Date: May 16, 2011

Title: Why the Alpha Magnetic Spectrometer-2 Experiment is Really Cool

Podcaster: Marcel-Jan Krijgsman

Links: Mijn Dosis Universum (

Description: The space shuttle Endeavour is about to launch an experiment called the Alpha Magnetic Spectrometer-2. It’s an experiment that can detect dark matter, if it exists. This podcast will talk about what the Alpha Magnetic Spectrometer-2 is, what dark matter is and why AMS-2 could detect it, and why such an experiment is installed on a manned space station.

Bio: Marcel-Jan Krijgsman has been an astronomy- and spaceflight-enthusiast for about thirty years. He blogs (in Dutch) about spaceflight and astronomy, on a blog called Mijn Dosis Universum (, on whatever topic interests him.

Sponsor: This episode of 365 Days of Astronomy is sponsored by — NO ONE. We still need sponsors for many days in 2011, so please consider sponsoring a day or two. Just click on the “Donate” button on the lower left side of this webpage, or contact us at



My name is Marcel-Jan Krijgsman. Today I would like to talk to you about the Alpha Magnetic Spectrometer-2 experiment and why it is rather interesting.

First of all: I am not a scientist. At day I am a database administrator in the Netherlands. At night, I fight crime and I blog about spaceflight and astronomy. My blog is a Dutch blog and it is called

If all goes well, the space shuttle Endeavour will launch today with a unique experiment. Hopefully Endeavour’s mission STS-134 already has three weeks delay.

The experiment

The experiment is called the Alpha Magnetic Spectrometer-2. The name doesn’t reveal much to non-scientists. I know what a spectrometer does: it separates wavelengths of light to learn about properties of the material that emits or reflects light. But what is a Magnetic Spectrometer, let alone an Alpha Magnetic Spectrometer?

Turns out it’s a particle detector, like you can find in particle accelerators like the Large Hadron Collider. You might have seen those diagrams with curly lines from particle accelerators? It is called a particle decay pattern and the different paths of subatomic particles is caused under the influence of the magnetic field of a giant magnet. In the Large Hadron Collider you’ll find this magnet in the ATLAS detector. This detector is huge. It weighs 7000 tonnes.

The AMS-2 experiment is much like such a particle detector, but it is not as big as the ATLAS experiment. Still, it is a hefty 7000 kg or 15200 pounds.

AMS-2 will be launched to the International Space Station (ISS). You might ask why you would install an experiment like that on a manned space station? Isn’t that dangerous in some way? Well, although the magnet is 3000 times stronger than Earth’s magnetic field, outside the container, it’s magnetic field can’t not be felt. A smaller version of AMS-2, AMS-1, has been flown on a shuttle in 1998 and it went fine.

So why will AMS-2 be installed on ISS? For 2 reasons: energy and a permanent datalink. Space station ISS has huge solar panels that have energy to spare for AMS-2’s needs. Also ISS has a permanent data link to Earth. Astronauts for example can use it to connect to the Internet, and AMS-2 can use that connection to send it’s data to scientists on the ground.

There is another difference between AMS-2 and the ATLAS experiment. ATLAS is placed in a particle collider, where it can detect subatomic particles that come of collisions of particles, like protons. AMS-2 sits in space, waiting. For what actually?

Dark Matter

Well, this is where it get’s interesting. Although there are no colliding protons in large volumes available nearby, outside Earth’s atmosphere there are numerous unsuspecting particles that will pass through AMS-2.

There is one special kind of particles that scientists hope to find with AMS-2, and those are particles that make up dark matter. Actually, they say if dark matter exists, AMS-2 will be able to detect it.

So, what is dark matter? It’s a kind of invisible matter, because interacts with next to nothing. Still, scientists have found it must exist. It has been shown that some objects in the universe are attracted by the gravity of large missing masses.

Evidence for a large missing mass came from the WMAP satellite that was launched in 2001 to look for the background radiation of the Big Bang. Based on WMAP’s findings scientists calculated that only 4% of the total mass of the universe consists of baryonic matter. That is matter made of atoms, like you, me, the planets, stars and everything else we can see.

It was actually kind of embarrassing. All of a sudden we found we didn’t know 96% of the universe. Scientists called it dark matter and dark energy.

Of dark matter, which take up 22% of the universe’s mass, scientists have a hypothesis of what this matter could be. They proposed new particles we hadn’t detected yet.

Several experiments on Earth where started to find those particles. Want to guess how much we’ve found so far? 2 particles. That’s not nearly enough to base science on.

But AMS-2 will be able to detect those particles it they exists. And outside Earth’s atmosphere we make a better chance finding them.

But dark matter is not all AMS-2 will be able to detect. For example, it will be able to detect anti-matter. This anti-matter should be a left-over from the Big Bang, when almost equal amounts of matter and anti-matter where created. Matter and anti-matter reacted with eachother rather violently and the leftovers where mainly matter: like us. Still, there might be some anti-matter particles flying around that never encountered matter and are still thinking how anti-matter could have lost the match 13 billion years ago.

If we had our theories wrong in some way, and dark matter doesn’t exists and we don’t find anti-matter for some reason, even then, AMS-2 has an ace up it’s sleave.

AMS-2 is a versatile particle detector. It can detect all kinds of particles it encounters, even the ones we haven’t thought of yet. No matter what the AMS-2 experiment will find, it will be interesting and it will possibly rewrite physics books one day.

I thank you for listening. Oh, and about the crime fighting: my alter persona is Baryonic Man. Watch out evil doers!

End of podcast:

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