1971-015A
Kosmos-397 carried out a slow pass interception of Kosmos-394 on its second revolution, and then exploded.
The target was in a 570 x 610 km orbit. If we look at the post-explosion elements for the payload, it passes through that altitude from 1422 to 1433 UTC on Feb 25, with closest approach at 1431 UTC; my inaccurate software gives a closest approach of 12 km at an altitude of around 590 km over 26E 57N.
At this time the stage 2 orbit was near perigee; we must assume an IS interception burn near apogee, possibly at first apogee at around 1210 UTC over the Antarctic.
NL Johnson suggests a 585 x 1000 km interception orbit, but this doesn't match the times - a lower apogee is needed to connect with the R/B orbit. The R/B is at apogee in the range 1150 to 1215 UTC; if the intercept is at 1431 then we need an orbit with a period of 140 - 166 min and thus an apogee above 5000 km exceeding the IS capability. I think it's more likely that the IS circularized its orbit near the target, which allows an intercept at the correct time.
| Kosmos-397 | |||
| Date | Time | Event | Orbit |
|---|---|---|---|
| 1971 Feb 25 | 1111 | Launch by 11K69 | KB |
| 1113 | Stage 2 burn | ||
| 1116? | Stage 2 sep | 92.3 144 x 629 x 65.1 | |
| 1210? | DU burn | 590? x 610? x 65.1 | |
| 575 x 1000? x 62.8 (NLJ) | |||
| 1431? | Intercept Kosmos-394 | ||
| 1432? | Exploded | ||
| 1971 Feb 26 | 1837 | 113.50 574 x 2199 x 65.8 | |
| 1971 Mar 6 | 1430 | 113.51 574 x 2202 x 65.73 (RAE) | |
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