Peeking at the Innards of the Universe
Peeking at the Innards of the Universe
May 5, 1997 (updated May 8)
Glass plates and plastic fibers are at the centers of two unusual telescopes Marshall Space Flight Center scientists are preparing for a unique peek at the universe - and even at a tiny moment of creation - with instruments aboard the oldest means of human flight, balloons (like the one at left, from an earlier mission).
"One prediction from theorists is that at high enough collisional energies, the primary nucleons melt from protons and neutrons into a quark-gluon plasma, a state of matter that existed in the early stages of the Big Bang," explained Dr. Thomas Parnell, director of high-energy astrophysics at Marshall Space Flight Center's Space Sciences Laboratory.
The only other places you can get such a primordial plasma is inside a neutron star, or by putting some lead in the way of high-energy cosmic rays and watching the sparks fly.
That's the job of SOFCAL, the Scintillating Optical Fiber Calorimeter, which uses plastic fibers to capture flashes from nuclear particles zipping along near the speed of light. It's forensic work as the scientists reconstruct a picture of the culprit by examining the damage left in its wake.
But first, it's waiting its place in line behind MIXE2 , the second Marshall Imaging X-ray Experiment, which has a special X-ray detector etched onto a glass plate behind a metal plate peppered with holes. It's a sophisticated pinhole camera that uses a little math (OK, a lot of math) to reconstruct an image of stars shining in hard X-rays.
Earlier balloon-borne experiments from Marshall helped lead to the High Energy Astronomy Observatories, Gamma Ray Observatory, and the Hubble Space Telescope.
Both instruments are to be launched from a spot just a few miles from where Billy the Kid met his fate, Fort Sumner, N.M., one of several launch sites operated for the National Scientific Ballooning Facility, a branch of NASA's Wallops Flight Facility at Wallops Island, Virginia. The site at Fort Sumner is operated under contract by the Physical Science Laboratory of New Mexico State University.
Ballooning gives scientists an inexpensive way of getting telescopes above most of Earth's atmosphere. From altitudes of 38 km altitude (126,000 feet; 23.8 miles), where the remaining atmospheric pressure is only 3 millibar (about 1/3 of 1 percent of sea level pressure), instruments can see the universe almost as clearly as the Hubble Space Telescope and other orbiting observatories. And while the ride last only 30 or 40 hours, it is far cheaper than a space launch.
Launch windows come in spring and fall during "turnaround," a period of a few days when the stratosphere at about 30 to 46 km (19 to 28 miles) - above the jet stream which occurs at 18 km (11 miles) slow down and often change directions. Then the 20-story-tall helium gas bags have a good chance of surviving the ascent to their cruise altitude. Also, the low wind speeds mean that the balloons won't travel too far and can be brought down before they stray over heavily populated areas.
For the past few days the Marshall team has been frustrated by high winds near the surface.
"The problem here has been what the meteorologist calls a low level jet," explained Fred Berry, one of the SSL engineers supporting the launch. "The surface winds are supposed to calm down near sunrise and sunset. Also, this low-level jet - just 30 to 1220 meters (100 to 4000 feet) above the surface - has been rather strong. The surface winds have to be below about 9 to 18 km/h (6-12 mph) and the low-level winds must be below 18 to 22 km/h (12-14 mph) and blowing in approximately the same direction as the surface wind.
"Imagine the balloon, flight train, parachute, and experiment as tall as the Empire State Building and as fragile as a dry cleaning bag. This balloon weighs over a ton and at float (expanded at high altitude) would fill a baseball stadium. Scientists are very particular about when they choose to launch these things."
So they they wait for conditions to be right, often
a key element of a science experiment.
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