| Expendable Launch Vehicle |
Article Index for Expendable |
Website Links For Expendable |
Information AboutExpendable Launch Vehicle |
| CATEGORIES ABOUT EXPENDABLE LAUNCH SYSTEM | |
| spacecraft propulsion | |
| space launch vehicles | |
|
DESIGN RATIONALE The ELV design differs from that of a Reusable Launch System , where the vehicle would be launched and recovered more than once. This might seem to make the ELV design a more expensive launch method, but in practice launches using ELVs have been less expensive than launches on the Space Shuttle , which is the only existing launch vehicle that is even partly reusable. (See Space Shuttle Program and Criticism Of The Space Shuttle Program for discussion of Space Shuttle economics). Most Satellite s are currently launched using expendable launchers; they are perceived as having a low risk of mission failure, a short time to launch and a relatively low cost. There have also been proposals for (as-yet theoretical) Single Stage To Orbit systems. In principle an expendable single stage to orbit vehicle would be impossible; it is generally more efficient to use staging when the vehicle is not meant to be recovered intact. HISTORY Most Orbital expendable launchers are derivatives of 1950s -era Ballistic Missile s. The Magellan Probe was the first planetary spacecraft launched by a Space Shuttle. Many see it as unfortunate that most "modern" orbital expendables are derived from ballistic missiles, as these missiles were built to Cold War specs and with Cold War budgets, and argue that this makes for horrendously expensive launch vehicles. A prime example of this is the Titan IV , probably the costliest per-unit launch vehicle in history (perhaps following the Space Shuttle). On the other hand, reusable launchers have to be built more robustly and thus carry extra dry weight to orbit, and require recovery systems, and thus everything else being equal (to a similarly constructed expendable), would have a very much smaller payload. Reusable launchers would thus not necessarily be enormously cheaper. DEVELOPMENT See Also: Private spaceflight European sponsorship On represent scientific, technical, financial and political entities from 10 different European countries. The major shareolder is the CNES, with 32,53% of capital. {Link without Title} American deregulation From the beginning of the Shuttle program until the . On s. Prior to the signing of this law, all commercial satellite launches in the United States were limited to NASA's Space Shuttle . On November 5 , 1990 , United States President George H. W. Bush signed into law the Launch Services Purchase Act. {Link without Title} The Act, in a complete reversal of the earlier Space Shuttle monopoly, ordered NASA to purchase launch services for its primary payloads from commercial providers whenever such services are required in the course of its activities. Russian privatization The Russian government sold part of its stake in RSC Energia to private investors in 1994. Energia together with Khrunichev constituted most of the Russian manned space program. In 1997, the Russian government sold off enough of its share to lose the majority position. American subsidization In 1996 the United States government selected Lockheed Martin and Boeing to each develop Evolved Expendable Launch Vehicle s (EELV) to compete for launch contracts and provide assured access to space. The government's acquisition strategy relied on the strong commercial viability of both vehicles to lower unit costs. This anticipated market demand did not materialize, but both the Delta IV and Atlas V EELVs remain in active service. Launch alliances Since 1995 Khrunichev's Proton Rocket is marketed through International Launch Services while the Soyuz Rocket is marketed via Starsem . Energia builds the Soyuz rocket and owns part of the Sea Launch project which flies the Ukrainian Zenit Rocket . In 2003 Arianespace joined with Boeing Launch Services and Mitsubishi Heavy Industries to create the Launch Services Alliance . In 2005, continued weak commercial demand for EELV launches drove Lockheed Martin and Boeing to propose a joint venture called the United Launch Alliance to monopolize the United States government launch market. {Link without Title} Today many commercial space transportation companies offer launch services to satellite companies and government space organizations around the world. In 2005 there were 18 total commercial launches and 37 non-commercial launches. {Link without Title} Russia flew 44% of commercial orbital launches, while Europe had 28% and the United States had 6%. SEE ALSO |
|
|