Alan Stern
Encyclopedia
S. Alan Stern is an American planetary scientist
. He is the principal investigator
of the New Horizons
mission to Pluto
.
Stern has been involved in 24 suborbital, orbital, and planetary space missions, including eight for which he was the mission principal investigator. One of his projects was the Southwest Ultraviolet Imaging System, an instrument which flew on two space shuttle missions, STS-85 in 1997 and STS-93 in 1999.
Stern has also developed eight scientific instruments for planetary and near-space research missions and has been a guest observer on numerous NASA satellite observatories, including the International Ultraviolet Explorer
, the Hubble Space Telescope
, the International Infrared Observer and the Extreme Ultraviolet Observer. Stern was Executive Director of the Southwest Research Institute
's Space Science and Engineering Division until becoming Associate Administrator of NASA
's Science Mission Directorate
in 2007. He resigned from that position after nearly a year. In early 2009 Dr. Stern's name has been mentioned as a potential contender for the position of NASA administrator under President Obama's Administration. Stern has stated however that he is not interested in the position at this time given his desire to spend time with his family.
in 1975. He then attended the University of Texas, Austin, where he received his bachelor's degrees in physics & astronomy and his master's degrees in aerospace engineering and planetary atmospheres. He earned a doctorate in astrophysics and planetary science from the University of Colorado, Boulder.
From 1983 to 1991 Stern held positions at the University of Colorado
in the Center for Space and Geoscience Policy, the office of the Vice President for Research, and the Center for Astrophysics and Space Astronomy. He received his doctorate in 1989. From 1991 to 1994 he was the leader of Southwest Research Institute's Astrophysical and Planetary Sciences group and was Chair of NASA's Outer Planets Science Working Group. From 1994 to 1998 he was the leader of the Geophysical, Astrophysical, and Planetary Science section in Southwest Research Institute's Space Sciences Department, and from 1998 to 2005 he was the Director of the Department of Space Studies at Southwest Research Institute. In 1995 he was selected to be a Space Shuttle
mission specialist finalist and in 1996 he was a candidate Space Shuttle payload specialist but did not have the opportunity to fly on the Space Shuttle.
His research has focused on studies of our solar system's Kuiper belt
and Oort cloud
, comet
s, the satellite
s of the outer planets, Pluto
, and the search for evidence of solar systems around other stars
. He has also worked on spacecraft rendezvous
theory, terrestrial polar mesospheric
clouds, galactic astrophysics, and studies of tenuous satellite atmospheres, including the atmosphere of the Moon.
In 2007, Stern was listed among Time Magazine's 100 Most Influential People in The World.
On 27 August 2008 Stern was elected to the Board of Directors of the Challenger Center for Space Science Education
.
Stern is currently active as a consultant for private sector space efforts and has stated:
On June 18, 2008, Stern joined Odyssey Moon Limited (Isle of Man), a private industry effort, as a part time Science Mission Director/consultant in their efforts to launch a robotic mission to the Earth's moon by participating in the $30 Million Google Lunar X-Prize competition.
On or about December 2008, Stern joined Blue Origin
, a company that was founded by Amazon.com's Jeff Bezos
as an independent representative for research and education Missions. The company has stated that their objective is to develop a new vertical take-off, vertical-landing vehicle known as New Shepherd that is designed to take a small number of astronauts on a sub-orbital journey into space and reduce the cost of space transportation. The company is located in Kent, Washington
and has flight tested some hardware.
astronomical satellite. He was the PI of the advanced, miniaturized HIPPS Pluto breadboard camera/IR spectrometer/UV spectrometer payload for the NASA/Pluto-Kuiper Express mission, and he is the PI of the PERSI imager/spectrometer payload on NASA's New Horizon's Pluto mission. Stern is also the PI of the ALI CE UV Spectrometer for the ESA/NASA Rosetta
comet orbiter. He was a member of the New Millennium Deep Space 1 (DS1) mission science team, and is a Co-investigator on both the ESA SPICAM Mars UV spectrometer launched on Mars Express
, and the Hubble Space Telescope Cosmic Origins Spectrograph (COS) installed in 2009. He is the PI of the SWUIS ultraviolet imager, which has flown two Shuttle missions, and the SWUIS-A airborne astronomical facility. In this capacity, Stern has flown numerous WB-57 and F-18 airborne research astronomy missions. Stern and his colleague, Dr. Daniel Durda, have been flying on the modified F/A-18 Hornet with a sophisticated camera system called the Southwest Ultraviolet Imaging System (SWUIS). They use the camera to search for a hypothetical group of asteroids (Vulcanoids) between the orbit of Mercury
and the Sun
that are so elusive and hard to see that scientists aren't sure they exist.
Although he is a qualified pilot, Stern and his colleague are not flying these missions but rather operating the instruments at up to 60,000 feet in the F/A-18's. With regards to mission preparation Stern has stated:
Science Working Group (DPSWG), the Solar System Exploration Subcommittee (SSES), the New Millennium Science Working Group (NMSWG), and the Sounding Rocket Working Group (SRWG). He was Chair of NASA's Outer Planets Science Working Group (OPSWG) from 1991 to 1994 and served as a panel member for the National Research Council
's 2003-2013 Decadal survey
on planetary science. Stern is a member of the AAAS, the AAS, and the AGU.
, essentially NASA's top-ranking official for science, in April 2007. In this position Stern directed a organization with 93 separate flight missions and a program of over 3,000 research grants. During his tenure a record 10 major new flight projects were started and deep reforms of the research and also the education and public outreach programs were put in place. Stern's style was characterised as "hard-charging" as he pursued a reform-minded agenda. He "made headlines for trying to keep agency missions on schedule and under budget" but faced "internal battles over funding". He was credited with making "significant changes that have helped restore the importance of science in NASA's mission".
On 26 March 2008 it was announced that Stern had resigned his position the previous day, effective 11 April. He was replaced by Ed Weiler, who was to serve his second stint in the position. The resignation occurred on the same day that NASA Chief Michael D. Griffin
overruled a decrease in funding for the Mars Exploration Rover
s and Mars Odyssey
missions that was intended to free up funds needed for the upcoming Mars Science Laboratory
. NASA officials would neither confirm nor deny a connection between the two events.
Stern left to avoid cutting healthy programs and basic research in order to cover cost overruns. He believed that cost overruns in the Mars program should be accommodated from within the Mars program, and not taken from other NASA programs. Michael D. Griffin
became upset with Stern for making major decisions without consulting him, while Stern was frustrated by Griffin's refusal to allow him to cut or delay politically sensitive projects. Griffin favored cutting "less popular parts" of the budget, including basic research, and Stern's refusal to do so led to his resignation.
Casting doubt on the theory that Stern resigned due to conflict with former Administrator Griffin is his statement of March 25, 2009 at spacepolitics.com:
On 23 November 2008, in a New York Times op-ed
criticizing NASA's inability to keep its spending under control, Stern said that, during his own time at NASA, "when I articulated this problem... and consistently curtailed cost increases, I found myself eventually admonished and then neutered by still higher ups, precipitating my resignation earlier this year." While complimenting current NASA Administrator Michael D. Griffin
, Stern suggested that Griffin's decision to again bail out an over-budget mission was motivated by fear "that any move to cancel the Mars mission would be rebuffed by members of Congress protecting local jobs".
Since leaving NASA, Stern has made constructive criticisms of the budgetary process and has advocated for revamping its public appeal.
. After the IAU's decision was made he was quoted as saying "It's an awful definition; it's sloppy science and it would never pass peer review" and claimed that Earth, Mars, Jupiter and Neptune have not fully cleared their orbital zones and has stated in his capacity as PI of the New Horizons project that "The New Horizons project [...] will not recognize the IAU's planet definition resolution of August 24, 2006.".
A 2000 paper by Stern and Levison proposed a system of planet classification that included both the concepts of hydrostatic equilibrium
and clearing the neighbourhood used in the new definition, with a proposed classification scheme labeling all sub-stellar objects in hydrostatic equilibrium as "planets" and subclassifying them into "überplanets" and "unterplanets" based on a mathematical analysis of the planet's ability to scatter other objects out of its orbit over a long period of time. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune were classified as neighborhood-clearing "überplanets" and Pluto was classified as an "unterplanet". One could take this classification system as planet
and dwarf planet
, respectively with the major difference of the IAU definition classifying the two as distinct categories of celestial bodies instead of two subsets of planets.
, e.g. Jupiter's Galilean moons
and Titan
. Stern has argued that location should not matter and only geophysical attributes should be taken into account in the definition of a planet, and proposes the term satellite planet for a planet-sized object orbiting another planet. Likewise planet-sized objects in the asteroid belt
or Kuiper belt
should also be planets according to Stern.
Planetary science
Planetary science is the scientific study of planets , moons, and planetary systems, in particular those of the Solar System and the processes that form them. It studies objects ranging in size from micrometeoroids to gas giants, aiming to determine their composition, dynamics, formation,...
. He is the principal investigator
Principal investigator
A principal investigator is the lead scientist or engineer for a particular well-defined science project, such as a laboratory study or clinical trial....
of the New Horizons
New Horizons
New Horizons is a NASA robotic spacecraft mission currently en route to the dwarf planet Pluto. It is expected to be the first spacecraft to fly by and study Pluto and its moons, Charon, Nix, Hydra and S/2011 P 1. Its estimated arrival date at the Pluto-Charon system is July 14th, 2015...
mission to Pluto
Pluto
Pluto, formal designation 134340 Pluto, is the second-most-massive known dwarf planet in the Solar System and the tenth-most-massive body observed directly orbiting the Sun...
.
Stern has been involved in 24 suborbital, orbital, and planetary space missions, including eight for which he was the mission principal investigator. One of his projects was the Southwest Ultraviolet Imaging System, an instrument which flew on two space shuttle missions, STS-85 in 1997 and STS-93 in 1999.
Stern has also developed eight scientific instruments for planetary and near-space research missions and has been a guest observer on numerous NASA satellite observatories, including the International Ultraviolet Explorer
International Ultraviolet Explorer
The International Ultraviolet Explorer was an astronomical observatory satellite primarily designed to take ultraviolet spectra. The satellite was a collaborative project between NASA, the UK Science Research Council and the European Space Agency...
, the Hubble Space Telescope
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
, the International Infrared Observer and the Extreme Ultraviolet Observer. Stern was Executive Director of the Southwest Research Institute
Southwest Research Institute
Southwest Research Institute , headquartered in San Antonio, Texas, is one of the oldest and largest independent, nonprofit, applied research and development organizations in the United States...
's Space Science and Engineering Division until becoming Associate Administrator of NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
's Science Mission Directorate
Science Mission Directorate
The Science Mission Directorate of the National Aeronautics and Space Administration engages the United States’ science community, sponsors scientific research, and develops and deploys satellites and probes in collaboration with NASA’s partners around the world to answer fundamental questions...
in 2007. He resigned from that position after nearly a year. In early 2009 Dr. Stern's name has been mentioned as a potential contender for the position of NASA administrator under President Obama's Administration. Stern has stated however that he is not interested in the position at this time given his desire to spend time with his family.
Biography
Stern graduated from St. Mark's School of TexasSt. Mark's School of Texas
The St. Mark's School of Texas is a nonsectarian preparatory day school for boys located in Preston Hollow, Dallas, Texas, USA. The School offers grades 1–12.-History:...
in 1975. He then attended the University of Texas, Austin, where he received his bachelor's degrees in physics & astronomy and his master's degrees in aerospace engineering and planetary atmospheres. He earned a doctorate in astrophysics and planetary science from the University of Colorado, Boulder.
From 1983 to 1991 Stern held positions at the University of Colorado
University of Colorado at Boulder
The University of Colorado Boulder is a public research university located in Boulder, Colorado...
in the Center for Space and Geoscience Policy, the office of the Vice President for Research, and the Center for Astrophysics and Space Astronomy. He received his doctorate in 1989. From 1991 to 1994 he was the leader of Southwest Research Institute's Astrophysical and Planetary Sciences group and was Chair of NASA's Outer Planets Science Working Group. From 1994 to 1998 he was the leader of the Geophysical, Astrophysical, and Planetary Science section in Southwest Research Institute's Space Sciences Department, and from 1998 to 2005 he was the Director of the Department of Space Studies at Southwest Research Institute. In 1995 he was selected to be a Space Shuttle
Space Shuttle
The Space Shuttle was a manned orbital rocket and spacecraft system operated by NASA on 135 missions from 1981 to 2011. The system combined rocket launch, orbital spacecraft, and re-entry spaceplane with modular add-ons...
mission specialist finalist and in 1996 he was a candidate Space Shuttle payload specialist but did not have the opportunity to fly on the Space Shuttle.
His research has focused on studies of our solar system's Kuiper belt
Kuiper belt
The Kuiper belt , sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune to approximately 50 AU from the Sun. It is similar to the asteroid belt, although it is far larger—20 times as wide and 20 to 200 times as massive...
and Oort cloud
Oort cloud
The Oort cloud , or the Öpik–Oort cloud , is a hypothesized spherical cloud of comets which may lie roughly 50,000 AU, or nearly a light-year, from the Sun. This places the cloud at nearly a quarter of the distance to Proxima Centauri, the nearest star to the Sun...
, comet
Comet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
s, the satellite
Natural satellite
A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called its primary. The two terms are used synonymously for non-artificial satellites of planets, of dwarf planets, and of minor planets....
s of the outer planets, Pluto
Pluto
Pluto, formal designation 134340 Pluto, is the second-most-massive known dwarf planet in the Solar System and the tenth-most-massive body observed directly orbiting the Sun...
, and the search for evidence of solar systems around other stars
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...
. He has also worked on spacecraft rendezvous
Space rendezvous
A space rendezvous is an orbital maneuver during which two spacecraft, one of which is often a space station, arrive at the same orbit and approach to a very close distance . Rendezvous requires a precise match of the orbital velocities of the two spacecraft, allowing them to remain at a constant...
theory, terrestrial polar mesospheric
Mesosphere
The mesosphere is the layer of the Earth's atmosphere that is directly above the stratosphere and directly below the thermosphere. In the mesosphere temperature decreases with increasing height. The upper boundary of the mesosphere is the mesopause, which can be the coldest naturally occurring...
clouds, galactic astrophysics, and studies of tenuous satellite atmospheres, including the atmosphere of the Moon.
In 2007, Stern was listed among Time Magazine's 100 Most Influential People in The World.
On 27 August 2008 Stern was elected to the Board of Directors of the Challenger Center for Space Science Education
Challenger Center for Space Science Education
' is a nonprofit educational organization with its headquarters in Alexandria, Virginia, and an international network of Challenger Learning Centers. The organization was founded in April 1986 by the families of the astronauts who died in the Space Shuttle Challenger disaster on January 28,...
.
Inspiration for Pluto/Kuiper Belt Mission
On 14 June 2007, in an address to the Smithsonian Institution for their "Exploring the Solar System Lecture Series," Stern commented on the New Horizons mission:Private Sector Experience
After completing a Master's degree in aerospace engineering Stern spent seven years as an aerospace systems engineer, concentrating on spacecraft and payload systems at the NASA Johnson Space Center, Martin Marietta Aerospace, and the Laboratory for Atmospheric and Space Physics at the University of Colorado.Stern is currently active as a consultant for private sector space efforts and has stated:
On June 18, 2008, Stern joined Odyssey Moon Limited (Isle of Man), a private industry effort, as a part time Science Mission Director/consultant in their efforts to launch a robotic mission to the Earth's moon by participating in the $30 Million Google Lunar X-Prize competition.
On or about December 2008, Stern joined Blue Origin
Blue Origin
Blue Origin is a privately funded aerospace company set up by Amazon.com founder Jeff Bezos. The company was awarded $3.7 million in funding in 2009 by NASA via a Space Act Agreement under the Commercial Crew Development program for development of concepts and technologies to support future human...
, a company that was founded by Amazon.com's Jeff Bezos
Jeff Bezos
Jeffrey Preston "Jeff" Bezos is the founder, president, chief executive officer , and chairman of the board of Amazon.com.-Early life and background:...
as an independent representative for research and education Missions. The company has stated that their objective is to develop a new vertical take-off, vertical-landing vehicle known as New Shepherd that is designed to take a small number of astronauts on a sub-orbital journey into space and reduce the cost of space transportation. The company is located in Kent, Washington
Kent, Washington
Kent is a city located in King County, Washington, United States, and is the third largest city in King County and the sixth largest in the state. An outlying suburb of Seattle, Kent is also the corporate home for companies such as REI and Oberto Sausage...
and has flight tested some hardware.
Space science mission
Stern has extensive experience in instrument development, with a strong concentration in ultraviolet technologies. Stern is a principal investigator (PI) in NASA's UV sounding rocket program, and was the project scientist on a Shuttle-deployable SPARTANSpartan
A Spartan is a person from the Greek city Sparta or the ancient Greek city-state of the same name. In the latter context, the term "Spartan" in its most technical sense refers to a member of the Spartiate caste and under some usages also encompasses the class of mothakes, residents of Sparta who...
astronomical satellite. He was the PI of the advanced, miniaturized HIPPS Pluto breadboard camera/IR spectrometer/UV spectrometer payload for the NASA/Pluto-Kuiper Express mission, and he is the PI of the PERSI imager/spectrometer payload on NASA's New Horizon's Pluto mission. Stern is also the PI of the ALI CE UV Spectrometer for the ESA/NASA Rosetta
Rosetta
Rosetta is a port city on the Mediterranean coast of Egypt. It is located east of Alexandria, in Beheira governorate. It was founded around AD 800....
comet orbiter. He was a member of the New Millennium Deep Space 1 (DS1) mission science team, and is a Co-investigator on both the ESA SPICAM Mars UV spectrometer launched on Mars Express
Mars Express
Mars Express is a space exploration mission being conducted by the European Space Agency . The Mars Express mission is exploring the planet Mars, and is the first planetary mission attempted by the agency. "Express" originally referred to the speed and efficiency with which the spacecraft was...
, and the Hubble Space Telescope Cosmic Origins Spectrograph (COS) installed in 2009. He is the PI of the SWUIS ultraviolet imager, which has flown two Shuttle missions, and the SWUIS-A airborne astronomical facility. In this capacity, Stern has flown numerous WB-57 and F-18 airborne research astronomy missions. Stern and his colleague, Dr. Daniel Durda, have been flying on the modified F/A-18 Hornet with a sophisticated camera system called the Southwest Ultraviolet Imaging System (SWUIS). They use the camera to search for a hypothetical group of asteroids (Vulcanoids) between the orbit of Mercury
Mercury (planet)
Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits...
and the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
that are so elusive and hard to see that scientists aren't sure they exist.
Although he is a qualified pilot, Stern and his colleague are not flying these missions but rather operating the instruments at up to 60,000 feet in the F/A-18's. With regards to mission preparation Stern has stated:
NASA Experience
Stern has served on various NASA committees, including the Lunar Exploration Science Working Group (LExSWG) and the Discovery ProgramDiscovery Program
NASA's Discovery Program is a series of lower-cost, highly-focused American scientific space missions that are exploring the Solar System. It was founded in 1992 to implement then-NASA Administrator Daniel S. Goldin's vision of "faster, better, cheaper" planetary missions...
Science Working Group (DPSWG), the Solar System Exploration Subcommittee (SSES), the New Millennium Science Working Group (NMSWG), and the Sounding Rocket Working Group (SRWG). He was Chair of NASA's Outer Planets Science Working Group (OPSWG) from 1991 to 1994 and served as a panel member for the National Research Council
United States National Research Council
The National Research Council of the USA is the working arm of the United States National Academies, carrying out most of the studies done in their names.The National Academies include:* National Academy of Sciences...
's 2003-2013 Decadal survey
Astronomy and Astrophysics Decadal Survey
The Astronomy and Astrophysics Decadal Survey is a review of astronomy and astrophysics literature produced approximately every ten years by the National Research Council of the National Academy of Sciences in the United States. The report surveys the current state of the field, identifies research...
on planetary science. Stern is a member of the AAAS, the AAS, and the AGU.
NASA Associate Administrator
Stern was appointed NASA's Associate Administrator for the Science Mission DirectorateScience Mission Directorate
The Science Mission Directorate of the National Aeronautics and Space Administration engages the United States’ science community, sponsors scientific research, and develops and deploys satellites and probes in collaboration with NASA’s partners around the world to answer fundamental questions...
, essentially NASA's top-ranking official for science, in April 2007. In this position Stern directed a organization with 93 separate flight missions and a program of over 3,000 research grants. During his tenure a record 10 major new flight projects were started and deep reforms of the research and also the education and public outreach programs were put in place. Stern's style was characterised as "hard-charging" as he pursued a reform-minded agenda. He "made headlines for trying to keep agency missions on schedule and under budget" but faced "internal battles over funding". He was credited with making "significant changes that have helped restore the importance of science in NASA's mission".
On 26 March 2008 it was announced that Stern had resigned his position the previous day, effective 11 April. He was replaced by Ed Weiler, who was to serve his second stint in the position. The resignation occurred on the same day that NASA Chief Michael D. Griffin
Michael D. Griffin
Michael Douglas Griffin is an American physicist and aerospace engineer. From April 13, 2005 to January 20, 2009 he served as Administrator of NASA, the space agency of the United States...
overruled a decrease in funding for the Mars Exploration Rover
Mars Exploration Rover
NASA's Mars Exploration Rover Mission is an ongoing robotic space mission involving two rovers, Spirit and Opportunity, exploring the planet Mars...
s and Mars Odyssey
2001 Mars Odyssey
2001 Mars Odyssey is a robotic spacecraft orbiting the planet Mars. The project was developed by NASA, and contracted out to Lockheed Martin, with an expected cost for the entire mission of US$297 million. Its mission is to use spectrometers and electronic imagers to hunt for evidence of past or...
missions that was intended to free up funds needed for the upcoming Mars Science Laboratory
Mars Science Laboratory
The Mars Science Laboratory is a National Aeronautics and Space Administration mission with the aim to land and operate a rover named Curiosity on the surface of Mars. The MSL was launched November 26, 2011, at 10:02 EST and is scheduled to land on Mars at Gale Crater between August 6 and 20, 2012...
. NASA officials would neither confirm nor deny a connection between the two events.
Stern left to avoid cutting healthy programs and basic research in order to cover cost overruns. He believed that cost overruns in the Mars program should be accommodated from within the Mars program, and not taken from other NASA programs. Michael D. Griffin
Michael D. Griffin
Michael Douglas Griffin is an American physicist and aerospace engineer. From April 13, 2005 to January 20, 2009 he served as Administrator of NASA, the space agency of the United States...
became upset with Stern for making major decisions without consulting him, while Stern was frustrated by Griffin's refusal to allow him to cut or delay politically sensitive projects. Griffin favored cutting "less popular parts" of the budget, including basic research, and Stern's refusal to do so led to his resignation.
Casting doubt on the theory that Stern resigned due to conflict with former Administrator Griffin is his statement of March 25, 2009 at spacepolitics.com:
On 23 November 2008, in a New York Times op-ed
Op-ed
An op-ed, abbreviated from opposite the editorial page , is a newspaper article that expresses the opinions of a named writer who is usually unaffiliated with the newspaper's editorial board...
criticizing NASA's inability to keep its spending under control, Stern said that, during his own time at NASA, "when I articulated this problem... and consistently curtailed cost increases, I found myself eventually admonished and then neutered by still higher ups, precipitating my resignation earlier this year." While complimenting current NASA Administrator Michael D. Griffin
Michael D. Griffin
Michael Douglas Griffin is an American physicist and aerospace engineer. From April 13, 2005 to January 20, 2009 he served as Administrator of NASA, the space agency of the United States...
, Stern suggested that Griffin's decision to again bail out an over-budget mission was motivated by fear "that any move to cancel the Mars mission would be rebuffed by members of Congress protecting local jobs".
Since leaving NASA, Stern has made constructive criticisms of the budgetary process and has advocated for revamping its public appeal.
Planetary classification
Stern has become particularly involved in the debate surrounding the 2006 definition of planet by the IAUInternational Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...
. After the IAU's decision was made he was quoted as saying "It's an awful definition; it's sloppy science and it would never pass peer review" and claimed that Earth, Mars, Jupiter and Neptune have not fully cleared their orbital zones and has stated in his capacity as PI of the New Horizons project that "The New Horizons project [...] will not recognize the IAU's planet definition resolution of August 24, 2006.".
A 2000 paper by Stern and Levison proposed a system of planet classification that included both the concepts of hydrostatic equilibrium
Hydrostatic equilibrium
Hydrostatic equilibrium or hydrostatic balance is the condition in fluid mechanics where a volume of a fluid is at rest or at constant velocity. This occurs when compression due to gravity is balanced by a pressure gradient force...
and clearing the neighbourhood used in the new definition, with a proposed classification scheme labeling all sub-stellar objects in hydrostatic equilibrium as "planets" and subclassifying them into "überplanets" and "unterplanets" based on a mathematical analysis of the planet's ability to scatter other objects out of its orbit over a long period of time. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune were classified as neighborhood-clearing "überplanets" and Pluto was classified as an "unterplanet". One could take this classification system as planet
Planet
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
and dwarf planet
Dwarf planet
A dwarf planet, as defined by the International Astronomical Union , is a celestial body orbiting the Sun that is massive enough to be spherical as a result of its own gravity but has not cleared its neighboring region of planetesimals and is not a satellite...
, respectively with the major difference of the IAU definition classifying the two as distinct categories of celestial bodies instead of two subsets of planets.
Satellite planets and belt planets
Some large satellites are of similar size or larger than the planet MercuryMercury (planet)
Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits...
, e.g. Jupiter's Galilean moons
Galilean moons
The Galilean moons are the four moons of Jupiter discovered by Galileo Galilei in January 1610. They are the largest of the many moons of Jupiter and derive their names from the lovers of Zeus: Io, Europa, Ganymede and Callisto. Ganymede, Europa and Io participate in a 1:2:4 orbital resonance...
and Titan
Titan (moon)
Titan , or Saturn VI, is the largest moon of Saturn, the only natural satellite known to have a dense atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found....
. Stern has argued that location should not matter and only geophysical attributes should be taken into account in the definition of a planet, and proposes the term satellite planet for a planet-sized object orbiting another planet. Likewise planet-sized objects in the asteroid belt
Asteroid belt
The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets...
or Kuiper belt
Kuiper belt
The Kuiper belt , sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune to approximately 50 AU from the Sun. It is similar to the asteroid belt, although it is far larger—20 times as wide and 20 to 200 times as massive...
should also be planets according to Stern.