SAMOS 5 (FTV 2203) reached orbit on 1961 Dec 22 after launch by Atlas Agena B from Point Arguello Naval Missile Facility. The Atlas SECO (main engine cutoff) came late, giving an extra 0.1 km/s velocity to the Agena. The orbit achieved was about 230 x 650 km (given in  as approx 125 x 350 nautical miles); without the excess velocity it would have been about 230 km circular. LMSC-448564 suggests that the orbit should have been 90.9 min, 230 x 410 km x 90.0.
The payload was a Program 101B SAMOS film return satellite with a 1.7-meter focal length panoramic camera. Three objects were cataloged in orbit, identified by NORAD as the payload, the Agena, and a `reflector', probably the mirror shown in the Lockheed document (see SAMOS 4).
Comparing with the E-5 mission profile, I identify these as the reentry vehicle, the Agena, and the mirror. The Agena and payload reentered within a few weeks, with their orbits on Dec 25 showing 187 km perigees. I concluded that the recovery attempt was initiated prior to Dec 25 (the date of the first element sets for the low orbit objects) but failed to completely deorbit the vehicle, perhaps because of the high apogee, leaving the Agena and capsule in a 187 x 300 km orbit. (Note: late 1980s editions of the SATCAT give the payload as Alpha Lambda 3, while mid 1990s editions claim it is Alpha Lambda 1; I suspect the reassignment is an error).
Based on a 1960 briefing document, the mass breakdown was: 2580 kg on orbit, including 630 kg Agena dry, 320 kg Agena prop, 730 kg E-5 spacecraft, 900 kg E-5 reflector and RV. (These figures are converted from imperial units and are only accurate to 1 significant figure).
A recently declassified document notes that the command programmer erroneously went to recovery mode on orbit 6, supporting my hypothesis.
|SAMOS 5 objects|
|0218||AlphaLambda 2||Agena B|
|1961 Dec 22||1912:33||Launch by Atlas Agena B||NMFPA|
|1916:58||SECO (T+4:25), LOX depletion|
|1917:15||Atlas sep (T+4:42)|
|1918:08||Agena burn (T+5:35)|
|1921:48||Agena MECO (T+9:15)||95.0 min 230 x 650 x ? (VCR)|
|1961 Dec 23||0500?||Command programmer to recovery mode|
|1961 Dec 23||Reflector jettisoned|
|Agena B burn (deorbit attempt)|
|Agena B MECO (premature)|
|Payload RV separated|
|1961 Dec 24||0536||Reflector orbit||95.24 235 x 825 x 89.7|
|1961 Dec 25||2154||Agena orbit||89.32 187 x 294 x 89.6|
|1961 Dec 25||2157||Payload orbit||89.49 187 x 310 x 89.61|
|1961?||Reflector orbit||94.1 237 x 706 x 89.5 (SATCAT)|
|1961 Dec 30||0542||Agena orbit||88.30 180 x 200 x 89.7|
|1961 Dec 31||Agena reentered (AlphaLambda2)|
|1962 Jan 4||0449||Payload orbit||87.96 139 x 208 x 89.7|
|1962 Jan 9||Payload reentered (AlphaLambda3)||89.4 187 x 310 x 89.6 (SATCAT)|
|1962 Mar 13||Reflector orbit||94.1 244 x 702 x 89.6 (RAE)|
|1962 Jun 5||Reflector orbit||92.1 228 x 524 x 89.6 (RAE)|
|1962 Aug 3||1430||Reflector orbit||89.6 201 x 299 x 89.6 (RAE)|
|1962 Aug 12||1936||Reflector orbit||88.12 181 x 181 x 89.7|
|1962 Aug 14||SAMOS 5 reflector reentered (AlphaLambda1)|