If earthlings are smart enough to split the atom and launch into outer space, asks a reader, why can't we take our country's 70,000 tons of radioactive waste and fly it off-planet? We can, but the high cost and the risk of launch accidents have kept this idea off the table. Until now, scientists have looked at carting the stuff off on the space shuttle (at $10,000 per pound) or crashing it into the moon on rockets (thus littering that orb). But gaining momentum among the blue-sky set is the concept of a space elevator, which would accelerate payloads up a 60,000-mile ribbon of superstrong fibers using energy beams and a little help from Earth's rotation. Ben Shelef, founder of the nonprofit Spaceward Foundation, thinks this cosmic lift could put nuclear cargos into geosynchronous...
Q) How long can a tick live without finding a host?
Charity Shumway, Corvallis, Oregon
A) These icky arachnids are no models of dietary moderation, eating 10 to 20 percent of their body weight in half an hour (in the case of soft ticks) or 50 to 100 times their weight over 10 to 15 days (if they're the hard variety, such as deer ticks). But those blood feasts have staying power: Hard ticks in the wild can go a year without feeding again, while softies can live at least two years, says Pete Teel, an entomology professor at Texas A&M University. During its one-to-three-year life span, a typical tick needs only three meals: when it metamorphoses from larva to nymph; from nymph to adult; and then once more to stay alive long enough to breed repeatedly. And it's a good thingfor the tick, that isconsidering the challenges of finding a host and filling up. Against such odds, only 10 percent of ticks reach adulthood.
Q) What's the greatest height from which a human has fallen and survived the impact?
Jeff Bray, Greensboro, North Carolina
A) Once a falling human body reaches its terminal velocityabout 120 miles per hour, after which air resistance stops it from acceleratingthere is little a person can do to save himself, says Major Philip Belmont Jr., chief of orthopedics at Missouri's General Leonard Wood Army Community Hospital. And since this speed is attained in roughly the first 1,500 feet of a fall, no one can survive such a drop unless he lands on a gentle slope or on something soft, or is otherwise slowed down. These principles are evident in the two highest survived chuteless falls on record, both of which occurred over Europe during World War II. The runner-up was Staff Sergeant Alan Magee, an American who bailed from his B-17 over France in 1943 and plummeted 20,000 feet, crashing through a train station's glass skylights, which, incredibly, broke his fall just enough to save him. Even scarier, Lieutenant I. M. Chisov, a Russian airman, fell 22,000 feet in 1942 before hitting a snow-covered ravine and rolling to the bottom, badly injured but alive.
Q) Do whales yawn?
Graham Austin, Macon, Georgia
A) Yawning occurs among most mammals and even in some birds and reptiles, but no one knows why we do it. The long-standing belief that it helps us get oxygen into our lungs has mostly been supplanted by theories positing a yawn as an ancient social cue that signaled activity changea subconscious behavior our ancestors picked up when they saw their leader doing it, signifying "This is getting old; let's go hunt some mammoths" or "Time to hit the hay." But apparently this tic doesn't carry over to sea mammalscetaceans do sleep, in series of catnaps, and they presumably get sleepy, but scientists have never observed them yawning to indicate such a thing, says Jim Sumich, a marine biologist at California's Grossmont College. That may be because of how they're built: Whales, of course, breathe through a blowhole, not their mouth. If you've ever seen a whale with its trap wide open, it was probably either feeding or engaged in the unromantic task of dislodging food stuck in its gullet.