[10] A mission extension, codenamed NExT, culminated in February 2011 with Stardust intercepting Comet Tempel 1, a small Solar System body previously visited by Deep Impact in 2005.

On 14 August 2014, scientists announced the identification of possible interstellar dust particles from the Stardust capsule returned to Earth in 2006.

[1] Stardust was competitively selected in the fall of 1995 as a NASA Discovery Program mission of low-cost with highly focused science goals.

However, the risk of interplanetary contamination by alien life was judged low,[15] as particle impacts at over 450 metres per second (1,000 mph), even into aerogel, were believed to be terminal for any known microorganism.

The bus was primarily constructed with graphite fiber panels with an aluminum honeycomb support structure underneath; the entire spacecraft was covered with polycyanate, Kapton sheeting for further protection.

Information for spacecraft positioning was provided by a star camera using FSW to determine attitude (Stellar Compass), an inertial measurement unit, and two Sun sensors.

The arrays also included Whipple shields to protect the delicate surfaces from the potentially damaging cometary dust while the spacecraft was in the coma of Wild 2.

The tennis racket-sized collector tray contained ninety blocks of aerogel, providing more than 1,000 square centimeters of surface area to capture cometary and interstellar dust grains.

To collect the particles without damaging them, a silicon-based solid with a porous, sponge-like structure is used in which 99.8 percent of the volume is empty space.

The aerogel was packed in an aluminium grid and fitted into a Sample Return Capsule (SRC), which was to be released from the spacecraft as it passed Earth in 2006.

Each pair featured 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.

In 2004, the spacecraft performed a course correction that would allow it to pass by Earth a second time in 2006, to release the Sample Return Capsule for a landing in Utah in the Bonneville Salt Flats.

A subsequent mission extension was approved on 3 July 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.

[7] At 19:21:28 UTC, on 2 January 2004, Stardust encountered Comet Wild 2[34] on the sunward side with a relative velocity of 6.1 km/s at a distance of 237 km (147 mi).

[36] On 19 March 2006, Stardust scientists announced that they were considering the possibility of redirecting the spacecraft on a secondary mission to image Comet Tempel 1.

[42][failed verification] Peak deceleration was 34 g,[43] encountered 40 seconds into the reentry at an altitude of 55 km over Spring Creek, Nevada.

[42] The phenolic-impregnated carbon ablator (PICA) heat shield, produced by Fiber Materials Inc., reached a temperature of more than 2,900 °C during this steep reentry.

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 silicates 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;[49] hydrous silicates and carbonate minerals were found to be absent, suggesting a lack of aqueous processing of the cometary dust; limited pure carbon (CHON)[clarification needed] 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.

[55] The comet samples show that the outer regions of the early Solar System were not isolated and were not a refuge where interstellar materials could commonly survive.

Glycine has been detected in meteorites before and there are also observations in interstellar gas clouds, but the Stardust find is described as a first in cometary material.

Isotope analysis indicates that the Late Heavy Bombardment included cometary impacts after the Earth coalesced but before life evolved.