Editing Project Echo (section)

{{Short description|First passive communications satellite experiment}}
{{Use American English|date=February 2021}}
{{Use dmy dates|date=February 2021}}
{{Redirect|Echo project|the music festival|The Echo Project}}
{{redirect|Echo 1|other uses|Echo I (disambiguation)}}
{{Infobox spaceflight
| name                = Echo 1A
| names_list          = ECHO 1<br/>NASA A-11
| image               = Echo-1.jpg
| image_caption       = Echo 1 sits fully inflated at a [[Weeksville Dirigible Hangar|Navy hangar in Weeksville]], [[North Carolina]].
| image_size          = 300px

| mission_type        = [[Communications satellite|Communications]]
| operator            = [[NASA]]
| Harvard_designation = 1960 Alpha 11
| COSPAR_ID           = 1960-009A
| SATCAT              = 00049
| mission_duration    = 7.75 years (achieved)

| spacecraft          = 
| spacecraft_type     = 
| spacecraft_bus      = ECHO
| manufacturer        = [[Bell Labs]]
| launch_mass         = {{cvt|180|kg}}
| dimensions          = {{cvt|30.48|m}} diameter sphere when inflated
| power               = 

| launch_date         = 12 August 1960, 03:39:43 [[Greenwich Mean Time|GMT]]
| launch_rocket       = [[Thor-Delta|Thor DM-19 Delta]] (Thor 270 / Delta 2)
| launch_site         = [[Cape Canaveral Space Force Station|Cape Canaveral]], [[Cape Canaveral Space Launch Complex 17|LC-17A]]
| launch_contractor   = [[Douglas Aircraft Company]]

| entered_service     = 
| destroyed           = 
| last_contact        = 
| decay_date          = 25 May 1968

| orbit_reference     = [[Geocentric orbit]]
| orbit_regime        = [[Low Earth orbit]]
| orbit_periapsis     = {{cvt|1524|km}}
| orbit_apoapsis      = {{cvt|1684|km}}
| orbit_inclination   = 47.2°
| orbit_period        = 118.3 minutes
| apsis               = gee

| programme           = 
| previous_mission    = 
| next_mission        = 
}}

{{Infobox spaceflight
| name               = Echo 2
| names_list         = NASA A-12
| image              = Echo 2.jpg
| image_caption      = Echo 2
| image_size         = 300px
| mission_type       = [[Communications satellite|Communications]]
| operator           = [[NASA]]
| COSPAR_ID          = 1964-004A
| SATCAT             = 00740
| mission_duration   = 5.5 years (achieved)
| spacecraft         = 
| spacecraft_type    = 
| spacecraft_bus     = ECHO
| manufacturer       = [[Bell Labs]]
| launch_mass        = 
| dimensions         = {{cvt|41|m}} diameter sphere when inflated
| power              = <!-- [[watt]]s -->
| launch_date        = 25 January 1964, 13:59:04 [[Greenwich Mean Time|GMT]]
| launch_rocket      = [[Thor-Agena|Thor-Agena B]] (Thor 397 / Agena 6301 / TA-2)
| launch_site        = [[Vandenberg Space Force Base|Vandenberg]], [[Vandenberg Space Launch Complex 2|LC-75-1-1 (SLC-2E)]]
| launch_contractor  = [[Douglas Aircraft Company]] (Thor)<br/>[[Lockheed Martin]] (Agena)
| entered_service    = 
| destroyed          = 
| last_contact       = 
| decay_date         = 7 June 1969
| orbit_reference    = [[Geocentric orbit]]
| orbit_regime       = [[Low Earth orbit]]
| orbit_periapsis    = {{cvt|1029|km}}
| orbit_apoapsis     = {{cvt|1316|km}}
| orbit_inclination  = 81.5°
| orbit_period       = 108.95 minutes
| apsis              = gee
| programme          = 
| previous_mission   = 
| next_mission       = 
}}

'''Project Echo''' was the first passive [[communications satellite]] experiment. Each of the two American spacecraft, launched in 1960 and 1964, were metalized [[balloon satellite]]s acting as passive [[reflection (physics)|reflectors]] of [[microwave]] signals. Communication signals were transmitted from one location on [[Earth]] and bounced off the surface of the satellite to another Earth location.<ref>{{cite web|url=http://samadhi.jpl.nasa.gov/msl/QuickLooks/echoQL.html|access-date=February 6, 2010|title=Echo 1, 1A, 2|work=Mission and Spacecraft Library|publisher=NASA|url-status=dead|archive-url=https://web.archive.org/web/20100527211747/http://samadhi.jpl.nasa.gov/msl/QuickLooks/echoQL.html|archive-date=May 27, 2010}} {{PD-notice}}</ref>

The first transmissions using Echo were sent from [[Goldstone, California]], to [[Crawford Hill]] in [[Holmdel Township, New Jersey|Holmdel, New Jersey]], on 12 August 1960. The last Echo satellite deorbited and burned up in the atmosphere on 7 June 1969.<ref name="astr01">[http://www.astronautix.com/craft/echo.htm Astronautix.com, ''Echo''] {{webarchive|url=https://web.archive.org/web/20080511221550/http://www.astronautix.com/craft/echo.htm |date=2008-05-11 }}</ref>