Launchers

by Jeanette Cain

More articles in Rockets

One of the biggest problems for sending spacecraft into orbit is deciding which model is most needed and best suited for the flight. The most important factors for all spacecraft: cost, technical capability, and reliability. Plus, launch companies have as many different models as a car lot. Probes sent on interplanetary journeys favor heavy-lift launches, so to, heavy-lift is preferred for sending satellites into high GEO (geostationary orbit) above Earth. The smaller space air launch rockets are best used for sending small payloads into LEO (low-Earth orbit).

The R-7 (Soviet launch vehicle) placed Sputnik, the first satellite, into orbit in 1957. The R-7 consisted of a central rocket with boosters. Apollo missions were lifted from Earth by the Saturn V rocket. On May 14, 1973, it launched the Skylab Space Station, which was its final flight into space. A Titan rocket was combined with the upper stage of a Centaur by NASA in 1974 with Voyager using this combination to begin its tour of Earth's outer solar system neighbors.

The challenges of keeping spacecraft in prime condition is complicated and complex. The slightest mistake may result in multi-million dollar disasters. The United States, Russia, or Japan are the places turned to for orders. Companies within these countries usually have the most experience in the manufacture of space technology equipment. Most other countries launch their own rockets, but have difficulty in selling them to others. China has started a campaign in attempts to sell it rockets to other nations.

For satellite owners the biggest question is finding the amount of lift that a launch vehicle is capable achieving. Another question is finding a nose cone with the right shape for their satellite to fit into for the trip. In addition, the satellite will need to be able to pass through forces exerting pressure on liftoff of payloads. Rockets, like humans, are unique individuals: each behaves is a different way, and each exerts a different force on payloads.

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The muscle rockets are the Russian Proton and Europe's Ariane 5 that place up to 22 tons of payload into LEO. The 22 tons is almost equal to 20 cars. The Proton works in 3 stages for this type of launch. Proton has launched the Asiasat HSG-1 to LEO, which sends television and telephone signals to the Pacific and to Asia. For spacecraft going on interplanetary journeys, a four stage version is used. Delta has been launching satellites since 1960. Delta II began launching in 1989, which can lift 2 tons for a transfer orbit into GEO. The Delta family has a good reputation for reliability, and is often considered the workhorse in rockets. The most recent addition to the Delta family is the Delta III with the ability to place 8.8 tons of payload in LEO or 4.4 tons of payload into GEO.

Pegasus was carried by an L1011 Stargazer aircraft to the altitude of 12.2 km. Stargazer releases the rocket when it is above the ocean, and its wings provide the aerodynamic lift needed for keeping Pegasus in flight. The first of 3 rocket stages will begin after 5 seconds. Payload makes orbit around 10 minutes later. Pegasus is capable of launching many small satellites needed for the new fleets of mobile communications satellites. LEO can receive 500 kg launched by Pegasus.

The heaviest elements needed for the International Space Station (ISS) received help from the United States Space Shuttle and the Russian Proton. These two actually had backup from other launches. The European Automated Transfer Vehicle is expected to be launched using Ariane 5, and will provide fuel needed for station maneuvers and provide supplies that will be needed. Japan plans to provide the H-II launcher for lifting the Hope space plane to the International Space Station.

SATURN V stats: First flight on November 9, 1967; lifted Apollo for first moon landing on July 16, 1969; and, made its last and final spaceflight on May 14, 1973.


Sources:

1. 1. Editors. Secrets of the Universe. International Master Publishing: US. 1999

2. Couper, Heather and Nigel Henbest. Space Encyclopedia: "Biographies." DK Publishing Book: NY, 1999