TopSat

{{Short description|British Earth observation satellite}}

{{Use dmy dates|date=April 2022}}

{{Infobox spaceflight

| name = TopSat

| image = Camera for TopSat (8166889838).jpg

| image_caption = The TopSat being made

| mission_type = Optical imaging

| operator =

| website =

| COSPAR_ID = 2005-043B{{Cite web|url=http://celestrak.com/satcat/2005/2005-043.asp|title=CelesTrak SATCAT: 2005-043}}

| SATCAT =

| mission_duration =

| spacecraft_bus =

| manufacturer = SSTL

| dry_mass =

| launch_mass =

| dimensions =

| power =

| launch_date = {{start-date|27 October 2005, 06:52:26|timezone=yes}} UTC

| launch_rocket = Kosmos-3M

| launch_site = Plesetsk 132/1

| launch_contractor =

| disposal_type =

| deactivated =

| last_contact =

| decay_date =

| orbit_epoch = 3 November 2005{{cite web |url=http://planet4589.org/space/log/satcat.txt |title=Satellite Catalog |publisher=Jonathan's Space Page |first=Jonathan |last=McDowell |access-date=3 May 2018}}

| orbit_reference = Geocentric

| orbit_regime = Sun-synchronous

| orbit_periapsis = {{convert|682|km|mi}}

| orbit_apoapsis = {{convert|707|km|mi}}

| orbit_inclination = 98.18 degrees

| orbit_period = 98.65 minutes

| apsis = gee

}}

TopSat (Tactical Operational Satellite, also known as TopSat 1 and TacSat 0) is a British Earth observation satellite, currently in Low Earth Orbit. The nanosatellite was launched in October 2005 alongside the Beijing-1 Disaster Monitoring Constellation satellite by a Cosmos rocket from Plesetsk Cosmodrome in Russia.{{cite web|title=TopSat|url=http://www.bis.gov.uk/ukspaceagency/missions/topsat-proving-uk-technology|publisher=UK Space Agency|access-date=25 June 2012}}