TacSat-4

{{Use American English|date=April 2021}}

{{Use dmy dates|date=April 2021}}

{{Infobox spaceflight

| name = TacSat-4

| names_list = JSW 1
COMMx
Tactical Microsatellite Innovative Naval Prototype (INP)

| image = TacSat-4.png

| image_caption = Computer model of TacSat-4

| image_size = 300px

| mission_type = Technology, Communications

| operator = Naval Research Laboratory (NRL)
Applied Physics Laboratory (APL)
Air Force Research Laboratory (AFRL)

| COSPAR_ID = 2011-052A

| SATCAT = 37818

| website =

| mission_duration = 2 years (planned)

| spacecraft = TacSat-4

| spacecraft_type = TacSat

| spacecraft_bus = JSW bus

| manufacturer = Naval Research Laboratory (bus and payload)
Applied Physics Laboratory (bus)

| launch_mass = {{cvt|468|kg}}

| dry_mass =

| dimensions =

| power = 1 kW

| launch_date = 27 September 2011,
15:49:00 UTC

| launch_rocket = Minotaur IV+

| launch_site = Kodiak Launch Complex, LP-1

| launch_contractor = Orbital Sciences Corporation (OSC)

| entered_service =

| disposal_type =

| deactivated =

| last_contact =

| decay_date =

| orbit_reference = Geocentric orbit

| orbit_regime = Low Earth orbit

| orbit_periapsis = {{cvt|472|km}}

| orbit_apoapsis = {{cvt|12291|km}}

| orbit_inclination = 63.1°

| orbit_period = 238.9 minutes

| apsis = gee

| insignia =

| insignia_caption =

| insignia_size = 200px

| programme = TacSat series

| previous_mission = TacSat-3

| next_mission = TacSat-6

}}

TacSat-4 is the third in a series of U.S. military experimental technology and communication satellites. The United States Naval Research Laboratory (NRL) is the program manager. The Office of Naval Research (ONR) sponsored the development of the payload and funded the first year of operations. The Office of the Director of Defense Research and Engineering (DDR&E) funded the standardized spacecraft bus and the Operationally Responsive Space Office (ORS) funded the launch that will be performed by the Air Force's Space and Missile Systems Center (SMC).

The spacecraft was completed by the end of 2009, and was launched on 27 September 2011, at 14:49:00 UTC, on a Minotaur IV launch vehicle into a highly elliptical orbit (HEO).{{cite web|url=http://www.kodiakdailymirror.com/?pid=19&id=9620|title=Next launch: May 5|date=March 1, 2011|access-date=March 9, 2011|newspaper=Kodiak Daily Mirror}}{{cite web

|url=http://www.nrl.navy.mil/pao/pressRelease.php?Y=2009&R=109-09r|archive-url=https://web.archive.org/web/20100620131245/http://www.nrl.navy.mil/pao/pressRelease.php?Y=2009&R=109-09r|url-status=dead|archive-date=20 June 2010|title=TacSat-4 spacecraft complete and awaiting launch|date=December 1, 2009|access-date=June 13, 2010|publisher=Naval Research Laboratory}} {{PD-notice}}{{cite web|url=http://spaceflightnow.com/tracking/|title=Launch Schedule|date=June 15, 2010|access-date=June 16, 2010|publisher=Spaceflight Now}}{{cite web |url=http://www.spacenews.com/military/100830-rapidly-delivered-systems.html|archive-url=https://archive.today/20120912211554/http://www.spacenews.com/military/100830-rapidly-delivered-systems.html|url-status=dead|archive-date=12 September 2012|title=Rapidly Delivered Systems|date=August 30, 2010|last=Brinton|first=Turner|access-date=October 25, 2010|publisher=SpaceNews}}