Space diver: what's it like to dive from the edge of space--a place no human has ever jumped from before? Cheryl Stearns plans to find out. (Atmosphere/Skydiving).IMAGINE: AT 40 kilometers (25 miles) above the ground--more than four times the flying altitude of a commercial jet--you huddle inside a small aluminum basket, tethered Attached to a data or power source by wire or fiber. Contrast with untethered. to a paper-thin helium balloon inflated to the size of a football stadium. Peering over the basket's edge, Earth is a little blue and green gumball gum·ball n. A small ball of chewing gum with a colored sugar coating. . Your mission is simple: Dive toward the gumball. Land on the gumball. Within 60 seconds of the leap, your body tears through clouds like a human torpedo Human torpedoes or manned torpedoes were secret naval weapons of World War II. The name is most commonly used to refer to the weapons that Italy and later Britain deployed in the Mediterranean and used to attack ships in enemy harbours. , reaching speeds up to 900 miles per hour. Ten minutes later, you hit dirt. Alive? Maybe, with the aid of a high-tech space suit and parachute. But then again, maybe not. The truth is, no one knows your fate, because no one has ever risked such an extreme plunge. That's reason enough for Cheryl Stearns to try it. In April 2003, Stearns, a 45-year-old pilot, will attempt to become the first person to skydive sky·dive intr.v. sky·dived, sky·div·ing, sky·dives To jump and fall freely from an airplane, performing various maneuvers before pulling the ripcord of a parachute. from the stratosphere, a thin layer of atmosphere extending 50 km (31 mi) above Earth. A successful jump would mean she'd break the world record for the highest skydive --31 km (19 mi), set in 1960. Amazingly, she'd also become the first human body to travel faster than the speed of sound--about 730 mph at 30 km (18 mi) above sea level--without the aid of a plane or spaceship. But besides shattering records, Stearns has a "higher" purpose for the jump: She hopes it will help scientists design better emergency ejection suits for fighter-jet pilots and astronauts. The big question is, how will she survive? SKY'S THE LIMIT Stearns tackled her first skydive at age 17 after convincing her mom to lend her the $40 jump fee. Since then, she's completed 14,500 jumps--more than any other woman in the world. She also holds the world record for the most jumps in one day: 352. But don't call Stearns a daredevil. "When it comes to pushing the envelope, I'm a big chicken," she claims. "I've never been hurt, mostly because I know what my limits are." A 21-member team of experts that includes aerospace flight surgeon Dr. Clayton Lay Thomas will support Stearns's death-defying leap. "Our job is to think of every possible thing that could go wrong," says Thomas. "Then prepare for it." During a typical skydive, you exit a plane at about 4 km (2.5 mi) above Earth. Belly first, you free-fall 3 km (1.9 mi), reaching speeds up to 120 mph. Then you yank Yank steamship stoker vainly tries to climb the social ladder, then fails in attempt to avenge himself on society. [Am. Drama: O’Neill The Hairy Ape in Sobel, 339] See : Failure (jargon) yank your parachute cord Parachute cord (also paracord or 550 cord) is a lightweight nylon kernmantle rope originally used in the suspension lines of US parachutes during World War II. Once in the field, paratroopers found this cord useful for many other tasks. at 914 m (2,999 ft). Your descent catapults you through the atmosphere's lowest layer, a 12-km (7-mi)-thick region of air called the troposphere troposphere: see atmosphere. troposphere Lowest region of the atmosphere, bounded by the Earth below and the stratosphere above, with the upper boundary being about 6–8 mi (10–13 km) above the Earth's surface. (see diagram, left). It contains about 75 percent of the atmosphere's gases, such as oxygen, nitrogen, and carbon dioxide--the molecules that make breathing possible. Climb higher than 4 km (2.5 mi), however, and breathing becomes a grueling task. Why? As altitude increases, atmospheric pressure atmospheric pressure or barometric pressure Force per unit area exerted by the air above the surface of the Earth. Standard sea-level pressure, by definition, equals 1 atmosphere (atm), or 29.92 in. (760 mm) of mercury, 14.70 lbs per square in., or 101. (the amount of force exerted by gravity) decreases, allowing gas molecules to float apart; every breath you take contains fewer gas molecules. Deprived of oxygen, the lungs and brain reel from hypoxia hypoxia Condition in which tissues are starved of oxygen. The extreme is anoxia (absence of oxygen). There are four types: hypoxemic, from low blood oxygen content (e.g., in altitude sickness); anemic, from low blood oxygen-carrying capacity (e.g. , a deadly condition that disrupts red blood cells' ability to absorb and transport oxygen. Minor symptoms of oxygen starvation, such as blurry vision, can appear at altitudes as low as 1.5 km (0.9 mi). At 5.5 km (3.4 mi) above sea level, "you black out and die," says Thomas. SMART DUDS Although her 25-mile plunge will last less than 10 minutes, Stearns will face danger every second. Her survival plan? "The key is the suit," she says. After 14 years of research, "it's the most advanced high-altitude gear ever designed." Like a wearable spaceship, it provides creature comforts such as heating and air conditioning air conditioning, mechanical process for controlling the humidity, temperature, cleanliness, and circulation of air in buildings and rooms. Indoor air is conditioned and regulated to maintain the temperature-humidity ratio that is most comfortable and healthful. , a steady flow of oxygen, and protection from deadly cosmic rays cosmic rays, charged particles moving at nearly the speed of light reaching the earth from outer space. Primary cosmic rays consist mostly of protons (nuclei of hydrogen atoms), some alpha particles (helium nuclei), and lesser amounts of nuclei of carbon, nitrogen, ejected from supernovas (exploding stars) and the Sun. At 12 km (7.5 mi), the suit becomes fully pressurized pres·sur·ize tr.v. pres·sur·ized, pres·sur·iz·ing, pres·sur·iz·es 1. To maintain normal air pressure in (an enclosure, as an aircraft or submarine). 2. to counterbalance decreasing air pressure during Stearns's three-hour balloon ascent. Without pressurization Pressurization generally refers to the application of pressure in a given situation or environment; and more specifically refers to the process by which atmospheric pressure is maintained in an isolated or semi-isolated atmospheric environment (for instance, in an aircraft, or , molecules inside her body would float apart, causing her to swell to twice her normal size! The suit's outer layer is crafted of a top-secret material designed to withstand extreme temperatures. As her body bullets through the warmer stratosphere, which averages about 0 [degrees] C (32 [degrees] F), the resulting air friction (rubbing force) will cook the outside of her suit to 149 [degrees] C (300 [degrees] F)! "This is the first suit to have boots and gloves that won't melt during a high-speed descent," says Stearns. But once she plunges into the troposphere, temperatures turn frigid: -62.2 [degrees] C (-80 [degrees] F) is the norm. "You definitely want your long johns on," Thomas says. More important: a face mask Face mask The simplest way of delivering a high level of oxygen to patients with ARDS or other low-oxygen conditions. Mentioned in: Adult Respiratory Distress Syndrome that won't shatter during the transition. ULTIMATE QUEST The one lingering unknown: What happens to the human body when it travels faster than the speed of sound, the rate at which sound waves pulsate pul·sate v. To expand and contract rhythmically; beat. through air? Within 60 seconds, Stearns will outpace that speed by nearly 240 mph, accelerating to Mach 1.3--faster than a fighter jet. (For more on Mach numbers, see diagram, above.) What will it feel like to free-fall at 900 mph toward Earth? "I'll only feel like I'm going about 150 mph, because the air is so thin," Stearns says. Fewer air molecules mean less matter (anything that occupies space) pressing against you. The thickening atmosphere will eventually slow Stearns down to a comfortable 300 mph, at which point her suit will depressurize de·pres·sur·ize tr.v. de·pres·sur·ized, de·pres·sur·iz·ing, de·pres·sur·iz·es To reduce the pressure of air or gas within (a chamber or vehicle, for example). . She'll then shift her body from a 70-degree downward angle to a standard "belly-to-Earth" skydiving skydiving Sport of jumping from an airplane at a moderate altitude (e.g., 6,000 ft [1,800 m]) and executing various body maneuvers before pulling the rip cord of a parachute. Competitive events include jumping for style, landing with accuracy, and performing in teams (e.g. position, which will grind her speed to about 180 mph. At 2 km (1.3 mi), she will activate her parachute and glide to Earth. Will the master skydiver pull off the ultimate dive? Stearns thinks so: "I don't plan on ending my life in this one jump," she says. For more on Stearns's quest, check out www.stratoquest.com. EARTH'S ATMOSPHERE: SIX LAYERS The atmosphere is a 700-km (430-mi)-thick protective blanket of gases that wraps around Earth. Its job: block harmful space rays, provide air to breathe, and maintain livable temperatures. With each successive layer, altitude increases and air thickness decreases. How does this affect a skydiver? [ILLUSTRATION OMITTED] MACH SPEED Cheryl Stearns will reach a Mach speed of 1.3 during her 40 km (25 mi) descent. That's faster than a commercial jet plane! But what does Mach mean? Mach numbers relate an object's speed relative to the speed of sound, which changes depending on altitude and temperature. A Mach number is determined by dividing an object's speed by the speed of sound. MACH 6.9 X-15A-2 (World's Fastest Aircraft) Hypersonic 4,534 mph (Mach >5) MACH 1.3 Cheryl Stearns Supersonic 900 mph (Mach >1) MACH 1 Speed of sound Transonic 660 mph (Mach =1) MACH 0.9 Boeing 747 Subsonic 608 mph (Mach <1) Lesson Plans [ILLUSTRATION OMITTED] Cross-Curricular Connection History: In August 1960, Air Force pilot Joseph Kittinger successfully completed the world's highest skydive: a 31 km (19.5 mi) leap to Earth. The record still stands today. Research Kittinger's jump. How did skydiving technology differ four decades ago? Did You Know? * What causes a sonic boom? Objects moving faster than the speed of sound cause airwaves to compress and uncompress. The resulting changes in air pressure create shock waves that sound like thunder as they hit your eardrum ear·drum n. The thin, semitransparent, oval-shaped membrane that separates the middle ear from the external ear. Also called drum, drumhead, drum membrane, myringa, myrinx, tympanic membrane, . * Cheryl Stearns's skydiving suit will be equipped with a biomedical bi·o·med·i·cal adj. 1. Of or relating to biomedicine. 2. Of, relating to, or involving biological, medical, and physical sciences. telemetry telemetry Highly automated communications process by which data are collected from instruments located at remote or inaccessible points and transmitted to receiving equipment for measurement, monitoring, display, and recording. system that monitors her core body temperature, oxygen absorption, breathing, and heart rate. The signals are transmitted digitally to a receiver on the ground. Should Stearns lose consciousness during her descent--an event her supervising doctor says is highly unlikely--the suit will automatically activate her parachute at 2 kilometers (7,000 feet) above ground. National Science Education Standards The National Science Education Standards (NSES) are a set of guidelines for the science education in primary and secondary schools in the United States, as established by the National Research Council in 1996. Grades 5-8: structure of the Earth system * motions and forces * structure and function in living systems * understanding about science and technology * risks and benefits Grades 9-12: the cell * motions and forces * understanding about science and technology * energy in the Earth system Resources "Terminal Velocity," by Craig Offman, Wired, 2002. p. 26-37. "Faster than Sound," NOVA Online, www.pbs.org/wgbh/nova/barrier Dictionary of the Earth by John Farndon (Dorling Kindersley, 1994). p. 138-139. CHECK FOR UNDERSTANDING
Name: --
Directions: Match the word in the left column with the correct
phrase in the right column.
-- 1. hypoxia a. exploding stars
-- 2. friction b. atmospheric layer closest to Earth
-- 3. pressure c. amount of force exerted by gravity
-- 4. supernovas d. deadly condition that disrupts red blood cells'
ability to process oxygen
-- 5. ionosphere e. atmospheric layer peaking 700 km above Earth
-- 6. stratosphere f. atmospheric layer 80-300 km above Earth
-- 7. troposphere g. rubbing force
-- 8. thermosphere h. thin atmospheric layer 50 km above Earth
ANSWERS 1. d 2. g 3. c 4. a 5. e 6. h 7. b 8. f |
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