Antimatter, Dark Matter And Strangelets – Oh My!

The Huntsville-based NanoSail-D team stands with the fully deployed sail. The sail is made of an ultra-thin polymer coated with aluminum. Credit: NASA

I’d almost given up seeing NanoSail-D, the 107-square foot solar sail that was deployed on January 20 this year. On a pass a month ago, I saw just one brief flash. Last night, the sail was slated to zip north of Saturn and into Bootes not far from Arcturus around 9:15. To my complete surprise, it was a fantastic sight.

Since deployment, the sail has settled into a ‘flat spin’ as it orbits the Earth, meaning it’s turning round and round with its flat side parallel to the ground. This way it encounters less drag with the upper atmosphere. Depending on how sunlight strikes the sail’s surface as it crosses the observer’s sky, its brightness changes throughout a pass. Last night, it slowly pulsed from faint to bright and back again at least a dozen times. For a few seconds it even equaled brilliant Arcturus! It was fascinating to realize the changes I saw indicated a spinning craft. As the sail moved off to the north, it gradually faded, but I was still able to follow it in binoculars. Cool! Next time I’ll set up my camera.

If the weather's good, Duluth and region should see an excellent pass of NanoSail-D tonight (April 29). The sail looks like a moving 'star' that slowly brightens and dims as it follows the indicated path (green). Be sure to go out a few minutes before to get oriented and 'dark-adapt' your eyes. Created with Stellarium

NanoSail-D is a NASA project with the aim of testing the use of sails for possible attachment to defunct satellites so they can be safely burned up in Earth’s atmosphere when and where they need to be. This control is accomplished by the slow, steady drag of the sail against the upper atmosphere.

The sail originally orbited some 400 miles high but in the past three months has dropped 28 miles. Scientists expect it to continue orbiting the planet for a total of six months to a year. That means we’ll have plenty of viewing opportunities. And the lower it descends, the brighter and easier the sail will be to see.

Artist's view of the large-tent-sized NanoSail-D in orbit. Credit: NASA

Currently, mid-northern latitudes are in the middle of a series of both evening and morning passes. You can use the map above, which is good for the Duluth, Minn. region tonight, or go to the Heavens Above website, login and click on the NanoSail-D link. You’ll be shown a chart with times and brightnesses (mag or magnitude column). When the mag number is 2.0 or less, it’s worth your effort to go out for a look. Clicking on a particular date will take you to  general and detailed maps showing the sail’s path that night. One caveat: Despite the listed brightness, not every pass is visible to the eye. If you don’t see it the first time, try again another night.

The Alpha Magnetic Spectrometer will detect cosmic rays emitted by antimatter galaxies, dark matter and strangelets. Credit: MIT

Speaking of things flying across the sky, the space shuttle Endeavour was scheduled to liftoff this afternoon, but the launch has now been postponed for at least 48 hours due to malfunctioning heaters in the craft’s auxiliary power unit.

When it does take off, Endeavour will carry a unique instrument called an Alpha Magnetic Spectrometer (AMS) to the International Space Station. The device will be used to hunt for galaxies made of antimatter, study the nature of ‘dark matter’ and look for a theoretical form of matter called strangelets. All of these exotic phenomena make their presence known through ultra-high energy, fast-moving particles called cosmic rays.

Mix antimatter and matter and you get a big boom!

During the origin of the Big Bang, equal amounts of matter and antimatter should have been created. Antimatter looks and feels like regular matter, but the particles it’s made of have the opposite electric charge. On our solar systems, electrons have a negative charge, but antimatter electrons are positively charged. There are anti-hydrogen atoms made of oppositely charged electrons and protons. There may even be entire anti-planets, anti-stars and anti-galaxies out there.

If matter and antimatter come into contact, they annihilate each other in a tremendous explosion of energy. Maybe you saw the movie Angels & Demons, where actor Tom Hanks attempts to prevent a rogue group from destroying Vatican City using a dab of antimatter stolen from a particle accelerator lab. Once the antimatter breaches its containment system and comes in contact with air (regular matter) – KABOOM!

Since we don’t see any signs of antimatter explosions in the sky, scientists are hoping the AMS will detect a nucleus or two of anti-helium, which may have drifted into the neighborhood from a distant corner of the universe, perhaps from the realm of those theoretical antigalaxies.

Galaxy clusters like this one called Abell 1689 are held together by invisible dark matter. Without the pull of dark matter, the individual galaxies would go their own way. Credit: NASA/ESA

Dark matter comprises 83% of all the matter in the universe and not a single person knows what it is. While invisible, we can measure its gravitational effects. For instance, if it weren’t for the tug of dark matter, many galaxy clusters would simply fly apart. A leading theory says that it could be made of particles called neutralinos, which produce anti-electrons (antimatter) when they collide. If AMS find an excess of energetic neutralinos, we may well be on the road to understanding what this mysterious substance is.

Finally we come to strangelets. An atom is formed of tightly-packed nucleus of protons and neutrons surrounded by cloud-like electrons. A hydrogen atom has just one proton orbited by one electron. Typical carbon atoms have six protons, six neutrons and six electrons. If we could peer more closely, we’d see that protons and neutrons aren’t ‘solid balls’ but instead made of three smaller particles called quarks. Protons are composed of two ‘Up’ quarks and one ‘Down’ quark. Yes, the names are weird but they had to call them something. Scientists are known for their quirky sense of humor. Neutrons have two Down and one Up. Six types of quarks called ‘flavors’ are known: Up, Down, Top, Bottom, Charm and Strange.

A proton in the nucleus of an atom is made of two 'up' quarks and one 'down' quark. Credit: Arpad Horvath

Strangelets, if they exist, are particles made of Up, Down and Strange quarks. These oddballs may have been created along with protons and neutrons in the early universe or later during cosmic ray collisions. Finding strangelets might tell us whether tiny black holes, postulated to have formed in the early universe, exist or not. They may also be responsible for converting ordinary matter into the dark variety. Check out this short article to learn more.

The American physicist Richard Feynman once said: “Our imagination is stretched to the utmost, not as in fiction, to imagine things which are not really there, but just to comprehend those things which are there.”

(Some of the material for this blog was adapted from this NASA press release.)

1 Response

  1. la vie, c'est dur

    with apologies to the Bard of Avon: there are things in heaven and earth….that [our] philosophers [scientists]have not dreamth of…. excellent blog but it does make one’s head swin.

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