# Presentation: 246636

## IV. Formation Flying Technology

**Session Facilitator:**
**Jesse A. Leitner**

## Outline

**Executive Summary**
**Formation Flying Capabilities to be Validated by ST-9**
**Overview and Introduction**
**What is Formation Flying?**
**Scope of the ST-9 Formation Flying Technology Capabilities Area**
**Science Mission Capabilities Roadmap and Timeline**
**Technology Capabilities Roadmap**
**Figure Of Merit (FOM) Definitions**
**State Of The Art**
**Acronym List**

## Executive Summary

**Workshop Addresses Following Technology Areas**
**“****Precision Formation Flying” (PFF): The frequency and tightness of formation control (not just navigation)**
**Continuous process of maintaining or tracking a desired geometric configuration**
**Sessions Topics**
**Future space science mission needs**
**Desired workshop products**
**Technology splinter session discussions**
**Needs/potential capabilities assessments**
**Splinter Session Topics**
**Relative Navigation, Relative Attitude, and metrology sensors and algorithms:  the engineering measurements of formation flying**
**Formation Control algorithms and actuators:  the logic and actuation hardware to calculate and produce forces needed for formation flying**
**Intersatellite Communications, timing, time transfer:  systems to share data between the spacecraft, synchronize spacecraft, and disseminate commands**
**Modeling, Simulation, and Mission Design Tools:  tools and methodologies needed to verify performance on the ground**
**Autonomous Constellation Management and Control:  the high level control layer for multi-spacecraft operations****	**

## Executive Summary (continued)

**Key Observations and Recommendations**
**The big challenge will be to craft a mission concept which is affordable and technology-centered, and has enough elements with sufficiently high performance to truly alleviate the future risks of upcoming strategic Space Science missions.**
**This team must find the right mix of proving relevance, reducing risk, and controlling cost.**
**For example, a scientific or instrument-centered demonstration - i.e., an interferometry or imaging demonstration, while providing the ultimate validation if successful, may have the tendency to break the bank.**
**Recommendations for ST-9 Flight Experiment**
**Importance of exercising system elements in an integrated manner**
**Demonstrate mature component technologies in an integrated package**
**Allocate virtually all risk into the system-level aspects instead of component-level**

## Formation Flying Capabilities to be Validated by ST9

## Overview and Introduction

**Precision Formation Flying System Technology is critical for a broad range of future NASA Space Science missions**
**TPF (ASO)**
**MAXIM, MAXIM PF (SEU)**
**Stellar Imager (SEC)**
**LF, PI, SPECS, ...**
**The “precision” qualifier carves out a somewhat well-defined niche in the formation flying field with the following characteristics**
**Continuous and robust, possibly high bandwidth intersatellite communications **
**On-board relative navigation/bearing at high data rate with high-precision through the communication links**
**Continuous formation control at high bandwidth and high-precision through the communication links**
**Highly-optimized formation/mission design and analysis**
**Integrated hardware-in-the-loop, high-fidelity simulations**
**Autonomous and robust closed-loop on-board control during science gathering**

## What is Formation Flying?

**What is Formation Flying?**

_**Engineering definition**_: the tracking
-  or maintenance of a desired separation
- between/among two or more spacecraft

_**Science definition**_:  the collective use
- of multiple spacecraft to perform the
- function of a single, large, virtual instrument

**ST-9**
**you are here**

- Rendezvous
- Docking

## Scope of the ST-9 FF TCA

**In the context of ST-9, we will focus on the problem of “Precision formation flying”**
**Precision, in this case, refers to a continuous process of maintaining or tracking a desired geometric configuration**
**Collectively, it is the frequency and tightness of formation control (not just navigation) **
**Since the focus is on demonstrating technologies critical to future NASA Space Science Enterprise missions, the orbits of primary interest: are HEO, libration points, heliocentric, deep space**

## Science Mission Capability Requirements Roadmap and Timeline

**	**

- Magnetospheric      Detect/ID planets    	Black hole phenomena    Asteroseismology    Imaging Planets

**loose formations**
-       **MMS**

**sub-micron rel pos estim. **
**cm s/c pos control, 5 s/c**
-         **TPF**

**micron rel nav**
**micron s/c pos control, 8 s/c**
-      **MAXIM**

**nm rel nav**
**nm control, 30 s/c**
-       **SI**

**<nm rel nav**
**nm control, 30+ s/c**
**         ****PI, LF**

**2009****	****	****2015****	****	****2017****	****	****2020****	****	****2025**

**Capability**

## Technology Capability Requirements Roadmap*

**	**

- Autonomous operations
- 		5 s/c		8 s/c		30 s/c
- Intersatellite Comm
- 100 kbps			1 Mbps
- S/C Formation Control
- 100m 		2 cm 	10 m			3 nm
- Rel Position Estimation
- 10m    10 cm 	3 nm				0.5 nm

- 2009		2015		2017		2020		2025

- *some requirements have already been achieved to TRL6 and above at the component level

## Figure Of Merit (FOM) Definitions

**Relative position estimate:  the estimated value of relative position between spacecraft**
**S/C Formation Control:  the controlled separation between selected references points between two spacecraft.**
**Intersatellite communications bandwidth:  the number of bits of data passed from one spacecraft to another.**
**Formation geometric dimension:  the number of dimensions in free-space spanned by the desired formation**
**Spacecraft-to-spacecraft relative bearing:  the angel composed of a combination of relative attitude and 3-dimensional position vector between spacecraft indicating the ability to maintain two spacecraft in a desired relative formation in six degrees of freedom.  **

## State Of The Art

**Relative position estimate:**
**1 micron range change, (relative, not absolute, range between spacecraft) GRACE in low-Earth orbit**
**2 cm ranging, post-processed (absolute range between spacecraft), determined from spacecraft in LEO to GPS transmitter over 20,000 km distance**
**Formation control:  kms (EO-1/LS-7)**
**Intersatellite comm data rate:  300 Mbps (large EIRP) TDRSS**
**Formation geometric dimension:  1 (rendezvous docking)**
**Number of s/c managed collectively:  ~50 (from the ground)**

## Acronym List

**MMS****	****	****Magnetospheric Multi-Scale Mission (SEC)**
**TPF****	****	****Terrestrial Planet Finder Mission (ASO)**
**MAXIM****	****	****Micro Arcsecond X-Ray Imaging Mission (SEU)**
**SI****	****	****	****Stellar Imager Mission (SEC)**
**PI****	****	****	****Planet Imager Mission (ASO)**
**LF****	****	****	****Life Finder Mission (ASO)**