Pioneer 5

Spacecraft n°: 59

US spacecraft n°: 48

Launch data: Designation 00027 / 1960 Alp 1 / 60001A Launch date 11 Mars 1960 - 13:00:07 UT Launch site CC, LC-17A Launch vehicle Thor-DM18 Able-4 (#219/DM-1812-6A) Mission Solar orbiter Heliocentric orbit (Sun orbit): Perihelion x Aphelion 0.806 x 0.992 A.U. Excentricity 0.104 Incl. to ecliptic 3.35° Period (around the Sun) 312 days

• Returned solar wind data to 26 Jun 1960.
  Pioneer 5 was designed to provide the first map of the interplanetary magnetic field. The vehicle functioned for a record 106 days and communicated with Earth from a record distance of 36.2 million km (22.5 million miles). The early Pioneers were exploratory missions that led to intriguing new questions that required more advanced types of spacecraft capable of exploring space to considerable distances within and beyond Earth's orbit.

Specifications:

Description:

• Launched on a direct solar orbit trajectory, Pioneer 5 successfully reached heliocentric orbit between Earth and Venus to demonstrate deep space technologies and to provide the first map of the interplanetary magnetic field. The spacecraft had originally been intended for a Venus flyby, but the mission was switched to a solar flyby.
• Pioneer 5 carried Telebit, the first digital telemetry system operationally used on a U.S. spacecraft; it was first tested on Explorer 6. The system used a 5-watt or a 150-watt transmitter, with a 5-watt transmitter acting as driver. Information rates varied from 64 to 8 to 1 bit per second.
• Scientific Instruments:
  1) magnetometer
  2) ionization chamber
  3) Geiger-Mueller tube
  4) micrometeoroid momentum spectrometer
  5) photoelectric cell aspect indicator
  6) proportional counter telescope

Mission details:

• Pioneer 5 was a spin-stabilized space probe used to investigate interplanetary space between the orbits of earth and Venus. The spacecraft measured magnetic field phenomena, solar flare particles, and ionization in the interplanetary region. The digital data were transmitted at 1, 8, and 64 bps, depending on the distance of the spacecraft from the earth and the size of the receiving antenna. Weight limitations on the solar cells prevented continuous operation of the telemetry transmitters. About four operations of 25-min duration were scheduled per day with occasional increases during times of special interest. A total of 138.9 h of operation was completed, and over 3 million binary bits of data were received. The major portion of the data was received at the Manchester and Hawaii tracking stations because their antennas provided grid reception. Pioneer 5 performed normally until April 30, 1960, after which telemetry transmission became too infrequent for any significant addition to the data. The spacecraft established a communications link with the earth from a record distance of 36.2 million km from Earth (later surpassed by Mariner 2) on June 26, 1960, which was the last day of transmission. Pioneer 5 was originally intended as an Venus fly-by probe, but due to delays in the program, it was launched into a heliocentric orbit.
• The probe, using its 18.1-kilogram suite of scientific instruments, confirmed the existence of previously conjectured interplanetary magnetic fields.