Stardust (spacecraft)
Encyclopedia
Stardust is a 300-kilogram robotic
space probe
launched by NASA
on February 7, 1999 to study the asteroid
5535 Annefrank
and collect samples from the coma
of comet
Wild 2
. The primary mission was completed January 15, 2006, when the sample return capsule returned to Earth. Operating for , Stardust intercepted comet Tempel 1 on February 15, 2011, a small Solar System body
previously visited by Deep Impact on July 4, 2005. It is the first sample return mission
to collect cosmic dust
and return the sample to Earth
and the first to acquire images of a previously visited comet.
became the first successful missions to return close-up data. However, the US cometary mission, Comet Rendezvous Asteroid Flyby
, was canceled for budgetary reasons. In the mid-1990s, further support was given to a cheaper, Discovery-class
mission that would study comet Wild 2 in 2004.
Stardust was competitively selected in the fall of 1995 as a NASA Discovery Program mission of low-cost with highly focused science goals. Construction of Stardust began in 1996, and was subject to the maximum contamination restriction, level 5 planetary protection
. However, the risk of interplanetary contamination by alien life was judged low, as particle impacts at over 1000 miles per hour, even into aerogel, were believed to be terminal for any known microorganism.
Comet Wild 2 was selected as the primary target of the mission for the rare chance to observe a long-period comet that has ventured close to the Sun
. The comet has since become a short period comet after an event in 1974, where the orbit of Wild 2 was affected by the gravitational pull of Jupiter
, moving the orbit inward, closer to the Sun. In planning the mission, it was expected that most of the original material from which the comet formed, would still be preserved.
The primary science objectives of the mission include:
The spacecraft was designed, built and is operated by Lockheed Martin Astronautics
as a Discovery-class mission in Denver, Colorado. JPL provides mission management for the NASA division for mission operations. The principal investigator of the mission is Dr. Donald Brownlee from the University of Washington.
. Each pair features engravings of well over one million names of people who participated in the public outreach program by filling out internet forms available in late 1997 and mid 1998. One pair of the microchips is positioned on the spacecraft and the other was attached to the sample return capsule.
. The bus is primarily constructed with graphite fiber panels with an aluminum honeycomb support structure underneath; the entire spacecraft is covered with polycyanate, Kapton
sheeting for further protection. To maintain low costs, the spacecraft incorporates many designs and technologies used in past missions or previously developed for future missions by the Small Spacecraft Technologies Initiative (SSTI). The spacecraft features five scientific instruments to collect data, including the Stardust Sample Collection tray, which was brought back to Earth for analysis.
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in Florida, aboard a Delta II 7426
launch vehicle. The complete burn sequence lasted for 27 minutes bringing the spacecraft into a heliocentric orbit that would bring the spacecraft around the Sun
and past Earth
for a gravity assist maneuver in 2001, to reach asteroid Annefrank in 2002 and comet Wild 2 in 2004 at a low flyby velocity of 6.1 km/s. In 2004, the direction of the spacecraft performed a deep space maneuver that would allow it to pass by Earth a second time in 2006, to release the Sample Return Capsule for a landing in Utah.
During the second encounter with Earth, Stardust was put into a "divert maneuver" immediately after the capsule was released. The maneuver corrected the spacecraft direction to avoid entering the atmosphere. Under twenty kilograms of propellant remained onboard after the maneuver.
On January 29, 2004, the spacecraft was put in hibernation mode with only the solar panels and receiver active, in a three-year heliocentric orbit that would return it to Earth vicinity on January 14, 2009.
A subsequent mission extension was approved on July 3, 2007, to bring the spacecraft back to full operation for a flyby of comet Tempel 1 in 2011. The mission extension was the first to revisit a small solar system body
and used the remaining propellant, signaling the end of the useful life for the spacecraft.
The relative velocity between the comet and the spacecraft was such that the comet actually overtook the spacecraft from behind as they traveled around the Sun. During the encounter, the spacecraft was on the sun-lit side of the nucleus, approaching at a solar phase angle of 70 degrees, reaching a minimum angle of 3 degrees near closest approach and departing at a phase angle of 110 degrees.
During the flyby the spacecraft deployed the Sample Collection plate to collect dust grain samples
from the coma
, and took detailed pictures of the icy nucleus
.
. The capsule was then transported by military aircraft from Utah to Ellington Air Force Base in Houston, Texas
, then transferred by road to the Planetary Materials Curatorial facility at Johnson Space Center in Houston to begin analysis. NASA officials claimed "prudence" dictated that the materials be transferred in secrecy, though no security threats were apparent.
The sample container was taken to a clean room with a cleanliness factor 100 times that of a hospital operating room to ensure the star and comet dust was not contaminated. Preliminary estimations suggested at least a million microscopic
specks of dust were embedded in aerogel
collector. Ten particles were found to be at least 100 micrometers
and the largest approximately 1000 micrometers. An estimated 45 interstellar dust impacts were also found on the sample collector, which reside on the back side of the cometary dust collector. Dust grains are being observed and analyzed by a volunteer team through the distributed computing
project, Stardust@Home
.
In December 2006, seven papers were published in the scientific journal, Science
, discussing initial details of the sample analysis. Among the findings are: a wide range of organic compounds, including two that contain biologically usable nitrogen
; indigenous aliphatic hydrocarbons
with longer chain lengths than those observed in the diffuse interstellar medium
; abundant amorphous silicate
s in addition to crystalline silicates such as olivine
and pyroxene
, proving consistency with the mixing of solar system and interstellar matter, previously deduced spectroscopically from ground observations; hydrous silicates and carbonate minerals were found to be absent, suggesting a lack of aqueous processing of the cometary dust; limited pure carbon (CHON)
was also found in the samples returned; methylamine
and ethylamine
was found in the aerogel but was not associated with specific particles.
In 2010 Dr Andrew Westphal announced that Stardust@home
volunteer Bruce Hudson found a track (labeled "I1043,1,30") among the many images of the aerogel that may contain an interstellar dust grain. The program allows for any volunteer discoveries to be recognized and named by the volunteer. Hudson named his discovery, Orion.
In April 2011, scientists from the University of Arizona
discovered evidence for the presence of liquid water in a Comet Wild 2. They have found iron and copper sulfide
minerals that must have formed in the presence of water. The discovery shatters the existing paradigm that comets never get warm enough to melt their icy bulk.
On July 3, 2007 the mission extension was approved and renamed New Exploration of Tempel 1 (NExT). This investigation will provide the first look at the changes to a comet nucleus produced after a close approach to the sun. NExT also will extend the mapping of Tempel 1, making it the most mapped comet nucleus to date. This mapping will help address the major questions of comet nucleus geology. The flyby mission was expected to consume the remaining fuel, signaling the end of the operability for the spacecraft.
The mission objectives included the following:
Primary objectives
Secondary objectives
Robotic spacecraft
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...
space probe
Space probe
A robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...
launched by 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...
on February 7, 1999 to study the asteroid
Asteroid
Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...
5535 Annefrank
5535 Annefrank
5535 Annefrank is an inner main-belt asteroid, and member of the Augusta family. It was discovered by Karl Reinmuth in 1942. It is named after Anne Frank, the Dutch-Jewish diarist who died in a concentration camp...
and collect samples from the coma
Coma (cometary)
frame|right|The [[153P/Ikeya-Zhang|comet Ikeya-Zhang]] exhibiting a bright, condensed coma In astronomy, a coma is the nebulous envelope around the nucleus of a comet. It is formed when the comet passes close to the Sun on its highly elliptical orbit; as the comet warms, parts of it sublimate...
of 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...
Wild 2
81P/Wild
Comet 81P/Wild, also known as Wild 2 , is a comet named after Swiss astronomer Paul Wild, who discovered it in 1978 using a 40-cm Schmidt telescope at Zimmerwald....
. The primary mission was completed January 15, 2006, when the sample return capsule returned to Earth. Operating for , Stardust intercepted comet Tempel 1 on February 15, 2011, a small Solar System body
Small Solar System body
A small Solar System body is an object in the Solar System that is neither a planet nor a dwarf planet, nor a satellite of a planet or dwarf planet:...
previously visited by Deep Impact on July 4, 2005. It is the first sample return mission
Sample return mission
A sample return mission is a spacecraft mission with the goal of returning tangible samples from an extraterrestrial location to Earth for analysis. Sample return missions may bring back merely atoms and molecules or a deposit of complex compounds such as dirt and rocks...
to collect cosmic dust
Cosmic dust
Cosmic dust is a type of dust composed of particles in space which are a few molecules to 0.1 µm in size. Cosmic dust can be further distinguished by its astronomical location; for example: intergalactic dust, interstellar dust, interplanetary dust and circumplanetary dust .In our own Solar...
and return the sample to Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
and the first to acquire images of a previously visited comet.
History
Beginning in the 1980s, scientists began seeking a dedicated mission to study a comet. During the early 1990s, several missions to study comet HalleyComet Halley
Halley's Comet or Comet Halley is the best-known of the short-period comets, and is visible from Earth every 75 to 76 years. Halley is the only short-period comet that is clearly visible to the naked eye from Earth, and thus the only naked-eye comet that might appear twice in a human lifetime...
became the first successful missions to return close-up data. However, the US cometary mission, Comet Rendezvous Asteroid Flyby
Comet Rendezvous Asteroid Flyby
The Comet Rendezvous Asteroid Flyby was a cancelled plan for a NASA led exploratory mission designed by the Jet Propulsion Laboratory during the mid-to-late 1980s and early 1990s, that planned to send a spacecraft to encounter an asteroid, and then to rendezvous with a comet and fly alongside it...
, was canceled for budgetary reasons. In the mid-1990s, further support was given to a cheaper, Discovery-class
Discovery 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...
mission that would study comet Wild 2 in 2004.
Stardust was competitively selected in the fall of 1995 as a NASA Discovery Program mission of low-cost with highly focused science goals. Construction of Stardust began in 1996, and was subject to the maximum contamination restriction, level 5 planetary protection
Planetary protection
Planetary protection is the term used to describe a guiding principle in design of an interplanetary mission that aims to prevent biological contamination of both the target celestial body and the Earth. This principle arises from the scientific need to preserve planetary conditions for future...
. However, the risk of interplanetary contamination by alien life was judged low, as particle impacts at over 1000 miles per hour, even into aerogel, were believed to be terminal for any known microorganism.
Comet Wild 2 was selected as the primary target of the mission for the rare chance to observe a long-period comet that has ventured close to 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...
. The comet has since become a short period comet after an event in 1974, where the orbit of Wild 2 was affected by the gravitational pull of Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
, moving the orbit inward, closer to the Sun. In planning the mission, it was expected that most of the original material from which the comet formed, would still be preserved.
The primary science objectives of the mission include:
- Provide a flyby of a comet of interest (Wild 2) at a sufficiently low velocity (less than 6.5 km/s) such that non-destructive capture of comet dust is possible using an aerogel collector.
- Facilitate the intercept of significant numbers of interstellar dust particles using the same collection medium, also at as low a velocity as possible.
- Return as many high resolution images of the comet coma and nucleus as possible, subject to the cost constraints of the mission.
The spacecraft was designed, built and is operated by Lockheed Martin Astronautics
Lockheed Martin
Lockheed Martin is an American global aerospace, defense, security, and advanced technology company with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It is headquartered in Bethesda, Maryland, in the Washington Metropolitan Area....
as a Discovery-class mission in Denver, Colorado. JPL provides mission management for the NASA division for mission operations. The principal investigator of the mission is Dr. Donald Brownlee from the University of Washington.
Stardust Microchip
Stardust was launched carrying two sets of identical pairs of square 10.16-centimeter silicon wafersWafer (electronics)
A wafer is a thin slice of semiconductor material, such as a silicon crystal, used in the fabrication of integrated circuits and other microdevices...
. Each pair features engravings of well over one million names of people who participated in the public outreach program by filling out internet forms available in late 1997 and mid 1998. One pair of the microchips is positioned on the spacecraft and the other was attached to the sample return capsule.
Spacecraft design
The spacecraft bus measures 1.7-meters in length, and 0.66-meters in width, a design adapted from the SpaceProbe deep space bus developed by Lockheed Martin AstronauticsLockheed Martin
Lockheed Martin is an American global aerospace, defense, security, and advanced technology company with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It is headquartered in Bethesda, Maryland, in the Washington Metropolitan Area....
. The bus is primarily constructed with graphite fiber panels with an aluminum honeycomb support structure underneath; the entire spacecraft is covered with polycyanate, Kapton
Kapton
Kapton is a polyimide film developed by DuPont which can remain stable in a wide range of temperatures, from -273 to +400 °C...
sheeting for further protection. To maintain low costs, the spacecraft incorporates many designs and technologies used in past missions or previously developed for future missions by the Small Spacecraft Technologies Initiative (SSTI). The spacecraft features five scientific instruments to collect data, including the Stardust Sample Collection tray, which was brought back to Earth for analysis.
Attitude control and propulsion
- The spacecraft is three-axis stabilized with eight 4.41-N hydrazineHydrazineHydrazine is an inorganic compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor. Hydrazine is highly toxic and dangerously unstable unless handled in solution. Approximately 260,000 tons are manufactured annually...
monopropellantMonopropellant rocketA monopropellant rocket is a rocket that uses a single chemical as its propellant.-Chemical-reaction monopropellant rockets:...
thrustersSpacecraft propulsionSpacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. There are many different methods. Each method has drawbacks and advantages, and spacecraft propulsion is an active area of research. However, most spacecraft today are propelled by forcing a gas from the...
, and eight 1-N thrusters to maintain attitude control; necessary minor propulsion maneuvers are performed by these thrusters as well. The spacecraft was launched with 80-kilograms of propellant. Information for spacecraft positioning is provided by a star tracker, an inertial measurement unit, and two sun sensors.
Communications
- For communicating with the Deep Space NetworkDeep Space NetworkThe Deep Space Network, or DSN, is a world-wide network of large antennas and communication facilities that supports interplanetary spacecraft missions. It also performs radio and radar astronomy observations for the exploration of the solar system and the universe, and supports selected...
, the spacecraft transmits data across the x-band using a 0.6-meter parabolic high-gain antennaHigh-gain antennaA high-gain antenna is an antenna with a focused, narrow radiowave beam width. This narrow beam width allows more precise targeting of the radio signal - also known as a directional antenna...
and a 15-watt transponderTransponderIn telecommunication, the term transponder has the following meanings:...
design originally intended for the Cassini spacecraftCassini-HuygensCassini–Huygens is a joint NASA/ESA/ASI spacecraft mission studying the planet Saturn and its many natural satellites since 2004. Launched in 1997 after nearly two decades of gestation, it includes a Saturn orbiter and an atmospheric probe/lander for the moon Titan, although it has also returned...
.
Power
- The probe is powered by two solar arrays, providing an average of 330-watts of power. The arrays also include whipple shieldWhipple shieldThe Whipple shield or Whipple bumper, invented by Fred Whipple, is a type of hypervelocity impact shield used to protect manned and unmanned spacecraft from collisions with micrometeoroids and orbital debris whose velocities generally range between ....
s to protect the delicate surfaces from the potentially damaging cometary dust while the spacecraft is in the coma of Wild 2. The solar array design is derived primarily from the Small Spacecraft Technology Initiative (SSTI) spacecraft development guidelines. A single nickel hydrogen (NiH2) batteryNickel hydrogen batteryA nickel–hydrogen battery is a rechargeable electrochemical power source based on nickel and hydrogen. It differs from a nickel–metal hydride battery by the use of hydrogen in a pressurized cell at up to 1200 psi pressure.The cathode is made up of a dry sintered porous nickel plaque, which...
is also included to provide the spacecraft with power when the solar arrays receive too little sunlight.
Computer
- The computer on the spacecraft operates using a radiation hardenedRadiation hardeningRadiation hardening is a method of designing and testing electronic components and systems to make them resistant to damage or malfunctions caused by ionizing radiation , such as would be encountered in outer space, high-altitude flight, around nuclear reactors, particle accelerators, or during...
RAD6000RAD6000The RAD6000 radiation-hardened single board computer, based on the IBM RISC Single Chip CPU, was manufactured by IBM Federal Systems. IBM Federal Systems was sold to Loral, and by way of acquisition, ended up with Lockheed Martin and is currently a part of BAE Systems...
32-bit processor card. For storing dataData storage devicethumb|200px|right|A reel-to-reel tape recorder .The magnetic tape is a data storage medium. The recorder is data storage equipment using a portable medium to store the data....
when the spacecraft is unable to communicate with Earth, the processor card is able to store 128-megabytes, 20% of which is occupied by the flight system software. The system software is a form of VxWorksVxWorksVxWorks is a real-time operating system developed as proprietary software by Wind River Systems of Alameda, California, USA. First released in 1987, VxWorks is designed for use in embedded systems.- History :...
, an embedded operating systemEmbedded operating systemAn embedded operating system is an operating system for embedded computer systems. These operating systems are designed to be compact, efficient, and reliable, forsaking many functions that non-embedded computer operating systems provide, and which may not be used by the specialized applications...
developed by Wind River SystemsWind River SystemsWind River Systems, Inc. is a company providing embedded systems, development tools for embedded systems, middleware, and other types of software. The company was founded in Berkeley, California in 1981 by Jerry Fiddler and David Wilner. On June 4, 2009, Wind River announced that Intel had bought...
.
Scientific instruments
| Navigation Camera (NC) | |||
| The camera is intended for targeting comet Wild 2 during the flyby of the nucleus. It captures black and white images through a filter wheel making it possible to assemble color images and detect certain gas and dust emissions in the coma. It also captures images at various phase angles Phase angle (astronomy) Phase angle in astronomical observations is the angle between the light incident onto an observed object and the light reflected from the object... , making it possible to create a three dimensional model of a target to better understand the origin, morphology, and mineralogical inhomogeneities on the surface of the nucleus. The camera utilizes the optical assembly from the Voyager Voyager program The Voyager program is a U.S program that launched two unmanned space missions, scientific probes Voyager 1 and Voyager 2. They were launched in 1977 to take advantage of a favorable planetary alignment of the late 1970s... Wide Angle Camera. It is additionally fitted with a scanning mirror to vary the viewing angle and avoid potentially damaging particles.
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| Cometary and Interstellar Dust Analyzer (CIDA) | |||
| The dust analyzer is a mass spectrometer able to provide real-time detection and analysis of certain compounds and elements. Particles enter the instrument after colliding with a silver Silver Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal... impact plate and traveling down a tube to the detector. The detector is then able to detect the mass of separate ions by measuring the time taken for each ion to enter and travel through the instrument. Identical instruments were also included on Giotto 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.... and Vega 1 and 2 Vega program The Vega program was a series of Venus missions which also took advantage of the appearance of Comet Halley in 1986. Vega 1 and Vega 2 were unmanned spacecraft launched in a cooperative effort among the Soviet Union and Austria, Bulgaria, Hungary, the German Democratic Republic, Poland,... .
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| Dust Flux Monitor Instrument (DFMI) | |||
| Located on the whipple shield Whipple shield The Whipple shield or Whipple bumper, invented by Fred Whipple, is a type of hypervelocity impact shield used to protect manned and unmanned spacecraft from collisions with micrometeoroids and orbital debris whose velocities generally range between .... at the front of the spacecraft, the sensor unit provides data regarding the flux and size distribution of particles in the environment around Wild 2. It records data by generating electric pulses as a special polarized plastic (PVDF) sensor is struck by high energy particles as small as a few micrometers.
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| Stardust Sample Collection (SSC) | |||
 |
The particle collector uses aerogel Aerogel Aerogel is a synthetic porous material derived from a gel, in which the liquid component of the gel has been replaced with a gas. The result is a solid with extremely low density and thermal conductivity... , a low-density, inert, microporous, silica-based substance, to capture dust grains as the spacecraft passes through the coma of Wild 2. After sample collection was complete, the collector receded into the Sample Return Capsule for entering the Earth's atmosphere. The capsule with encased samples would be retrieved from Earth's surface and studied.
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| Dynamic Science Experiment (DSE) | |||
| The experiment will primarily utilize the X band X band The X band is a segment of the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of X band is rather indefinitely set at approximately 7.0 to 11.2 gigahertz . In radar engineering, the frequency range is specified... telecommunications system to conduct radio science on Wild 2, to determine the mass of the comet; secondarily the inertial measurement unit is utilized to estimate the impact of large particle collisions on the spacecraft.
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Sample collection
- Comet and interstellar particles are collected in ultra low density aerogelAerogelAerogel is a synthetic porous material derived from a gel, in which the liquid component of the gel has been replaced with a gas. The result is a solid with extremely low density and thermal conductivity...
. The tennis racket-sized collector tray contains ninety blocks of aerogel, providing more than 1,000 square centimeters of surface area to capture cometaryComet dustComet dust refers to cosmic dust that originates from a comet. Comet dust can provide clues to comets' origin.-Dust and comet origin:The models for the origin of comets are: 1) the interstellar model, 2) the solar system model, 3) primordial rubble piles 4) aggregation of planetesimals in the dust...
and interstellar dust grains.
- To collect the particles without damaging them, a siliconSiliconSilicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
-based solid with a porous, sponge-like structure is used in which 99.8 percent of the volume is empty space. Aerogel is 1,000 times less dense than glassGlassGlass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
, another silicon-based solid. When a particle hits the aerogel, it becomes buried in the material, creating a long track, up to 200 times the length of the grain. The aerogel was packed in an aluminum grid and fitted into a Sample Return Capsule (SRC), which was to be released from the spacecraft as it passed Earth in 2006.
- To analyze the aerogel for interstellar dust, one million photographs will be needed to image the entirety of the sampled grains. The images will be distributedGrid computingGrid computing is a term referring to the combination of computer resources from multiple administrative domains to reach a common goal. The grid can be thought of as a distributed system with non-interactive workloads that involve a large number of files...
to home computer users to aid in the study of the data using a program titled, Stardust@homeStardust@homeStardust@home is a citizen science project that encourages volunteers to search images for tiny interstellar dust impacts. The project began providing data for analysis on August 1, 2006....
.
Mission profile
| Timeline of travel | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Earth return of sample capsule.
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Flyby encounter with Tempel 1.
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End of mission.
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Launch and trajectory
Stardust was launched on February 7, 1999, at 21:04:15 UTC by the National Aeronautics and Space Administration from Space Launch Complex 17A at the Cape Canaveral Air Force StationCape Canaveral Air Force Station
Cape Canaveral Air Force Station is an installation of the United States Air Force Space Command's 45th Space Wing, headquartered at nearby Patrick Air Force Base. Located on Cape Canaveral in the state of Florida, CCAFS is the primary launch head of America's Eastern Range with four launch pads...
in Florida, aboard a Delta II 7426
Delta II
Delta II was an American space launch system, originally designed and built by McDonnell Douglas. Delta II is part of the Delta rocket family and was in service from 1989 until November 1, 2011...
launch vehicle. The complete burn sequence lasted for 27 minutes bringing the spacecraft into a heliocentric orbit that would bring the spacecraft around 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...
and past Earth
Earth
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...
for a gravity assist maneuver in 2001, to reach asteroid Annefrank in 2002 and comet Wild 2 in 2004 at a low flyby velocity of 6.1 km/s. In 2004, the direction of the spacecraft performed a deep space maneuver that would allow it to pass by Earth a second time in 2006, to release the Sample Return Capsule for a landing in Utah.
During the second encounter with Earth, Stardust was put into a "divert maneuver" immediately after the capsule was released. The maneuver corrected the spacecraft direction to avoid entering the atmosphere. Under twenty kilograms of propellant remained onboard after the maneuver.
On January 29, 2004, the spacecraft was put in hibernation mode with only the solar panels and receiver active, in a three-year heliocentric orbit that would return it to Earth vicinity on January 14, 2009.
A subsequent mission extension was approved on July 3, 2007, to bring the spacecraft back to full operation for a flyby of comet Tempel 1 in 2011. The mission extension was the first to revisit a small solar system body
Small solar system body
A small Solar System body is an object in the Solar System that is neither a planet nor a dwarf planet, nor a satellite of a planet or dwarf planet:...
and used the remaining propellant, signaling the end of the useful life for the spacecraft.
Encounter with Annefrank
On November 2, 2002, at 04:50:20 UTC, Stardust encountered asteroid 5535 Annefrank from a distance of 3079 km (1,913 mi). The solar phase angle ranged from 130 deg to 47 degrees during the period of observations. This encounter was used primarily as an engineering test of the spacecraft and ground operations in preparation for the encounter with comet Wild 2 in 2003.Encounter with Wild 2
On January 2, 2004, at 19:21:28 UTC, Stardust encountered Comet Wild 2 on the sunward side with a relative velocity of 6.1 km/s at a distance of 237 km (147 mi). The original encounter distance was planned to be 150 km (93 mi), but this was changed after a safety review board increased the closest approach distance to minimize the potential for catastrophic dust collisions.The relative velocity between the comet and the spacecraft was such that the comet actually overtook the spacecraft from behind as they traveled around the Sun. During the encounter, the spacecraft was on the sun-lit side of the nucleus, approaching at a solar phase angle of 70 degrees, reaching a minimum angle of 3 degrees near closest approach and departing at a phase angle of 110 degrees.
During the flyby the spacecraft deployed the Sample Collection plate to collect dust grain samples
Comet dust
Comet dust refers to cosmic dust that originates from a comet. Comet dust can provide clues to comets' origin.-Dust and comet origin:The models for the origin of comets are: 1) the interstellar model, 2) the solar system model, 3) primordial rubble piles 4) aggregation of planetesimals in the dust...
from the coma
Coma (cometary)
frame|right|The [[153P/Ikeya-Zhang|comet Ikeya-Zhang]] exhibiting a bright, condensed coma In astronomy, a coma is the nebulous envelope around the nucleus of a comet. It is formed when the comet passes close to the Sun on its highly elliptical orbit; as the comet warms, parts of it sublimate...
, and took detailed pictures of the icy nucleus
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...
.
Sample return
On January 16, 2006, at 05:57:00 UTC, the Sample Return Capsule successfully separated from Stardust and re-entered the Earth's atmosphere at 09:57:00 UTC, at a velocity of 12.9 km/s, the fastest re-entry speed into Earth's atmosphere ever achieved by a man-made object. The capsule then parachuted to the ground, finally landing at 10:10:00 UTC at the Utah Test and Training Range (40°21.9′N 113°31.25′W), near the U.S. Army Dugway Proving GroundDugway Proving Ground
Dugway Proving Ground is a US Army facility located approximately 85 miles southwest of Salt Lake City, Utah in southern Tooele County and just north of Juab County...
. The capsule was then transported by military aircraft from Utah to Ellington Air Force Base in Houston, Texas
Houston, Texas
Houston is the fourth-largest city in the United States, and the largest city in the state of Texas. According to the 2010 U.S. Census, the city had a population of 2.1 million people within an area of . Houston is the seat of Harris County and the economic center of , which is the ...
, then transferred by road to the Planetary Materials Curatorial facility at Johnson Space Center in Houston to begin analysis. NASA officials claimed "prudence" dictated that the materials be transferred in secrecy, though no security threats were apparent.
Sample processing
Microscopic
The microscopic scale is the scale of size or length used to describe objects smaller than those that can easily be seen by the naked eye and which require a lens or microscope to see them clearly.-History:...
specks of dust were embedded in aerogel
Aerogel
Aerogel is a synthetic porous material derived from a gel, in which the liquid component of the gel has been replaced with a gas. The result is a solid with extremely low density and thermal conductivity...
collector. Ten particles were found to be at least 100 micrometers
Micrometre
A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...
and the largest approximately 1000 micrometers. An estimated 45 interstellar dust impacts were also found on the sample collector, which reside on the back side of the cometary dust collector. Dust grains are being observed and analyzed by a volunteer team through the distributed computing
Distributed computing
Distributed computing is a field of computer science that studies distributed systems. A distributed system consists of multiple autonomous computers that communicate through a computer network. The computers interact with each other in order to achieve a common goal...
project, Stardust@Home
Stardust@home
Stardust@home is a citizen science project that encourages volunteers to search images for tiny interstellar dust impacts. The project began providing data for analysis on August 1, 2006....
.
In December 2006, seven papers were published in the scientific journal, Science
Science (journal)
Science is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....
, discussing initial details of the sample analysis. Among the findings are: a wide range of organic compounds, including two that contain biologically usable nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
; indigenous aliphatic hydrocarbons
Aliphatic compound
In organic chemistry, aliphatic compounds are acyclic or cyclic, non-aromatic carbon compounds.Thus, aliphatic compounds are opposite to aromatic compounds.- Structure :...
with longer chain lengths than those observed in the diffuse interstellar medium
Interstellar medium
In astronomy, the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space...
; abundant amorphous silicate
Silicate
A silicate is a compound containing a silicon bearing anion. The great majority of silicates are oxides, but hexafluorosilicate and other anions are also included. This article focuses mainly on the Si-O anions. Silicates comprise the majority of the earth's crust, as well as the other...
s in addition to crystalline silicates such as olivine
Olivine
The mineral olivine is a magnesium iron silicate with the formula 2SiO4. It is a common mineral in the Earth's subsurface but weathers quickly on the surface....
and pyroxene
Pyroxene
The pyroxenes are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. They share a common structure consisting of single chains of silica tetrahedra and they crystallize in the monoclinic and orthorhombic systems...
, proving consistency with the mixing of solar system and interstellar matter, previously deduced spectroscopically from ground observations; hydrous silicates and carbonate minerals were found to be absent, suggesting a lack of aqueous processing of the cometary dust; limited pure carbon (CHON)
CHON
CHON is an mnemonic acronym for the four most common elements in living organisms: carbon, hydrogen, oxygen, and nitrogen....
was also found in the samples returned; methylamine
Methylamine
Methylamine is the organic compound with a formula of CH3NH2. This colourless gas is a derivative of ammonia, but with one H atom replaced by a methyl group. It is the simplest primary amine. It is sold as a solution in methanol, ethanol, THF, and water, or as the anhydrous gas in pressurized...
and ethylamine
Ethylamine
Ethylamine is an organic compound with the formula CH3CH2NH2. This colourless gas has a strong ammonia-like odor. It is miscible with virtually all solvents and is considered to be a weak base, as is typical for amines. Ethylamine is widely used in chemical industry and organic...
was found in the aerogel but was not associated with specific particles.
In 2010 Dr Andrew Westphal announced that Stardust@home
Stardust@home
Stardust@home is a citizen science project that encourages volunteers to search images for tiny interstellar dust impacts. The project began providing data for analysis on August 1, 2006....
volunteer Bruce Hudson found a track (labeled "I1043,1,30") among the many images of the aerogel that may contain an interstellar dust grain. The program allows for any volunteer discoveries to be recognized and named by the volunteer. Hudson named his discovery, Orion.
In April 2011, scientists from the University of Arizona
University of Arizona
The University of Arizona is a land-grant and space-grant public institution of higher education and research located in Tucson, Arizona, United States. The University of Arizona was the first university in the state of Arizona, founded in 1885...
discovered evidence for the presence of liquid water in a Comet Wild 2. They have found iron and copper sulfide
Copper sulfide
Copper sulfides describe a family of chemical compounds and minerals with the formula CuxSy. Both minerals and synthetic materials comprise these compounds. Some copper sulfides are economically important ores....
minerals that must have formed in the presence of water. The discovery shatters the existing paradigm that comets never get warm enough to melt their icy bulk.
New Exploration of Tempel 1 (NExT)
On March 19, 2006, Stardust scientists announced that they were considering the possibility of redirecting the spacecraft on a secondary mission to image Tempel 1. The comet was previously the target of the Deep Impact mission in 2005, sending an impactor into the surface. The possibility of this extension could be vital for gathering images of the impact crater Deep Impact was unsuccessful in capturing due to dust from the impact, obscuring the surface.On July 3, 2007 the mission extension was approved and renamed New Exploration of Tempel 1 (NExT). This investigation will provide the first look at the changes to a comet nucleus produced after a close approach to the sun. NExT also will extend the mapping of Tempel 1, making it the most mapped comet nucleus to date. This mapping will help address the major questions of comet nucleus geology. The flyby mission was expected to consume the remaining fuel, signaling the end of the operability for the spacecraft.
The mission objectives included the following:
Primary objectives
- Extend the current understanding of the processes that affect the surfaces of comet nuclei by documenting the changes that have occurred on comet Tempel 1 between two successive perihelion passages, or orbits around the sun.
- Extend the geologic mapping of the nucleus of Tempel 1 to elucidate the extent and nature of layering, and help refine models of the formation and structure of comet nuclei.
- Extend the study of smooth flow deposits, active areas and known exposure of water ice.
Secondary objectives
- Potentially image and characterize the crater produced by Deep Impact in July 2005, to better understand the structure and mechanical properties of cometary nuclei and elucidate crater formation processes on them.
- Measure the density and mass distribution of dust particles within the coma using the Dust Flux Monitor Instrument instrument.
- Analyze the composition of dust particles within the coma using the Comet and Interstellar Dust Analyzer instrument.
Encounter with Tempel 1
On February 15, 2011, at 04:42:00 UTC, Stardust-NExT encountered Tempel 1 from a distance of 181 km (112 mi). An estimated 72 images were acquired during the encounter. These showed changes in the terrain and revealed portions of the comet never seen by Deep Impact. The impact site from Deep Impact was also observed, though it was barely visible due to material settling back into the crater..End of mission
On March 24, 2011, Stardust conducted a burn to consume its remaining fuel. The spacecraft was running on fumes and Scientists hoped the data collected would help in the development of a more accurate system for estimating fuel levels on spacecraft. After the data had been collected, no further antenna aiming was possible and the transmitter was switched off. The spacecraft sent an acknowledgement from approximately 312000000 kilometre away in space.See also
- GenesisGenesis (spacecraft)The Genesis spacecraft was a NASA sample return probe which collected a sample of solar wind and returned it to Earth for analysis. It was the first NASA sample return mission to return material since the Apollo Program, and the first to return material from beyond the orbit of the Moon...
- HayabusaHayabusawas an unmanned spacecraft developed by the Japan Aerospace Exploration Agency to return a sample of material from a small near-Earth asteroid named 25143 Itokawa to Earth for further analysis....
- List of unmanned spacecraft by program
- Robotic spacecraftRobotic spacecraftA robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...
- Space explorationSpace explorationSpace exploration is the use of space technology to explore outer space. Physical exploration of space is conducted both by human spaceflights and by robotic spacecraft....
- Space probeSpace probeA robotic spacecraft is a spacecraft with no humans on board, that is usually under telerobotic control. A robotic spacecraft designed to make scientific research measurements is often called a space probe. Many space missions are more suited to telerobotic rather than crewed operation, due to...
- Timeline of artificial satellites and space probesTimeline of artificial satellites and space probesThis timeline of artificial satellites and space probes includes unmanned spacecraft including technology demonstrators, observatories, lunar probes, and interplanetary probes. First satellites from each country are included. Not included are most earth science satellites, commercial satellites or...
- Timeline of first orbital launches by country
- Timeline of planetary exploration