Introduction

Mir Station

The Russian Space Agency (RKA) was formed after the breakup of the former Soviet Union and the dissolution of the Soviet space program. The highest profile program that the RKA is currently flying is the Mir Space Station. The Mir Space Station will be de-orbited within the next few years and will be replaced the the International Space Station program.

Columbia

The space shuttle Columbia is scheduled to launch April 16, 1998, at 1:19 p.m. CST from launch pad 39-B at Kennedy Space Center.

The primary payload is Neurolab, which consists of investigations focusing on the effects of microgravity on the nervous system. Specifically, experiments will study the adaptation of the vestibular system and space adaptation syndrome, the adaptation of the central nervous system and the pathways that control the ability to sense location in the absence of gravity, and the effect of microgravity on a developing nervous system.

The Neurolab payload consists of 26 human and nonhuman scientific experiments and associated hardware in a Spacelab long module and the orbiter middeck. The experiment disciplines are primarily involved with life science investigations utilizing human subjects and laboratory animals.

The full NASA Shuttle Web will be available three days before launch, when the countdown starts.

Galileo Space Probe

Beginning

The Galileo Project is a NASA unmanned mission to explore the planet Jupiter and its surrounding moons and magnetosphere. The spacecraft, which started its journey on October 18, 1989 with the launch of the Space Shuttle Atlantis, consisted of an atmospheric entry probe (Galileo Probe) designed to enter Jupiter's atmosphere, and an orbiter (Galileo Orbiter) designed to orbit the planet and observe Jupiter, its moons, and radiation belts. This homepage is devoted to background information and scientific results from the Galileo atmospheric entry probe portion of the mission.

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The Galileo Probe successfully descended into Jupiter's atmosphere on December 7,1995 and directly measured the atmosphere of a Giant Planet for the first time. Results from this most difficult atmospheric entry in the solar system have permitted us to better understand many of the scientific mysteries of the largest planet in our solar system. The Galileo Probe no longer exists and is now part of Jupiter's atmosphere as expected. The Galileo Orbiter successfully entered orbit well above the cloud tops of Jupiter on December 7, 1995 and is currently observing the Jupiter system.

The latest observations of Jupiter and its moons from the Galileo Orbiter are available at the Jet Propulsion Laboratory's Project Galileo Homepage.

NASA's Ames Research Center near Mountain View, California managed the Galileo Probe Project and conducted scientific and engineering studies enabling this most difficult atmospheric entry. Hughes Space and Communications Company built the Galileo Probe. NASA's Jet Propulsion Laboratory in Pasadena, California managed the overall Galileo Project and built the Galileo Orbiter for NASA.

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The Galileo Probe spacecraft design reflects the very demanding conditions of a first entry into the atmosphere of a gas giant planet. The Probe must traverse the intense inner radiation belts of Jupiter, which are far stronger than the Van Allen radiation belts about Earth, as it approaches the top of the atmosphere. No spacecraft has previously journeyed into such a high radiation environment. Without specially designed electronic components, the electronic subsystems on the Probe, which are so vital to this exploration, would fail. The Probe must be rugged enough to withstand the extreme heat generated by the high-speed plunge into Jupiter's atmosphere. As the Probe is pulled in by massive Jupiter's strong gravity, an enormous release of energy occurs as the spacecraft is slowed from 170,000 km/hr (106,000 mph) to 430 km/hr (250 mph) in four minutes. The 15,500 degree C (28,000 degree F) incandescent plasma envelope generated ahead of the Probe, which is produced by supersonic compression and friction with the atmosphere, will briefly be brighter than the Sun's surface. Finally, the Probe's scientific instruments and supporting subsystems must be able to function at the 20 bars of atmospheric pressure (20 times sea level barometric pressure on Earth) which the Probe will encounter in the depths of Jupiter's atmosphere before its transmission of data comes to an end.

Diagram of Galileo Probe

The Probe is composed of two major segments, the deceleration module and the descent module. The total mass of the Probe is 339 kg (747 lb). The deceleration module includes the fore and aft heat shields, the structure that supports the heat shields, and the thermal control hardware for mission phases up to entry. The descent module is the package that descends through the Jovian atmosphere by parachute while the atmospheric science data are gathered. It contains the science instruments and the Probe subsystems required to support the instruments and transmit the data back to the overflying Orbiter, which stores the data for later transmission to Earth.

Deceleration module

The forward heat shield is made of carbon phenolic while the aft heat shield is made of phenolic nylon. Although these materials have been used extensively for Earth re-entry vehicles, on the Galileo Mission they will be subjected to conditions never before experienced in flight due to the high entry velocity caused by Jupiter's massive gravitational pull. The heat shield dissipates heat principally by absorbing the energy through an ablation process and allowing the heat to be carried away by the gases coming off the surface. During the high speed high temperature entry phase, mechanical erosion of the forward heat shield reduces its mass from about 152 kg (335 lb) to about 65 kg (143 lb).

Parachute deployment

A main parachute is used to separate the descent module from the deceleration module at the appropriate time and to control the rate of descent of the descent module through the atmosphere. The main chute deployment takes about 2 seconds and is initiated with the firing of a mortar to deploy a pilot parachute into the wake of the Probe. After the pilot chute is established, the aft cover is pyrotechnically released and the main parachute is deployed.

Descent Module

Atmosphere Structure Instrument

Provides information about temperature, density, pressure, and molecular weight of atmospheric gases. These quantities were determined from the measured deceleration of the Probe during the atmospheric entry phase. During the parachute-descent phase, the temperature and pressure were measured directly by sensors extending from the body of the spacecraft.

Neutral Mass Spectrometer

Analyzes the composition of gases by measuring their molecular weights.

Nephelometer

Locates and measures cloud particles in the immediate vicinity of the Galileo Probe. This instrument uses measurements of scatterred light from a laser beam directed at an arm extending from the Probe to detect and study cloud particles.

Lightning and Radio Emissions Detector

Searches and records radio bursts and optical flashes generated by lightning in Jupiter's atmosphere. These measurements are made using an optical sensor and radio receiver on the Probe.

Helium Abundance Detector

Determines the important ratio of hydrogen to helium in Jupiter's atmosphere. This instrument accurately measures the refractive index of Jovian air to precisely determine the helium abundance.

Net Flux Radiometer

Senses the differences between the flux of light and heat radiated downward and upward at various levels in Jupiter's atmosphere. Such measurements can provide information on the location of cloud layers and power sources for atmospheric winds. This instrument employs an array of rotating detectors capable of sensing small variations in visible and infrared radiation fluxes.

Energetic Particles Instrument

Used before entry to measure fluxes of electrons, protons, alpha particles, and heavy ions as the Probe passes through the innermost regions of Jupiter's magnetosphere and its ionosphere.

RELAY RADIO SCIENCE EXPERIMENTS

Variations in the Probe's radio signals to the Orbiter will be used to determine wind speeds and atmospheric absorptions.

Doppler Wind Experiment

Uses variations in the frequency of the radio signal from the Probe to derive variation of wind speed with altitude in Jupiter's atmosphere.

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