| NODIS Library | Program Formulation(7000s) | Search |

NPR 7150.2D
Effective Date: March 08, 2022
Expiration Date: March 08, 2027
Printable Format (PDF)

Subject: NASA Software Engineering Requirements

Responsible Office: Office of the Chief Engineer

| TOC | Preface | Chapter1 | Chapter2 | Chapter3 | Chapter4 | Chapter5 | Chapter6 | AppendixA | AppendixB | AppendixC | AppendixD | AppendixE | ALL |

Chapter 3: Software Management Requirements

3.1 Software Life Cycle Planning

3.1.1 Software life cycle planning covers the software aspects of a project from inception through retirement. The software life cycle planning is an organizing process that considers the software as a whole and provides the planning activities required to ensure a coordinated, well-engineered process for defining and implementing project activities. These processes, plans, and activities are coordinated within the project. At project conception, software needs for the project are analyzed, including acquisition, supply, development, operation, maintenance, retirement, decommissioning, and supporting activities and processes. The software effort is scoped, the development processes defined, measurements defined, and activities are documented in software planning documents.

3.1.2 The project manager shall assess options for software acquisition versus development. [SWE-033]

Note: The assessment can include risk, cost, and benefits criteria for each of the options listed below:

a. Acquire an off-the-shelf software product that satisfies the requirement.

b. Develop a software product or obtain the software service internally.

c. Develop the software product or obtain the software service through contract.

d. Enhance an existing software product or service.

e. Reuse an existing software product or service.

f. Source code available external to NASA.

See the NASA Software Engineering Handbook for additional detail.

3.1.3 The project manager shall develop, maintain, and execute software plans, including security plans, that cover the entire software life cycle and, as a minimum, address the requirements of this directive with approved tailoring. [SWE-013]

Note: The recommended practices and guidelines for the content of different types of software planning activities (whether stand-alone or condensed into one or more project level or software documents or electronic files) are defined in NASA-HDBK-2203. The project should include, or reference in the software development plans, procedures for coordinating the software development and design, and the system or project development life cycle.

3.1.4 The project manager shall track the actual results and performance of software activities against the software plans. [SWE-024]

a. Corrective actions are taken, recorded, and managed to closure.

b. Changes to commitments (e.g., software plans) that have been agreed to by the affected groups and individuals are taken, recorded, and managed.

3.1.5 The project manager shall define and document the acceptance criteria for the software. [SWE-034]

3.1.6 The project manager shall establish and maintain the software processes, software documentation plans, list of developed electronic products, deliverables, and list of tasks for the software development that are required for the project’s software developers, as well as the action required (e.g., approval, review) of the Government upon receipt of each of the deliverables. [SWE-036]

Note: A list of typical software engineering products or electronic data products used on a software project is contained in Chapter 6 of this directive. The software activities should include plans for software product verification and validation activities, software assurance, methods, environments, and criteria for the project.

3.1.7 The project manager shall define and document the milestones at which the software developer(s) progress will be reviewed and audited. [SWE-037]

3.1.8 The project manager shall require the software developer(s) to periodically report status and provide insight into software development and test activities; at a minimum, the software developer(s) will be required to allow the project manager and software assurance personnel to: [SWE-039]

a. Monitor product integration.

b. Review the verification activities to ensure adequacy.

c. Review trade studies and source data.

d. Audit the software development processes and practices.

e. Participate in software reviews and technical interchange meetings.

3.1.9 The project manager shall require the software developer(s) to provide NASA with software products, traceability, software change tracking information, and nonconformances in electronic format, including software development and management metrics. [SWE-040]

3.1.10 The project manager shall require the software developer(s) to provide NASA with electronic access to the source code developed for the project in a modifiable format. [SWE-042]

Note: The electronic access requirements for the source code, software products, and software process tracking information implies that NASA gets electronic copies of the items for use by NASA at NASA facilities. This requirement should include MOTS software, ground test software, simulations, ground analysis software, ground control software, science data processing software, hardware manufacturing software, and Class E and Class F software.

3.1.11 The project manager shall comply with the requirements in this NPR that are marked with an “X” in Appendix C consistent with their software classification. [SWE-139]

3.1.12 Where approved, the project manager shall document and reflect the tailored requirement in the plans or procedures controlling the development, acquisition, and deployment of the affected software. [SWE-121]

3.1.13 Each project manager with software components shall maintain a requirements mapping matrix or multiple requirements mapping matrices against requirements in this NPR, including those delegated to other parties or accomplished by contract vehicles or Space Act Agreements. [SWE-125]

Note: A project may have multiple software engineering requirements mapping matrices if needed for multiple software components on a given project.

Note: Project relief from an applicable “X” requirement can be granted only by the designated TAs, Engineering, and SMA, or, for security issues, the NASA CIO. The record of their approval of the tailored requirements in a Requirements Mapping Matrix will be indicated by the Authority signature or signatures in the Requirements Mapping Matrix. The projects will document their related mitigations and risk acceptance in the approved Requirements Mapping Matrix. When the requirement and software class are marked with an “X,” the projects record the risk and rationale for any requirements that are entirely or partially relieved in the Requirements Mapping Matrix. The CIO has institutional authority on all Class F software projects.

3.1.14 The project manager shall satisfy the following conditions when a COTS, GOTS, MOTS, OSS, or reused software component is acquired or used: [SWE-027]

a. The requirements to be met by the software component are identified.

b. The software component includes documentation to fulfill its intended purpose (e.g., usage instructions).

c. Proprietary rights, usage rights, ownership, warranty, licensing rights, transfer rights, and conditions of use (e.g., required copyright, author, and applicable license notices within the software code, or a requirement to redistribute the licensed software only under the same license (e.g., GNU GPL, ver. 3, license)) have been addressed and coordinated with Center Intellectual Property Counsel.

d. Future support for the software product is planned and adequate for project needs.

e. The software component is verified and validated to the same level required to accept a similar developed software component for its intended use.

f. The project has a plan to perform periodic assessments of vendor reported defects to ensure the defects do not impact the selected software components.

Note: The project responsible for procuring off-the-shelf software is responsible for documenting, prior to procurement, a plan for verifying and validating the software to the same level that would be required for a developed software component. The project ensures that the COTS, GOTS, MOTS, reused, and auto-generated code software components and data meet the applicable requirements in this directive assigned to its software classification as shown in Appendix C.

3.2 Software Cost Estimation

3.2.1 To better estimate the cost of development, the project manager shall establish, document, and maintain: [SWE-015]

a. Two cost estimate models and associated cost parameters for all Class A and B software projects that have an estimated project cost of $2 million or more.

b. One software cost estimate model and associated cost parameter(s) for all Class A and Class B software projects that have an estimated project cost of less than $2 million.

c. One software cost estimate model and associated cost parameter(s) for all Class C and Class D software projects.

d. One software cost estimate model and associated cost parameter(s) for all Class F software projects.

3.2.2 The project manager’s software cost estimate(s) shall satisfy the following conditions: [SWE-151]

a. Covers the entire software life cycle.

b. Is based on selected project attributes (e.g., programmatic assumptions/constraints, assessment of the size, functionality, complexity, criticality, reuse code, modified code, and risk of the software processes and products).

c. Is based on the cost implications of the technology to be used and the required maturation of that technology.

d. Incorporates risk and uncertainty, including end state risk and threat assessments for cybersecurity.

e. Includes the cost of the required software assurance support.

f. Includes other direct costs.

Note: In the event of a decision to outsource, it is a best practice that both the acquirer (NASA) and the provider (contractor/subcontractor) be responsible for developing software cost estimates. For any class of software that has significant risk exposure, consider performing at least two cost estimates.

3.2.3 The project manager shall submit software planning parameters, including size and effort estimates, milestones, and characteristics, to the Center measurement repository at the conclusion of major milestones. [SWE-174]

3.3 Software Schedules

3.3.1 The project manager shall document and maintain a software schedule that satisfies the following conditions: [SWE-016]

a. Coordinates with the overall project schedule.

b. Documents the interactions of milestones and deliverables between software, hardware, operations, and the rest of the system.

c. Reflects the critical dependencies for software development activities.

d. Identifies and accounts for dependencies with other projects and cross-program dependencies.

3.3.2 The project manager shall regularly hold reviews of software schedule activities, status, performance metrics, and assessment/analysis results with the project stakeholders and track issues to resolution. [SWE-018]

3.3.3 The project manager shall require the software developer(s) to provide a software schedule for the project’s review, and schedule updates as requested. [SWE-046]

3.4 Software Training

3.4.1 The project manager shall plan, track, and ensure project specific software training for project personnel. [SWE-017]

Note: This includes any software assurance personnel assigned to the project.

3.5 Software Classification Assessment


3.5.1 The project manager shall classify each system and subsystem containing software in accordance with the highest applicable software classification definitions for Classes A, B, C, D, E, and F software in Appendix D. [SWE-020]

Note: The expected applicability of requirements in this directive to specific systems and subsystems containing software is determined through the use of the NASA-wide definitions for software classes in Appendix D in conjunction with the Requirements Mapping Matrix in Appendix C. These definitions are based on (1) usage of the software with or within a NASA system, (2) criticality of the system to NASA’s major programs and projects, (3) extent to which humans depend upon the system, (4) developmental and operational complexity, and (5) extent of the Agency’s investment.

Software assurance may perform an independent software classification, or concur with engineering’s software classification decision. Software engineering and software assurance technical authorities need to agree on the classification of each system and subsystem containing software. If there is a disagreement between the technical authorities, then the dissenting opinion process for your center should be followed.

3.5.2 The project manager shall maintain records of each software classification determination, each software Requirements Mapping Matrix, and the results of each software independent classification assessments for the life of the project. [SWE-176]

3.6 Software Assurance and Software Independent Verification & Validation

3.6.1 The project manager shall plan and implement software assurance, software safety, and IV&V (if required) per NASA-STD-8739.8, Software Assurance and Software Safety Standard. [SWE-022]

Note: Software assurance activities occur throughout the life of the project. Some of the actual analyses and activities may be performed by engineering or the project. Software Assurance directions, requirements, and guidance can be found in the NASA-STD-8739.8.

3.6.2 For projects reaching Key Decision Point A, the program manager shall ensure that software IV&V is performed on the following categories of projects: [SWE-141]

a. Category 1 projects as defined in NPR 7120.5.

b. Category 2 projects as defined in NPR 7120.5, that have Class A or Class B payload risk classification per NPR 8705.4, Risk Classification for NASA Payloads.

c. Projects selected explicitly by the Mission Directorate Associate Administrator (MDAA) to have software IV&V.

3.6.3 If software IV&V is required for a project, the project manager, in consultation with NASA IV&V, shall ensure an IPEP is developed, approved, maintained, and executed in accordance with IV&V requirements in NASA-STD-8739.8. [SWE-131]

Note: The IV&V Advisory Board will review the scope of NASA IV&V activities on an annual basis as part of the budget planning process.

3.6.4 If software IV&V is performed on a project, the project manager shall ensure that IV&V is provided access to development artifacts, products, source code, and data required to perform the IV&V analysis efficiently and effectively. [SWE-178]

Note: The artifacts and products should be provided electronically in original format (i.e., non-pdf) and, where possible, direct read-only electronic access to project document repositories and data stores should be provided. Appropriate security products should be completed and transferred as part of the overall package.

3.6.5 If software IV&V is performed on a project, the project manager shall provide responses to IV&V submitted issues and risks and track these issues and risks to closure. [SWE-179]

3.7 Safety-Critical Software

3.7.1 The project manager, in conjunction with the SMA organization, shall determine if each software component is considered to be safety-critical per the criteria defined in NASA-STD-8739.8. [SWE-205]

3.7.2 If a project has safety-critical software, the project manager shall implement the safety-critical software requirements contained in NASA-STD-8739.8. [SWE-023]

3.7.3 If a project has safety-critical software or mission-critical software, the project manager shall implement the following items in the software: [SWE-134]

a. The software is initialized, at first start and restarts, to a known safe state.

b. The software safely transitions between all predefined known states.

c. Termination performed by software functions is performed to a known safe state.

d. Operator overrides of software functions require at least two independent actions by an operator.

e. Software rejects commands received out of sequence when execution of those commands out of sequence can cause a hazard.

f. The software detects inadvertent memory modification and recovers to a known safe state.

g. The software performs integrity checks on inputs and outputs to/from the software system.

h. The software performs prerequisite checks prior to the execution of safety-critical software commands.

i. No single software event or action is allowed to initiate an identified hazard.

j. The software responds to an off-nominal condition within the time needed to prevent a hazardous event.

k. The software provides error handling.

l. The software can place the system into a safe state.

Note: These requirements apply to components that reside in a mission-critical or safety-critical system, and the components control, mitigate, or contribute to a hazard as well as software used to command hazardous operations/activities.

3.7.4 If a project has safety-critical software, the project manager shall ensure that there is 100 percent code test coverage using the Modified Condition/Decision Coverage (MC/DC) criterion for all identified safety-critical software components. [SWE-219]

Note: In MC/DC coverage, every condition in a decision is tested independently to reach full coverage. Each condition will be executed twice, once with the results true and once with the results of false, but with no difference in the truth values of all other conditions in the decision. In addition, it will be shown that each condition independently affects the decision. Any deviations from 100 percent should be reviewed and waived with rationale by the TAs approval. It is recommended that someone independent of the developer of the code under test design and perform this testing to ensure requirement interpretation or incorrect assumptions do not escape this testing.

3.7.5 If a project has safety-critical software, the project manager shall ensure all identified safety-critical software components have a cyclomatic complexity value of 15 or lower. Any exceedance shall be reviewed and waived with rationale by the project manager or technical approval authority. [SWE-220]

Note: Cyclomatic complexity is a metric used to measure the complexity of a software program. This metric measures independent paths through the source code. The point of the requirement is to minimize risk, minimize testing, and increase reliability associated with safety-critical software code components, thus reducing the chance of software failure during a hazardous event. The software developer should assess all software safety-critical components with a cyclomatic complexity score over 15 for testability, maintainability, and code quality. For more guidance on this requirement, see NASA-HDBK-2203.

3.8 Automatic Generation of Software Source Code

3.8.1 The project manager shall define the approach to the automatic generation of software source code including: [SWE-146]

a. Validation and verification of auto-generation tools.

b. Configuration management of the auto-generation tools and associated data.

c. Description of the limits and the allowable scope for the use of the auto-generated software.

d. Verification and validation of auto-generated source code using the same software standards and processes as hand-generated code.

e. Monitoring the actual use of auto-generated source code compared to the planned use.

f. Policies and procedures for making manual changes to auto-generated source code.

g. Configuration management of the input to the auto-generation tool, the output of the auto-generation tool, and modifications made to the output of the auto-generation tools.

3.8.2 The project manager shall require the software developers and custom software suppliers to provide NASA with electronic access to the models, simulations, and associated data used as inputs for auto-generation of software. [SWE-206]

Note: The term electronic access includes access to the data from NASA facilities.

3.9 Software Development Processes and Practices

3.9.1 The CMMI® model is an industry-accepted model of software development practices. It is utilized to assess how well NASA projects are supported by software development organization(s) having the necessary skills, practices, and processes in place to produce reliable products within cost and schedule estimates. The CMMI® model provides NASA with a methodology to:

a. Measure software development organizations against an industry-wide set of best practices that address software development and maintenance activities applied to products and services.

b. Measure and compare the maturity of an organization’s product development and acquisition processes with the industry state of the practice.

c. Measure and ensure compliance with the intent of the directive’s process related requirements using an industry standard approach.

d. Assess internal and external software development organization’s processes and practices.

e. Identify potential risk areas within a given organization’s software development processes and practices.

3.9.2 The project manager shall acquire, develop, and maintain software from an organization with a non-expired CMMI®-DEV rating as measured by a CMMI® Institute Certified Lead Appraiser as follows: [SWE-032]

a. For Class A software: CMMI®-DEV Maturity Level 3 Rating or higher for software.

b. For Class B software (except Class B software on NASA Class D payloads, as defined in NPR 8705.4): CMMI®-DEV Maturity Level 2 Rating or higher for software.

Note: Organizations need to complete an official CMMI® Institute defined appraisal against either the CMMI®-DEV model V1.3 or V2.0. Organizations are to maintain their rating and have their results posted on the CMMI® Institute Website, or provide an Appraisal Disclosure Statement so that NASA can assess the current maturity/capability rating. Software development organizations need to maintain their appraisal rating during the period they are responsible for the development and maintenance of the software. CMMI® ratings can cover a team, a group, a project, a division, or an entire organization.

For Class B software, an exception can be exercised for those cases in which NASA wishes to purchase a product from the "best in class provider," but the best in class provider does not have the required CMMI® rating. For Class B software, instead of a CMMI® rating by a development organization, the project will conduct an evaluation, performed by a qualified evaluator selected by the Center ETA, against the CMMI®-DEV Maturity Level 2 practices, and mitigate any risk, if deficiencies are identified in the evaluation. If this approach is used, the development organization and project are responsible for correcting the deficiencies identified in the evaluation. When this exception is exercised, the OCE and Center ETA are notified of the proposition and provided the results of the evaluation. The project manager should seek guidance from the Office of Procurement (OP) for help in exercising the exception.

3.10 Software Reuse

3.10.1 The project manager shall specify reusability requirements that apply to its software development activities to enable future reuse of the software, including the models, simulations, and associated data used as inputs for auto-generation of software, for U.S. Government purposes. [SWE-147]

3.10.2 The project manager shall evaluate software for potential reuse by other projects across NASA and contribute reuse candidates to the appropriate NASA internal sharing and reuse software system. However, if the project manager is not a civil servant, then a civil servant will pre-approve all such software contributions; all software contributions should include, at a minimum, the following information: [SWE-148]

a. Software Title.

b. Software Description.

c. The Civil Servant Software Technical POC for the software product.

d. The language or languages used to develop the software.

e. Any third-party code contained therein, and the record of the requisite license or permission received from the third party permitting the Government’s use and any required markings (e.g., required copyright, author, applicable license notices within the software code, and the source of each third-party software component (e.g., software URL & license URL)), if applicable.

Note: Currently, there are more than one Agency-wide software inventories and repositories, several options can be found in NASA-HDBK-2203. In order to obtain and reuse the internal software reuse candidates from these repositories, NASA civil servants may request a copy by requesting and completing a simple Acknowledgment of Receipt of the software form that identifies any restrictions on NASA’s right to use the software, including limiting its use to governmental purposes only. The Civil Servant Software Technical POC for the software product will keep a list of all contributors to the software. Any software shared will contain appropriate disclaimer and indemnification provisions (e.g., in a “README” file) stating that the software may be subject to U.S. export control restrictions, and it is provided “as is” without any warranty, express, or implied and that the recipient waives any claims against, and indemnifies and holds harmless, NASA and its contractors and subcontractors (see paragraph

f. Release notes.

3.10.3 In accordance with NPD 2091.1, Inventions Made by Government Employees, NASA Civil Servant employees who make an invention embodied by software will submit to NASA a disclosure of such invention. Likewise, such inventions made by NASA contractors will be reported to NASA, preferably through the NASA electronic New Technology Report (e-NTR) system, pursuant to the terms of their respective contract. Such disclosures are made through the NASA e-NTR system available at http://invention.nasa.gov/.

3.11 Software Cybersecurity

3.11.1 Software defects are a central and critical aspect of computer security vulnerabilities. Software defects with cybersecurity ramifications include implementation bugs such as buffer overflows and design flaws such as inconsistent error handling.

Note: Software security relies on high-quality code development and testing practices (clean code, modular structure, well-defined interfaces) – anything that reduces error rates and opportunities for misinterpretation or error; considers both the development and deployment/operational context for the software; has the ability to rapidly assess, triage, correct, and deploy security-related updates while the software is in deployment/operations.

3.11.2 The project manager shall perform a software cybersecurity assessment on the software components per the Agency security policies and the project requirements, including risks posed by the use of COTS, GOTS, MOTS, OSS, or reused software components. [SWE-156]

3.11.3 The project manager shall identify cybersecurity risks, along with their mitigations, in flight and ground software systems and plan the mitigations for these systems. [SWE-154]

Note: Project Protection Plans describe the program’s approach for planning and implementing the requirements for information, physical, personnel, industrial, and counterintelligence/counterterrorism security, and for security awareness/education requirements in accordance with NPR 1600.1, NASA Security Program Procedural Requirements, NPD 1600.2, the NASA Security Policy, NPD 2810.1, and NPR 2810.1. Include provisions in the plan to protect personnel, facilities, mission-essential infrastructure, and critical program information from potential threats and vulnerabilities that may be identified during the threat and vulnerability assessment process.

3.11.4 The project manager shall implement protections for software systems with communications capabilities against unauthorized access per the requirements contained in the NASA-STD-1006, Space System Protection Standard. [SWE-157]

3.11.5 The project manager shall test the software and record test results for the required software cybersecurity mitigation implementations identified from the security vulnerabilities and security weaknesses analysis. [SWE-159]

Note: Include assessments for security vulnerabilities during Peer Review/Inspections of software requirements and design. Utilize automated security static analysis as well as coding standard static analyses of software code to find potential security vulnerabilities.

3.11.6 The project manager shall identify, record, and implement secure coding practices. [SWE-207]

3.11.7 The project manager shall verify that the software code meets the project’s secure coding standard by using the results from static analysis tool(s). [SWE-185]

Note: If a static analysis tool will not work with the selected coding standard, other methods are acceptable, including manual inspection.

3.11.8 The project manager shall identify software requirements for the collection, reporting, and storage of data relating to the detection of adversarial actions. [SWE-210]

Note: Monitoring of key software observables (e.g., number of failed login attempts, performance changes, internal communication changes) is needed to detect adversarial actions that threaten mission success. When an adversarial action occurs, it should be reported. Raw event data should be further analyzed to determine whether an anomalous event represents an attack, and if so, the nature of the attack.

3.12 Software Bi-Directional Traceability

3.12.1 The project manager shall perform, record, and maintain bi-directional traceability between the following software elements: [SWE-052]

Table 1. Bi-directional traceability by software classification

Bi-directional Traceability Class A, B,
and C
Class D Class F
Higher-level requirements to the software requirements X X
Software requirements to the system hazards X X
Software requirements to the software design components X
Software design components to the software code X
Software requirements to the software verification(s) X X X
Software requirements to the software non-conformances X X X

Note: The project manager will maintain bi-directional traceability between the software requirements and software-related system hazards, including hazardous controls, hazardous mitigations, hazardous conditions, and hazardous events.

| TOC | Preface | Chapter1 | Chapter2 | Chapter3 | Chapter4 | Chapter5 | Chapter6 | AppendixA | AppendixB | AppendixC | AppendixD | AppendixE | ALL |
| NODIS Library | Program Formulation(7000s) | Search |


This document does not bind the public, except as authorized by law or as incorporated into a contract. This document is uncontrolled when printed. Check the NASA Online Directives Information System (NODIS) Library to verify that this is the correct version before use: https://nodis3.gsfc.nasa.gov.