a tra je c to ry m o d e llin g to o l fo r m u lti-p h a se d e sc e n...

Multi-phase descent trajectory modelling

A trajectory modelling tool for multi-phase descent

The Right Answer

A Tessella Company

Dr Dave Dungate

4 October 2006

Astrodynamics Tools and Techniques Workshop, ESTEC


Analyticon Space Experience

Mission Experience

EXOMARS, Beagle 2, ENVISAT, XMM, Integral, Herschel, Planck, Topsat, GIOVE-A, AEOLUS, EUROSTAR 2000+/3000 Platforms

Main Areas of Capability

AOCS: Subsystem, Control & Estimator design, Analysis, Performance Assessment & Support to Subsystem Test

Flight Dynamics: Mission Analysis, Fuel Budgeting, Orbit Manoeuvres

Descent & Landing Systems: System level trade-offs, detailed design & optimisation, simulation & performance assessment, management of production & test


EDLS design overview

Analyticon’s integrated approach

System-level trade-off and sizing tool

Detailed simulation capability (PASDA)

PASDA details

Heritage

Capabilities

Simulation framework

Examples

Summary

Contents


EDLS question splits into two parts:

Sizing calculations

Find masses for all components, canopy sizes, airbag designs

Can look at different options (e.g. single-stage vs two-stage parachute)

Trajectory simulation

Test proposed designs

Tight integration of the two parts

Results of simulation feed into improved design

Find best choice of control parameters

Analyticon’s approach


Integrated tools

Design Input Parameters

Flight Database

35 kgRetro

fuel mass

120 kgAirbag

mass

Design

Scripts

Report Generation

Simulation & Visualisation

1.2 1.4 1.6 1.8 2 2.2

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

X Position (Km)

Y P

ositio

n (Km

)

Descent Module and Heat Shield final positions

0500100015002000

0

500

1000

1500

2000

2500

3000

3500

4000

X Position (m)

Trajectory

Y Position (m)

Altitude (m

)


In-house EDLS Trade-off Tool

Design

Self Mass Iteration

Atmosphere

Materials

Constraints

Input Design

Parameters

Component Masses

Trigger Parameters

Parameter grids / Monte Carlo

Trade-offs and sensitivity analyses

Design parameters

Different sequence options


1 1.1 1.2 1.3 1.4 1.51

1.2

1.4

1.6

1.8

22-Stage Parachute System, Vented Airbag

Airbag MMM

System

mas

s in

crea

se/A

irbag

mas

s

Total DLSDrogueMainAirbag

2

3

4

5

0

10

20

30100

150

200

250

gMain Deployment

(gmars

)


Impact vvert

(ms-1)

Tota

l D

LS M

ass (k

g)

140160

180200

220

350

400

450

500135

140

145

150

mrocket carrier

(kg)


mpayload

(kg)

Tota

l D

LS M

ass (k

g)

In-house EDLS Trade-off Tool


PArachute System Design and Analysis

Originally developed for ESA

Irvin Aerospace, Dornier, GMV

Recent updates by Analyticon

Any number of linked bodies

New physical effects

Analyticon simulation framework

Analysis of wind effects on Huygens

Currently in use for ExoMars phase B1

PASDA - History


PASDA - Capabilities

! 3-dof modelling or full 6-dof, 9-component aerodynamics

! any number of linked bodies / phases

! use EMCD, atmosphere lookup etc.

! apply wind models and/or gusts

! Monte-Carlo on any parameter

cable and wake interactions

two-way wakes between separating bodies

bridle collapse effects

controlled lowering

modelled parachute inflation

general triggering algorithms

track separated

bodies to ground

line-of-sight

calculations to orbiters

ballistic phases

retro rockets


PASDA – Multi-phase descents

Complex sequences in one

simulation

Careful handling of phase transitions

Entry, parachutes, rockets, airbags

Defined triggering algorithms

Separation can create branches

Follow each object separately

Integration ends at the boundary

Framework transforms bodies / state as needed


PASDA – Advanced effects

‘Complex’ wakes

Controlled separations

‘Simple’ wakes

Close bodies such as separated heatshield

Each body affects the other’s properties

Viking wind-tunnel data can be adapted

Lines with break-ties

Elastic cords

Trailing bodies affect up-stream bodies

Various wakes for different bodies


PASDA – Example trajectory

Entry and descent of a parachute-probe-heatshield system


PASDA – Atmospheric inputs

European Mars Climate Database

support

Can add mesoscale winds

separately

Specify gusts for individual runs

Interpolates in provided

lookup tables

Look up atmospheric

data on the fly

External atmospheres


PASDA – Mars Trajectory Workshop results

0 50 100 150 200 250 300 350 4000

1

2

3

4

5

6

7

8Total aerodynamic load factor vs Time

Time (s)

Aero

dynam

ic load facto

r (g

)

225 230 235 240 245

1

1.5

2

2.5

3

3.5

4

4.5

5

5.5

6

Total aerodynamic load factor vs Time

Time (s)

Aero

dynam

ic load facto

r (g

)

Drogue parachute

deployment

Main parachute

deployment

Front shield

separation

Three degree-of-freedom (3DOF) simulations of three-stage descent


PASDA – Analysis of Huygens

ESA technology study

Modelled gust effects on Huygens probe


PASDA – Simulation framework

Based on Analyticon simulator framework

Brings excellent benefits:

Run entire campaigns unattended

Automated report generation

Monte-Carlo/grid on any parameter

Full parameter control/

traceability

Very rapid and flexible setup


PASDA – Monte-Carlo example

0

1

20

0.51

1.5

0.5

1

1.5

2

2.5

3

3.5

4

Y Position (Km)

Descent Module and Heat Shield positions

X Position (Km)

Altitude (Km

)

1.2 1.4 1.6 1.8 2 2.2

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

X Position (Km)

Y P

osition (Km

)

Descent Module and Heat Shield final positions

Descent Module

Heat Shield

Follow heatshield after separation


EDLS design has unique challenges

Integration of the process has benefits

Design parameter selection tool

Detailed trajectory modelling tool

PASDA has been successfully integrated

Brought up to date with recent work

N-body 3- or 6-dof simulations

Flexible, powerful simulator framework

Currently in use on ExoMars

Summary


The Right Answer

A Tessella Company

a tra je c to ry m o d e llin g to o l fo r m u lti-p h a se d e sc e n...

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