Canadian citizen-scientist discovers one of seven dust grains that may have formed around other stars
Thanks to the help of Midland, Ontario resident Bruce Hudson, NASA's Stardust comet sample-return mission may have discovered grains of dust that originate from beyond our solar system!
Back in 1999, NASA launched a spacecraft named Stardust, whose mission was to circle around the Sun twice, 'draft' behind a ball of ice and dirt named Comet Wild 2 for a little while, and then make one more spin around the Sun, swinging by Earth in the process to drop off some precious cargo. What was this cargo? Arrays of gel packs - filled with a remarkable substance called aerogel, which is 99.8 per cent air - that the spacecraft had twice exposed to space to potentially pick up grains from the interstellar dust stream, and then again while drafting the comet to capture material streaming off of it. Pulling in behind the comet to collect particles was a careful but fairly straight-forward part of the mission, but to collect the faster-moving interstellar particles, without having them be completely destroyed upon impacting the gel, took some more careful planning. The mission scientists liken our solar system passing through the interstellar dust stream like a car driving through a snowstorm.
NASA Stardust mission. Credit: S.Sutherland, adapted
"So what you're going to do is you drive your car in the direction of the wind," Andrew Westphal, a physicist at the UC Berkeley's Space Sciences Laboratory, told CBC News, "and you'll collect snowflakes gently on your back windscreen."
It took over seven years to get the gel packs pack on Earth after the mission started, and when they did, the NASA scientists were faced with a dilemma. The mission was a success. The gel packs were riddled with dust motes and the tracks they made as they penetrated the gel. However, the amount of dust they collected meant that it would take years to go through it all. In some projects like this, computers can be very useful to go through results, but in this case they needed the powers of the human brain to get anything truly meaningful out of it. So, after imaging all of the dust particles and tracks, they launched the Stardust@home project on the internet in 2006.
Participating in the project is fairly simple. You sign up, go through a quick tutorial to show you how the controls work, what you're looking for and how to tell true tracks from contamination or flaws in the gel, and then you dive right into the science. Up pops a page with a square image of a section of aerogel that's just a few hundred microns on a side. To the right of the image is a 'slidebar' of blue bars - move your cursor up and down this 'slidebar' and you change the depth of the view, from above the top surface of the gel, through the surface and all the way through to the bottom. Your job is to find the dust tracks in the gel - which can often take a keen eye to find, as these tracks are just a fraction of the width of a human hair - and then click on the lowest part of the track you can see. Going through all the images like this, with multiple people seeing each set of images to add their results, allows the science team to sift through all the chaff - things like flaws in the gel, dust on the camera lens and even tiny bits of the spacecraft chipped off by micrometeorites while in flight - so that they can just focus on the unusual incidences that need their attention, and the true finds.
One such true find has turned out to be fairly extraordinary. It was discovered by Bruce Hudson, of Midland, Ontario, and it not only could be out of this world, but also from outside of our solar system!
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