Of all of the missions sent into the cosmos, the 2004 Star Dust mission was one of the most unusual.
Scientists have long wondered what comets are made of and have spent years trying to analyze and deduce, without actual proof.
Theories about comets included that they contain materials from the beginning of the solar system, preserved in ice.
These ancient building blocks could give us a lot of information about the formation of our solar system and the development of the various planets, including Earth.
Some of the comet dust was also thought to be older than our sun and these were called stardust or pre-solar grains.
To validate scientific theories, the Star Dust mission was established and it had a goal of getting close to a comet, collecting some of the dust and debris, and then return the uncontaminated samples to Earth for study.
Scientists expected the materials to contain ice that had been preserved for billions of years.
The challenge was to be able to collect the stardust without harming them or changing them in any way, and to just preserve them.
Capturing the stardust was tricky because the particles were traveling at speeds up to six times faster than a speeding rifle bullet.
Even though these particles were tinier than a grain of sand, the high speed capture hitting hard might damage their chemical composition or shape or even destroy them completely.
To achieve capture, scientists developed a material substance called “aerogel.” This substance is silicon-based, and although solid, it also has a sponge-like structure, is very porous, and 99.8% of the volume is empty space.
If you look at aerogel is almost appears clear and wispy, with a smoky blue appearance.
When a material hits aerogel it is buried in the light-weight gel and creates a carrot-shaped track that is almost 200 times its own length.
The aerogel slows the material down until it stops and preserves it without harming it.
The “tracks” are used by scientists to locate the tiny particles that are held within the aerogel.
Aerogel isn’t like any type of foam that we are all familiar with as it is a special substance that has what is called “extreme microporosity on a micron scale.”
It’s made up of individual features that can only be seen in a micron telescope and are made up of only a few nanometers in size.
These are linked in a highly porous dendritic-like (tree-like) structure.
Aerogel is an exotic substance with a lot of unusual properties including low thermal conductivity.
Aerogel was made and flight qualified at JPL (Jet Propulsion Laboratory) and was also used in the Mars Pathfinder mission.
It’s strength and durability in space launches and environments made it the perfect substance for the Stardust mission and it has been recovered on other Shuttle flights, Eureca, and Spacelab II.
The Stardust Mission had a goal of making a close flyby to the comet Wild-2, collecting some of the interstellar dust in the onboard aerogel, and then returning the samples back to Earth two years later.
After landing in the Utah desert, scientists collected the samples and began examining them to confirm their belief that comets carried materials that were ejected from the early formation of our solar system.
The samples from the Stardust Mission astounded scientists.
The found out that most of the materials captured weren’t rocky materials, but instead formed inside the solar system at extremely high and white-hot temperatures.
The samples verified that although comets do have a lot of ice, they are made up of a mix of materials created under the conditions of both “fire and ice.”
Comets are formed out in the far regions of space, well beyond Neptune, but the bulk of their mass are the rocks and they are formed closer to the Sun in areas that are hot enough to evaporate our bricks.
The Stardust samples from the Wild 2 comet also contain pre-solar “stardust” grains that are considered to be very rare and are identified by their unusual composition.
- Scientists were excited to find pieces of what are called CAIs and chondrules in the materials collected.
These are so rare that when the results was presented at a conference of 600 scientists they were shocked and astounded.
The discovery of those materials proved that a lot of matter formed within our inner solar system and was transported to the edge of our younger solar system during the first formation of comets.
This means that a majority of the rocks within the comet were formed closed to the sun and then sprayed out throughout the younger solar system and incorporated into moons and planets.
- Another major surprise that Stardust gave us was the discovery in 2009 that the materials contained amino acid glycine in such tiny particles that were moving at high speeds.
This important find showed that our planet may have received at least one amino acid delivered by comets.
- Scientists had a theory that when the dust escaped the comet the particle impact speed on the spacecraft would increase with time, then hit a peak, and then be reduced as the nucleus (center) of the comet disappeared behind the spacecraft.
Surprisingly, the rate of impact changed in varying spurts which was caused by the changing comet dust flowing off of the nucleus, breaking up, and creating cometary “dirt clouds.”
It seems that the nucleus and ice kind of acted as a “glue” to hold everything together.
The Stardust Mission had a camera as part of its equipment and took 72 images during the pass of the comet.
Everyone thought that the comet would be a rather boring object, comparing it to a black potato.
The images sent back showed something quite different including kilometer-sized deep holes surrounded by vertical, cliffs, flat-topped hills bounded by cliffs, spiky pinnacles pointed skyward that were hundreds of meters tall, many dust jets of gas escaping into space including 2 that came from the night side of the comet.
This last part was a bit shocking because scientists thought the dark side was inactive.
After returning to Earth, the spacecraft was recycled for the Stardust-Next mission that did a flyby on Feb. 14, 2011 of the Tempel 1 comet.
Q&A:
- What is the material on the Stardust Mission that captured the comet samples?
aerogel - What is the name of the comet that the Stardust Mission examined?
Wild 2 - Where is the bulk of the mass of comets formed?
close to the sun - What substance was found in the comet materials that could have affected Earth?
amino acid glycine - What surprising discovery was seen on the dark side of the comet?
dust jets of gas - How many images did the Stardust 2 mission take?
72