Story highlights
- NASA's Cassini spacecraft discovered 36 special cosmic particles near Saturn's orbit
- Scientists concluded that this dust is from outside our solar system
(CNN)NASA just discovered some special particles floating in our cosmic neighborhood.
The Cassini spacecraft, which has been orbiting Saturn since 2004, has detected alien dust that came from outside our solar system.
Scientists suspect that this dust is interstellar in origin because it moves fast and in different directions, compared to the dust found on Saturn, according to a recently published report in the journal of Science. And although this alien dust was faint, it had a distinct signature.
Cassini has been studying the gas giant and its moons. During its tenure, the spacecraft used its cosmic dust analyzer to sample millions of ice-rich dust grains.
Can we really go to another planet? 04:55
Most of the dust grains came from Saturn's moon Enceladus. The moon has a global ocean beneath its icy surface and it has active jets that spray water vapor and other particles into space.
Out of the millions of cosmic particles the spacecraft collected, 36 were special. These were alien dust grains. Scientists concluded that the dust came from interstellar space -- the void that exists between stars.
Scientists have come across alien dust in our solar system before, so the discovery is not unprecedented. In the 1990s, international researchers from the ESA/NASA Ulysses mission made an observation of foreign dust, which was traced back to an interstellar cloud.
"From that discovery, we always hoped we would be able to detect these interstellar interlopers at Saturn with Cassini. We knew that if we looked in the right direction, we should find them," said Nicolas Altobelli, Cassini project scientist at the European Space Agency and lead author of the study.
These microscopic dust particles were traveling at high speed through space when Cassini detected them. They were moving at a rate of 45,000 mph, a speed so fast the dust can essentially avoid being trapped by our sun's gravitational forces.
Photos: Cool unmanned space missions
Two new missions to Venus -- DAVINCI+ and VERITAS -- have been selected by NASA. These missions will shed light on how Venus became the inhospitable world it is today, despite the fact that it shares many characteristics with Earth.
Hide Caption
1 of 22
Photos: Cool unmanned space missions
This illustration shows the position of NASA's Voyager 1 and Voyager 2 probes outside the heliosphere, a protective bubble created by the sun that extends well past the orbit of Pluto.
Hide Caption
2 of 22
Photos: Cool unmanned space missions
SPHEREx, the Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer, will study the beginning and evolution of the universe and determine how common the ingredients for life are within the planetary systems found in our galaxy, the Milky Way. It is targeted to launch in 2024.
Hide Caption
3 of 22
Photos: Cool unmanned space missions
This illustration shows NASA's Dragonfly rotorcraft-lander approaching a site on Saturn's exotic moon, Titan. Taking advantage of Titan's dense atmosphere and low gravity, Dragonfly will explore dozens of locations across the icy world, sampling and measuring the compositions of Titan's organic surface materials to characterize the habitability of Titan's environment and investigate the progression of prebiotic chemistry.
Hide Caption
4 of 22
Photos: Cool unmanned space missions
NASA's Wide Field Infrared Survey Telescope, slated to launch in the mid-2020s, has been named the Nancy Grace Roman Space Telescope, after NASA's first chief astronomer.
Hide Caption
5 of 22
Photos: Cool unmanned space missions
This is an artist's concept of the Europa Clipper spacecraft, which will investigate Jupiter's icy moon.
Hide Caption
6 of 22
Photos: Cool unmanned space missions
Bright swaths of red in the upper atmosphere, known as airglow, can be seen in this image from the International Space Station. NASA's ICON mission will observe how interactions between terrestrial weather and a layer of charged particles called the ionosphere create the colorful glow.
Hide Caption
7 of 22
Photos: Cool unmanned space missions
NASA's Global-scale Observations of the Limb and Disk mission -- known as the GOLD mission -- will examine the response of the upper atmosphere to force from the sun, the magnetosphere and the lower atmosphere.
Hide Caption
8 of 22
Photos: Cool unmanned space missions
NASA's Transiting Exoplanet Survey Satellite launched in April and is already identifying exoplanets orbiting the brightest stars just outside our solar system. In the first three months since it began surveying the sky in July, it has found three exoplanets, with the promise of many more ahead.
Hide Caption
9 of 22
Photos: Cool unmanned space missions
This is an artist's concept of the Solar Probe Plus spacecraft approaching the sun. In order to unlock the mysteries of the corona, but also to protect a society that is increasingly dependent on technology from the threats of space weather, we will send Solar Probe Plus to touch the sun.
Hide Caption
10 of 22
Photos: Cool unmanned space missions
Breakthrough Starshot – This illustration shows light beams from Earth pushing a tiny spacecraft's sail. The proposed Breakthrough Starshot project would send hundreds of "nanocraft" space probes 4.37 light years away -- at speeds of up to 100 million miles an hour -- to to explore Alpha Centauri, our nearest star system. The ambitious project is many years away from becoming reality.
Hide Caption
11 of 22
Photos: Cool unmanned space missions
Breakthrough Starshot – Philanthropist Yuri Milner, left, and astrophysicist Stephen Hawking host a press conference to announce Breakthrough Starshot on Tuesday, April 12, 2016, in New York City. Facebook co-founder Mark Zuckerberg also sits on the mission's board of directors.
Hide Caption
12 of 22
Photos: Cool unmanned space missions
New Horizons – No spacecraft had ever gone to Pluto before NASA's New Horizons made its fly-by on July 14, 2015. The probe sent back amazing, detailed images of Pluto and its largest moon, Charon. It also dazzled scientists with new information about Pluto's atmosphere and landscape. New Horizons is still going today, heading out into the Kuiper Belt.
Hide Caption
13 of 22
Photos: Cool unmanned space missions
Curiosity Mars Rover – This image shows the Curiosity rover doing a test drill on a rock dubbed "Bonanza King" to see if it would be a good place to dig deeper and take a sample. Curiosity was launched in 2011, and it is the most advanced rover ever built. It's helping scientists determine whether Mars is, or ever was, habitable for life forms.
Hide Caption
14 of 22
Photos: Cool unmanned space missions
Kepler – The Kepler space observatory is the first NASA mission dedicated to finding Earth-size planets in or near the habitable zones of stars. Launched in 2009, Kepler has been detecting planets and planet candidates with a wide range of sizes and orbital distances. Yes, we are still finding new planets.
Hide Caption
15 of 22
Photos: Cool unmanned space missions
NEOWISE – NASA's infrared-wavelength space telescope called NEOWISE may help make us safer. The space telescope hunts for asteroids and comets, including those that could pose a threat to Earth. During its planned three-year survey through 2016, NEOWISE will identify near-Earth objects, gather data on their size and take other measurements. The probe was launched on December 14, 2009, for its original mission -- to perform an all-sky astronomical survey. The probe was put in hibernation for several years, but it was fired up again in December 2013 to hunt for asteroids. Its images are now available to the public online.
Hide Caption
16 of 22
Photos: Cool unmanned space missions
Dawn – NASA's Dawn spacecraft began orbiting the dwarf planet Ceres in March. Scientists were surprised by the large white spots shining on Ceres, seen above. On its way to Ceres, Dawn spent time studying the proto-planet Vesta in 2001. Ceres and Vesta are the two most massive bodies in the main asteroid belt between Mars and Jupiter. The mission, launched in 2007, is giving scientists new knowledge of how the solar system formed and evolved.
Hide Caption
17 of 22
Photos: Cool unmanned space missions
Deep Impact/EPOXI – NASA's Deep Impact spacecraft was launched on January 12, 2005, and it traveled 268 million miles (431 million kilometers) to hurl its coffee table-sized probe into comet Tempel 1 on July 4, 2005. This image of Tempel 1 was taken by Deep Impact's camera 67 seconds after the probe hit the comet. Scattered light from the collision saturated the camera's detector and caused the bright splash seen in this image. The Deep Impact mission was supposed to end a few weeks later, but NASA approved an extension and renamed the spacecraft EPOXI and sent it on to fly by Comet Hartley 2 in November 2010. The probe stopped communicating with mission managers in September 2013 and was declared lost.
Hide Caption
18 of 22
Photos: Cool unmanned space missions
Cassini – The Cassini spacecraft ended its mission in 2017. The probe was launched on October 15, 1997, from Cape Canaveral Air Force Station in Florida. It arrived at Saturn on June 30, 2004. The spacecraft dropped a probe called Huygens to the surface of Saturn's moon Titan. It was the first landing on a moon in the outer solar system.
Hide Caption
19 of 22
Photos: Cool unmanned space missions
Stardust – The Stardust spacecraft was launched on February 7, 1999, from Cape Canaveral, Florida. After traveling 3.5 billion miles (5.6 billion kilometers), the spacecraft made history by capturing images of asteroid Annefrank and collecting samples of comet Wild 2 and successfully returning them to Earth. It also took spectacular images of comet Tempel 1. The probe's mission ended on March 25, 2011, when mission managers put it in safe mode and turned off the transmitter for the last time.
Hide Caption
20 of 22
Photos: Cool unmanned space missions
Surveyor – Surveyor 1 was the first U.S. spacecraft to make a soft landing on the Moon. The program ran during the mid-1960s and was declared a success. The program's focus eventually switched to support of the Apollo program.
Hide Caption
21 of 22
Photos: Cool unmanned space missions
Explorer 1 – A model of Explorer 1, America's first satellite, is held by, from left, NASA official William Pickering, scientist James Van Allen and rocket pioneer Wernher von Braun. The team was gathered at a news conference at the National Academy of Sciences in Washington to announce the satellite's successful launch. It had been launched a few hours before, on January 31, 1958.
Hide Caption
22 of 22
Unlike previous missions, Cassini was able to analyze the alien dust, which revealed the dust grains were made of minerals, not ice. The composition was primarily rock-forming elements such has magnesium, silicon, iron and calcium.
Stardust found in some meteorites are generally pristine and diverse because they have been preserved since the birth of our universe. But the particles Cassini picked up are not like that.
Instead, these particles pretty much have the same chemical makeup, which is surprising. Scientists theorize that when the dust was created from a dying star, it was destroyed and reformed, shaping similar cosmic particles every time.
"Cosmic dust is produced when stars die, but with the vast range of types of stars in the universe, we naturally expected to encounter a huge range of dust types over the long period of our study," said Frank Postberg of the University of Heidelberg, a co-author of the paper and co-investigator of Cassini's dust analyzer.
Understanding the makeup of interstellar dust can help scientists learn more about how stars, planets and, ultimately, our universe has taken shape.
