Editing Strategic Defense Initiative (section)

===Laser and mirror experiments===
[[File:SDIO LACE Spacecraft.jpg|thumb|upright|Technicians at the Naval Research Laboratory (NRL) work on the [[Low-Power Atmospheric Compensation Experiment]] (LACE) satellite.]]
The High Precision Tracking Experiment (HPTE), launched with the [[Space Shuttle Discovery]] on [[STS-51-G]], was tested on June 21, 1985, when a Hawaii-based low-power laser successfully tracked the experiment and bounced the laser off of the HPTE mirror.

The Relay mirror experiment (RME), launched in February 1990, demonstrated critical technologies for space-based relay mirrors that would be used with an SDI [[directed-energy weapon]] system. The experiment validated stabilization, tracking, and pointing concepts and proved that a laser could be relayed from the ground to a {{cvt|60|cm|in|order=flip}} mirror on an orbiting satellite and back to another ground station with a high degree of accuracy and for extended durations.<ref>{{cite web|first=Malcolm R. |last=O'Neill|url=http://www.mda.mil/mdalink/html/oneilltest.html |title=Statement of Lieutenant General Malcolm R. O'Neill, USA, Director, BMDO before the Committee on National Security, House of Representatives |date=April 4, 1995|archive-url=https://web.archive.org/web/20060113224616/http://www.mda.mil/mdalink/html/oneilltest.html |archive-date=January 13, 2006 |access-date=March 11, 2006}}</ref>

Launched on the same rocket as the RME, the Low-power Atmospheric Compensation Experiment (LACE) satellite was built by the [[United States Naval Research Laboratory]] (NRL) to explore atmospheric distortion of lasers and real-time adaptive compensation. The LACE satellite included several other experiments to help develop and improve SDI sensors, including target discrimination using background radiation and tracking ballistic missiles using [[Ultraviolet]] Plume Imaging (UVPI).<ref>{{cite encyclopedia|encyclopedia=Encyclopedia Astronautica |access-date=2024-07-05 |url=http://www.astronautix.com/craft/lace.htm |title=Low-power Atmospheric Compensation Experiment (LACE) |archive-url=https://web.archive.org/web/20090721031741/http://www.astronautix.com/craft/lace.htm |archive-date=July 21, 2009 }}</ref> LACE was also used to evaluate ground-based [[adaptive optics]], a technique now used in civilian telescopes to remove atmospheric distortions.