Sub-orbital in the context of "Dogs in space"

A spaceplane is a vehicle that can fly and glide as an aircraft in Earth's atmosphere and function as a spacecraft in outer space. To do so, spaceplanes must incorporate features of both aircraft and spacecraft. Orbital spaceplanes tend to be more similar to conventional spacecraft, while sub-orbital spaceplanes tend to be more similar to fixed-wing aircraft. All spaceplanes as of 2024 have been rocket-powered for takeoff and climb, but have then landed as unpowered gliders.

Four examples of spaceplanes have successfully launched to orbit, reentered Earth's atmosphere, and landed: the U.S. Space Shuttle, Russian Buran, U.S. X-37, and the Chinese Shenlong. Another, Dream Chaser, is under development in the U.S. As of 2024 all past and current orbital spaceplanes launch vertically; some are carried as a payload in a conventional fairing, while the Space Shuttle used its own engines with the assistance of boosters and an external tank. Orbital spaceflight takes place at high velocities, with orbital kinetic energies typically greater than suborbital trajectories. This kinetic energy is shed as heat during re-entry. Many more spaceplanes have been proposed.

Animals in space originally served to test the survivability of spaceflight, before human spaceflights were attempted. Later, many species were flown to investigate various biological processes and the effects microgravity and space flight might have on them. Bioastronautics is an area of bioengineering research that spans the study and support of life in space. To date, seven national space programs have flown non-human animals into space: the United States, Soviet Union, France, Argentina, China, Japan and Iran.

A wide variety of non-human animals have been launched into space, including monkeys and apes, dogs, cats, tortoises, mice, rats, rabbits, fish, frogs, spiders, insects, and quail eggs (which hatched on Mir in 1990). The US launched the first Earthlings into space, with fruit flies surviving a 1947 flight, followed by primates in 1949. The Soviet space program launched multiple dogs into space, with the first sub-orbital flights in 1951, and first orbital flights in 1957.