Encyclopedia Astronautica
Tacsat-2



ztacsat.jpg
Tacsat
American military surveillance satellite. One launch, 2006.12.16. Tactical Satellite-2's objective was to demonstrate techniques to dramatically shorten the development time for small satellites.

Objectives were to take the spacecraft from concept to launch under 14 months; to achieve full on-orbit functionality within a week after launch; to demonstrate communication, command and control of the satellite by tactical field units; to image targets on earth with a resolution of under 1 m; to geolocate emitting radio targets and image them in the same pass; and demonstrate several further advanced technology experiments. The prototypes were to lead to a production TacSat design that would give Joint Task Force Commanders a direct operational capability by 2010.

The spacecraft bus was developed by MicroSat Systems of Littleton, Colorado using the spare bus of the canceled TechSat-21 program. The bus structure consisted of composite facesheets over an aluminum honeycomb core, comprising only 13% of the spacecraft mass. The basic structure was an irregular octagon with a payload and a separation deck. The platform was 3-axis stabilized, capable of providing a pointing accuracy of = 0.15. The ADCS (Attitude Determination and Control Subsystem) employed 3 reaction wheels (Dynacon MW-1000) and 3 torque rods as actuators. A star camera, referred to as ISC (Interstellar Compass), provided high-precision attitude measurements. An IMU (Inertial Measurement Unit), analog sun sensors, and a magnetometer completed the ADCS sensor suite. Electric power of up to 550 W was provided by the solar array. The Li-Ion battery had a capacity of 30 Ah. The bus power system provided 28 V switched power. The C&DH (Command and Data Handling) subsystem employed a Power PC. Bus communication were provided by a Mini-SGLS (Miniature Space-to-Ground Link Subsystem), using 2 pairs of patch antennas for full spherical coverage and an encryption device. The spacecraft had a mass of about 370 kg.

The most important innovation of TacSat-2 was the use of a space-based CDL. Flying a CDL transponder required ground-breaking work in frequency allocations and communications security (COMSEC) approaches. Direct tasking and data dissemination were implemented using the SIPRNet (Secret Internet Protocol Routing Network) capabilities, a classified network of DoD. The SIPRNet system objectives were to integrate all space assets into the forces so that the Joint Task Force (JTF) Commander could call up assets by deciding the payload capability required, i.e., the area of interest, the area for direct downlink, and the date the assets must be operational.

Tacsat-2 flew the following sensor/experiment complement:

  • ESI (Earth Surface Imager) developed by AFRL and SAIC (Science Applications International Corporation). ESI was the prime instrument of TacSat-2 (pushbroom imager). The objective was to provide high-resolution imagery at < 1 m GSD (Ground Sample Distance). The instrument featured a Pan band and 3 multispectral bands (red, green, and blue) in the visible range across a swath of 6144 pixels (5 km swath width). The optics subsystem employed a COTS telescope of 50 cm aperture by RC Optical Systems. The imager used a Fairchild Imaging CCD 583 TDI line scan array, sampling at approximately 9600 lines/s. The TDI (Time Delay Integration) process was essentially noise-free, allowing charge accumulation to take place over the number of TDI stages, and preserved the ground resolution capability of the very high rates that the TDI lines were "scanned" off the array.

  • TIE (Target Indicator Experiment), provided by NRL. It consisted of a wideband sensor to gather radar, radio and handheld communication signals. The objective was to locate targets based on RF signatures and in conjunction with P-3 aircraft. TIE was an improved version of that flown on the TacSat-1 satellite. TIE used a total of 11 antennas. The TIE payload performed real-time signal geolocation and SEI (Specific Emitter Identification) services of radio frequency (RF) signals using space- and air-based collection platforms. It was also capable of collecting the AIS (Automated Identification System) signal now required on large ships for port safety and homeland defense. The TIE payload was also reprogrammable on orbit for acquiring new targets. The TIE package featured a commercial telescope of 50 cm aperture to take high-resolution imagery in the same pass.

  • CDL (Common Data Link) was an AFRL experimental communication system. The objective was to use it in combination with a ground-based CDL terminals. This high-performance system permitted downlink data rates of up to 274 Mbit/s. DoD designated CDL as its standard for use in imagery and signals intelligence in 1991. This link consisted of a secure, jam-resistant uplink operating at 200 kbit/s and a down link that could operate at various data rates. CDL was currently also being used on UAVs (Unmanned Aerial Vehicle) including Global Hawk and Predator.

  • ROPE (Roadrunner On-orbit Processing Experiment). This payload consisted of an array of FPGAs (Field Programmable Gate Array) designed to process imagery into standard military imaging formats. ROPE supported event processing to identify likely targets, and JPEG data compression for real-time data transmission to the ground segment.

  • HET (Hall Effect Thruster), provided by AFRL at Edwards AFB, CA. This demonstration ion engine was based on the Busek Tandem Hall Thruster BHT-200-X3 (Busek Co. Inc., Natik, MA). HET featured an Isp of up to 1600 s, variable thrust levels, and variable power usage. The nominal 200 W thruster had an operating envelope ranging from 50 to 300 W. The thrust range was 4-17 mN with nominally 12.4 mN. The instrument had a mass of < 1 kg and a size of 100 mm diameter and a length of 105 mm. HET was used was to maintain orbit against drag. The BHT-200-X3 represented the first U.S.-designed and built HET to fly in space.

  • IGOR (Integrated GPS On-orbit Receiver), developed by Broad Reach Engineering (BRE), Tempe, AZ. IGOR was of BlackJack heritage of JPL. The objective was to conduct ionospheric reflection and transmission experiments. In addition, IGOR provided the spacecraft with a precise navigation solution in support of high-precision imaging observations. The instrument had dimensions of 200 mm x 240 mm x 105 mm, a mass of 4.6 kg, and a power consumption of 23 W (peak). 9)

  • ADS (Atmospheric Density Specifications). ADS consisted of two complementary experiments to characterize the neutral wind of the upper atmosphere.

    • ACME (Anemometer Cross-track Measurement Experiment). ACME measured the cross-track component of the very rarefied atmosphere at the orbital altitude of 350 km; it required precise pointing knowledge to remove the spacecraft in-track velocity component from its measurement. ACME was being by the University of Texas at Dallas, TX.

    • ADMS (Absolute Density Mass Spectrometer). ADMS measured the atomic mass of the prevailing species in the wind in the range from 1 to 50. ADMS was being developed at AFRL, Hanscom AFB, MA.

    The coordinated ADS package measurements permitted a better understanding of the dynamic processes that affect the variability of the upper atmosphere.

  • MVIS (Miniaturized Vibration Isolation System). The objective of MVIS was to demonstrate damping of spacecraft jitter - in support of higher-quality observation measurements. MVIS consisted of a series of actuators placed at the imager telescope assembly center of gravity.

  • ESA (Experimental Solar Array), an innovative, low-cost, and lightweight flexible Thin Film Photovoltaic solar array system developed by MSI.

  • Autonomy, developed by ICS (Interface & Control Systems, Chapel Hill, NC). Autonomy consisted of two subsystems: OOCE (On-Orbit Checkout Experiment), and ATE (Autonomous Tasking Experiment). The OOCE featured an enabling technology for autonomously commissioning the spacecraft (checkout) during its first day of orbital life. ATE permitted non-expert users in the battlefield to send data requests to the spacecraft (example: "image a particular region in latitude and longitude") and to receive the response directly, if possible with regard to the current spacecraft location in orbit. ATE also served as long-term and short-term experiment scheduler for all the payloads.

First Launch: 2006.12.16.
Number: 1 .


Associated Countries
See also
  • Minotaur Minotaur was developed for the US Air Force's Orbital/Suborbital Program (OSP) as a low-cost, four-stage Space Launch Vehicle (SLV) using a combination of government-supplied surplus Minuteman II ICBM motors and proven Orbital space launch technologies. Proposed growth versions would use surplus Peacekeeper rocket stages. More...

Associated Launch Vehicles
  • Minotaur 1 American all-solid orbital launch vehicle. Orbital launch vehicle consisting of a surplus Minuteman M55A1 first stage, Minuteman SR19 second stage, and new Orion 50XL third stage, Orion 38 fourth stage, and optional HAPS fifth stage for velocity trim and multiple payload deployment. Payload 580 kg to an 185 km, 28.5 degree orbit from Cape Canaveral; 310 kg to a 740 km sun-synchronous orbit from Vandenberg. More...
  • Minotaur American all-solid orbital launch vehicle. Minotaur was developed for the US Air Force's Orbital/Suborbital Program (OSP) as a low-cost, four-stage Space Launch Vehicle (SLV) using a combination of government-supplied surplus Minuteman II ICBM motors and proven Orbital space launch technologies. The Minotaur 4 version used surplus Peacekeeper rocket stages. More...

Bibliography
  • McDowell, Jonathan, Jonathan's Space Home Page (launch records), Harvard University, 1997-present. Web Address when accessed: here.

Associated Launch Sites
  • Wallops Island Small NASA launch site for sounding rocket launches and occasional Scout launches to orbit. Air launches are conducted from the Drop Zone Wallops Island, 37.00 N 72.0 W. With the last orbital launch in 1985 and the decline in sounding rocket launches, Wallops fell into near-disuse as a launch center. Its fortunes revised with the establishment of Mid-Atlantic Regional Spaceport in 2005 and orbital launches resumed in 2010. More...

Tacsat-2 Chronology


2006 December 16 - . 12:00 GMT - . Launch Site: Wallops Island. Launch Complex: Wallops Island LA0B. LV Family: Minotaur. Launch Vehicle: Minotaur 1. LV Configuration: Minotaur 1 6.
  • Tacsat-2 - . Mass: 370 kg (810 lb). Nation: USA. Agency: AFRL. Manufacturer: MicroSats. Class: Surveillance. Type: Military surveillance satellite. Spacecraft: Tacsat-2. USAF Sat Cat: 29653 . COSPAR: 2006-058A. Apogee: 426 km (264 mi). Perigee: 410 km (250 mi). Inclination: 40.0100 deg. Period: 92.93 min. Tacsat-2 was a prototype rapid development/rapid deployment tactical military satellite that provided American Joint Task Force commanders direct control of a satellite providing both SIGINT and imagery with a resolution of better than 1-m. The known communications payload used an 8 GHz (X-band) downlink. This was the first orbital launch from Wallops Island since 1985. TacSat-2 was to have been launched by a Falcon-1 from Vandenberg into a sun-synchronous orbit. However, the failure of Falcon-1 on its long-delayed maiden in March 2006 caused AFRL to award a new launch contract for TacSat-2 and TacSat-3 to OSC in May 2006. The launch was achieved using OSC's Minotaur launch vehicle only seven months after contract award.


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