Gravity Gradient Technology Satellite

{{short description|U.S. Gravity Gradient Satellite}}{{Self-published|date=August 2024}}{{Infobox spaceflight

| name = Gravity Gradient Test Satellite (GGTS)

| image = File:Gravity Gradient Technology Satellite (GGTS).jpg

| image_caption = Gravity Gradient Technology Satellite (GGTS)

| mission_type = Gravity-gradient stabilization

| operator = United States Air Force

| Harvard_designation =

| COSPAR_ID = 1966-053A

| SATCAT = 2207{{cite web|url=https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1966-053A|title=GGTS 1|website=NASA Space Science Data Coordinated Archive|access-date=November 21, 2019}}

| spacecraft_bus =

| manufacturer =

| dry_mass =

| launch_mass = {{convert|47|kg|lb|0|sp=us}}

| power =

| launch_date = {{start-date|June 16, 1966|timezone=yes}} 14:00:01 UTC

| launch_rocket = Titan IIIC

| launch_site = Cape Canaveral LC41

| deactivated =

| decay_date =

| orbit_epoch =

| orbit_reference = Geocentric

| orbit_regime = Geosynchronous

| orbit_periapsis = {{convert|33663|km|mi|0|sp=us}}

| orbit_apoapsis = {{convert|33858|km|mi|0|sp=us}}

| orbit_inclination = 4.2°

| orbit_period = 1,334.00 minutes{{cite web|url=http://www.astronautix.com/g/ggts.html|archive-url=https://web.archive.org/web/20161228022830/http://astronautix.com/g/ggts.html|url-status=dead|archive-date=December 28, 2016|title= GGTS|publisher=Astronautix|access-date=November 22, 2019}}

| apsis = gee

}}

The Gravity Gradient Test Satellite was launched by the US Air Force from Cape Canaveral LC41 aboard a Titan IIIC rocket on June 16, 1966, at 14:00:01 UTC.{{Cite web|url=http://planet4589.org/space/log/launchlog.txt|title=Launch Log|last=McDowell|first=Jonathan|publisher=Jonathon's Space Report|access-date=December 30, 2018}} The satellite was launched along with seven IDCSP satellites, with which it shared a bus. In contrast to the solar-powered IDCSP satellites, GGTS was battery powered.

GGTS utilized the {{convert|26.4|lb|kg|adj=on}} Magnetically Anchored Gravity Systems (MACS), which consisted of two identical subsystem packages, each containing an extensible rod unit and a magnetically anchored spherical viscous damper.{{Cite conference |last=Weygandt |first=P. |last2=Moyer |first2=R. |date=August 1966 |title=Attitude Control for the Gravity Gradient Test Satellite |url=https://arc.aiaa.org/doi/abs/10.2514/6.1966-1821 |conference=Guidance and Control Conference |doi=10.2514/6.1966-1821 |via=American Institute of Aeronautics and Astronautics}} The rod units had an extended length of {{convert|15.8|m|ft|sp=us}}, and their {{convert|5|kg|adj=on}} damper tip weights gave the satellite a symmetric dumbbell configuration. The dampers were produced by General Electric and consisted of two concentric spheres separated by a viscous damping fluid. The internal sphere contained a hollow cylindrical magnet which served to "anchor' the inner sphere to the Earth's magnetic field, stabilizing the satellite over time.

It had been hoped that within 60 days of launch, the satellite would reach a stabilization of ±8° on the x- and y-axis. The results were compromised, as one of the dampers was magnetically contaminated.

A follow-up GGTS mission was lost due to a launch vehicle failure on August 28, 1966.{{cite web|url=https://space.skyrocket.de/doc_sdat/ggts-1.htm|title=GGTS 1,2|publisher=Gunter's Space Report|access-date=22 Nov 2019}}