# Presentation: 016416

## VI. Descent and Terminal Guidance for Pinpoint Landing and Hazard Avoidance

**Session Chair:**
**Dr. Sam W. Thurman**

## Executive Summary

**Workshop Addressed Following Technology Areas**
**“****Pinpoint” Landing**
**Hazard Detection and Avoidance**
**Sessions Topics and Activities**
**Future space science mission needs**
**Desired workshop products**
**Technology splinter session discussions**
**Needs/potential capabilities assessments**
**Splinter Session Topics**
**Guidance, Navigation and Control (GN&C) Systems**
- Modeling and Simulation
- Sensors/Algorithms for Guidance and Navigation
- Aerodynamic/Propulsive Maneuvering System Options
**Terrain Sensing and Hazard Recognition Systems**
- Terrain Sensors and Hazard Detection/Recognition Algorithms
- Architectural Options for GN&C Systems with Terrain Sensors
**Key Splinter Session Observations and Recommendations**
**Target body environment characteristics driving descent/landing system design tend to group into airless bodies and those with atmospheres**
**Mars environment viewed as stressing case in many important aspects**
- Presence of atmosphere allows/requires use of aerodynamic deceleration systems
- Low atmospheric density effectively also  requires propulsive maneuvering systems to accomplish targeted landing with hazard avoidance capability

## Executive Summary (continued)

**Recommendations for ST-9 Flight Experiment**
**Important to exercise system elements in an integrated manner**
- Onboard navigation incorporating both inertial and terrain sensing capability
- Hazard recognition, safe target landing site selection, and aerodynamic/propulsive steering using navigation data
**Terrestrial sub-orbital (via sounding rocket boost) or descent-from-orbit flight test mission recommended**
- Lander Test Vehicle with Following Capabilities
- Onboard Navigation
- Inertial sensors and prototype terrain sensor(s)
- Navigation algorithms and computations for inertial/terrain sensor data fusion
- Hazard recognition and safe landing site selection algorithms and computations
- Onboard Guidance & Control
- Targeted parachute descent using “smart” parachute deployment logic
- Consider propulsive terminal descent to soft landing (if it fits cost target)
**Rationale**
- Enables operation of integrated GN&C system in flight-like manner
- Dynamical scaling can be used to create flight dynamics environment representative of many different “smart” landing mission environments
- Near-Earth environment offers low-cost multiple test flight opportunities and ability to acquire  many detailed measurements for model correlation and validation
**This approach would validate a GN&C system architecture capable of scaling to meet most projected future mission needs over next 10-15 years**

## Descent/Terminal Guidance Capabilities to be Validated by ST9

## Overview and Introduction

**Future Space Science Mission Needs**
**Variety of desired missions for planetary surface exploration**
- Lunar and Mars exploration and sample return
- Comet and asteroid sample return
- Europa lander
- Venus and Titan exploration
**Many scientific objectives benefit/enabled by new engineering capabilities for delivery of scientific payloads to planetary surfaces**
- “Pinpoint” Landing
- Hazard Detection and Avoidance
**Workshop Conducted with Following Objectives**
**Identify potential mission needs and requirements via diverse group of engineering experts from government, industry, academia**
**Survey component/subsystem technologies for meeting these needs**
- Functionality and performance
- Technology maturity, test/validation requirements and approaches
- Modeling and scaling of test/validation results to different mission environments
**Synthesize survey results to map and prioritize technology candidates versus mission needs**
**Formulate recommendations for ST-9 Flight Experiment scope and content to be considered during subsequent Pre-Phase A and Phase A study effort**

## “Smart” Landing Overview

**“****Smart” Landing Technologies**
**Pinpoint Landing**
**Hazard Detection & Avoidance**
**Science Mission Benefits**
**Ability to reach landing sites which may lie in areas containing hazardous terrain features**
- Escarpments
- Craters
- Slopes and rocks
**Ability to land accurately at select landing sites of high science value**
- Small terrain types/features or isolated locations (e.g., safe target site within larger region of hazardous terrain)
**State of the Art**
**No existing system-level capability**
**Some previous examples of propulsive maneuvering in Apollo/Viking era**
- Apollo Lunar Module descent/landing
- Surveyor and Viking Landers
**Some recent terrestrial examples of terrain sensing in “smart” weapons**

**Technical Approach**
**Onboard Navigation**
- Accurately determine current and predicted lander flight path
**Terrain Sensing**
- Sense terrain characteristics and recognize hazardous features
- Identify safe landing site that can be reached given lander’s maneuverability
**Onboard Guidance**
- Provide maneuvering capability (aerodynamic or propulsive) to steer lander to touchdown at desired safe landing site

## Science Capabilities Roadmap

**Potential Mission Timeline**
**2009/10**
**Mars Science Laboratory**
**Lunar South Pole/Aitken Basin Sample Return**
**2012/13**
**Comet/Asteroid Surface Sample Return**
**Venus In-Situ Explorer**
**2014/15**
**Mars Sample Return**
**2020 +**
**Europa Lander**
**Titan Explorer**
**Mars and Lunar Robotic Outposts**
**Human Exploration Missions**

**“****Smart” Landing Capability Needs**
**2009/10**
**Landing accuracy <6 km (Mars), 0.1-1 km (Moon)**
**100 m maneuvering to avoid hazardous slopes/rocks**
**2012/13**
**Landing accuracy <0.1 km (small body), 10-100 km (Venus)**
**100-200 m maneuvering to avoid small body terrain hazards**
**2014/15**
**Landing accuracy 1-3 km**
**100-300 m maneuvering to avoid all hazardous terrain features**
**2020+**
**Landing accuracy < 0.1 km (airless bodies and Mars), 10-100 km (Titan)**
**100-500+ m maneuverability to avoid all hazardous terrain (airless bodies, Mars)**

## Technology Capabilities Roadmap

**Current Generation (today)**
**Landing Accuracy**
- Bodies with Atmosphere: 100-300 km
- Airless Bodies: 1-10 km
**Hazard Detection and Avoidance**
- none
**Next Generation (incorporating results from ST-9)**
**Landing Accuracy**
- Bodies with Atmosphere: 3-6 km
- Airless Bodies: 0.1-1 km
**Hazard Detection and Avoidance**
- detecting 99% of rocks > 0.75 m; detect > 20o slopes
- 100-200 m divert capability
**Future Generation Goals (beyond ST9)**
**Landing Accuracy**
- Bodies with Atmosphere: < 100 m
- Airless Bodies: < 10 m
**Hazard Detection and Avoidance **
- detecting 99% of rocks > 0.2 m; detect / analyze terrain features at and near landing site (including non-geometric hazards)
- 0.5-5.0 km divert capability

## Figure Of Merit (FOM) Definitions

**Pinpoint Landing**
**Delivery Accuracy**
- Miss distance between target landing site and actual landing location
**Hazard Detection and Avoidance**
**Hazard detection/recognition**
- Detection and recognition of geometric and non-geometric terrain hazards
- Detection and recognition of geometric hazards such as craters, escarpments, rocks, slopes, etc.
- Key metrics: probability of missed detection of hazardous terrain and probability of false positive from non-hazardous terrain
- Detection and recognition of  non-geometric hazards such as terrain areas with low/insufficient bearing strength
- Key metric is similar to above
**Maneuver capability for hazard avoidance**
- Site redesignation capability versus altitude/velocity regime during descent