First launcing of USAF Aerobee-Hi sounding rocket. Rocket test, 98 kg payload. Launched at 0858 local time. Reached 198 km.

It also allowed follow-on manned systems to be pursued.

Maximum Speed - 4946 kph. Maximum Altitude - 32000 m.

Carried SNAP-9A nuclear power source. After this launch failure it was decided that operational Transits would be solar-powered only.

Radiation monitoring.

Four earlier CSAT attempts (April 15-20) were marred by numerous minor anomalies. The vehicle acceptance team inspection began April 26 and concluded April 30, with GLV-5 found acceptable. The vehicle was removed from the test cell May 7-8, formally accepted by the Air Force May 15, and shipped to Cape Kennedy. Stage I arrived at the Cape on May 17 and stage II on May 19.

This was a reserve day in the L1 countdown, in case of problems in preparation. However all is on schedule for the launch. The same cannot be said for the N1. There are many delays. Mishin promised the first N1 rollout in the first half of March, but it is still in the assembly building, with no end in sight of preparations. The weather at the cosmodrome is -5 deg at night, clear pleasant days. The Hotel Kosmonavt was finished on 15 April. Although it has all of its furniture, it was not completely painted before the furniture was moved in!

Operation of a system of long range telephone-telegraph radiocommunication, and transmission of USSR Central Television programmes to the stations of the Orbita network.

The Director of Apollo Test in the NASA Hq. Apollo Program Office, LeRoy E. Day, was detailed to head the MSF Space Shuttle Task Group. The group would provide NASA with material for a report on the Space Shuttle to the President's Space Task Group.

Pratt and Whitney filed a protest against NASA's award to Rocketdyne of the SSME contract. This action prevented further work on Rocketdyne's contract until the issue was adjudicated.

Rocketdyne finally receives the contact for development of the shuttle main engine. By the end of the century the total value will have exceeded $5.6 billion.

Development of systems for air defence and the control of outer space.

Explored lunar surface near LM and deployed ALSEP unmanned scientific station equipment.

First static firing, MPTA-098, NSTL (2.5 seconds; stub nozzles)

For the first time three SSME engines are run on the MPTA test article mated to an external tank - for 2.5 seconds.

Ocean surveillance; nuclear powered.

Released 25 Romb radar calibration subsatellites.

Photo surveillance; returned film capsule.

Unmanned supply vessel to Mir. Deorbited May 11, 1987. Docked with Mir at 343 X 363 1705 23 April at rear port of Kvant. Undocked May 11 03:10. Deorbited28 May 02:59 .
Officially: Transporting sundry cargoes to the Mir orbital station. Docked with Salyut 7 on 23 Apr 1987 17:04:51 GMT. Undocked on 11 May 1987 03:10:01 GMT. Destroyed in reentry on 11 May 1987 08:28:00 GMT. Total free-flight time 2.30 days. Total docked time 17.42 days.

Operation of the long-range telephone and telegraph radio communications system, transmission of television programmes to stations in the Orbita network and international cooperation. Replaced Molniya 3-41.

European Remote Sensing; carried SAR; ocean, land, ice, and atmospheric observations.

Minisat-01 carried the EURD extreme ultraviolet spectrograph to study interstellar gas, the LEGRI gamma ray burst detector, and the CPLM microacceleration in liquids experiment.

Preparations for the first test launch of China's first manned spacecraft were underway at the launch site, a Shanghai newspaper reported. It said the first flight would be launched in late 1999. The space cabin, telemetry system and power system had been developed in Shanghai.

Two special wind tunnels in southwest China's Sichuan Province were nearing completion. The new tunnels would be used for testing China's future space shuttle, launch vehicles, and strategic missiles. A high-frequency plasma wind tunnel and a supersonic flow wind tunnel were being built by China Aerodynamics Research and Development Center and would be the most advanced in Asia.

First launch of Russia's Dnepr launch vehicle, a converted R-36M2 ICBM. The Dnepr was launched from a silo. The third stage maneuvring bus (used on the ICBM for dispensing multiple warheads) placed UoSAT-12 into a 638 km x 652 km x 64.6 deg orbit. The third stage separated from the payload at 05:13 GMT and then made a burn into a 599 km x 1403 km x 64.6 deg orbit. UoSAT-12 was the first test of the Minibus platform, at 325 kg a larger spacecraft than earlier 50 kg Surrey UoSATs. It carried a mobile radio experiment (MERLION), a GPS receiver, and imaging cameras.