Difference between revisions 1813703 and 1813704 on enwikiversity

[[Image:Skylab-73-HC-440HR.jpg|thumb|right|200px|The Saturn V SA-513 lifts off to boost the Skylab Orbital Workshop into Earth orbit on March 14, 1973. Credit: NASA.]]
[[Astronomy]] is performed by location and is subject to local conditions. The shapes and sizes of observatories have changed over time, as have their altitude. The motivations for putting an observatory manned or unmanned at different altitudes has led to a great variety in '''lofting technology'''.
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| author=William Harwood
| work=Spaceflight Now
| title=First images from Spitzer Space Telescope unveiled
| url=http://www.spaceflightnow.com/news/n0312/17sstresults/
| date= December 18, 2003
| accessdate=2008-08-23 }}</ref>


"Cryogenic satellites that require liquid helium (LHe, T ≈ 4 K) temperatures in near-Earth orbit are typically exposed to a large heat load from the Earth, and consequently entail large usage of LHe coolant, which then tends to dominate the total payload mass and limits mission life. Placing the satellite in solar orbit far from Earth allowed innovative passive cooling such as the sun shield, against the single remaining major heat source to drastically reduce the total mass of helium needed, resulting in an overall smaller lighter payload, with major cost savings. This orbit also simplifies telescope pointing, but does require the [[w:Deep Space Network|Deep Space Network]] for communications."<ref name=SpitzerSpaceTelescope/>

"An Earth Trailing Solar Orbit (ETSO)" causes Spitzer "to drift from Earth at a rate of about 0.1 AU per year."<ref name=Johnson>{{ cite book
|author=Wyatt R. Johnson
|title=SIM Trajectory Design
|publisher=NASA
|location=Jet Propulsion Laboratory, Pasadena, California, USA
|month=
(contracted; show full)[[Category:Astronomy learning projects/Lectures]]
[[Category:Astronomy/Lectures]]
[[Category:Astrophysics/Lectures]]
[[Category:History/Lectures]]
[[Category:Radiation astronomy/Lectures]]
[[Category:Resources last modified in February 2018]]
[[Category:Technology/Lectures]]
[[Category:Vehicles/Lectures]]