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Night of the Perseids

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Measuring Cosmic Rays at the Edge of Space

It’s a bird!  It’s a plane!  It’s a… SuperTIGER?

No, that’s not the latest superhero spinoff movie - it’s an instrument launching soon from Antarctica! It’ll float on a giant balloon above 99.5% of the Earth’s atmosphere, measuring tiny particles called cosmic rays.

Right now, we have a team of several scientists and technicians from Washington University in St. Louis and NASA at McMurdo Station in Antarctica preparing for the launch of the Super Trans-Iron Galactic Element Recorder, which is called SuperTIGER for short. This is the second flight of this instrument, which last launched in Antarctica in 2012 and circled the continent for a record-breaking 55 days.  

SuperTIGER measures cosmic rays, which are itty-bitty pieces of atoms that are zinging through space at super-fast speeds up to nearly the speed of light. In particular, it studies galactic cosmic rays, which means they come from somewhere in our Milky Way galaxy, outside of our solar system.

Most cosmic rays are just an individual proton, the basic positively-charged building block of matter. But a rarer type of cosmic ray is a whole nucleus (or core) of an atom - a bundle of positively-charged protons and non-charged neutrons - that allows us to identify what element the cosmic ray is. Those rare cosmic-ray nuclei (that’s the plural of nucleus) can help us understand what happened many trillions of miles away to create this particle and send it speeding our way.

The cosmic rays we’re most interested in measuring with SuperTIGER are from elements heavier than iron, like copper and silver. These particles are created in some of the most dynamic and exciting events in the universe - such as exploding and colliding stars.

In fact, we’re especially interested in the cosmic rays created in the collision of two neutron stars, just like the event earlier this year that we saw through both light and gravitational waves. Adding the information from cosmic rays opens another window on these events, helping us understand more about how the material in the galaxy is created.

Why does SuperTIGER fly on a balloon?

While cosmic rays strike our planet harmlessly every day, most of them are blocked by the Earth’s atmosphere and magnetic field.  That means that scientists have to get far above Earth - on a balloon or spacecraft - to measure an accurate sample of galactic cosmic rays.  By flying on a balloon bigger than a football field, SuperTIGER can get to the edge of space to take these measurements.  

It’ll float for weeks at over 120,000 feet, which is nearly four times higher than you might fly in a commercial airplane. At the end of the flight, the instrument will return safely to the ice on a huge parachute. The team can recover the payload from its landing site, bring it back to the United States, repair or make changes to it, if needed, and fly it again another year!

There are also cosmic ray instruments on our International Space Station, such as ISS-CREAM and CALET, which each started their development on a series of balloons launched from Antarctica. The SuperTIGER team hopes to eventually take measurements from space, too.  

Why do we launch from Antarctica?

McMurdo Station is a hotspot for all sorts of science while it’s summer in the Southern Hemisphere (which is winter here in the United States), including scientific ballooning.  The circular wind patterns around the pole usually keep the balloon from going out over the ocean, making it easier to land and recover the instrument later. And the 24-hour daylight in the Antarctic summer keeps the balloon at a nearly constant height to get very long flights - it would go up and down if it had to experience the temperature changes of day and night. All of that sunlight shining on the instrument’s array of solar cells also gives a continuous source of electricity to power everything.

Antarctica is an especially good place to fly a cosmic ray instrument like SuperTIGER. The Earth’s magnetic field blocks fewer cosmic rays at the poles, meaning that we can measure more particles as SuperTIGER circles around the South Pole than we would at NASA scientific ballooning sites closer to the Earth’s equator.  

The SuperTIGER team is hard at work preparing for launch right now - and their launch window opens soon! Follow @NASABlueshift for updates and opportunities to interact with our scientists on the ice.

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