| Kosmos 27 | |
| Mission Type: | Venus impact probe |
| Operator: | OKB-1 |
| Cospar Id: | 1964-014A |
| Satcat: | 00770 |
| Spacecraft Type: | 3MV-1 |
| Manufacturer: | OKB-1 |
| Dry Mass: | 948 kg (including an impact probe of 285 kg) |
| Launch Mass: | 6520 kg[1] |
| Launch Date: | 27 March 1964, 03:24:43 GMT |
| Launch Rocket: | Molniya 8K78 s/n T15000-27 |
| Launch Site: | Baikonur, Site 1/5 |
| Launch Contractor: | OKB-1 |
| Decay Date: | 28 March 1964 |
| Orbit Epoch: | 27 March 1964 |
| Orbit Reference: | Geocentric[2] |
| Orbit Regime: | Low Earth |
| Orbit Periapsis: | 167 km |
| Orbit Apoapsis: | 198 km |
| Orbit Inclination: | 64.8° |
| Orbit Period: | 88.7 minutes |
| Apsis: | gee |
| Programme: | Venera |
| Previous Mission: | Venera 3MV-1 No.2 |
| Next Mission: | Venera 2 |
Kosmos 27 (Russian: Космос 27 meaning Cosmos 27), also known as Zond 3MV-1 No.3 was a space mission intended as a Venus impact probe. The spacecraft was launched by a Molniya 8K78 carrier rocket from Baikonur. The Blok L stage and probe reached Earth orbit successfully, but the attitude control system failed to operate.[3]
Kosmos 27 was launched at 03:24:43 GMT on 27 March 1964, atop a Molniya 8K78 s/n T15000-27 carrier rocket flying from Site 1/5 at the Baikonur Cosmodrome.
Kosmos 27 was a "third-generation" deep space planetary probes of the 3MV series of the Soviet Union. The Soviet engineers planned four types of the 3MV, the 3MV-1 (for Venus impact), 3MV-2 (for Venus flyby), 3MV-3 (for Mars impact), and 3MV-4 (for Mars flyby). The primary difference over the second-generation was vastly improved (and in many cases doubled) orientation system elements as well as improved onboard propulsion systems. While these four versions were meant to study Mars and Venus.[4]
The probe was the first dedicated 3MV spacecraft that the Soviets launched (earlier missions had been of the test "Object-Probe" versions as Kosmos 21). It was designed to accomplish atmospheric entry into Venus followed by descent and impact. On 27 March 1964, it had a perigee of 167km (104miles) and an apogee of 198km (123miles), with an inclination of 64.8° and an orbital period of 88.7 minutes. The spacecraft successfully reached Earth orbit but failed to leave for Venus when the Blok L upper stage malfunctioned. The upper stage lost stable attitude due to a failure in the circuit of the power supply circuit that powered the valves for the attitude control system; hence, the stage remained uncontrollable and not ready to initiate a burn to leave Earth orbit. The problem was traced to a design error, the examination of telemetry data found that the failure was due to a design flaw in the circuitry of the BOZ unit, which resulted in power not being transferred to the attitude control jets on the Blok L stage, rather than one related to quality control. The spacecraft burned up in Earth's atmosphere the following day, on 28 March 1964. If successful, this mission would have been given a "Venera" designation.[4]