Attachment O - L10 Lexicon.pdf

Attachment No. O

Landsat 10 Lexicon

RFP 80GSFC26R0015

National Aeronautics and Space Administration Goddard Space Flight Center

L10 SC RFP Lexicon L10-SC-DESC-0066, Revision -ii Use or disclosure of data contained on this page is subject to the restriction(s) on the title page of this document.

Table of Contents TABLE OF CONTENTS ................................................................................................................ II

1.0 INTRODUCTION

2.0 LEXICON

2.1 Numbers and Symbols

2.2 A

2.3 B

2.4 C

2.5 D

2.6 E

2.7 F

2.8 G

2.9 H

2.10 I 8

2.11 J

2.12 L

2.13 M

2.14 N

2.15 O

2.16 P

2.17 Q

2.18 R

2.19 S

2.20 T

2.21 U

2.22 V

2.23 W

L10 SC RFP Lexicon L10-SC-DESC-0066 Revision -

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1.0 INTRODUCTION

These definitions were generated from the Landsat 10 Common Lexicon, L10-SYS-DESC-0004 Draft Rev E.

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2.0 LEXICON

2.1 NUMBERS AND SYMBOLS

3-Sigma – A set of values with a standard distribution is considered to meet a 3-sigma requirement if no fewer than 99.7% of the values are within the specified limits of the requirement.

2.2 A

Acceptance Tests – The verification process that demonstrates that software, firmware, and hardware is acceptable for flight. It also serves as a quality control screen to detect deficiencies and, normally, to provide the basis for delivery of an item under terms of a contract.

Activity Defintion – A repeatable, spacecraft-defined collection of commands, execution logic, and rules/constraints used by the flight system to enable operational autonomy and translate requests into the spacecraft schedules on board.

Alignment – The relative orientation of 2 reference frames.

Alignment Control – The process of controlling the maximum difference between the actual orientation of a reference frame and its nominal orientation.

Alignment Control Error – The maximum difference between the actual orientation of a reference frame and its nominal orientation.

Alignment Drift – Changes in the alignment between 2 reference frames that occur during normal on-orbit operations, excluding effects due to jitter. For the alignment of LandIS relative to the spacecraft, one source of drift is structural distortions arising from orbital and seasonal changes in thermal conditions.

Alignment Knowledge – The estimate of the relative orientation between 2 reference frames.

Alignment Knowledge Uncertainty – The uncertainty in the knowledge of the relative orientation between 2 reference frames.

Alignment Shift – A change in the alignment between 2 reference frames that occurs over one finite, defined, period of time, typically prior to and not changing significantly during normal on orbit operations. For the alignment of the LandIS relative to the spacecraft, alignment shifts arise from structural distortion effects such as launch loads, moisture outgassing and the relief of gravity loads.

Allocated Mass – [syn. Allowable Mass] - The limit against which mass margins are calculated.

Allocation – An allocation is a requirement which is derived by partitioning a higher-level requirement into lower-level component requirements and making an assignment of values to that lower level. Allocation statements use the verb “shall.”

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Altitude Range – Range of altitudes around the orbit. Altitude varies around the orbit because the orbit is not circular and because the Earth is not spherical. The frozen nature of the orbit means the orbital perigee does not precess around the orbit, and thus in a perfectly-frozen orbit the altitude at a given latitude has minimal variation from orbit to orbit. However, altitude will also vary due to natural orbit decay between drag make-up maneuvers, within the bounds of the WRS-2 control box, and due to the allowable variations in the frozen orbit specifications.

Ancillary Data – A selected subset of observatory telemetry that provides information about the on-orbit environment and observatory status at the time of the image sensor data collections.

Ancillary data includes all observatory telemetry necessary to produce a scene data product.

Ancillary data typically includes relevant LandIS parameters, calibration parameters, observatory attitude and ephemeris, etc.

Anomaly – An unexpected event, hardware or software damage, or departure from established procedures, that is outside of design/performance specification limits or is inconsistent with proper system behavior. Note: An anomaly can result in a nonconformance. Design limits are those identified in approved design-level documents.

Argument of Perigee – The angle that specifies the location of perigee in the orbit, relative to the ascending node.

Assembly (Flight System Hardware Levels of Assembly) – Power Amplifier, IMSC, Laser Source, VNIR Focal Plane Assembly, SWIR Focal Plane Assembly, TIR Focal Plane Assembly, SWIR Dewar Assembly, TIR Dewar Assembly (inclusive of the dewar box and relays), Strongback Structure, Scan Mirror DEB, Scan Mirror w/o DEB, Cryo-Isolator

See Flight System Hardware Levels of Assembly.

Audit – A review of a developer’s, contractor's, or subcontractor's documentation, software, firmware or hardware to verify that it complies with project requirements.

Authentication – A security measure designed to establish the validity of a transmission, message, or originator. Authentication provides the assurance that information transmitted from a claimed source (i.e., a source's identity) actually originated from that source.

Autonomy – Autonomous operations consist of the actions taken by a component or system based on logic contained in the flight code (software, Field Programmable Gate Array [FPGA], Application Specific Integrated Circuits [ASIC], etc.). Autonomy does not preclude or include stored command sequences (absolute or relative) or pre-defined command sequence responses to on-orbit conditions.

2.3 B

Boresight – The LandIS pointing reference direction coinciding with or at a known offset to the LandIS optical axis, nominally intersecting the center of the focal plane array.

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2.4 C

Calibration Maneuver – A spacecraft attitude adjustment made to view a calibration source (i.e., deep space, moon, earth limb, ground target).

Characterize – The use of a set of measurements and analyses to describe the performance of a device or product over the relevant operating range. Characterization includes taking point measurements, modeling the variation in a characteristic as a function of one or more parameters (e.g., temperature, time), measuring stability over a range of conditions, and computing error estimates.

Close Call – An event requiring first aid treatment or less, or property damage/mission failure direct cost of less than $20,000, but has NASA mishap potential considering and documenting either most likely or worst case estimates by the responsible organization.

Collect – To acquire, downlink, and subsequently transfer data from the observatory to the ground system.

Command and Telemetry Data Bus – The mechanism used to communicate between and coordinate operations of observatory components and subsystems. The reference to command and telemetry data bus is a logical interface and is not meant to imply a physical interface requirement.

Command and Telemetary Simulator (CTSS) – The Command and Telemetry Simulator (CTSS) is a low-fidelty system for simulating realistic spacecraft command & telemetery responses with basic scripting capability. It is primarily used for ground station and ground system checkout activities.

Communications Activity Schedule (CAS) – A time-based sequence of all activities necessary to support any planned ground contacts.

Configuration – The functional and physical characteristics of the payload and all its integral parts, assemblies and systems that are capable of fulfilling the fit, form and functional requirements defined by performance specifications and engineering drawings.

Contact – A single Observatory Acquisition of Signal (AOS) to Loss of Signal (LOS) session taken at either a ground station or a communication satellite such as the Tracking and Data Relay Satellite System (TDRSS). Can also be referred to as a pass.

Contamination – The presence of materials of molecular or particulate nature which degrade the performance of hardware.

Critical Weld – A weld in which a single failure will result in loss of load carrying capability under the applied loading condition.

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2.5 D

Demonstrate – To show that the current knowledge of one or more system parameters is correct and accurate by collecting and processing test data using current calibration parameters and analyzing the performance of the processed results.

Design Qualification Tests – Tests intended to demonstrate that the test item will function within performance specifications under simulated conditions more severe than those expected from ground handling, launch, and mission operations. Their purpose is to uncover deficiencies in design and method of manufacture. They are not intended to exceed design safety margins or to introduce unrealistic modes of failure. The design qualification tests may be to either “prototype” or “protoflight” test levels.

Detector – Generic term for a sensing element that produces an electrical output in response to incident electromagnetic radiation. May be a single element or a sum of multiple elements or a 2D array of multiple elements. Values from a detector are unsigned integers known as digital numbers.

Deviation – Specific written authorization, granted prior to the manufacture or testing of an item, to depart from a particular performance or design requirement, where the intent of the requirement can be met through alternate means.

Discrepancy – Refer to Nonconformance

Displacement Damage – Degradation in a bipolar or opto-electronic device resulting from displacement of atoms in the semiconductor lattice by energetic particles.

2.6 E

Electromagnetic Compatibility (EMC) – The condition that prevails when various electronic devices are performing their functions according to design in a common electromagnetic environment.

Electromagnetic Interference (EMI) – Electromagnetic energy which interrupts, obstructs, or otherwise degrades or limits the effective performance of electrical equipment.

Electromagnetic Susceptibility – An undesired response by a component, subsystem, or system to conducted or radiated electromagnetic emissions.

Encryption – A security measure designed to prevent unauthorized access to data or control of the observatory. Encryption is achieved by converting plain text to equivalent cipher text by means of a code.

End-to-End Tests – Tests performed on the integrated ground and flight system, including all elements of the observatory, its control, stimulation, communications, and data processing to demonstrate that the entire system is operating in a manner to fulfill all mission requirements and

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objectives.

Entropy – State of disorder or randomness within data. Traditionally the higher the entropy, the lower the compressibility of data.

Ephemeris Data – A set of data that provides the position, velocity, and time of a celestial body (including a manmade satellite) for regular intervals in time. Ephemeris data helps to characterize the conditions under which remote sensing data are collected and may be used to correct the sensor data prior to analysis.

Equatorial Altitude – The altitude when the satellite crosses the equator. We assume the orbit remains frozen, therefore the equatorial altitude does not vary over time.

2.7 F

Failure – A departure from specification that is discovered in the functioning or operation of the hardware or software.

Failure Modes, Effects and Criticality Analysis (FMECA) – A procedure by which each credible failure mode of each item from a low-indenture level to the highest is analyzed to determine the effects on the system and to classify each potential failure mode in accordance with the severity of its effect.

Fail-safe – Ensures that, because of structural redundancy, a structural element will not cause collapse of the remaining structure or have any detrimental effects on mission performance.

Field of View – The instantaneous object space sampled with the sensor scanner or observatory at a fixed position. If the instrument does not include a scanning methodology, the Field of View is equivalent to the Field of Regard. It is a solid angle through which the detectors are sensitive to electromagnetic radiation.

Flight Acceptance – See Acceptance Tests.

Flight Hardware – Hardware to be used operationally in space.

Flight System Hardware Levels of Assembly – Flight System Hardware Levels of Assembly provides a hierarchy of levels of assembly for the flight hardware, with examples. These level designators are based on those used in the Space Systems Engineering Database developed by The Aerospace Corporation for the Air Force, and agreed to by NASA Headquarters, GSFC, and JPL. The ObsERD environmental test requirements generally start at the “unit” level and end at the “mission payload” level. However, screening and life-tests often occur at lower levels, and overall system verification continues beyond the “mission payload” level.

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Focal Plane Array – The detectors and associated electronics assembled with the spectral bandpass filters.

Follow-On Hardware – Flight hardware built in accordance with a design that has been qualified either as prototype or as protoflight hardware; follow-on hardware is subject to a flight acceptance test program.

Fracture Control Program – A systematic project activity to ensure that hardware intended for flight has sufficient structural integrity as to present no critical or catastrophic hazard as well as to ensure quality of performance in the structural area for any observatory (spacecraft) project.

Central to the program is fracture control analysis, which includes the concepts of fail-safe and safe-life.

Frozen Orbit – The orbit where the eccentricity and argument of perigee have been chosen to prevent perigee from drifting.

As a result, the altitude over a given latitude stays nearly constant.

For Landsat we set argument of perigee near 90 deg, so perigee is at the north end of the orbit.

Functional Tests – The operation of the unit in accordance with a defined operational procedure to determine whether it performs per the specified requirements. A functional test may be executed as part of a performance test.

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2.8 G

Geocentric Nadir – Geocentric Nadir is defined at any point in the orbit as the direction toward the center of the mass of the Earth.

Ground Contact Request (GCR) – Time-based, loaded-from-ground requests to schedule specific ground contacts.

Ground Directed Activity Timeline (GDAL) – A time-sequenced list of the onboard, active SpCRs (higher priority than the Imaging Plan.)

Ground System to Spacecraft Integration Rack (GSSIR) – GFE test equipment provided by the USGS that contains RF demodulation and mission data processing capability to monitor SC testing and capture samples of the mission data stream for archival and other GS test purposes (data for GS-level testing, simulating GN operations for MRTs, etc.). Also provides S-Band capability for use in supporting specific testing, e.g. – RF compat. The GSSIR is connected to the SC via SC vendor EGSE.

Ground Track Spacing at Equator – The distance between two adjacent ground paths at the equator. This equals the equatorial circumference of 40,075 km divided by the number of paths in the Repeat Ground Track.

2.9 H

Hardware – As used in this document, there are two major categories of hardware.

• Prototype Hardware (See Prototype Hardware)

• Flight Hardware (See Flight Hardware)

High Entropy – Realistic image data that has significant randomness impacting the compression algorithm. Example is cumulus (popcorn) clouds over mountains or plains during green up.

This data is not a test pattern.

Housekeeping Data – Data that provides information about the health and status of the unit.

Housekeeping (Telemetry) – The engineering, health and safety, monitoring, and diagnostic telemetry data that are used in the control and operations of the observatory (spacecraft and image sensor[s]).

2.10 I

Imaging Plan – Defines the set of all WRS grid segments to be imaged, based on the onboard LCR and SCRs

Inclination – The angle from equator to orbit plane.

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Integrated Onboard Timeline (IOT) – Timeline that incorporates all planned activities from the Imaging Plan, GDAL, and CAS for a 48-hour time period.

Instrument Data Block (IDB) – LandIS collects, compresses, and sends instrument data blocks to the spacecraft for storage and downlink. Nominal science instrument data block is one, 7.5 second, scan of compressed LandIS data (compressed by band) and uncompressed instrument ancillary data, where a 7.5 second scan is approx. 5 seconds of Earth imaging and 2.5 seconds of calibration and telescope movement. For diagnostic purposes, an instrument data block can also consist of diagnostic information and uncompressed data, as requested.

2.11 J

Jitter – High-frequency variations in sensor position and/or angular orientation leading to deviations in the actual sensor line of sight relative to the ideal line of sight over time periods up to a few seconds. Jitter may be induced by mechanical vibrations from external disturbances or internal mechanisms.

2.12 L

LandIS Interface Simulator (LIS) – The interface simulator provided by LandIS to the spacecraft. It allows data injection of canned data for interface check-out. Also receives commands from the spacecraft for to confirm interface compatibility.

LandIS Operational Simulator (LOpS) – The LandIS Operational Simluator (LOpS) is a realistic instrument simulator. It is a high-fidelity operational simulator that simulates realistic instrument telemetry and command respond and instrument modes of operations and respond to autonomous actions. LOpS provides science data output (compress and uncompressed) and the abilityto inject known Image earth data to perform ground readiness tests (GRT). The LOpS provides platform for mission database checkout and observatory integration and test procedure development.

Landsat Ground Network (LGN) – The set of ground stations that are used for routine mission operations in support of the Landsat. The stations are located in Sioux Falls, South Dakota and Fairbanks, Alaska.

Launch Vehicle Interface Simulator (LVIS) – The Launch Vehicle Interface Simulator (LVIS) simulates the mission payload interface to the launch vehicle. It will be integrated with the launch vendor simulator to verify mission payload interfaces.

Limit Level – The maximum expected flight level (consistent with the minimum probability levels of Table 2.4-2).

Low Entropy – Image data having little randomness allowing for highly compressed imagery.

Examples include ice/snow covered regions, deserts, or night scenes.

Long-Term Acquistion Plan (LTAP) Collection Reqest (LCR) – Defines the individual

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path/row segments among the full WRS grid to be imaged

2.13 M

Main Bus Power – The unregulated power bus connected directly to the spacecraft bus battery.

Margin – The amount by which software, firmware, or hardware capability exceeds requirements.

Mean Eccentricity – The orbit eccentricity in Brouwer-Lyddane mean orbit elements. (Mean orbit elements are contrasted with osculating orbit elements, which change over the course of an orbit.)

Mean Local Time at the Descending Node – Local Time at the Descending Node, averaged over the annual variation in Sun position.

Mean Semimajor Axis – Orbit semimajor axis in Brouwer-Lyddane Mean Orbit Elements.

Measure – Provide a value for a particular system parameter or performance characteristic by direct observation

Metadata – A set of descriptive information about the scene data contained in the archive.

During the process of scene query and selection, the information is sufficient for a user to determine at a minimum: geographic coverage, date of collection, sensor gain mode, time of acquisition, cloud cover, and other qualitative measurements.

Mishap – See NASA Mishap, Type A Mishap, Type B Mishap, Type C Mishap and Type D Mishap

Mission Data – The time-correlated data set containing Landsat 10 imaging sensor data, spacecraft and LandIS ancillary data.

Mission Date File (MDF) – Mission Date Files (MDF) will use a consistent, defined format (including specific attributes), which associates ancillary and imaging data into a single file.

Within each MDF, the ancillary data will span the time of capture of each instrument data block within the MDF by 30 seconds. The 30s of spacecraft ancillary data includes pre-image collection and post-image data. MDFs can be marked by the spacecraft as priority files, based on the Imaging Plan.

Mission Lifetime – The Landsat 10 Mission lifetime starts at the NASA acceptance of the Landsat 10 Observatory and continues until the completion of the Decommissioning Phase of the Landsat 10 Observatory.

Mission Payload – The Landsat 10 mission payload consists of the observatory.

Mission Payload (Flight System Hardware Level of Assembly) – Observatory

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See Flight System Hardware Levels of Assembly.

Mission Operations Center (MOC) – The facility used to coordinate command and control the observatory for LEO, commissioning and on-orbit operations. This facility will be used during end-to-end testing of all elements of the Landsat 10 before launch.

Model Calibration – The process of adjusting numerical or modeling parameters in the model to improve agreement with a referent. Note: Model correlation is understood to be equivalent terminology.

Model Validation – The process of determining the degree to which a model or a simulation is an accurate representation of the real world from the perspective of the intended uses of the model.

Model Verification – The process of determining the extent to which a model is compliant with its requirements and specifications as detailed in its conceptual models, mathematical models, or other constructs.

2.14 N

Nadir – The direction from the observatory towards the center of the Earth. (See Reference:

Space Mission Analysis and Design, Wiley J. Larson and James R. Wertz, page 94, Second Edition - 1992.)

Narrowband Data – Observatory data down linked over a narrow band width, typically S-band, which includes housekeeping data, tracking data, commands and diagnostic telemetry. In addition, narrowband data includes the commands, software updates, and hard commands up linked to the observatory.

NASA Mishap – A NASA mishap is an unplanned event resulting in at least one of the following:

a. Occupational injury or occupational illness to non-NASA personnel caused by NASA operations.

b. Occupational injury or occupational illness to NASA personnel caused by NASA operations.

c. Destruction of or damage to NASA property, public or private property, including foreign property, caused by NASA operations or NASA-funded research and development projects.

d. NASA mission failure before the scheduled completion of the planned primary mission.

Nonconformance – A condition of any hardware, software, material, or service in which one or more characteristics do not conform to specified requirements or procedures or result in hardware or software damage. Nonconformances are grouped into two categories:

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• Major nonconformance (Class I) – Those that affect critical factors including form, fit or function, critical path schedule, cost performance or interfaces; safety, reliability or contract requirements.

• Minor nonconformances (Class II) – Those that can be corrected without affecting Class I critical factors.

Non-Uniformity Correction (NUC) – The process of performing a reversible on-board relative correction of gain and offset for each pixel to reduce the entropy of a scene to improve data compressibility and/or reduce errors in on-board aggregation or resampling.

2.15 O

Observatory – The spacecraft plus LandIS, that are flown as part of the Landsat 10 mission.

Off-the-shelf Software – (a) Commercial-off-the-shelf (COTS) software - Software that is sold, leased, or licensed to the general public, either as a standalone software product or embedded in a software system.

(b) Modified-off-the-shelf (MOTS) software - COTS software that is modified to meet unique requirements of a specific customer. This software requires ongoing unique maintenance for the life of the system not normally offered by the vendor.

(c) Government-off-the-shelf (GOTS) software - Software provided to the customer as government-furnished equipment (GFE) with no warranty or maintenance provided.

Operational Power – Main Bus Power supplied to the subsystems or instrument for the purpose of powering the functions necessary to accomplish mission objectives.

Observatory Operational Simulator (OOpS) – The Observatory Operational Simulators (OOpS) consists of the Spacecraft Operational Simulator (SOpS) and Landis Operational Simulator (LOpS). It is a high-fidelty simuator that serves as the workhorse tool for operations in ground system and operations readiness checkouts.

Orbit Average Power – The orbit average power allocated by the system for use by the Spacecraft/LandIS/Subsystem for a specified mode (i.e. if left in a particular mode for an entire orbit, how much power is needed?). Orbit Average is used to determine adequate energy balance for the observatory.

Outgassing – The emanation of volatile materials under vacuum conditions resulting in a mass loss and/or material condensation on nearby surfaces.

2.16 P

Part (Flight System Hardware Levels of Assembly) – Resistor, Integrated Circuit (IC), Connector, Bolt, Bracket, Valve, Structural Panel, Optical Filter, Crystal Oscillator, Detector

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See Flight System Hardware Levels of Assembly.

Performance Verification – Determination by test, analysis, or a combination of the two of how well the element operates as required in a particular mission; this includes proving that the design of the element has been qualified and that it has been verified as meeting the design requirements and ready for flight operations.

Pointing – The process of controlling the location or direction of a line of sight with respect to an intended target location or direction.

Power Service – Comprises all parts, wire, connectors and board traces in series between the Main Bus and the individual load for power, and between the load and Spacecraft Single Point Ground (SPG) for power return. May include fault protection and switching.

Protoflight Testing – See Protoflight Hardware.

Protoflight Hardware – Flight hardware of a new design; it is subject to a qualification test program that combines elements of prototype and flight acceptance verification; that is, the application of design qualification test levels and flight acceptance test durations.

Prototype Hardware – Hardware of a new design. Prototype hardware is subject to a design qualification test program, and it is not intended for flight.

Prototype Testing – See Hardware.

2.17 Q

Qualification – See Design Qualification Tests.

2.18 R

Raw Detector Data – Digital number value of a detector (e.g., detector element, TDI detector, or aggregated detector).

Reserve Mass – Mass reserved by the customer's program management for potential changes or unforeseen impacts to the mass budget.

Radio Frequency Suitecase (RF Suitcase) – The Radio Frequency Suitcase (RF Suitcase) siimulates Ka-band RF output from the spacecraft. It takes raw CADU data captured from the flight spacecraft and generates a representative Ka-band signal for ground stations.

Risk – The combination of the likelihood that a project will experience an undesired event and the consequences of the event. Likelihood can be expressed as the probability (qualitative or quantitative). The undesired event may be a cost overrun, schedule slippage, safety mishap, or technical impact such as failure to achieve a needed technological breakthrough. The

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consequences are expressed in terms of the impact or severity of the undesired event, should it occur.

Note (1): The concept of risk is used to describe a future uncertain event, the outcome of which, if it did occur, would be negative for the enterprise in question (see Note 2 below).

Any estimate of the probability of the risk (event) occurring is referred to as a measure of the risk’s likelihood. The significance to the project if the risk does happen is referred to as its consequence (or impact). A risk’s impact must, in general, be evaluated as a combination of cost impact, schedule impact, technical or performance impact, and/or safety impact. The basic concept of risk is completed with the idea of a risk’s priority or exposure that is conceived in qualitative terms as a function of the risk’s likelihood and impact measures.

Note (2): Positive-outcome events can similarly be considered. For simplicity, only the more typical negative-outcome events are considered in these definitions.

Risk Management – A process in which the PM leads the project team in identifying, analyzing, planning, tracking, controlling, and communicating the risks and the actions to handle the risks.

Effective communication must occur within the team and with management and customers. RM is driven by established success criteria and is a continuous, iterative process to manage risk to achieve safety and mission success.

2.19 S

Safe-life – Ensures that the largest flaw that could remain undetected after non- destructive examination would not grow to failure during the mission.

Safe Configuration – The subsystems or instrument will survive indefinitely for the conditions described. This is sometimes called "Safe Hold Configuration".

Section/Group of Components (Flight System Hardware Levels of Assembly) – Communications (Comms) Panel (comm boxes on a single panel), Solar Array (full wing), Thruster Band (Rocket Engine Module (REM), Catalyst Bed Heater, Bracket), Opto-Mechanical Assembly (inclusive of the cryo isolation system)

See Flight System Hardware Levels of Assembly.

Software Simulator (SoftSim) – The Software Simulator (SoftSim) is a software-based (emulated hardware) simulator of the spacecraft. it is comprised of a high-fidelty spacecraft simulator (executable/patchable flight software, modeled subsystems, environmental truth modeling, etc.) with low-fidelity LandIS capability (basic command and telemetry only). It is primarily used for spacecraft and ground procedure development, ground software development, and ground readiness tests.

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Space Segment – The Space Segment is the Landsat 10 Observatory.

Spacecraft Attitude Determination Frame – The right-handed orthogonal reference frame which the attitude determination system on board each Landsat 10 Observatory estimates in flight.

Spacecraft Operational Simulator (SOps) – The Spacecraft Operational Simulator (SOps) is a high-fidelity spacecraft siimulator (no instrument) that provides flight-like command telemetry response, redundancy, subsystem models, timing, compression and science data generation/flow.

The SOpS executes spacecraft flight software, with the ability to use and update as in flight.

Spare Hardware – Hardware whose design has been proven in a design qualification test program; it is subject to a flight acceptance test program and is used to replace flight hardware that is no longer acceptable for flight.

Special Collection Request (SCR) – Defines an individual WRS scene imaging request (higher priority than the LCR.) SCRs generally represent short-term acquisition interests.

Special Command Requests (SpCRs) – Time-based command requests from the ground, which are used to schedule non-path/row defined activities at absolute times, such as maneuvers, diagnostic activities, non-recurring calibrations, partial path off-nadir imaging and non-Earth-pointing imaging.

Spectral Band – An interval in the electromagnetic spectrum commonly designated by a spectral bandwidth and a center wavelength.

Standby mode – When the spacecraft is in proper attitude for imaging, and the instrument suite is powered on but not imaging.

Subassembly (Flight System Hardware Levels of Assembly) – Wire Harness, Populated Printed Circuit Card, Motor Housing, Solar Diffuser, On Board Black Body Calibrator, Stim Lamps, Beam Splitters, Radiator

See Flight System Hardware Levels of Assembly.

Survive – Refers to the ability of the subsystem or instrument to endure a condition without damage or degradation and return to the same level of performance following the removal of that condition.

Swath – The strip on the Earth that the instrument observes as it passes overhead.

System/Instrument (Flight System Hardware Levels of Assembly) – Bus Structure, Power, Attitude Control System (ACS), Command & Data Handling (C&DH), Telemetry, Tracking and Control (TT&C), Propulsion

See Flight System Hardware Levels of Assembly.

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2.20 T

Temperature Cycle – A transition from some initial temperature condition to temperature stabilization at one extreme and then to temperature stabilization at the opposite extreme and returning to the initial temperature condition.

Thermal Balance Test – A test conducted to verify the adequacy of the thermal model, the adequacy of the thermal design, and the capability of the thermal control system to maintain thermal conditions within established mission limits.

Thermal-Vacuum Test – A test conducted to demonstrate the capability of the test item to operate satisfactorily in a vacuum at temperatures based on those expected for the mission. The test, including the gradient shifts induced by cycling between temperature extremes, can also uncover latent defects in design, parts, and workmanship.

To Be Determined (TBD) – Means that no representative value/parameter has been identified for the requirement. Requirement determination will be made in coordination with the Landsat 10 Project Office.

To Be Resolved (TBR) – Means the requirement has at least two potentially conflicting values.

A TBR is subject to review for appropriateness and is subject to revision. The resolution is made in coordination with the Landsat 10 Project Office.

Total Ionizing Dose (TID) – A degradation mechanism in active electronic devices resulting from trapping of charge generated by ionizing radiation in the oxides of the device.

True-of-Date – A coordinate system based on the equatorial plane and ecliptic plane at the specified epoch. True-of-date is commonly used for low-earth orbit missions because the true-of-date inclination does not change if the launch data changes. (By contrast, the J2000 inclination can change if the launch date changes.)

Type A Mishap – A mishap resulting in one or more of the following:

a. Occupational injury or illness resulting in a fatality or a permanent total disability.

b. Total direct cost of mission failure and property damage of $2,000,000 or more.

c. Crewed aircraft hull loss.

d. Unexpected aircraft departure from controlled flight for all aircraft except when departure from controlled flight has been pre-briefed (e.g., upset recovery training, high AOA envelope testing, aerobatics, or Out of Controlled Flight for training) or mitigated through the flight test process inherent at each Center.

Type B Mishap – A mishap causing an occupational injury or illness resulting in permanent partial disability; hospitalization for inpatient care of three or more people within 30 workdays of

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the mishap; or a total direct cost of mission failure and property damage of at least $500,000, but less than $2,000,000.

Note: Hospitalization does not include any hospital stay intended only for medical testing, diagnosis, or observation to determine nature or extent of injury or illness.

Type C Mishap – A mishap resulting in a nonfatal OSHA-recordable occupational injury or illness causing days away from work, restricted duty, or transfer to another job beyond the day or shift on which the mishap occurred; hospitalization for inpatient care of one or two people within 30 workdays of the mishap; or a total direct cost of mission failure and property damage of at least $50,000 but less than $500,000.

Type D Mishap – A mishap resulting in a nonfatal OSHA-recordable occupational injury or illness that does not meet the definition of a Type C mishap or a total direct cost of mission failure and property damage of at least $20,000, but less than $50,000.

2.21 U

Unit/Component (Flight System Hardware Levels of Assembly) – Electronic Module, Telescope, Scan Mirror (inclusive of mirror, motor, encoder, and DEB), CryoCooler Electronics, CryoCooler TMU, Shutter Mechanism, Cover Mechanism (inclusive of pin pullers), Battery, Antenna, REM, Star Tracker, Reaction Wheel, Solar Array Panel, Propulsion Tank

See Flight System Hardware Levels of Assembly.

2.22 V

Validation – The term Validation is used in two distinct manners within the Landsat 10 mission requirements. Validation means to check and ensure that the desired outcome is indeed the expected outcome of a requirement, process or test. The second meaning is as an independent check of the quality of the mission data to ensure that requirements are met.

Variance – A difference between planned and actual performance that requires further review, analysis, or action. Appropriate thresholds are established in advance as to the magnitude of variance that will require formal variance analysis.

Verification – The process of ensuring mission/segment requirements are satisfied. Verification occurs using one or more of these methods: analysis, test, demonstration, or inspection.

Vibroacoustics – An environment induced by high-intensity acoustic noise associated with various segments of the flight profile; it manifests itself throughout the flight hardware in the form of directly transmitted acoustic excitation and as structure-borne random vibration.

Visible – EM radiation in the range of 380-750 nm.

Volume Table of Contents (VTOC) – The spacecraft mass storage system maintains a Volume

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Table of Contents (VTOC) that includes a list of all Mission Date File (MDF) currently stored in mass storage to be able to track and report the listing of files and their locations in memory.

Every time an MDF is downlinked, recorded, or the playback status is changed, the spacecraft updates the VTOC, and the VTOC itself is automatically downlinked over wide band whenever an MDF is downlinked, or it can be downlinked via command over narrowband to ensure ground always has access to the current knowledge of the files the spacecraft has attempted to downlink.

2.23 W

Waiver – Specific written authorization, granted after the manufacture or testing of an item, to depart from a particular performance or design requirement, where item is considered suitable for use “as is”.

Wideband Data – The downlinked Mission Data that have been processed and formatted for efficient data transmission.

Examples of wideband data processing steps for Landsat 10 purposes include lossless compression, error detection and correction coding, and pseudo-noise encoding. Examples of wideband data formatting include packet and frame-level organization of the Landsat 10 image sensor, ancillary data and stored housekeeping data.

Workmanship Tests – Tests performed during the environmental verification program to verify adequate workmanship in the construction of a test item. It is often necessary to impose stresses beyond those predicted for the mission in order to uncover defects. Thus random vibration tests are conducted specifically to detect bad solder joints, loose or missing fasteners, improperly mounted parts, etc. Cycling between temperature extremes during thermal-vacuum testing and the presence of electromagnetic interference during Electromagnetic Compatibility (EMC) testing can also reveal the lack of proper construction and adequate workmanship.

Worldwide Reference System (WRS) – A path/row coordinate system used to define the ground tracks of the Landsat 10 Observatory. The system specifies latitudinal and longitudinal coordinates for image centers and corners. In addition, the WRS assigns integer path (ground track) and row designations to each image center. The corner points corresponding to each path/row designation subtend a 164-km-by-168-km area on the Earth’s surface.