Mission Planning Technical Guide

Purpose:

This document outlines the process for defining mission requirements, establishing verification and validation (V&V) methods, and structuring an effective mission planning session. It also includes a worked example based on NASA’s MarCO mission to demonstrate how real missions define and verify requirements.

1. Systems Engineering Process Overview

1.1 Define Mission Objectives

Mission objectives describe the purpose of the mission in qualitative terms. They answer “why” the mission exists and what scientific or technical outcome it aims to achieve.

Example:

Demonstrate real-time communications relay capability during an interplanetary mission.
Quantify CO₂ concentrations above wildfire plumes using hyperspectral imaging.

1.2 Derive Mission Requirements

Mission requirements are quantitative, verifiable statements describing what must be true for the mission to succeed. Each requirement should have:

- A measurable quantity or condition
- A direct link to a higher-level objective
- A defined verification method

Each should follow this structure: The system shall [do X / achieve Y] under [specified conditions].

Categories of Requirements:

Type	Example
Functional	The satellite shall downlink telemetry packets every orbit.
Performance	The payload shall measure spectral radiance with SNR ≥ 200.
Physical	The spacecraft shall not exceed a total mass of 4.0 kg.
Operational	The spacecraft shall operate in a 500 km sun-synchronous orbit for at least six months.
Environmental	The structure shall survive launch vibration levels up to 10 g RMS.
Interface	The power subsystem shall supply 3.3 V ±5% to the onboard computer.

1.3 Establish Verification and Validation (V&V)

Each requirement must be associated with a verification method that confirms it has been met. The four standard verification methods are listed below.

Method	Description	Example
Test (T)	Physically measure or demonstrate performance in real or simulated conditions.	Thermal vacuum test verifies operation between −20 °C and +60 °C.
Analysis (A)	Use models, simulations, or calculations.	Thermal model shows component temperature <70 °C under peak load.
Inspection (I)	Visually confirm configuration or dimensions.	Verify harness routing per mechanical drawing.
Demonstration (D)	Operate the system in a relevant environment or testbed.	Command and receive telemetry via ground station.

Each requirement statement should indicate its verification method, for example: The ADCS shall maintain pointing accuracy ≤ 2° (verified by analysis and on-orbit demonstration).

1.4 Build the Requirement Breakdown Structure (RBS)

The RBS is a hierarchical organization of requirements. It helps trace each subsystem requirement back to a top-level mission objective.

Mission Requirements: define the overall mission goals.
2. System Requirements: describe satellite-level capabilities and performance.
3. Subsystem Requirements: define what each subsystem must achieve.
4. Component Requirements: specify measurable conditions for individual parts.

1.5 Supporting Analyses

Subsystem teams should conduct preliminary analyses to establish feasibility and support requirements definition. These include power budget, mass budget, link budget, and thermal budget.

1.6 Requirement Tracking Format

ID	Requirement	Rationale	Verification
SYS-01	The spacecraft shall transmit at least one health beacon per orbit.	Confirms operability and contact.	Demonstration (on-orbit test)
ADCS-03	The spacecraft shall maintain pointing error < 3°.	Ensures payload alignment with target.	Analysis and test
THM-02	Components shall remain between −10 °C and +50 °C.	Prevents thermal degradation.	Thermal test and analysis

2. Worked Example: NASA MarCO (Mars Cube One)

NASA’s MarCO consisted of two 6U CubeSats that relayed telemetry from the InSight lander during its descent to Mars.

2.1 Mission Objective

Demonstrate that a CubeSat can provide a real-time UHF relay link from Mars to Earth during entry, descent, and landing.

2.2 Top-Level Requirements

ID	Requirement	Rationale	Verification
MR-1	The spacecraft shall receive UHF data from InSight and relay it to Earth in real time.	Defines primary mission success.	Demonstration (Mars EDL relay)
MR-2	The spacecraft shall operate at Mars distance (1.5 AU) for at least 30 days.	Ensures system survivability.	Analysis and operations log
MR-3	The downlink rate to DSN shall be ≥ 8 kbps.	Enables continuous relay.	Analysis (link budget) and test
MR-4	The spacecraft mass shall not exceed 14 kg.	Complies with rideshare launch limits.	Inspection (mass measurement)
MR-5	The power system shall provide ≥ 30 W peak to the communication subsystem.	Supports high-gain antenna operation.	Electrical test

2.3 Subsystem Requirements

Communications

The X-band high-gain antenna shall provide ≥ 20 dBi gain at 8.4 GHz. (Test)
The transponder shall maintain a bit error rate < 10⁻⁵ at 8 kbps link. (Analysis + Test)

Power

The solar array shall generate 35 W at 1 AU. (Analysis + Test)
The battery shall support 15 min eclipse with ≥ 90% depth of discharge. (Analysis)

ADCS

The spacecraft shall maintain pointing within 1° during downlink. (Analysis + Test)

Thermal

The spacecraft shall survive between −20 °C and +50 °C. (Thermal vacuum test)

3. Mission Planning Worksheet Template

Level

Requirement

Rationale

Verification

Responsible Subsystem

Guidance

Use precise, measurable verbs in requirement statements (“shall measure,” “shall transmit,” “shall maintain”) rather than vague ones (“optimize,” “improve,” “support”). Each requirement must be independently testable and traceable to a mission objective.