ATTITUDE CONTROL SYSTEMS/GUIDANCE NAVIGATION AND CONTROL (ACS/GNC)

The NSROC ACS/GNC Group provides attitude determination and control packages, supplemental attitude sensors, pneumatic control packages, and boost guidance systems. Our systems have a long flight history and come as standard designs or designs that can be customized to a client 's requirements. Space and Ground Segment services are provided. All systems are designed with post-flight refurbishment in mind.

ATTITUDE CONTROL & BOOST GUIDANCE SYSTEMS

Working with the customer, the group builds boost guidance and attitude systems based on the following flight proven implementations.

Type	System	Knowledge	Control	Sensors
Boost Guidance	DS-19	0.66/0.40%		DMARS Inertial Gyro
	S-19D	7.5/7.5%		DMARS Inertial Gyro
	S-19L	7.5/7.5%		LN200 Fiber Optic Gyro
Coarse Attitude Control	Rate Control	0.2 deg/s	0.2-0.5 deg/s	3 axis rate sensor
	Magnetic ACS (NMACS)	< 2.0 deg	User Defined	three axis magnetometer,3 axis rate sensor
	Inertial ACS (NIACS)	< 2.0 deg	User Defined	GLNMAC platform
	Velocity Vector ACS	< 2.0 deg		GLNMAC platform + GPS
Fine Attitude Control	Celestial ACS, coarse	<15 arcsec	< 30 arcsec/sec	GLNMAC + ST5000
	Celestial ACS, fine	< 2 arcsec	< 0.5 arcsec/sec	LN251 + ST5000

Click here to see a video demonstrating the accuracy of NSROC's NIACS System.

S-19 Boost Guidance System	NIACS (NSROC Inertial ACS)

PNEUMATIC SYSTEMS

Cold gas pneumatics support the attitude control systems, offering a selection of gas, tank capacity, thrust level and mounting orientation. Coarse Attitude Control System pneumatics are generally self-contained. Fine Attitude Control Pneumatic Systems offer the additional options listed below providing fine levels of control.

System	Regulators	Accelerations
Bi-Level SPS	P&Y Course	2.5 deg / sec^2
	P&Y Fine	0.14 deg / sec^2
	Roll Coarse	6.4 deg / sec^2
	Roll Fine	0.32 deg / sec^2
Tri-Level Roll SPS	Roll Coarse	7.5 deg / sec^2
	Roll Intermediate	2.5 deg / ec^2
	Roll Fine	0.2 deg / sec^2
Tri-Level P&Y SPS	P&Y Fine	0.5 deg / sec^2

SUPPLEMENTAL ATTITUDE SENSORS

Some missions require very detailed knowledge of attitude history with lesser requirements for attitude control. Supplemental attitude sensors are used to collect the data needed for post-flight definitive attitude determination. The sensors are generally mounted in the telemetry section (TM). While such data is collected and telemetered, it is not used for passive attitude control, either. Sensor models and vendors vary with lead-time and requirements but fall well within the accuracy listed below.

SENSOR	ACCURACY
Coarse Sun Sensors	< 2.0
IR (earth) Sensors	< 3.0 deg
Three Axi Magnetometers	< 2.0 deg
Inertial Gyros	< 1.0 deg
Star Sensors	< 0.1 arcmin
Fine Sun Sensors	~ 0.2 arcsec
3 Axis Rate Sensors	0.2 deg/s
Aspect Camera	< 5 arcmin

GROUND SEGMENT SUPPORT

The GNC Group provides technical support to the mission from requirements definition through post-flight operations. The team performs system design, component level test & evaluation, electrical integration, system level test & evaluation, re-integration and system level testing at the launch site, launch operations and post-flight data analysis and reduction. Specialized support provided by the group is discussed in the following sections.

Gyro Evaluation Support

The Gyro Evaluation Lab evaluates a variety of inertial units used to support the Sounding Rocket Program. Technicians and engineers test all units to program specifications, certifying the unit's flight worthiness. The general functions performed by the ACS/GNC Group include:

	Receive vendor-supplied units and evaluate supplier log and performance data.
	Verify specification compliance through Acceptance Testing of units.
	Reduce and analyze performance data.
	Assemble and test the GLNMAC gyro package.
	Assign proper gyro to Boost Guidance, Attitude Control and TM Systems.
	Support integration and test of the unit at the component and system level.
	Support pre-launch field operations and launch.
	Resolve any issues concerning unit performance.

Star Sensor Support

The Star Sensor Evaluation Lab is a dedicated darkroom in which pre- flight qualification and post flight evaluation of star sensors is performed. In addition, the GNC Group offers a 900 sq. ft. dark room equipped with well-maintained F2.7 and F5.4 collimators, used as star simulators. These two facilities support Star Sensor operations during mission integration and post-flight test.

Air Bearing Testing in the Celestial Dark Room

During mission integration at WFF, the star simulators are used in combination with an ACS Cradle to simulate vehicle response to the firing of the ACS valves. Using position information from the star sensor, the ACS will activate the necessary valves to point the experiment at the simulated star. Installing a mass model of the star tracker with an alignment flat in place of the lens then checks the experiment to Star Sensor alignment.

ST5000 STAR TRACKER	ST5000 with Electronics; Test Round 12.054

Following the flight of a mission, star sensors are returned to the facility for a thorough evaluation by the GNC Group. The Star Sensor Evaluation Lab facilities are utilized to measure sensor performance and determine refurbishment requirements. Upon completion of refurbishment, the sensors are Acceptance Tested to flight specifications. The units are securely stored, awaiting reassignment to future missions.

A Laser Auto-Collimator is used for fine attitude measurement on the air bearing or cradle, it has a better than 0.1 arcsec resolution. It is used with a reference flat on the instrument being measured.

Boost Guidance System Support

The Boost Guidance System Lab evaluates units used to support the Sounding Rocket Program. Technicians and engineers test all units to program specifications, certifying the unit's flight worthiness. The general functions performed by GNC Boost Guidance include:

	Receive vendor-supplied units and evaluate supplier log and performance data.
	Verify specification compliance by Acceptance Testing of units.
	Reduce and analyze performance data.
	Ship systems to White Sands Missile Range for integration.
	Integrate systems at Wallops as follows:
	» TM Integration » Full up Testing » Pre Vibration Testing » Vibration » Post Vibration Testing » Pack & Ship Module to launch site.
	Support pre-launch field operations and launch.
	Resolve any issues concerning unit performance.

Pneumatic System Support

The Pneumatic Lab supports the design, fabrication and evaluation of pneumatic systems used in the Sounding Rocket Program. Technicians and engineers test all units to program specifications, certifying the unit's flight worthiness. The Pressure Test Cell is utilized to certify pressure vessels used in the program. The general functions performed by GNC Pneumatics include:

	Pneumatics system design and design assistance
	Pneumatics system and component testing and qualification
	Pneumatic system fabrication for flight and GSE
	Publication of pneumatics system procedures and consultation reviews
	Review of customer designed pneumatics systems
	Pneumatics system design consultations
	Post flight refurbishment of reusable pneumatics systems
	Component and system level integration and test support
	Support of pre-launch field operations and launch.

ADDITIONAL ACS LAB FACILITIES

In addition to the facilities indicated above, the GNC Group makes use of the Air Bearing Test Facility and Magnetic Calibration Facility located at WFF. Additional information on the subject matter contained on this link may be found in Chapter 5 of the Sounding Rocket Handbook which can be accessed, in PDF format, from the Main Menu or by clicking here.