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A secondary payload is a smaller-sized payload transported to orbit on a launch vehicle that is mostly paid for—and with the date and time of launch and the orbital trajectory determined—by the entity that contracts and pays for the primary launch.〔〔 As a result, the secondary payload typically obtains a substantially reduced price for transportation services to orbit, by accepting a trade off of the loss of control once the contract is signed and the payload is delivered to the launch vehicle supplier for integration to the launch vehicle. These tradeoffs typically include having little or no control over the launch date/time, the final orbital parameters, or the ability to halt the launch and remove the payload should a payload failure occur during ground processing prior to launch, as the ''primary payload'' typically purchases all of these launch property rights via contract with the launch services provider. ==Market== While originally a US government-centric option for government-owned launches—where secondary payload slots were often given away by whatever allocation means a government agency might choose—an entire market has emerged over time to take advantage of the lower cost of access to space through secondary payload opportunities.〔 The small satellite segment of the satellite launch industry has been growing rapidly in recent years. Development activity has been particularly high in the 1–50 kg size range. In the 1–50 kg range alone, there were fewer than 15 satellites launched annually in 2000 to 2005, 34 in 2006, then fewer than 30 launches annually during 2007 to 2011. This rose to 34 launched in 2012, and 92 small satellites launched in 2013.〔 〕 Offering of secondary launch services vary by launch provider. US commercial launcher United Launch Alliance (ULA) offers virtually no access for secondary payloads commercially, although the US military offers some secondary payload slots on ULA launchers Atlas V and Delta IV, that are then controlled by government launch slot allocation processes. SpaceX offered a priced set of secondary payload launches on their Falcon 9 rocket beginning in 2011 with prices between for secondary payloads delivered to low-Earth orbit (LEO).〔 〕 SpaceX indicated that they continue to launch some secondary payloads, but are not doing a lot of them, as there is "not a lot of money in the secondary payload market."〔 〕 ILS, a US company that markets launches of the Russian Proton rocket, does not and has no plans to launch commercial secondary payloads of smallsats or CubeSats.〔 〕 SeaLaunch, a US-based consortium of US company Boeing and Russian company RSC Energia (RSCE) (now majority owned by RSCE), also does not currently launch commercial secondary payloads.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Secondary payload」の詳細全文を読む スポンサード リンク
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