A particle fountain is a small but dangerous spatial anomaly that was encountered in an episode of Star Trek: Voyager, "Alice". In that episode, the sentient ship Alice compelled Tom Paris to take "her" to a particle fountain, describing it as her "home". Starfleet is said to have lost over a dozen ships attempting to study particle fountains and, consequently, the phenomenon was poorly-understood.

Little is known about interstellar particles in real astrophysics. The major form of heavy elements in interstellar space is in dust. This interstellar dust plays a major role in the formation of new stars and planetary systems. Our own Solar System formed from gas and dust in the interstellar medium 4.6 billion years ago. The heavy elements making up Earth and our bodies were once interstellar dust. But we don't even know what the typical interstellar dust grain looks like.

Interstellar dust was first discovered flowing across the Solar System by dust detectors aboard the Ulysses spacecraft in 1993 and was later confirmed by the Galileo mission to Jupiter. The particles were identified as coming from a location in the sky in the Constellation Ophiuchus, looking toward the center of the Milky Way Galaxy. Interstellar dust is small, ranging in size from 0.01 microns all the way up to 20 microns. They are made of different minerals such as silicates, graphitic carbon, hydrogenated amorphous carbon, alumina, and even diamond carbon.

Stardust was a NASA Discovery Mission that was launched in 1999 to visit a comet and collect and return dust from it for study on Earth. In addition, Stardust carried an equally important payload on the opposite side of the cometary collector: the first samples of contemporary interstellar dust ever collected. Certain types of ancient interstellar dust-older than the Solar System have been isolated from meteorites in the past and analyzed. However, the interstellar dust collected by Stardust comes directly from local interstellar space.