Once the sample return capsule is recovered, its contents will be immediately transported to its final destination, the planetary material curatorial facility at NASA's Johnson Space Center in Houston. The Johnson Space Center's curation laboratory is a special facility designed for payload cleaning and curation of samples returned from space missions. It includes facilities for the Apollo lunar samples, Antarctic meteorites, cosmic dust, samples from NASA's Genesis mission collecting solar particles, hardware exposed to the environment of space.

The laboratory consists of numerous cleanrooms maintained at varying degrees of cleanliness. The laboratory currently being developed for Stardust samples will be class 100. AA class 100 cleanroom maintains less than 100 particles larger than 0.5 microns in each cubic foot of air space (or about 3,530 particles per cubic meter of air).

Once safely at the curation laboratory, technicians will open the Stardust sample return capsule. The aerogel and its collection of comet and interstellar dust will be inspected, extracted, characterized, and made available to the scientific community for analysis.

The Stardust curation team has developed exacting techniques for the removal and analysis of captured grains from the silica aerogel in which it is embedded. They will continue to improve and practice these techniques before the comet samples are in their hands in 2006.

Most particles from a comet are smaller than the diameter of a human hair. The expected total mass of the sample returned by Stardust will probably be about 1 milligram -- less than a thimbleful. Though this sample quantity could seem small, to cometary scientists this celestial acquisition is nearly an embarrassment of riches. Abundant evidence indicates that solid samples from both cometary and interstellar sources are very fine-grained, most of them on the scale of a micron (1/50th the diameter of a human hair) or smaller. Because the Stardust science team is focused on these grains, they do not require a large sample mass. A single 100-micron cometary particle could be an aggregate composed of millions of individual interstellar grains.

The key information in these samples is retained at the micron level, and even aggregates of 10 microns in size are considered giant samples.

Planetary protection
The U.S. is a signatory to the United Nations' 1966 Treaty of Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies. Known as the "Outer Space Treaty," this document states in part that exploration of the Moon and other celestial bodies shall be conducted "so as to avoid their harmful contamination and also adverse changes in the environment of the Earth resulting from the introduction of extraterrestrial matter."

Comets are believed to be primordial bodies made up of material that is virtually unchanged since their creation when the solar system formed 4.6 billion years ago. This means that any evolutionary processes leading to the emergence of life have not occurred. There is no scientific reason to believe that bacteria or viruses or any other life exist on comets. One of the objectives of the Stardust mission is to investigate whether the chemical building blocks of life exist on comets. But even if such building blocks do reside there, comets have not provided the hospitable environment required over millions of years to accommodate the complex processes that could result in the emergence of even single-celled organic life.

On Stardust, all comet particles that are collected will be heated to extremely high temperature due to their impact speed on the aerogel collector. The temperature caused by the compression interaction between the aerogel and any given particle is calculated to be at least 1,000 C (roughly 1,800 F). In fact, the collector material literally melts to encapsulate the captured particles. Such high temperatures are naturally sterilizing. As a particle hits the aerogel sample collector, it will come to a dead stop within a microsecond, having traveled about 3 centimeters (1.2 inches) into the aerogel. By that point, the aerogel, which is silica-based, will have melted around the particle, trapping it in glass.

It should be noted that particles from space, including material from comets, fall onto Earth's surface at a rate of approximately 40,000 tons per year, and some of this material is believed to survive atmospheric entry without severe heating.