Questions from students

1. Have any dinosaur fossils been found in Antarctica, and what type of prehistoric animals had lived there? -- Kristen at Evergreen Mill Elementary School

   Yes, dinosaur fossils have been found in Antarctica. A lot more information can be found on the Zoom School and Discover Learning sites.

2. Have fossils been found in Antarctica that would support the Theory of Continental Drift? -- Katie at Evergreen Mill Elementary School

   A plant called Glossopteris was one of the first fossils used to support the Theory of Continental Drift. It is found on all the southern continents (South America, Africa, Australia, and Antarctica) and led Eduard Suess, an Austrian geologist, to suggest that the southern continents were at one point combined into one supercontinent, Gondwanaland. More info can be found on the Exploratorium site.

3. How many kinds of animal species live in Antarctica, and what is your favorite? -- Megan at Evergreen Mill Elementary School

   There are some invertebrates like nematodes (worms), but the only vertebrates (animals with bones) around McMurdo Station (where I was) are:

   • South Polar Skuas (a large seagull)
   • Adelie Penguins
   • Emperor Penguins
   • Several types of seals (Weddell seals are the most common, but there are also Leopard Seals and Crabeater Seals).
   
   I've got pictures of some of these on the wildlife page.

   My favorite was Adelie Penguins, but if I had seen Emperor Penguins, they might have become my favorite.

4. Have you seen any polar bears? -- Kelly at Evergreen Mill Elementary School

   No, polar bears are only found near the North Pole, not the South Pole. But even when I was launching balloons up in northern Canada, I didn't see any polar bears. There have never been polar bears in Antarctica.

5. Are there any volcanoes in Antarctica? If so, are any of them active? -- Kris at Evergreen Mill Elementary School

   Yes, there are many volcanoes on Antarctica, and a few of them are active. I was working with sight of the southernmost active volcano on the planet, Mt. Erebus, at 3794 meters (12,448 feet), and there are pictures of it on the website (see my November 21, 2003 journal entry, for example).

6. Could there have been any cold-blooded dinosaurs in Antarctica? -- Matt at Evergreen Mill Elementary School

   Antarctica was once closer to the equator and a lot warmer. Fossils of both tropical plants and dinosaurs (it is not known if dinosaurs were cold-blooded or not) have been found there. Even if dinosaurs were cold-blooded, in the Mesozoic Era (when dinosaurs roamed the Earth), Antarctica was warm enough to have them.

7. How is aerogel made? -- Old Bridge High School

   I've never made it myself, but I found a good website on how to make it at the Berkeley Lab.

8. Is there any way to tell what kind of interference a GCR (galactic cosmic ray) may have experienced on its way to TIGER? -- Old Bridge High School

   There is no way to tell the history of an individual GCR. It is possible to tell on a statistical (average) way some things about the travels of GCRs, i.e. their average age, how much matter they've passed through, etc. These have been determined with other cosmic ray instruments, not TIGER.

9. How does the new TIGER balloon compare with the balloons used in the past? -- Old Bridge High School

   This is the first year that 40 million cubic foot zero-pressure balloons have been launched from Antarctica (the new launch vehicle allows the bigger balloons to be launched). Before this, we (and others) flew on 28 million cubic foot (mcf) balloons. But both the 40 mcf and 28 mcf balloons are identical to balloons that have flown for years from other parts of the world.

10. Why is this program so important to the NASA and NOAA administrations? -- Old Bridge High School

    It is important to NASA because the scientific community (through independent reviews of our TIGER proposals for funding) has decided that understanding the origin of galactic cosmic rays is scientifically interesting and fits with NASA Office of Space Science's goals for research. NOAA isn't very interested in TIGER.

11. Is there any evidence or realistic possibility of the results being converted to the everyday world? -- Old Bridge High School

    TIGER does pure science and there are really not immediate practical results. This sort of research helps us understand the universe better and may have practical applications eventually, but exploration is often useful just for its own sake.

12. What is the Mechanical Technician (Dana Braun) in charge of doing concerning the program? -- Old Bridge High School

    He's done a lot of the actual assembly of the instrument - bolting together structure, attaching photomultiplier tubes, making and installing the thermal shields, etc.

13. Who is funding the program, and is it enough to meet your needs? -- Old Bridge High School

    NASA is funding the program (with the National Science Foundation covering some of the costs of being in Antarctica). We have not had a lot of money to make improvements that would be nice, and we've had to reuse a lot of old detectors to save money, but since the program has been very successful, we've obviously had sufficient funds to do good science.

14. We are having trouble understanding the zero-pressure balloon. If it were open to the atmosphere, there would be zero pressure but the helium would diffuse into the atmosphere. Can you shed some more light on the physics of the balloon? -- Marissa High School

    A zero pressure balloon IS open to the atmosphere at the bottom. The correct name should be "zero-differential pressure balloon", because the helium inside does have pressure. It is at exactly the same pressure as the atmosphere outside the balloon. This puts a minimum amount of stress on the balloon plastic.

    The balloon traps the helium gas. The gas, being lighter than air, rises and gets trapped underneath the film that makes up the balloon. The helium does diffuse somewhat into the atmosphere, but this is actually a pretty slow process (at the opening, there is local diffusion of helium, but it tends to migrate back upwards into the balloon because it is lighter than air).

    The major helium loss occurs because of day/night temperature differences (the helium shrinks and expands, and when it expands, some of it "flows" out the bottom). We don't have that problem in Antarctica; actually, because there are some daily temperature variations due to the changing angle of the Sun, the problem does exist in 24 hour sunlight, it just is a lot less. But every day the balloon sags lower and lower in the atmosphere. At some point, it goes too low to do useful science. It becomes a danger to air traffic and must be cut down. This is why NASA is developing sealed, superpressure balloons.

1. If galactic cosmic rays leave the galaxy where do they go, and do they ever return? How vital are these rays to the survival of our Galaxy? -- Old Bridge High School

   Galactic cosmic rays continually leak out of the Galaxy. They then wander around the Universe, occasionally passing through other galaxies. Some cosmic rays here at Earth are from galaxies other than the Milky Way. Estimates are that about one in a million is extragalactic at these energies, so during the last flight, we may have gotten one. There is no way to distinguish it from any of the others, however.

   Cosmic rays don't really affect the "survival" of the Galaxy. But they do affect how the Galaxy evolves. They contain as much energy, on average, as starlight, the galactic magnetic field, and the interstellar gas. So they can affect how the gas moves in the Galaxy, which affects the star-forming regions that create the next generation of stars.

2. Does the extreme cold of the area affect the equipment? -- Old Bridge High School

   As TIGER goes up through the atmosphere, it can see temperatures as low as -70 Fahrenheit, so it is designed for low temperatures. For the most part, we are running in an insulated and heated building, so there is no problem. The biggest cold affect on equipment I've dealt with directly is with batteries. They don't last very long when they're cold. Flashlights (which we used in Scott's Hut) and cameras need either recharging or battery replacement pretty often.

3. Was the material made for TIGER's scintillator, poly-vinyl toluene, invented specifically for this mission? Was it in existence before? Can this PVT and/or the scintillator be recycled for different missions and projects dealing with GCRs? -- Old Bridge High School

   Poly-vinyl toluene is a very common type of plastic. The sheets we used had two extra "dyes" mixed in. One of them (p-Terphenol), makes the plastic give off much more light (scintillation) as the cosmic ray passes through it. The scintillation light is mostly in the ultraviolet, so the second dye is a wavelength shifter that turns the UV light into a bluer light that the photomultiplier tubes are more sensitive to. That dye is probably something called Bis-MSB, but the company (Bicron) that we bought the scintillator from considers the exact formulation proprietary. Bis-MSB is short for 1,4-bis[2-methlystyryl]benzene, if you're interested.

   This type of scintillator is used in many cosmic ray and particle physics experiments, and each sheet costs about $1000, so we will re-use them, if possible. Over time, the sheets get "crazed", meaning the surface distorts, and you get less light out to the photomultipliers (which is not as good).

4. Are there any considerations for turning to outside Earth orbit observations, such as solar-focused satellites (such as SOHO and GOES), ISS, or Chandra to gather further or possibly better data on cosmic rays? -- Old Bridge High School

   The scientific community that studies cosmic rays proposes all the time to get satellites built that will study cosmic rays (see for example HNX), but many propose and few are accepted. Satellites are expensive (the cheapest are currently $120 million).

5. Is the resolution of the 2003 version of TIGER superior to that of the 2001 version - enough that we can gather much more data on particles with atomic number > 32? -- Old Bridge High School

   TIGER2003 does not really have better resolution than TIGER2001. We will get a little improvement in our measurements because we've "thinned down" TIGER and will be flying higher (with a bigger balloon), so we'll lose less heavy GCRs to fragmentation. But basically we're just trying to double the number of atomic number > 32 particles we've measured (we only got about 300 in the last flight).

1. What initially motivated you to take on such a challenge? -- Old Bridge High School

   This is really the cumulation of a long history of life choices. The direct and relatively recent motivations are pretty simple. The science return from flying TIGER in Antarctica is very high, and when you add to that the personal adventure (how many people get to go to Antarctica?), it certainly appealed to me. So when TIGER was offered an Antarctic launch opportunity, I was all for it.

2. Why is a balloon a better option to use than launching a satellite into space? -- Old Bridge High School

   Cost. The least expensive satellites now cost about $120 million dollars (which includes instruments, spacecraft, and the rocket). TIGER is much, much less, even including the expense of coming to Antarctica. There are real advantages to satellites that balloons will never beat, but until we get approved for a spacecraft, we can refine our methods and still do good science for a fraction of the cost. Balloons allow one to test new instruments without the full expense of putting them in space.

3. What makes the galactic cosmic rays so difficult to measure? -- Old Bridge High School

   The cosmic rays that TIGER measures are subatomic particles (bare atomic nuclei) moving at almost the speed of light. They also tend to break apart in the instruments you use to try and measure them. But the methods that TIGER uses are actually technology that has been around for many years. The biggest difficulty is actually the rarity of the cosmic rays that TIGER is interested in. In our record breaking 31.5 day flight in 2001-2002, we only collected about 300 particles of the elements between 30 and 40 (the main ones we're interested in). That's only about 10 per element, which doesn't give us a great measure of the relative abundance, which is necessary for our science. For some of the elements, we still did better than any earlier experiments, but we really need to collect more data. Which is why we're back in Antarctica.

4. How will this benefit mankind? -- Old Bridge High School

   This is "pure science" that tells us about the creation and evolution of the matter that makes up us, the Earth, the Solar System, and the Galaxy. This is part of exploring and understanding the Universe, but won't have any practical benefit in the near future.