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Mission Schedule

Launch: February 1999Encounter: January 2004

Earth Return: January 2006

The STARDUST spacecraft was launched into space on February 7, 1999. Its destination - Comet Wild 2 (pronounced “Vilt 2); its mission, to capture cometary materials before returning to earth in 2006.

STARDUST will encounter Wild 2 in 2004, while nearly 390 million kilometers (242 million miles) from earth. En Route to the comet, the spacecraft will collect interstellar dust particles. These samples will provide a window into the distant past, helping scientists around the world to unravel the mysteries surrounding the birth and evolution of our Solar System.

The spacecraft was designed and built by Lockheed Martin Astronautics Operations (LMAO), Denver, Colorado, for the Jet Propulsion Laboratory (JPL), California Institute of Technology. JPL manages the STARDUST mission for the National Aeronautics and Space a Administration (NASA) under direction of Principal Investigator, Professor Donald Brownlee at the University of Washington.

What instruments are aboard STARDUST?

The Navigation Camera (NC), an engineering subsystem, will be used to optically navigate the spacecraft upon approach to the comet. This will allow the spacecraft to achieve the proper flyby distance, near enough to the nucleus, to assure adequate dust collection

The CIDA instrument is a mass spectrometer, which separates ions' masses by comparing differences in their flight times. The operating principle ofthe instrument is the following: when a dust particle hits the target of the instrument, ions are extracted from it by the electrostatic grid. Depending on the polarity of the target positive or negative ions can be extracted. The extracted ions move through the instrument, are reflected in the reflector, and detected in the detector. Heavier ions take more time to travel through the instrument than lighter ones, so the flight times of the ions are then used to calculate

their masses.

The primary objective of the STARDUST mission is to capture both comet coma samples and contemporary interstellar grains moving at high velocity with minimal heating and other effects of physical alteration.

The purpose of the Whipple Shield is to protect the spacecraft from damage from impacting dust particles. The Dust Flux Monitor Instrument (DFMI) is used to monitor the dust particle impacts and transmit this information directly back to Earth.

The spacecraft will encounter Wild 2 at 97.5 days past perihelion at 1.86 AU from the Sun when Wild 2 is far from its peak active period and relatively safe for a close flyby. The spacecraft will approach Wild 2 from above its orbital plane, then dip slightly below it. The image shows the geometry of the flyby, which will be at 150 km on the sun side.

Interstellar Particle Collection

Cometary Particle CollectionAlthough the dust/volatiles ratio varies greatly from comet to comet, the volatile material is a significant fraction of the mass of every comet nucleus. Because the volatile and refractory components of comets may have condensed in very different locations and environments, complete knowledge of the composition of a comet requires study ofboth phases. The objectives of the volatile collection experiment are to determine the elemental and isotopic compositions of cometary volatiles. Of special interest are the biogenic elements (C,H,N,O,P and S) and their molecules. Some molecular bonds in large molecules can remain unbroken in a 6 km/s impact, as shown by laboratory experiment. At the very least, the obtainable information on gaseous components will be elemental andIsotopic.

The comet samples will be collected during a 6.1 km/s flyby of Comet Wild 2. At this extraordinarily low flyby speed, coma dust in the 1 to 100 micron size range will be captured by impact into ultra-low density aerogel and similar microporous materials. Particle collection at this speed has been extensively demonstrated in laboratory simulations and Shuttle flights and we have shown that the comet dust collection can be done with acceptable levels of sample alteration.

This phase of the STARDUST mission begins two weeks before Earth re-entry and ends when the SRC is transferred to its ground-handling team. The planned landing site is the Utah Test and Training Range (UTTR) as shown. The Space Return Capsule (SRC) will be recovered by helicopter or ground vehicles and transported to a staging area at UTTR for retrieval of the sample canister. The canister will then be transported to the planetary materials curatorial facility at Johnson Space Center. The Earth Return is divided into four sub-phases:

1) Earth Approach2) Entry3) Terminal4) Recovery

Earth Return of Sample Particles

The primary objective of the STARDUST mission is to capture both comet coma samples and contemporary interstellar grains moving at high velocity with minimal heating and other effects of physical alteration. To achieve this a new intact capture technology has been developed over the past decade specifically for comet flyby sample return missions in which hypervelocity particles are captured by impact into under-dense, microporous media known as aerogel.

This is not like conventional foams, but is a rather special porous material that has extreme microporosity at the micron scale. Aerogel is composed of individual features only a few nanometers in size, linked in a highly porous dendritic-like structure.

This exotic material has many unusual properties, such as uniquely low thermal conductivity, refractive index, and sound speed, in addition to its exceptional ability to capture hypervelocity dust.

Aerogel is made by high temperature and pressure critical point drying of a gel composed of colloidal silica structural units filled with solvents. Over the past several years, aerogel has been made and flight qualified at the Jet Propulsion Laboratory.

When hypervelocity particles are captured in aerogel they produce narrow cone-shaped tracks, that are hollow and can easily be seen in the highly transparent aerogel by using a stereo microscope. The cone is largest at the point of entry, and the particle is collected intact at the point of the cone.

Aerogel Collector Grid(above)

Dr. Peter Tsou, JPL (above)

A captured particle. Aerogel Magnified 6500x (above)