Pioneer Venus Multiprobe: Difference between revisions

{{short description|AmericanNASA roboticatmospheric spacecraft sendmission to Venus in (1978; last spacecraft in Pioneer program)}}

| image_caption = Artist's impression of the five components of ''Pioneer Venus13'' Multiprobeapproaching Venus

| operator = [[NASA]]{{\}}[[Ames Research Center|ARCAmes]]

| website = [httphttps://nssdc.gsfcscience.nasa.gov/planetarymission/pioneer_venuspioneer-venus-2/ science.html National Space Science Data Center (NASA)nasa.gov]

| mission_duration = 4 months,{{time 1 day,interval|8 13Aug hours,1978|9 22Dec minutes1978}}

| launch_rocket = [[Atlas-Centaur|Atlas SLV-3D Centaur-D1AR]] (AC-51)

| last_contact = December 9, 1978, 20:22:55&nbsp;UTC <br><small>(main bus)</small><br />{{end-date|December 9, 1978, 20:55:34|timezone=yes}}&nbsp;UTC <br><small>(dayDay probe)</small>

| programme = '''[[Pioneer program|Pioneer]]'' ([[Pioneer Venus project|Pioneer Venus]])'

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 [[Satellite bus|spacecraft bus]] which was launched from Earth. The bus carryingcarried one large and three smaller probes, which, after separating, each penetrated the Venusian atmosphere at a different location, returning data as they descended into the planet's thick atmosphere. The entryentries occurred on December 9, 1978.

The spacecraft carried one large and three small atmospheric probes, designed by Senior Scientist and Program Manager Irwin Baker of Hughes Aircraft Company, to collect data as they descended into the [[atmosphere of Venus]]. The probes did not carry photographic instruments, and were not designed to survive landing – the smaller probes were not equipped with parachutes, and the larger probe's parachute was expected to detach as it neared the ground. All four probes continued transmitting data until impact; however, one survived and continued to transmit data from the surface.

Below thean altitude of {{convert|50|km}} the temperatures measured by the four probes arewere identical to within a few degrees. They are, between {{convert|448|and|459|C}} on the surface.; Thethe ground pressure is, between {{convert|86.2|and|94.5|bar}}. Nephelometers identified three [[cloud]] layers with different characteristics. The most remarkable discovery was that the ratio of [[Argon|³⁶argon]] / [[Argon|⁴⁰argon]] [[isotope]]s was much higher than in the Earth's atmosphere, which seems to indicate that the genesis of the [[Atmosphere of Venus|Venusian atmosphere]] is very different from that of [[Atmosphere of Earth|Earth's]]. The reconstituted trajectory of the atmospheric probes determined that the wind averaged a speed of {{convert|200|m/s}} in the middle cloud layer at, {{convert|50|m/s}} at the base of these clouds and just {{convert|1|m/s}} aton the ground. Overall data from airborne sensors confirmed, whileand specifyingrefined the data obtained by the [[Soviet Union|Soviet]] space probe [[Venera]] program that preceded thisthe American mission to Venus.<ref>Paolo Ulivi et David M. Harland, ''Robotic Exploration of the Solar System Part 1'', The Golden Age 1957–1982, Springer Praxis, 2007 ({{ISBN|978-0-387-49326-8}})</ref>

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=== External linksBibliography ===