The first mission carried a set of piggyback scientific experiments from the Air Force Cambridge Research Labs (AFCRL), including neutron albedo measurements, electron number density and retarding potential analyser instruments, and an infrared radiometer, as well as a nuclear emulsion experiment to measure cosmic radiation. Emulsion experiments were also carried on CORONA satellites and were placed in the SRVs for later examination after recovery. The success of the experiment on Agena 2401 is evidence that it too carried an SRV which was recovered . However, other sources claim the E-6 was never recovered successfully, and a 30 April NRO memo  refers to the `recently lost SAMOS shot', with another NRO document reporting that the mission had `indicated success in camera functioning and total failure in recovery'. Launch was on 1962 Apr 26 by Atlas Agena B from Point Arguello. Neither the RAE nor the SATCAT nor the UN provide orbital data for the mission, but the Vandenberg launch report indicates that the orbit achieved was 209 x 219 km x 90.4 deg, compared to an intended orbit of 200 x 217 km x 90.4 deg (but LMSC-448564 suggests an intended inclination of 92.0 deg). This was the first launch on which the Agena SPS (Secondary Propulsion System) was used, with two auxiliary engines for added thrust. The SATCAT lists the spacecraft as FTV 2401; the Vandenberg launch report  identifies the Agena stage as 2401 and the payload section as PVP 851. It was deorbited on Apr 28, two days after launch according to the SATCAT; the VAFB data reports that it was stable until orbit 18 on Apr 27. The 90 degree inclination is a little puzzling in that all subsequent launches of the series were to a 96 degree plane.
The inclination given is actually that of the Atlas ballistic stage, i.e. that of Agena prior to ignition. On later missions the Atlas flew at 94.3 deg and the orbit was at 96 deg; if we assume a similar inclination change the achieved orbit would have been 92 deg in this case.
An Agena history document records that the retrorocket engine had a thrust misalignment. It's not clear what this means (the main engine used for retrofire, or a retro used to separate from the RV?).
|Program 201 PVP 851, FTV 2401|
|1962 Apr 26||1856:08||Launch by Atlas Agena B||NMFPA|
|1900:52||Atlas sep (T+4:44)||-5000? x 219 x 90.37 (VCR)|
|1901:40||SPS burn (T+5:32)|
|1901:50||Agena burn (T+5:42)|
|1901:50||SPS cutoff (T+5:42)|
|1905:27||Agena MECO (T+9:19)||209 x 219 x 92? (VCR)|
|1962 Apr 27||2100??||End of orbital ops, rev 18?|
|1962 Apr 28||Agena B retrofire|
|SRV landed in US?|