space debris risk assessment of spacecraft...

SPACE DEBRIS RISK ASSESSMENT OF SPACECRAFT PROTECTED BY 3D PRINTED

PANELS

IAC-18,A6,IP,19,x45205

Dr. Hedley Stokes, PHS Space Ltd, UK ([email protected]) &

Prof. Alessandro Francesconi, University of Padova, Italy Dr. Lorenzo Olivieri, University of Padova, Italy

Dr. Scott Walker, University of Southampton, UK

69th International Astronautical Congress

Bremen, Germany 1 – 5 October 2018

Introduction

• The work described here has been performed as part of an ongoing EC-funded H2020 research project called ReDSHIFT (Revolutionary Design of Spacecraft through Holistic Integration of Future Technologies)

• The ReDSHIFT project aims, through a holistic approach, to find passive means to mitigate the proliferation of space debris. This goal is pursued by a twofold research activity based on theoretical astrodynamics, computer simulations and the analysis of legal aspects of space debris, coupled with an experimental activity on advanced additive manufacturing (3D printing) applied to the production of a novel small satellite

• Several different aspects relating to the design and production of a debris compliant spacecraft are treated, including shielding, area augmentation devices for deorbiting (solar and drag sails) and design for demise. A strong testing activity, mainly based on design for demise wind tunnel experiments and hypervelocity impacts is also being performed

• Further information on the ReDSHIFT project is available in: – A. Rossi et al., “RESULTS FROM THE H2020 REDSHIFT PROJECT: A GLOBAL APPROACH TO SPACE

DEBRIS MITIGATION”, presented at this conference in the 16th IAA SYMPOSIUM ON SPACE DEBRIS (IAC-18,A6,4,6,x45666)

– http://redshift-h2020.eu/

Objective

• This paper focuses on those aspects of ReDSHIFT relating to the definition and assessment of new shielding concepts for protecting unmanned spacecraft against non-catastrophic space debris impacts

• In particular, an impact risk assessment is presented to show how a spacecraft might benefit from the application of new shield panels that are manufactured using 3D printing

3D printed shield panels (1/3)

• As an enabling technology, 3D printing is well suited to rapid prototyping of panel structures

• Furthermore, it allows the construction of unusual panel designs which might be difficult to realise using traditional manufacturing techniques

• In keeping with the project’s holistic design approach, several different multi-functional 3D printed panel designs have been developed and investigated

• Two of these panel designs are considered here: – a multi-shock panel (MSP) comprising four equally-spaced

bumper layers, and – a double-wall panel sandwiching a single corrugated

bumper layer (SCP)


• Multi-shock panel:

• Single corrugated panel:


• A 3D printed Single Corrugated Panel:

Preliminary impact risk analysis (1/5)

• An impact risk analysis has been performed using PHS Space’s SHIELD3 model to provide a preliminary evaluation of the shielding performance of the MSP and the SCP

• This helped to define the design of the panels for subsequent impact test investigations

SHIELD3 impact risk assessment process

• For more on SHIELD3 see: – Stokes, P.H. and Swinerd, G.G., “Debris Protection Optimisation of a Realistic Unmanned Spacecraft using SHIELD”.

Presented at the 4th European Conference on Space Debris, ESOC, Darmstadt, Germany, 18 – 20 April, 2005. – Stokes, H., Cougnet, C., Gelhaus, J., Oswald, M., Schaefer, U., and Theroude, C., “A Detailed Impact Risk

Assessment of Two Low Earth Orbiting Satellites”, IAC-12-A6.3.2, 63rd International Astronautical Congress, Naples, Italy, 2012.

• Pre-existing damage equations in SHIELD3, such as the NASA multi-shock shield ballistic limit equation, were used in the analysis

• Almost 700 simulations were run. The main design variables in the analysis were:

– bumper thicknesses (0.25 mm ~ 1.0 mm) – rear wall thickness (1.0 mm ~ 3.0 mm) – stand-off distance (2.0 cm ~ 15.0 cm) – ratio of equipment wall area to panel area (0.125 ~ 1.0)


• The performance of the two panel designs were investigated by applying them to a 1-metre box-shaped satellite operating in a circular, 820 km altitude, 98.7° inclination orbit for one year

• This “standard” satellite was used in the analysis as a proxy for a typical LEO satellite in a high risk orbit. It is based on a benchmark case defined by the IADC

• In the preliminary analysis the satellite was assumed to have an internal equipment unit represented by a single aluminium wall

𝒅𝒄 = 𝑲𝑯−𝑴𝑺 𝒕𝒘𝝆𝒘 𝟏 𝟑 𝝆𝒑−𝟏 𝟑 𝝈 𝟒𝟎 𝟏 𝟔 𝑽−𝟏 𝟑 𝐜𝐨𝐬𝜽 −𝟏 𝟑 𝑺𝟐 𝟑

where 𝑉 ≥ 6.4 cos 𝜃 −1 4


• Results were provided in several forms. The following shows example plots of ballistic limit curves and penetration distributions:

Ballistic limit curves for a multi-shock panel at various distances, S, in front of an aluminium rear wall (where tb1 = tb2 = tb3 = tb4 = 0.5 mm; tw = 2.0 mm; impact angle = 0°)

Number of penetrations from debris particles in the size range 0.46 mm to 3.16 mm through a 1 m2 aluminium wall located behind a multi-shock panel on the front face of a 1-metre cube-shaped satellite (where tb1 = tb2 = tb3 = tb4 = 0.5 mm; tw = 2.0 mm; S = 5.0 cm)


• The following table shows an example of the Effectiveness of an SCP when applied to each side of the box satellite (where tb = 0.5 mm, tcb = 0.3 mm, Aw/Ap = 0.25)

• A measure of the Survivability of the satellite is also shown. This helps to identify the optimum solution

S tw Effectiveness Effectiveness Effectiveness Effectiveness Effectiveness Effectiveness Survivability

(cm) (cm) Efront Erear Eright Eleft Etop Ebottom Stotal

2.00 0.200 0.00231 0.14429 0.00323 0.00320 0.06980 0.07273 0.01155

2.50 0.200 0.00262 0.12399 0.00380 0.00376 0.07806 0.08051 0.01323

5.00 0.200 0.01196 0.18770 0.05952 0.05955 0.11048 0.11309 0.07658

7.50 0.200 0.06214 0.25868 0.07848 0.07818 0.13698 0.14062 0.29166

10.00 0.200 0.06927 0.26008 0.08953 0.08941 0.16528 0.17016 0.32847

12.50 0.200 0.07603 0.26017 0.09809 0.09818 0.19696 0.20343 0.36135

15.00 0.200 0.08263 0.26025 0.10626 0.10660 0.23345 0.24200 0.39338

2.00 0.300 0.00248 0.32378 0.00379 0.00376 0.07458 0.07639 0.01275

2.50 0.300 0.00305 0.31539 0.00513 0.00507 0.08066 0.08234 0.01609

5.00 0.300 0.03834 0.31559 0.07085 0.06965 0.11030 0.11300 0.20193

7.50 0.300 0.05956 0.31575 0.08200 0.08072 0.14069 0.14465 0.28738

10.00 0.300 0.06701 0.31589 0.09242 0.09110 0.17505 0.18068 0.32457

12.50 0.300 0.07423 0.31602 0.10260 0.10126 0.21610 0.22408 0.36091

15.00 0.300 0.08140 0.31613 0.11280 0.11147 0.26747 0.27893 0.39734


• The results of the impact risk analysis allowed us to conclude that, based on the available damage equations, the MSP and SCP designs have the potential to provide comparable or better protection than equivalent honeycomb sandwich panels

• The results also helped us to define a set of 3D printed samples of the MSP and SCP designs for impact testing

• The main design variables in the impact tests were as follows:

Panel type Panel thickness Flat bumpers Corrugated bumpers

MSP 10 mm 4 x 0.5 mm N/A

20 mm 4 x 0.5 mm N/A

SCP

10 mm 2 x 0.5 mm (external) 1 x 0.3 mm (internal)

2 x 0.5 mm (external) 1 x 0.7 mm (internal)

20 mm 2 x 0.5 mm (external) 1 x 0.3 mm (internal)

2 x 0.5 mm (external) 1 x 0.7 mm (internal)

Impact testing of shield panels (1/2)

• Damage caused by a 2.9 mm Al1100 spherical projectile impacting an SCP sample at 4.87 km/s and 0°. The SCP overall thickness is 20 mm; front and rear plates are 0.5 mm thick; the corrugated bumper is 0.7 mm thick

• For more detailed information on the impact tests see: – L. Olivieri et al., “EXPERIMENTAL CHARACTERIZATION OF MULTI-LAYER 3D-PRINTED SHIELDS

FOR MICROSATELLITES”, presented at this conference in the 16th IAA SYMPOSIUM ON SPACE DEBRIS (IAC-18,A6,3,7,x44856)

Impact testing of shield panels (2/2)

• Video of a 1.5 mm Al1100 spherical projectile impacting an SCP sample at 4.84 km/s and 0°. The SCP overall thickness is 10 mm; front and rear plates are 0.5 mm thick; the corrugated bumper is 0.7 mm thick

• The rear plate of the panel is not perforated

Further work

• Upon completion of the impact test programme the resulting damage equations will be imported into SHIELD3 and a more sophisticated impact risk analysis will be conducted

• The MSP and SCP designs will be optimised for a box satellite with 27 internal equipment units

• These results will be used to help design and test enhanced versions of the MSP and SCP 3D-printed panels

• The work will be presented in a future paper

Acknowledgement

• This work is funded through the European Commission Horizon 2020, Framework Programme for Research and Innovation (2014-2020), under the ReDSHIFT project (grant agreement no. 687500)

Thank you

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