John H. Hoffman
Encyclopedia
John Hoffman is a space scientist who developed instruments for Apollo 15
, Apollo 16
, Apollo 17
, the Pioneer Venus project
, and Giotto mission
. He also designed the mass spectrometer for the Phoenix Mars Lander mission in May 2008. He is currently a professor of physics at the University of Texas at Dallas
.
in Winona
, Minnesota
and continued his education at the University of Minnesota
under the mentorship of Professor A. O. C. Nier who pioneered the field of mass spectrometry
. His PhD dissertation was on the helium isotopic distribution in large iron meteorites.
Dr. Hoffman joined the Graduate Research Center of the Southwest in 1966. His main interest was in the study of atmospheric/ionospheric composition and isotopic ratios for which he has developed instrument packages that have flown on many rockets and satellites.
His instrument flew on the Pioneer Venus mission to Venus in 1978. Data was received throughout the descent of the probe to the surface. Carbon dioxide is the dominant gas in the atmosphere. A surprise discovery showed that for the two "sister" planets there is a two order of magnitude difference in the isotopic ratios (the ratio of the heavier to lighter forms of these gases) for hydrogen and argon than for those gases on earth. These isotopic ratio differences have had large implications on models of the nature of the solar nebula and the formation of the present (secondary) atmospheres of the terrestrial planets.
Hoffman was a member of the team who flew a mass spectrometer on the European Space Agency's Giotto mission to Halley's Comet in 1986. This instrument was developed by laboratories in four countries, three European and at UT Dallas. It measured both the neutral and ionized constituents of the comet's coma. The coma contains, besides water vapor and H30 ions, an extended source of carbon monoxide. The atmosphere forms around a comet as it comes near the sun and is heated by radiation from the sun.
Hoffman has also flown mass spectrometers on earth orbiting satellites, Explorer 31, ISIS-II, AE-C, D, and E, and Wake Shield, plus numerous sounding rockets and stratospheric balloon flights. The first observations of the polar wind, ions flowing out from the atmosphere, were made by his ion mass spectrometer flown on the ISIS spacecraft in 1971.
Dr. Hoffman is a co-investigator for the TEGA experiment that will fly on the Mars Scout Phoenix mission in 2007. The spacecraft will land in the far northern region of Mars, above the Arctic Circle in the area that the Mars Odyssey spacecraft has found evidence for water. An arm on the lander will dig a trench a meter deep in the surface of Mars to look for water ice and other water related substances (minerals). These will be scooped up and analyzed in a series of small furnaces. The effluents from the furnaces will be analyzed by the UT Dallas mass spectrometer to determine the presence of water and the mineralogical composition of soil samples. Isotopic ratios of the principal elements in the samples will be determined and compared to the isotopic ratios of the atmospheric gases that will be measured by the mass spectrometer when it is not analyzing samples from the TEGA furnaces.
Apollo 15
Apollo 15 was the ninth manned mission in the American Apollo space program, the fourth to land on the Moon and the eighth successful manned mission. It was the first of what were termed "J missions", long duration stays on the Moon with a greater focus on science than had been possible on previous...
, Apollo 16
Apollo 16
Young and Duke served as the backup crew for Apollo 13; Mattingly was slated to be the Apollo 13 command module pilot until being pulled from the mission due to his exposure to rubella through Duke.-Backup crew:...
, Apollo 17
Apollo 17
Apollo 17 was the eleventh and final manned mission in the American Apollo space program. Launched at 12:33 a.m. EST on December 7, 1972, with a three-member crew consisting of Commander Eugene Cernan, Command Module Pilot Ronald Evans, and Lunar Module Pilot Harrison Schmitt, Apollo 17 remains the...
, the Pioneer Venus project
Pioneer Venus project
The Pioneer mission to Venus consisted of two components, launched separately. Pioneer Venus 1 or Pioneer Venus Orbiter was launched in 1978 and studied the planet for more than a decade after orbital insertion in 1978. Pioneer Venus 2 or Pioneer Venus Multiprobe sent four small probes into the...
, and Giotto mission
Giotto mission
Giotto was a European robotic spacecraft mission from the European Space Agency, intended to fly by and study Halley's Comet. On 13 March 1986, the mission succeeded in approaching Halley's nucleus at a distance of 596 kilometers....
. He also designed the mass spectrometer for the Phoenix Mars Lander mission in May 2008. He is currently a professor of physics at the University of Texas at Dallas
University of Texas at Dallas
The University of Texas at Dallas, also referred to as UT Dallas or UTD, is a public research university in the University of Texas System. The main campus is in the heart of the Richardson, Texas, Telecom Corridor, north of downtown Dallas...
.
Education
John Hoffman received his bachelor's degree from St. Mary's CollegeSaint Mary's University of Minnesota
Saint Mary's University of Minnesota is a private, comprehensive, coeducational university with an undergraduate campus in the city of Winona, Minnesota, United States...
in Winona
Winona
- Places :United States* Winona, Arizona* Winona, California, former name of Squeaky Springs, California* Winona Lake, Indiana* Winona, Kansas* Winona, Michigan* Winona County, Minnesota** Winona, Minnesota, the county seat of Winona County...
, Minnesota
Minnesota
Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...
and continued his education at the University of Minnesota
University of Minnesota
The University of Minnesota, Twin Cities is a public research university located in Minneapolis and St. Paul, Minnesota, United States. It is the oldest and largest part of the University of Minnesota system and has the fourth-largest main campus student body in the United States, with 52,557...
under the mentorship of Professor A. O. C. Nier who pioneered the field of mass spectrometry
Mass spectrometry
Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of charged particles.It is used for determining masses of particles, for determining the elemental composition of a sample or molecule, and for elucidating the chemical structures of molecules, such as peptides and...
. His PhD dissertation was on the helium isotopic distribution in large iron meteorites.
U. S. Naval Research Laboratory
He spent 7 years at the U. S. Naval Research Laboratory, Washington, D. C., developing miniaturized mass spectrometers for space flight. These were flown on Aerobee and Javelin rockets.Dr. Hoffman joined the Graduate Research Center of the Southwest in 1966. His main interest was in the study of atmospheric/ionospheric composition and isotopic ratios for which he has developed instrument packages that have flown on many rockets and satellites.
Apollo missions
He developed instruments for the Apollos 15, 16, and 17 lunar missions, the latter being part of the ALSEP surface package. The goal was to detect and determine the composition of the lunar atmosphere. There is an atmosphere on the moon composed mainly of noble gases and hydrogen, but the pressure is lower than that in the best vacuum systems on earth.His instrument flew on the Pioneer Venus mission to Venus in 1978. Data was received throughout the descent of the probe to the surface. Carbon dioxide is the dominant gas in the atmosphere. A surprise discovery showed that for the two "sister" planets there is a two order of magnitude difference in the isotopic ratios (the ratio of the heavier to lighter forms of these gases) for hydrogen and argon than for those gases on earth. These isotopic ratio differences have had large implications on models of the nature of the solar nebula and the formation of the present (secondary) atmospheres of the terrestrial planets.
Hoffman was a member of the team who flew a mass spectrometer on the European Space Agency's Giotto mission to Halley's Comet in 1986. This instrument was developed by laboratories in four countries, three European and at UT Dallas. It measured both the neutral and ionized constituents of the comet's coma. The coma contains, besides water vapor and H30 ions, an extended source of carbon monoxide. The atmosphere forms around a comet as it comes near the sun and is heated by radiation from the sun.
Hoffman has also flown mass spectrometers on earth orbiting satellites, Explorer 31, ISIS-II, AE-C, D, and E, and Wake Shield, plus numerous sounding rockets and stratospheric balloon flights. The first observations of the polar wind, ions flowing out from the atmosphere, were made by his ion mass spectrometer flown on the ISIS spacecraft in 1971.
Dr. Hoffman is a co-investigator for the TEGA experiment that will fly on the Mars Scout Phoenix mission in 2007. The spacecraft will land in the far northern region of Mars, above the Arctic Circle in the area that the Mars Odyssey spacecraft has found evidence for water. An arm on the lander will dig a trench a meter deep in the surface of Mars to look for water ice and other water related substances (minerals). These will be scooped up and analyzed in a series of small furnaces. The effluents from the furnaces will be analyzed by the UT Dallas mass spectrometer to determine the presence of water and the mineralogical composition of soil samples. Isotopic ratios of the principal elements in the samples will be determined and compared to the isotopic ratios of the atmospheric gases that will be measured by the mass spectrometer when it is not analyzing samples from the TEGA furnaces.