NSSDCA/COSPAR ID: 1972-061A
The primary objective of the Meteoroid Technology Satellite (MTS, Explorer 46) were to measure the meteoroid penetration rates in a bumper-protected target in the near Earth environment in order to evaluate the effectiveness of the bumpers. Secondary objectives were to obtain data on meteoroid impact velocity and to measure impact flux of small mass meteoroids. Scientific capability of the mission was deprecated when the bumper panels failed to deploy properly, limiting the useful data obtained.
The main bus of the Meteoroid Technology Satellite was a hexi-cylindrical platform with the fourth stage booster still attached. With the burned-out fourth stage attached the total mass was 206.4 kg (455 lbs). The central hub of the satellite itself (without the 4th stage) was basically an octagonal prism, 320 cm (10.5 ft) high and about 60 cm across, total mass was 167.8 kg (370 lbs). Two pairs of meteoroid bumper targets, consisting of three panels, two oriented vertically (parallel to the axis on the spaceship) and one horizontally, were to have been extended in a windmill-like configuration. Each bumper panel was 320 cm long and 48.92 cm wide, giving the spacecraft an overall width of 701.5 cm. Power is provided by solar cells on the front of the spacecraft and on four aft-facing flip-out panels. There is a yo-yo despin mechanism. Attitude control is provided by a system of nitrogen jets.
The spacecraft had two telemetry systems. Telemetry A transmitted data from all spacecraft measurements and provided a carrier signal for spacecraft tracking on ground command in 3 minute bursts. Power is through secondary batteries charged by the solar cells. Telemetry B is powered directly by solar cells and operates continuously when in sunlight. Telemetry B only transmits data from the bumper experiment. Communications are through a 136.650 MHz transmitter and a turnstile antenna array located in the attached fourth stage booster. The bumper data rate is 43.75 bps, and the general data rate is 103.125 bps.
The bumper targets on the four extendable paddles consisted of a 0.0025 cm (0.001 inch) thick stainless steel target mounted 1.25 cm (0.5 in) in front of a 0.005 cm (0.002 in) thick stainless steel wall consisting of pressurized cell detectors. The target was divided into 12 panels, each holding 8 detector cells. There were 12 box-shaped (20.3 x 20.3 x 15.2 cm; 8 x 8 x 6 in) meteoroid velocity detectors mounted around the central hub. The detectors had measurement stations a known distance apart to determine the speed of particles penetrating both stations. Thin film capacitor detectors mounted on the central hub were used to provide data on particle populations.
The Meteoroid Technology Satellite was launched on 13 August 1972 on a solid propellant Scout booster with an Algol III first stage, a Castor II second stage, an Antares II third stage, and an Altair fourth stage. Launch was from Wallops Island, Virginia, into a 496 x 814 km (308 x 506 mile) altitude orbit with an inclination of 37.7 degrees and a period of 97.8 minutes. A heat shield that protected the experiments from aerodynamic heating was jettisoned at 131 km. A yo-yo despin mechanism was used to slow the rotation to zero, after which deployment of the experiments and solar panels started. After deployment, nitrogen jets spun the spacecraft to 3 rpm.
When one pair of bumper wings failed to fully deploy, the resulting spacecraft spin axis was 90 degrees from planned. This caused overheating of many components, including the batteries, and affected the telemetry system. The other experiments were suspended on 22 August, nine days after launch, to get maximum data from the two fully deployed wings and two partially deployed wings of the bumper experiment. About 20 impacts were recorded through December, 1972, and after one year of operations 31 of the 96 cells were punctured. At the final interrogation of the experiment on 29 January 1975, 53 possible impacts had been registered. The capacitor detectors recorded about 2000 micrometeoroids in the first two weeks before being turned off. The secondary experiments were turned on for one week in August 1974. By this time, the spacecraft data acquisition rate was reported as sub-standard. The orbit decayed and the spacecraft reentered the atmosphere on 2 November 1979.
Launch Date: 1972-08-13
Launch Vehicle: Scout
Launch Site: Wallops Island, United States
Mass: 206.4 kg
Questions and comments about this spacecraft can be directed to: Dr. David R. Williams
Name | Role | Original Affiliation | |
---|---|---|---|
Mr. R. L. Mitchell | General Contact | NASA Goddard Space Flight Center | |
Dr. William H. Kinard | Project Scientist | NASA Langley Research Center | w.h.kinard@larc.nasa.gov |
Mr. Charles V. Woerner | Project Manager | NASA Langley Research Center |