I really should change my personal text
- May 13, 2008
- Reaction score
I am aware of the IR factor. The speed of the vehicle was deemed such that it didn't much matter--no Soviet missile or missile intercept attempt would get close enough. Even with some lead detection time. This was projected through at least 1980.Even ISINGLASS seems to have fallen down in part on IR vulnerability analysis.A manned hypersonic vehicle that either flies in low Earth orbit, or just about flies at that altitude (highest endo-atmospheric), has been a very attractive subject for US policy makers for a very long time, over time. Just because the declassified literature "dies out" by 1971 or 1972 doesn't mean the concept wasn't pursued beyond that date. It just means that government declassification officials have deemed that follow-ons to ISINGLASS aren't to be acknowledged, or to be known by the public at this time.
It's a recurring theme; you can find papers from the 80's on IR tracking of transatmospheric vehicles.
Detecting and tracking the much more modest SR-72 via a small sat constellation equipped with
some basic MWIR sensors looks quite achievable.
You are talking about 2000 K scramjet exhaust and IR spectra that's not going to be much attenuated
against spaceborne sensors at the typical scramjet altitudes.
This constellation probably isn't going to be transmitting fire control quality tracks but
accurate enough warning such that vulnerable sites can get their counter-ISR techniques in place.
See the set of overhead transparencies with this particular document dated to 1968. All the calculations were done. Soviet interception not viable. Not even with nuclear warhead detonations (although if it was a hydrogen bomb, there was some expectation that there was a potential likelihood for high irradiation of the pilot(s)). "If you don't announce yourself, they can't expect to know when you'll arrive."