satellite shootdown

[mr fish]

just seen a report on the bbc about the US shooting down an old spy sat, what system will they use?. was thinking the 80s ASAT but that uses an F15, might be a problem there:E

[MightyGem]

The broadcast that I heard mentioned firing the missile from a ship. Didn't think that that capability was possible.

[vikingdriver]

Similarities to the Chinese and their wx sat anyone?

As I understood it all, of the Intel gathering sats had charges on them to destroy the equipment at the end of life, but this would certainly seem a useful opportunity to test a ground based missile.

Were the F15 launched ASAT's manufactured by Lockheed? I have vague recollections of reading someware that the remaining ones had issues with some of the propellant / and or structural integrity? :confused:

[ZH875]

I wonder which nations satellite the Americans will hit instead of theirs....:O

[WolvoWill]

I seem to recall reading that the Russians went ape over the suggestion of ASAT, claiming it broke some long standing agreement or other over space weapons, and as such it never reached operational service or largescale production - unlikely to be a serviceable weapon or crews trained in its usage (never mind the aforementioned problem of it only being employable from the F-15....).

Think AEGIS and its SAMs will be the weapon of choice this time, rather than using the experimental(ish) missiles proposed for the missile defence shield.

[Ewan Whosearmy]

ZH875

Did you come up with that on your own, or did someone help you?

[noregrets]

They're looking at a Standard missile from an Aegis ship:

http://news.bbc.co.uk/1/hi/world/americas/7245578.stm

I was amazed to discover just how many satellites are tootling around up there - the vast majority admittedly are comms birds, but just imagine the effect on national morale if China/NK/AQ managed to bring down the Sky satellite...

[0497]

There appears to be a lot of skepticism of the dangers of letting the satellite fall naturally back down.

[RETDPI]

How do you actually shoot down a satellite?
Or have some of Newton's laws now been repealed? :8

[Ewan Whosearmy]

RETDPI

I believe that this satellite was always going to come back down to earth as it never fully left the earth's gravitational pull (IIRC). I believe that Newton's law remains intact... for now!

[Ewan Whosearmy]

Since the ASM-135 ASAT missile a) no longer exists, and b) probably couldn't be programmed into the F-15's PACS in time even if it did, it makes sense to use a SAM. But I am surprised they are using a modified Standard Missile instead of a modified PAC-3 or similar.

ZH

Looks like you struggle to write complex sentences. Best stick to the short ones, hey?

[Ewan Whosearmy]

More detail from the US DoD:

DoD To Engage Decaying Satellite

An uncontrollable U.S. experimental satellite which was launched in December 2006 is expected to reenter Earth’s atmosphere between the end of February and early March. Because the satellite was never operational, analysis indicate that approximately 2,500 pounds (1134 kgs) of satellite mass will survive reentry, including 1,000 pounds (453 kgs) of propellant fuel (hydrazine), a hazardous material.

Although the chances of an impact in a populated area are small, the potential consequences would be of enough concern to consider mitigating actions. Therefore, the President has decided to take action to mitigate the risk to human lives by engaging the non-functioning satellite. Because our missile defense system is not designed to engage satellites, extraordinary measures have been taken to temporarily modify three sea-based tactical missiles and three ships to carry out the engagement.

Based on modeling and analysis, our officials have high confidence that the engagement will be successful. As for when this engagement will occur, we will determine the optimal time, location, and geometry for a successful engagement based on a number of factors. As the satellite’s path continues to decay, there will be a window of opportunity between late February and early March to conduct this engagement. The decision to engage the satellite has to be made before a precise prediction of impact location is available.

Contact with hydrazine is hazardous. Direct contact with skin or eyes, ingestion or inhalations from hydrazine released from the tank upon impact could result in immediate danger. If this operation is successful, the hydrazine will then no longer pose a risk to humans.

The U.S. government has been and continues to track and monitor this satellite. Various government agencies are planning for the reentry of the satellite. In the event the engagement is not successful, all appropriate elements of the U.S. Government are working together to explore options to mitigate the danger to humans and to ensure that all parties are properly prepared to respond. In the unlikely event satellite pieces land in a populated area, people are strongly advised to avoid the impact area until trained hazardous materials (HAZMAT) teams are able to properly dispose of any remaining hydrazine.

Satellite Shootdown Going Forward: The Pentagon has chosen to proceed with plans to shoot down an "uncontrollable" classified US intelligence satellite that is reentering Earth's atmosphere at the end of the month, using an element of the ballistic missile defense network, senior officials confirmed at the Pentagon Thursday. Marine Corps Gen. James Cartwright, vice chairman of the Joint Chiefs of Staff, told reporters that some 2,500 pounds of satellite mass might survive reentry and would include about 1,000 pounds of the propellant hydrazine, a hazardous material. While the chances of impact in a populated area are low, President Bush has elected to take action to mitigate the potential risk if it impacts near a populated area, said James Jeffrey, the deputy national security advisor. Talks with other space agencies and countries have been ongoing since January regarding the satellite and potential action against it, he added. The Pentagon has elected to use a Navy Standard Missile 3 anti-missile interceptor and believes that the window of opportunity will be only a few days. The goal is to hit the satellite at about 130 nautical miles away from the Earth. Navy personnel have been reprogramming the SM-3's software so that it will be able to better target a disintegrating satellite, which has a different and far more erratic trajectory than an aerodynamic ballistic missile. There will be one missile primed for the attempt with two backups, and three ships will be on station for the operation, Cartwright said. The area of operation is not yet set, but the Navy will deploy the ships to a location somewhere in the northern hemisphere in the Pacific Ocean, he said.

[hunterboy]

The more cynical amongst us still think its more to do with testing current anti satellite capability. The problems with the damaged satellite provide the US with a perfect cover story.

[Dan Winterland]

The risk of blowing up a satellite in orbit is that it will leave a huge amount of debris for other vehicles to run into. Space junk is a real problem - a space shuttle windscreen was damaged by a flake of paint from a saturn rocket once. It penetrated several mm and would have fatally injured the occupant of a space suit if it had collided.

It is far better to let it burn up in the atmosphere, the risk of any debris is minimal. And as hydrazine is a highly volatile monofuel, the chances of any of it reaching the Earth's surface is zero.

This sounds like an excuse to test a missile. A similar test by the Chinese was heavily berated bu the US!

[Focks 2]

RETDPI

I believe that this satellite was always going to come back down to earth as it never fully left the earth's gravitational pull (IIRC).

You had no help with that sentence then! :p All satellites re-enter eventually, even the ones at over 20,000 mile altitudes. Earths gravitational influence extends to something like 7x the distance to the Moon. The satellite in question is currently at around 160 miles altitude (far lower than any 'enemy' satellites that one would like to destroy), and its orbit is decaying at about 0.5+ miles/day, and that figure is constantly increasing as it meets more of our atmosphere. If the satellite is hit at 130 miles altitude, most of the debris will re-enter after a few orbits. It could demonstrate the ability to hit small high-speed objects in LEO. :ok:

[eagle 86]

F2
Does that mean that the moon is eventually going to crash to Earth!!?
GAGS
E86

[lamer]

well, maybe .......

but don't worry, you've got 5 billion years!

http://www.space.com/scienceastronomy/070122_temporary_moon.html

[Brian Abraham]

You're safe E86, long may you continue to soar. The radius of the moons orbit is increasing by 3.8 cm per year. The more worrying aspect is that this is causing the length of a day on earth to increase by 0.002 seconds per century. Think how all that extra sun light is going to fade the curtains. :eek:

[eagle 86]

And I thought "climate change" was all I had to worry about!!
GAGS E86

[GreenKnight121]

1. The hydrazine tank is allegedly likely to survive re-entry intact (being thick to hold the pressurized material, as well as insulated and surrounded by the rest of the satellite). Thus it could survive to burst on impact, releasing the fuel at ground level.

2. The SM-3 missiles are the same as those used for theater & re-entry-phase ballistic-missile interception.

3. At the altitude, speed, & flight path that will exist at the time of the shootdown attempt(s), the satellite will be acting much like a missile beginning re-entry (with a few extra zigs & zags).

4. The maximum range of the PAC-3 is nowhere close to what will be needed here.
"The goal is to hit the satellite at about 130 nautical miles away from the Earth."
What I have seen for the PAC-3 lists a max missile-intercept range of 45km, and a max altitude of 15km.

[GreenKnight121]

Just ran across this discussion of the same topic on another board:http://bobhenneman.info/forum/viewtopic.php?t=1066&start=0&postdays=0&postorder=asc&highlight=

Note the following info brought up:

1. Data for RIM-161A ( i.e. SM-3):

Length (incl. booster) 6.55 m (21 ft 6 in)
Finspan 1.57 m (61.8 in)
Diameter 0.34 m (13.5 in)
Weight ?
Speed 9600 km/h (6000 mph)
Ceiling > 160 km (100 miles)
Range > 500 km (270 nm)
Propulsion Booster: United Techologies MK 72 solid-fueled rocket
Sustainer: Atlantic Research Corp. MK 104 dual-thrust solid-fueled rocket
3rd stage: Alliant Techsystem MK 136 solid-fueled rocket
Warhead Hit-to-kill kinetic warhead (KW)

2. When Columbia came apart, the fuel tanks for the thrusters came through, or some of them did, in fair shape and still had (much to just about every-body's surprise) some fuel in them. Corrosive and toxic fuel - I know one of the people who had a fuel tank land on their farm, not far from the house. NASA came and got it, with a Hazmat team.

The current concern is that IF the satellite comes down on land, its maneuvering fuel tanks will get through intact and with fuel in them. With a kinetic kill warhead, the whole satellite will be ruptured and broken up and the tank breached in orbit. And things will be safer on the ground.




Colombia is the space shuttle which broke up during re-entry, for those few who just crawled out of their caves (95% of us knew that already).

[0497]

The offending satellite is much larger (apparently the size of a bus) than what the SM-3 is designed to to be used for.

[Double Zero]

Yes the Standard Arm 3 with Aegis seems to do the job quite nicely - and a long time ago Soyuz 6 had inter-space anti-satellite lasers.

The Reagan SDI programme was alleged to have an offensive capabity, and do you really believe the shuttle is unarmed ?! Not talking " Moonraker" B0----ks here...

[Agaricus bisporus]

I suspect there is a bit of hype going on here. No doubt the D of D is concerned at a ton of Hydrazine landing intact, and this is a good way to test or stretch the capability of the Standard, and one that is too tempting to pass by.

I am certain is that the Standard cannot possibly reach a satellite in a stable orbit, so here is the hype. The target is clearly in a decaying orbit and is way, way lower than was intended- otherwise it would be unreachable. So all you have to do is predict its terminal trajectory and as it scrapes lower and lower until in the last few days it is so low that even an anti aircraft missile - albeit a hairy-arsed brute like the Standard, can reach it. Hence the "window" of a couple of days. Earlier, and it's too high, later and its in a freefall fireball.

Certainly isn't the scenario that immediately comes to mind with the headline "shooting down a satellite". No way can you blow uop a satellite in a stable orbit, or one with a long time left in orbit - the debris would cause havoc up there. You gotta wait until it is nearly down, then break it up in the last part of its fall.

And apart from anything else, they probably don't want anyone else getting their hands on large bits of wreckage - imagine if it landed in N Korea or China...

[Satellite_Driver]

This came up on another discussion forum I'm on, so I did a little Q&A to tackle some of the comments I've seen in the media. Here it is, with apologies if it goes over ground others around here have already covered.


What are they aiming at? The satellite in question is USA 193, a satellite launched a few months ago as a covert project of the National Reconnaissance Office - in other words, a spy satellite. It apparently failed soon after launch, stranding it in a low orbit which atmospheric drag is now pulling lower and lower, to the point that left to itself it will re-enter in about a month's time.

Is the satellite a ten-ton monster? The figure of 'ten tons' seems to be being bandied around rather a lot. This is probably because the phrase 'spy satellite' tends to be associated with the NRO's line of massive high-resolution optical reconnaissance satellites descended from the KH9 'Big Bird' of the early 1970s. These are allegedly around about the size of Hubble, and have been launched by heavyweight boosters such as Titan III and IV, which have the capability to put 12 to 20 tons into orbit.

USA 193, by contrast, was launched by a Delta II, specifically the 7920 variant, a standard medium-weight launcher that can put little more than 3 tons into a polar orbit. Whilst hardly small, USA-193 is a medium-weight satellite no larger than many other science or Earth-resources satellites.

Does it pose a hazard to the ground? To begin with, the likelihood of debris from an uncontrolled re-entry falling in a populated area is low. Something like three-quarters of the area under this satellites orbital path is water, and much of the rest is thinly inhabited. However, equally it encompasses the vast bulk of the Earth's populated land area, so the chances of it landing near a populated region can't be disregarded. But then again, the space shuttle Columbia broke up during re-entry over a densely-populated swathe of Texas, but caused only limited damage and no injury to anyone on the ground.

If it does come down near a built-up area, what is likely to survive? Two sorts of material tend to reach the ground from uncontrolled re-entry: dense, heavy items and, perversely, very light ones. The former reach the ground because they are dense enough to punch through the atmosphere and solid enough to resist melting, whilst the latter have little enough kinetic energy in comparison with their surface area that they are slowed down without overheating and fall relatively slowly to ground. As it happens, empty fuel tanks are such an item, and quite a few have survived satellite re-entry in the past.

So, is this the satellite's fuel tank a hazard? The justification for the proposed shootdown is indeed that USA 193 has a fuel tank on board; the concern is not so much that the tank itself might reach the ground intact, but that it might spill its load of hydrazine fuel when doing so. Now, I've known people in the space business who've worked with hydrazine, and they will tell you that it is indeed a spectacularly nasty substance: toxic, inflammable, carcinogenic and smelly to boot. I was sceptical at first that there was any chance of the tank reaching the ground with any hydrazine aboard, as it would certainly rupture during re-entry. However, the suggestion from the US is that the hydrazine has frozen, in which case I can see that it might not all leak from even if the tank loses containment. That it would freeze is quite possible if USA 193 has indeed been out of control for several months. Satellite thermal control is a difficult problem and without careful measures such as carefully maintaining the angle at which the it faces the Sun and using active heating or cooling systems, satellites usually overheat or get far too cold.

But does this justify a shootdown? Frankly, I'm sceptical. Plenty of other satellites have failed in low orbit with a full fuel load and have burned up without too much of a problem. My suspicion, like that of many others, is that this is a convenient excuse for the US Dept of Defense to demonstrate, following the Chinese anti-satellite test last year, that it too is capable of intercepting space vehicles. The other suggestion, that the plan is to deny the prospect of sensitive components from reaching the ground intact, is possible but I suspect less likely.

Can you actually shoot a satellite down? Not as such. At present, USA 193 is in a very low (and getting lower through atmospheric drag) circular orbit. The weapon that would be used to attack it - an updated version of the US Navy's long-serving Standard surface-to-air missile - does not have a warhead as such, but rather has a guided final stage that flies into the target at a closing speed of around 10 km/s. At that speed, the kinetic energy of the collision is equivalent to the interceptor's own weight in explosive, so the interceptor and much of the satellite would be vaporised in a powerful explosion. The surviving fragments of the satellite would end up in new orbits all of which passed through the point of interception but which were perturbed to some extent from the original circular orbit. Now, given how close the original orbit is to the atmosphere, it's easy to see that any significant deviation from it is likely to be an orbit that dips into the atmosphere at some point. In other words, most of the debris is likely to end up in orbits that will hit the atmosphere within a single pass around the Earth, although a fraction of the remains - those parts that were flung directly forward from the impact - will end up in elliptical orbits with a low point at the original orbit height but a new, higher apogee (high point). Even so, these will burn up within a few months at most as their perigee (low point) will be low enough for atmospheric drag to pose a significant effect.

Is there a risk to other satellites? A small one. As noted above, some debris is likely to be flung into short-lived orbits above the original one, and there is a chance that these might cross the paths of operational satellites. However, the risk is small; bear in mind that the single biggest target in low orbit is the Space Station, and the DoD and NASA will have had to assess the risk to it as minimal to be proceeding with this plan. The Chinese test, which was carried out against a satellite in much higher orbit, probably produced much more in the way of potentially hazardous space debris than this shootdown would.

Will it work? The US anti-missile system has had a very chequered record in tests, but to be fair shooting at a minibus-sized satellite in a known orbit is likely to be much easier than aiming at an oil-drum-sized warhead launched only a few minutes previously. If the Americans are planning this as a bit of sabre-rattling, then I'd assume that they are fairly confident that it's going to work.

[Focks 2]

hold on, hold on, wait for me whilst I quote Wikipedia and try to sound knowledgeable!

:{ :rolleyes:
Come on then O' God given sourceless fountain of knowledge, lets hear your take on the subject.

Oh, this time I have a quote from Wiki: "The Leghorn Blows at Midnight (1950)."

[0497]

Looks like they've done it.


Navy missile hits failing spy satellite

The first shot, fired at about 7:30 p.m., strikes its target. But officials say they don't know yet whether the fuel tank was destroyed.

By Peter Spiegel, Los Angeles Times Staff Writer
9:00 PM PST, February 20, 2008

HONOLULU -- Firing a three-stage missile from a Navy cruiser off the coast of Hawaii, the U.S. military hit a failed intelligence satellite speeding 133 miles above the Earth on the first try tonight, a shot the Pentagon hopes destroyed the spacecraft's fuel tank filled with 1,000 pounds of potentially toxic gas.

The missile, shot from the cruiser Lake Erie, came just as the window for the operation opened, at about 7:30 p.m. Pacific.


The Pentagon waited until the space shuttle Atlantis landed this morning to begin the operation. Planners determined the best time to attempt the shot was late afternoon local time, when the cold, tumbling satellite would have maximum exposure to the sun, warming it up enough for the heat-seeking "kill vehicle" atop the missile to find it.

Pentagon officials were not immediately able to say whether the fuel tank of the spy satellite had been destroyed, but officials have said that any hit would reduce the risk of danger to humans. In a statement, the Pentagon said it would be able to tell within 24 hours whether the fuel tank was ruptured.

The 5,000-pound satellite is so big that only half of it was expected to burn up on reentry. By shattering it with the missile, the spacecraft is likely to break up into smaller pieces that will be destroyed before entering the Earth's atmosphere.

In a sign of how important the military viewed the shoot-down, Defense Secretary Robert M. Gates gave the final approval to fire the Standard Missile-3. According to Pentagon Press Secretary Geoff Morrell, Gates gave the go-ahead during a conference call with commanders aboard his airplane while it was traveling over the Pacific en route to Hawaii.

Although weather reports earlier in the day had warned of choppy seas, the waters had calmed by the afternoon, and "the secretary was told conditions were ripe for an attempt," Morrell said.

Gates landed in Hawaii on an overnight stop here ahead of a weeklong trip to Asia less than two hours before the missile was fired, and was informed of the successful hit just minutes after it occurred.

Some experts with knowledge of military satellite programs have expressed skepticism about the danger posed by the spacecraft and its hydrazine jet fuel, arguing that the Pentagon was seeking to prove its ability to strike down a satellite just a year after China shot down one of its own aging weather satellites.

Military officials have denied any ulterior motive, and Navy Adm. Timothy J. Keating, commander of all U.S. forces in the Pacific, told reporters here that in multiple conversations with nations in the region, he had been told of no objections to the test.

According to the Pentagon statement, the Lake Erie fired the missile at 7:26 p.m. Pacific and hit the satellite as it was speeding more than 17,000 miles per hour. Nearly all of the debris is expected to burn up within 48 hours, with the rest reentering the Earth's atmosphere within 40 days.

[Madbob]

I'm ex RAF and as (sadly) I never got to fly one I'm not very clued-up on this, but I seem to recall that the firies and ATC took special "care" if ever an F16 arrived with an emergency. Isn't hydrazine used as a fuel for their EPU or something? If so, wouldn't every F16 crash site be contaminated with the stuff?

I don't know the volume carried, nor the particular risks apart from being extremely volatile. Can anyone expand on this?

[Bushfiva]

Did anyone notice SBX-1 moved into the area? Maybe that's the kit that was used to detect how many bits were knocked off US-193 immediately after the hit.

Is this NOTAM standard format?

NOTAM: A0601/08 - QXXXX SBX-1, A SURFACE VESSEL TESTING A HIGH POWERED X BAND RADAR SYSTEM WILL BE OPERATING IN THE VICINITY OF 2700N/16300W. THE VESSEL ALSO HAS A SEARCH RADAR ON BOARD FOR DETECTING AIRCRAFT WITHIN APPROXIMATELY 81NM OF THE VESSEL. IF AIRCRAFT ARE DETECTED WITHIN 8.5 NM OF THE VESSEL TESTING OF THE HIGH POWERED RADAR SYSTEM WILL BE SUSPENDED. WIE UNTIL 05 MAR 23:59 2008. CREATED: 11 FEB 13:55 2008

[OFBSLF]

My suspicion, like that of many others, is that this is a convenient excuse for the US Dept of Defense to demonstrate, following the Chinese anti-satellite test last year, that it too is capable of intercepting space vehicles.But how does it achieve that? Since this satellite is in such a low orbit and the missile being used can't reach the typical heights used by satellites, then all it does is prove that the US can shoot down a satellite that has almost already entered the atmosphere on its own.

In other words, it demonstrates nothing that is useful. Therefore, I highly doubt it is the real reason behind the launch.

[GPMG]

Edited for accuracy......

"this is a convenient excuse for the US Dept of Defense to demonstrate that every crackpot in the world will boil up a conspiricy theory given any chance"

Anyway it wasn't the US military, it was the Iluminati.

[Tourist]

It does, conveniently, however demonstrate the ability of their Navy to destroy ICBMs during their reentry phase.

That couldn't possibly be the real reason for the big US air defense destroyers and the RN type 45 could it?
Surely not.......

[ORAC]

But how does it achieve that? Since this satellite is in such a low orbit and the missile being used can't reach the typical heights used by satellites, then all it does is prove that the US can shoot down a satellite that has almost already entered the atmosphere on its own.

In other words, it demonstrates nothing that is useful. Therefore, I highly doubt it is the real reason behind the launch.

Demonstrates the USN capability for fleet protection from Chinese ICBM conventional attack. It shows incoming missiles can be intercepted upon re-entry. I am sure the Chinese will have got the message....

China develops anti-ship missile (http://www.janes.com/defence/naval_forces/news/jdw/jdw060118_1_n.shtml)

The Chinese People's Liberation Army (PLA) is in the advanced stages of developing a revolutionary anti-ship ballistic missile to supplement its well known Ying-Ji family of anti-ship cruise missiles.

The development programme has been confirmed by both US government and Asian military sources, with the latter estimating that the PLA may be able to deploy the space targeting systems needed to make its anti-ship ballistic missile operational by 2009.

PLA efforts to provide terminal guidance capabilities to both its 600 km-range DF-15 (CSS-6) short-range ballistic missile and DF-21 (CSS-5) medium-range ballistic missile with a range of 2,150 km, or 2,500 km for the DF-21A (CSS-5 Mod 2), have been known since the mid-1990s. The existence of a terminally guided DF-21C has long been reported. Asian military sources said that the PLA will be using a version of the DF-21 for its ballistic anti-ship missions........

[Lazer-Hound]

AFAIK, T45 has zero ABM capability and it would take significant investment to give it some - we couldn't just buy into US ABM developments as the T45 weapons & radar fit is completely different.

T45 also lacks any siginificant land attack or ASW capability too, but that's a different story...

[Tourist]

Lazer.

You reckon.
Remember this conversation in 10yrs time.

"T45 also lacks any siginificant land attack or ASW capability too, but that's a different story... "

erm.....it's an air defence destroyer?

[Lazer-Hound]

Tourist, I will! If you think there's money in the MoD's budget to leverage Aster/Sampson to ABM capabilities, you must know something the rest of us don't! The first T45 won't have even anti-air operational capability for another 2 years.

Arliegh Burke, F100, Dutch LCF and German F124 are also Air Defence Destroyers but retain significant ASW capabilities. An AB also carries a fair number of TLAM's.

[mr fish]

seems the chinese are well on the way to an american style carrier battle group, if i were taiwanese i would book that flight to oz pretty soon. either that or be ready to s:mad:t me pants!!!!

[ALock]

Could have been a Bloodhound. Range is about right. I'll go and check if the one at Duxford is still on it's launcher! :ugh:

[N Joe]

Like Madbob, I remember sqn exchanges with F16s and the hydrazine emergency brief "run as far and fast as you can into the wind". And that was due to the dribble of hydrazine that was apparently left after the EPU had fired.

Given that, any chance that the 1000lb that was onboard the sat might survive seems like the perfect excuse for a bit of target practice.

N Joe

[OFBSLF]

Demonstrates the USN capability for fleet protection from Chinese ICBM conventional attack. It shows incoming missiles can be intercepted upon re-entry.Does it?

Isn't the Standard missile a hit-to-kill missile? I suspect that an incoming warhead is significantly smaller than a spy satellite. In addition, the US military had weeks to prepare for this shot and study the satellite's orbit.

I'm not sure I would be quite so confident about the USN capability.

[Bushfiva]

I suspect that an incoming warhead is significantly smaller than a spy satellite

Correct. But the satellite was also travelling twice as fast as an ICBM, and had a much lower heat signature. In that context, it would be harder for the seeker to detect it, and be harder for the course correction pulses to engage the target. With no references to hand, I seem to remember the missiles assigned to this mission were pulled from the production line, were reprogrammed, and the unused ones have been returned to the production line to have the changes reversed. As I mentioned before, I imagine SBX-1 was in the loop on this particular shootdown.