StarDestroyer.Net BBS

From this thread. Thanas asked me to post my private message to Flagg here.

Flagg wrote:Sorry, I wasn't clear enough: Back in the early '00s, the contractors selected to build and test the ABM systems would basically put on a show for visiting Generals and other DoD staff by essentially "telling" the sensors what the exact trajectory of the incoming missile to be shot down was to vastly increase the likelihood of a "successful test". Basically putting on a show that was "Rigged for their pleasure".

I don't want to hijack the thread to babble about ABM too much (plus I have something of a history of pro-ABM partisanship..) but I thought you might like to know more about those tests.

Not all of the components were ready (in particular, the high-resolution radars to give early tracking information) but they wanted to test the guidance system on the "kill vehicle" itself. They strapped a GPS transponder onto the simulated missile's booster to give basic information on "where to point the interceptor", which stopped working as soon as the simulated missile staged and released its payload. The ABM's kill vehicle itself then had to independently target and engage at that point without external aides. I don't know if I'd call it "rigged" as "incomplete testing". Later testing was "all-up" without the need of such beacons.

GPS was on an actual target RV, it also had one decoy RV they hoped to observe in the optics as the missile guidance discrimination software was active, it just wouldn't be allowed to control the KV. 2000 era GPS data is not remotely good enough to score a kill on at those kind of closing velocities. It did serve for initial camera pointing.

This was actually the first attempt at an actual intercept by GBI. The only prior flight was a no target test of the basic flight systems. Due to the high cost of the target missiles, which must by nature be ICBM class projectiles themselves, they wanted to make sure the test went as well as possible to get as much value for the money on this, the first true test of the interceptor. That meant they needed it to see the target so all the optics and ironically the anti decoy software could be checked out. The KV missed in that test anyway, because the IIR seeker didn't cool, so it couldn't actually see the target.

Sea Skimmer wrote:GPS was on an actual target RV, it also had one decoy RV they hoped to observe in the optics as the missile guidance discrimination software was active, it just wouldn't be allowed to control the KV. 2000 era GPS data is not remotely good enough to score a kill on at those kind of closing velocities. It did serve for initial camera pointing.

Huh. Thanks for that clarification - I thought it was on the booster only.

Booster wouldn't make any sense, the missile already relies on ground based mid course guidance via Pave Paws and upgraded BMEWS radar tracking to get onto anything like the proper trajectory, even after the missile is done boosting. In the tests this is provided by an array of radars on Pacific Islands, including the prototype for Sea Based X-band radar, I forget what it is called. All operational ABM missiles, even short range PAC-3 missiles, rely on mid course guidance for this purpose.

In the case of GBI though the kill vehicle has to optically acquire the threat or threat cloud at a range of 1000-1500km in ordered to start discrimination in time to make an engagement. The shot isn't head on either, its from some angle to the the side, and to a point the KV is flying sideways into the target.

GPS on the RV was a way to ensure the still highly experiment KV would acquire the thread cloud at that sort of required range and thus gain the maximum possible time to gather optical data and observe the actual function of the system. The ground based cuing wasn't considered reliable enough to ensure this, on top of additional possible failure modes on the KV search function, it can wobble wobbles its cameras around to scan a wider arc.

But as said, KV didn't work anyway.