The Week In Numbers: The Cost Of A DIY Spacesuit, The Calories In A Human Body, And More

Detail Of Small Arms Of WWI Collaborative Project

Detail from the larger image. At the center is the Colt/Browning Model 1895 machine gun, used by the Dominion of Canada and the Kingdom of Belgium in World War I.C&Rsenal

113: the number of hand-held weapons used World War I and catalogued by this crowd-sourced project. The project is incomplete, so you can add arms if you know of them.

60 percent: reduction in levels of the air pollutant nitrogen dioxide in the U.S. since 1980. The U.S. Environmental Protection Agency credits the reduction to improvements in car fuel efficiency and coal-plant technology.

$65,000 to $68,000: estimated cost of a ReWalk exoskeleton in the U.S. ReWalk devices help people with spinal-cord injuries to sit, stand and walk independently. ReWalk's maker, Argo Medical Technologies, recently received U.S. Food and Drug Administration approval to market the device in the U.S.

ReWalk Users in London

Courtesy of Argo Medical Technologies

$2,000: cost of the materials for this DIY pressurized spacesuit. Pressurized spacesuits typically cost upwards of $30,000.

DIY pressure suit

Courtesy Jev Olsen/Copenhagen Suborbitals

$142: the cost of administering one dose of contraception to a wild female elephant. Although elephant populations are still considered vulnerable worldwide, in certain regions, they've made strong comebacks. Park rangers give elephants birth control in regions where they've become too populous for the reserves in which they live.

22,000: estimated number of African elephants killed illegally in 2013.

Fruzsina Eördögh

20 seconds: how long weightlessness lasts at the top of each parabola in a zero-gravity flight.

32: the number of parabolic zero-gravity flights Popular Science assistant editor Rose Pastore took while reporting for this story. She took the flights to observe a team of Stanford University students, who were testing whether their heart imaging system would work in zero gravity. It did. Pastore reports she did not throw up.

A NASA aircraft during parabolic flight

NASA

81,500: calories in an adult male human body. Yes, we mean if you ate one.

200,000: calories in a horse.

600,000: calories in a bear.