Computer model of TacSat-4
NamesJSW 1
Tactical Microsatellite Innovative Naval Prototype (INP)
Mission typeTechnology, Communications
OperatorNaval Research Laboratory (NRL)
Applied Physics Laboratory (APL)
Air Force Research Laboratory (AFRL)
COSPAR ID2011-052A Edit this at Wikidata
SATCAT no.37818
Mission duration2 years (planned)
Spacecraft properties
Spacecraft typeTacSat
BusJSW bus
ManufacturerNaval Research Laboratory (bus and payload)
Applied Physics Laboratory (bus)
Launch mass468 kg (1,032 lb)
Power1 kW
Start of mission
Launch date27 September 2011,
15:49:00 UTC
RocketMinotaur IV+
Launch siteKodiak Launch Complex, LP-1
ContractorOrbital Sciences Corporation (OSC)
Orbital parameters
Reference systemGeocentric orbit
RegimeLow Earth orbit
Perigee altitude472 km (293 mi)
Apogee altitude12,291 km (7,637 mi)
Period238.9 minutes

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).[1][2][3][4]


TacSat-4 is equipped with a 3.6 m (12 ft) antenna operating 10 Ultra High Frequency (UHF) channels that can be used for any combination of communications, data ex-filtration or Blue Force Tracking (BFT). TacSat-4 will fly the highly elliptical, 4-hour, orbit (12,050 kilometers at peak) providing typical payload communication periods of two hours per orbit. TacSat-4's orbit also allows it to cover the high latitudes.

Part of its capability is rapid (within 24 hours) reallocation to different theaters worldwide, in support of unexpected operations. Command and control of TacSat-4 will be performed at the United States Naval Research Laboratory (NRL) Satellite Operations Center at Blossom Point, Maryland. Payload tasking will be performed via the SIPRNet based Virtual Mission Operations Center (VMOC).


All TacSat satellites are designed to demonstrate the ability to provide real-time data collected from space to combatant commanders in the field.[5]

The spacecraft bus was built by NRL and Johns Hopkins University Applied Physics Laboratory (APL) to mature ORS bus standards developed by an Integrated (government and industry) System Engineering Team, the "ISET Team", with active representation from AeroAstro, Air Force Research Laboratory, Johns Hopkins University Applied Physics Laboratory, ATK Space, Ball Aerospace & Technologies, Boeing, Design Net Engineering, General Dynamics AIS, Microcosm, Sierra Nevada Corp., Massachusetts Institute of Technology, Lincoln Laboratory, Orbital Sciences Corporation, NRL, SMC, Space Systems/Loral, and Raytheon. Lithium-ion battery power provided by Quallion.


TacSat-4 with deployed UHF antenna
TacSat-4 at Naval Research Lab
Bus and COMMx payload
System overview


  1. ^ "Next launch: May 5". Kodiak Daily Mirror. 1 March 2011. Retrieved 9 March 2011.
  2. ^ "TacSat-4 spacecraft complete and awaiting launch". Naval Research Laboratory. 1 December 2009. Retrieved 13 June 2010. Public Domain This article incorporates text from this source, which is in the public domain.
  3. ^ "Launch Schedule". Spaceflight Now. 15 June 2010. Retrieved 16 June 2010.
  4. ^ Brinton, Turner (30 August 2010). "Rapidly Delivered Systems". SpaceNews. Archived from the original on 12 September 2012. Retrieved 25 October 2010.
  5. ^ Ferster, Warren (7 November 2005). "U.S. Air Force Payload for TacSat 4". SpaceNews. Archived from the original on 15 May 2008. Retrieved 28 July 2008.