Propulsion Laboratory in Pasadena, California, for a celebration to bid the spacecraft goodbye.
Dr Claudia Alexander, Galileo project manager said:
“We learned mind-boggling things. This mission was worth its weight in gold.”
Having travelled approximately 4.6 billion kilometres (about 2.8 billion miles), the hardy spacecraft endured more than four times the cumulative dose of harmful Jovian radiation it was designed to withstand. During a previous fly-by of the moon Amalthea in November 2002, flashes of light were seen by the star scanner that indicated the presence of rocky debris circling Jupiter in the vicinity of the small moon. Another measurement of this area was taken today during Galileo’s final pass, further analysis of which may help confirm or constrain the existence of a ring at Amalthea’s orbit.
Dr Torrance Johnson, Galileo project scientist:
“We haven’t lost a spacecraft, we’ve gained a stepping stone into the future of space exploration.”
The spacecraft was deliberately put on a collision course with Jupiter because the onboard propellant was nearly depleted. Consequently it was necessary to eliminate any chance of an unwanted impact between the spacecraft and Jupiter’s moon Europa, which Galileo discovered is likely to have a subsurface ocean. Without propellant it would be impossible to control the spacecraft because it would not be able to point its antenna toward Earth or adjust its trajectory. The possibility of life existing on Europa is so compelling and has raised so many unanswered questions that it is prompting plans for future spacecraft to return to the icy moon.
The exciting list of discoveries started even before Galileo got a glimpse of Jupiter. As it crossed the asteroid belt in October 1991, Galileo snapped images of Gaspra, returning the first ever close-up image of an asteroid. Less then a year later, the spacecraft got up close to yet another asteroid, Ida, revealing it had its own little “moon”, Dactyl, the first known moon of an asteroid. In 1994 the spacecraft made the only direct observation of a comet impacting a planet – comet Shoemaker-Levy 9’s collision with Jupiter.
The descent probe made the first in-place studies of the planet’s clouds and winds, and it furthered scientists’ understanding of how Jupiter evolved. The probe also made composition measurements designed to assess the degree of evolution of Jupiter compared to the sun.
Galileo made the first observation of ammonia clouds in another planet’s atmosphere. It also observed numerous large thunderstorms on Jupiter many times larger than those on Earth, with lightning strikes up to 1,000 times more powerful than on Earth. It was the first spacecraft to dwell in a giant planet’s magnetosphere long enough to identify its global structure and to investigate the dynamics of Jupiter’s magnetic field. Galileo determined that Jupiter’s ring system is formed by dust kicked up as interplanetary meteoroids smash into the planet’s four small inner moons. Galileo data showed that Jupiter’s outermost ring is actually two rings, one embedded within the other.
Galileo extensively investigated the geologic diversity of Jupiter’s four largest moons: Ganymede, Callisto, Io and Europa. Galileo found that Io’s extensive volcanic activity is 100 times greater than that found on Earth. The moon Europa, Galileo unveiled, could be hiding a salty ocean up to 100 kilometres (62 miles) deep underneath its frozen surface, containing about twice as much water as all the Earth’s oceans. Data also showed Ganymede and Callisto may have a liquid-saltwater layer. The biggest discovery surrounding Ganymede was the presence of a magnetic field. No other moon of any planet is known to have one.
The prime mission ended six years ago, after two years of orbiting Jupiter, but NASA extended the mission three times to continue taking advantage of Galileo’s unique capabilities for accomplishing valuable science. The mission was possible because it drew its power from two long-lasting radioisotope thermoelectric generators provided by the Department of Energy.
Sean O’Keefe, NASA administrator, said:
“The mission was a testimonial to the persistence of NASA even through tremendous challenges. It was a phenomenal mission.”
JPL, a division of the California Institute of Technology in Pasadena, not only designed and built the Galileo orbiter, but also managed and operated the Galileo mission for NASA’s Office of Space Science, Washington, DC.
In 2003 the estate of the science fiction author Robert Heinlein offered substantial prize money for innovations in space.
On 2 October 2003 a major new award for practical accomplishments in commercial space activities was announced today at the 54th International Aeronautical Congress underway in Bremen, Germany. Trustees of the Robert A. and Virginia Heinlein Prize Trust revealed that the first Heinlein Prize award has been set at $500,000 USD.
The Heinlein Prize may be given as frequently as annually to one or more individuals who have achieved practical accomplishments in the field of commercial space activities. The Trustees emphasize that the award is for effort by an individual – not corporate or government sponsored activities – and that the Heinlein Prize is intended to be worldwide in scope.
“The purpose of the Heinlein Prize is to provide an incentive to spur the advancement of the commercial use of outer space,” explained Arthur M. Dula of Houston, Texas, USA, one of three Trustees.
“In order to accomplish that goal, the Trustees will establish an Advisory Board drawn from respected persons in space activities from around the world. The Advisory Board will keep abreast of developments in space commercialization and will review nominations and propose its own candidates for the Heinlein Prize. The Trustees will select recipients of the Prize based upon recommendations from the Advisory Board. The Heinlein Prize will be awarded on July 7th of those years in which the Prize is given.”
The Trustees are currently in the process of selecting the Board of Advisors. Until the Board of Advisors is announced, nominations for the Heinlein Prize may be made directly to the Trustees though the Heinlein Prize website at www.heinleinprize.com.
The Trustees of the Robert A. and Virginia Heinlein Prize Trust are Mr Dula, Dr Buckner Hightower of Austin, Texas, USA, and Mr James Miller Vaughn, Jr., also of Houston, Texas.
The Heinlein Prize honors the memory of Robert A. Heinlein, a renowned American author. Through his body of work in fiction spanning nearly fifty years during the commencement of man’s entry into space, Mr Heinlein advocated human advancement into space through commercial endeavors. After Mr Heinlein’s death in 1988, his widow, Virginia Gerstenfeld Heinlein, established the Trust in order to further her husband’s vision of humanity’s future in space. Funding for the Heinlein Prize came from Mrs Heinlein’s estate after her death earlier this year.
On 8 December 2003 the Space Frontier Foundation in Los Angeles hailed the rollout of a new SpaceX rocket.
The new “Falcon” launch system by SpaceX Inc. was seen as a symbol of major change in the commercial space arena. The group sees the new entrant in the space launch field as the first of several new
