page_title: Pioneer Venus Multiprobe
section_title: Large probe
hierarchical_section_title: Pioneer Venus Multiprobe / Probes / Large probe
context_page_description: The Pioneer Venus Multiprobe, also known as Pioneer Venus 2 or Pioneer 13, was a spacecraft launched in 1978 to explore Venus as part of NASA's Pioneer program. This part of the mission included a spacecraft bus which was launched from Earth carrying one large and three smaller probes, which after separating penetrated the Venusian atmosphere at a different location, returning data as they descended into the planet's thick atmosphere. The entry occurred on December 9, 1978.
context_section_description: The large probe carried seven experiments, contained within a sealed spherical pressure vessel. The science experiments were:
  LNMS - neutral mass spectrometer to measure the atmospheric composition
  LGC - gas chromatograph to measure the atmospheric composition
  LSFR - solar flux radiometer to measure solar flux penetration in the atmosphere
  LIR - infrared radiometer to measure distribution of infrared radiation
  LCPS - cloud particle size spectrometer to measure particle size and shape
  LN - nephelometer to search for cloud particles
  temperature, pressure, and acceleration sensors
  This pressure vessel was encased in a nose cone and aft protective cover. After deceleration from initial atmospheric entry at about 11.5 kilometers per second (7.1 mi/s) near the equator on the night side of Venus, a parachute was deployed at 67 km altitude. The large probe was about 150 centimeters (59 in) in diameter and the pressure vessel itself was 73.2 centimeters (28.8 in) in diameter.
caption: Pioneer Venus Large Probe opens its parachute (artist's rendition)
exif: {"Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS5 Windows", "Image DateTime": "2015:12:05 11:07:41", "Image ExifOffset": "164", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "302", "Thumbnail JPEGInterchangeFormatLength": "4776", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "800", "EXIF ExifImageLength": "1051"}