svengrahn.pp.se
* Click on "What's new?"
* Select entry for 16 January 2005

Many thanks to Gregory Karambelas!

Best Wishes

Sven Grahn

Good article as always. Thanks.

Some quaint pieces of trivia that come to mind regarding this program.

- At some point, it was identified as Program 1005, the number being
the decimal of Roman numeral MV.

- While AvWeek had identified the program as the Miniature Homing
Vehicle, the Arms Control Impact Statements of the time referred to
Miniature (deleted) Vehicle.

- The divert capabilities are classified, but Soviet planners must have
been concerned about F15's flying in the southern hemisphere being able
to intercept their Molniya and HEO early warning assets around perigee.

Pat Flannery wrote:
Which makes it interesting in regards to my joint ASAT/ABM test
speculation; if you want to do ABM kill vehicle tests without having to
get the funding for them, then a test against a object that may well
resemble a balloon-encased warhead as well as a target satellite,

Except... A balloon encased warhead won't resemble the ASAT target at
all.

and that is in an elliptical orbit that may well simulate a section of a
ICBM's flight trajectory is a great way to kill two birds with one stone.

Except... Such an orbit resembles an ICBM trajectory not at all.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

"Mike Chan" wrote:

- The divert capabilities are classified, but Soviet planners must have
been concerned about F15's flying in the southern hemisphere being able
to intercept their Molniya and HEO early warning assets around perigee.

That's why I always thought a F14 based version made more sense.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL