Tag: space

Introducing Our Galaxy to a Child

A clear night with our Milky Way galaxy seeming to glow iridescently is unforgettable. I remember seeing it once as a child, looking up from a field in the darkness of rural Texas, once from the deck of a rolling ship in the tropics, once from my aircraft on a beautiful night flight headed home, and once on the deck of a beach house on Cape San Blas, Florida. In each instance the conditions were ideal; no clouds, no moon, with very little obscuring moisture in the atmosphere.

The most thrilling time was the last time, when I left the bed where a three-year old was snuggled next to me, and joined my wife and our 11-year old granddaughter on the deck. It was late, and I was surprised to see them up, but when I looked up into the night sky I saw why they remained.

“Isn’t that the Milky Way?” my wife asked.

The eleven-year old had never seen the bright swath of starry light that is the interior of our galaxy. She was puzzled. “If we’re in it, how can we see it?”

The Milky Way and comet McNaught Druckmuller (Image credit: Miloslav Druckmuller.)

I was thrilled to have the chance to explain, best I could, how on just such rare nights we could see in the direction of the galactic center, but yet we can’t see the actual center because of obscuring dust. I further explained that lurking in the center of the billions of stars in the galactic center is a massive black hole.

Our neighbor, the Andromeda galaxy

I know she had seen pictures of galaxies, like M31, Andromeda. She knew how galaxies should look, and what she saw did not match the photographs. She had never thought about how a galaxy, our galaxy, appears from the inside.

When our children were still young I drove the family from the Washington suburbs to the Blue Ridge Mountains to go star-gazing with binoculars and a telescope. But I think the most wondrous experience for them was what they saw unaided, the vast panorama of visible stars relatively bright and close to our planet. At the time, my preteen daughter, then about the age of our present eleven-year old granddaughter, was sleepy and complaining about the cold. Now that she’s an educated adult she  recognizes what a special experience that was.

One of the benefits of keeping children up past their bed times, at least on occasion, is the chance to see the stars. It will have a lasting effect on them; at least it did for me. Before my first night of star-gazing, my world had ended a few feet ahead of me, and a few hours ahead in time. My concerns, like those of most children, were immediate. But after that one starry night experience, my perspective stretched to the stars.

That is a wonderful experience to share with children of an appropriate age, lest they forever close their visual boundaries to all things lying beyond our Earth’s horizon.

[Milky Way in the desert photo (top) by Jurvetson (flickr)]

Going Nowhere Fast – Military Aviation Centrifuges

I was securely strapped into one of the world’s largest human centrifuges at the Naval Air Development Center (NADC) Warminster, Pennsylvania, jocked-down like a pilot in a high performance fighter. As the gondola started moving, I felt the pneumatic cushions in my G-suit inflate, squeezing my legs and abdomen, helping to prevent blood from pooling. Excess pooling would cause a decrease in the volume of blood being pumped to my brain, potentially resulting in unconsciousness. That type of blackout is called G-LOC, or G-induced loss of consciousness.

G is the term for the acceleration of gravity, about 9.8 m/s2. I was being exposed to a relatively mild but prolonged 3-Gs. To put that acceleration into perspective, the shuttle astronauts are exposed to no more than 3-Gs near the end of their climb to orbit, and briefly during reentry. The Apollo astronauts headed to the moon were limited to a maximum of 4 Gs, again during only a brief period of time.

The author at NADC

But my three-G exposure was not brief. If I had been launched upwards with a 3-G acceleration for three minutes  I would have been travelling at almost 12,000 miles per hour at the end of those 3-minutes, over mach 15, and would have climbed 296 miles, well above the altitude of the International Space Station. It would have been a sight to behold.

Another 3 and a half minutes and I would have been going fast enough to escape Earth’s gravity.

Alas, in reality I wasn’t going anywhere, except in circles around the inside of the centrifuge room, attached to a 4000 hp electric motor by a 50-foot long arm.

Author going for a spin

During the run I experienced about what I’d expected — I felt heavy, very heavy, like 3 times my body weight heavy. But I was not at all expecting the sensation I got when they put on the brakes. I felt like a bowling ball careening down a bowling lane. I felt like a gymnast doing impossibly fast forward somersaults.

It was not pleasant.

And I’m very glad the photographer took a photo before the run, rather than after.

I was at Warminster to study the stresses imposed on F/A-18 fighter pilots during high-G exposures.  In the 1990s, losses of aircraft and pilots were an all too frequent occurrence during high-speed maneuvering flight due to G-LOC. To prevent G-LOC pilots need to perform, with precision, an anti-G straining manuever, even though they wear the same anti-G suit I was wearing.

From the cockpit of an F-18

To understand the fighter pilots’ problems, anti G-suits provide at most 1-1.5 G protection advantage. and most people lose consciousness above 3-5 Gs without a G-suit. But a fighter like the F/A-18 can easily pull 8-9 Gs during close in combat. That is where the anti-G straining manuever comes in. The pilots grunt and strain, contracting their leg and abdominal muscles during the high-G portion of the pull, forcing blood from their abdomen into their chest cavity, making blood available for the heart and brain.

Astronaut Alan Shepard

The NADC centrifuge had been used to train the Mercury, Gemini, and Apollo astronauts. Quoting from the Air & Space Smithsonian magazine, “John Glenn called it a “dreaded” and “sadistic” part of astronaut training. Apollo 11’s Michael Collins called it “diabolical.” Time magazine referred to it as “a monstrous apparatus,” a “gruesome merry-go-round,” and, less originally, a “torture chamber.”

http://www.airspacemag.com/history-of-flight/the_g_machine.html

Compared to the centrifuge ride, a flight to the moon was a cake-walk, except for Apollo 13 of course.

The NADC centrifuge was closed by the BRAC committee in 1996. The Navy Aerospace Medical Research Laboratory in Pensacola FL also has a centrifuge in which I’ve ridden, but NAMRL is closing as well, in September 2011.

It seems like military man-rated centrifuges aren’t as popular as they used to be.

Click for a larger image.

Fortunately, NASA has a modern centrifuge, although its maximum G-force capability is about half that of the NADC centrifuge. Nevertheless, anyone who has ridden a centrifuge will tell you the 20-G capability of the NASA Ames centrifuge is more than enough to test human endurance to the forces of acceleration.