INSIGHT INTO THE REQUIREMENTS OF SELF-AWARE,

ADAPTIVE AND RELIABLE EMBEDDED SUB-SYSTEMS

OF SATELLITE SPACECRAFT

Rajeev Kumar Kanth, Pasi Liljeberg, Hannu Tenhunen

Turku Centre for Computer Science, University of Turku, Joukahaisenkatu 3-5 B, Turku, Finland

Qiansu Wan, Waqar Ahmad, Li-Rong Zheng, Harish Kumar

Royal Institute of Technology, Kista, Sweden

DOECE, BIT, Muzaffarnagar, India

Keywords: Self-aware System, Satellite Sub-System, Telemetry Tracking and Command, Embedded Sub-Systems,

Adaptive Antenna, Satellite Spacecraft, Adaptive Space Hardware, On-Board Data Handling.

Abstract: This position paper gives an insight for self-aware and adaptivity requirements of the sub-systems

embedded in a satellite spacecraft. The most signiﬁcant and considerable issues of self-aware and adaptive

systems that are necessary in present and future on-board satellite spacecraft are illustrated in this paper. An

attempt has been made to discuss several embedded sub-systems and space environment scenarios of the

spacecraft. As a case study, an adaptive sierpinski based dual band antenna has been devised. The adaptive

nature of this antenna provides a foundation of longer and more reliable mission life of a spacecraft.

Through this paper it will be shown that adaptive, reconﬁgurable and reliability issues are the most

prominent and potential area of research for outer space communication technology.

1 INTRODUCTION

A sub-system or system in a satellite spacecraft is

called space hardware. Space hardware consists of

several parts (electronics and mechanical) and

materials with suitable surface treatment for

withstanding environmental effects while on ground

and on space. As maintenance in space during

mission life is impossible, so the parts, materials and

the processes used for making spacecraft sub-

systems must be highly self-aware, adaptive and

reliable.

This position paper describes different self-

aware and adaptive issues that spacecraft sub-

systems encounter during its useful life period. The

nature of the spacecraft sub-systems are supposed to

be extremely insensitive to the external environment.

The need for achieving mass efficient adaptive

designs, selection and control of parts, materials and

processes of the sub-systems are the major

challenges in structuring a satellite spacecraft.

Structure also plays an important role in the thermal

control of the spacecraft by providing conductive

paths, radiating surfaces and acting as heat sinks.

A spacecraft sub-system begins its life in ground

and usually long storage time is envisaged in

different environmental conditions. While on

ground, the spacecraft materials and components

encounter all classical aging problems like oxidation

and corrosion, effect of variable humidity, biological

attack, losses due to evaporation, metal migration

etc. The launch environment encompasses a range of

simultaneous applied energy loads created due to

random vibration, acoustical noise, pressure

variations and acceleration. Space hardware

including their components and materials are

assessed by different mechanical and environmental

tests for their suitability in the launch environment.

When a satellite is positioned in the parking slot

in space, its mission life starts (Maral and

Bousquet). During this period, sub-systems of

satellite spacecraft encounter environment which is

made of vacuum, extreme high and low temperature

(+80

C to -180

C in GEO) and radiation of different

dose levels. The embedded onboard sub-systems of

603

Kanth R., Liljeberg P., Tenhunen H., Wan Q., Ahmad W., Zheng L. and Kumar H..

INSIGHT INTO THE REQUIREMENTS OF SELF-AWARE, ADAPTIVE AND RELIABLE EMBEDDED SUB-SYSTEMS OF SATELLITE SPACECRAFT.

DOI: 10.5220/0003406706030608

In Proceedings of the 1st International Conference on Pervasive and Embedded Computing and Communication Systems (SAAES-2011), pages

603-608

ISBN: 978-989-8425-48-5

 2011 SCITEPRESS (Science and Technology Publications, Lda.)

spacecraft must follow the space qualiﬁcation. The

activity by which it is ensured that the parts and

materials used in satellite sub-system will be able to

withstand effects of the above three environments

without degrading performance is known as space

qualiﬁcation.

Motivated by the evidence of adverse space

environment for satellite spacecraft, our aim is to

develop an understanding the issues and importance

of self-aware, reconﬁgurable and adaptive designs

for the onboard spacecraft sub-systems. Through this

paper, we are aiming to grab the reader’s attention at

self-aware and adaptive sub-systems of satellite

spacecraft are the most potential and prominent area

of research.

Our paper is structured as follows. Section II

describes the existing literature in context with our

research work. The next two sections provide the

practical underpinnings of satellite sub-systems and

space environment respectively. Section V describes

a list of self-aware and adaptability issues related to

satellite spacecraft. The development of adaptive

dual band antenna is discussed in section VI,

conclusion and future works are presented in Section

VII.

2 RELATED WORKS

Substantial research has been conducted on several

key areas related to the self-aware and adaptive

space hardware sub-systems. The recent existing

literatures (Maral and Bousquet), (Vassev et al.,

2010), (Striemer and Akoglu, 2010), (Kang et al.,

2010), (Lee and Choi, 2010), (Jung, 2010),

(Santambrogio et al., 2010), (Cheng et al., 2010),

(Stauffer, 2009) of adaptive systems for space

applications include self-conﬁgurable swarm-based

space exploration systems, low density parity check

(LDPC) engine for space based communication

systems and several papers on reconﬁgurable and

self-aware computing architectures for onboard

spacecraft embedded sub-systems. In the same way,

a number of papers can be found for reconﬁgurable

multi core architectures, built-in self-test and self-

repair, adaptive signal processing, image data

compression and power ampliﬁer.

The most available literature do not focus on

reconﬁgurable, adaptive and self-aware issues for

each of the embedded onboard satellite sub-systems

and satellite payload. Therefore here our work is to

enlighten those several issues that spacecraft

encounters during its mission life. We also make an

effort to describe several problems that takes place

in on-board spacecraft concerning adverse space

environment.

3 SATELLITE SUB-SYSTEM

Communication satellites are very complex and

extremely expensive to construct & launch.

Currently communication satellites are designed and

developed for 12 to 15 years of life time during

which the communication capability of the satellite

earns revenue, to recover the initial and operating

costs. Since the satellite has to operate over a long

period out in the space, the sub-systems of the

satellite are required to be very reliable. Major sub-

systems of a satellite are bus sub-systems and

payload. The satellite-bus-sub-systems include

mechanical structure, attitude and orbit control

system (AOCS), propulsion system, electrical power

system, tracking telemetry and command (TTC)

system and thermal control system. Similarly

satellite payload comprises of communication

transponder and antennas. Since a communication

satellite earns revenue, the satellite must carry as

many communications channels as possible.

However, a large communication channel capacity

necessitates large electrical power from large solar

arrays and battery, results larger mass and volume of

the satellite. Parking a heavy satellite in

geosynchronous orbit is very expensive; therefore it

is logical to keep the size and mass of the satellite

small. Lightweight materials optimally designed to

carry the load and withstand vibration and large

temperature cycles are considered to be signiﬁcant

parameters for the structure of the satellite.

Attitude and orbit control system (AOCS) (Yoon

and Tsiotras, 2002), (mackunis et al., 2008)

maintains the orbital location of the satellite and

controls the attitude of the satellite by using different

sensors and ﬁring small thrusters located in different

sides of the satellite. Liquid fuel and oxidizer are

carried in the satellite as part of the propulsion

system for ﬁring the thrusters in order to maintain

the satellite attitude and orbit. The amount of fuel

and oxidizer carried by the satellite also determines

the effective life of the satellite.

The electrical power in the satellite is derived

mainly from the solar cells. The power is used by the

communication payload and also by all other

electrical sub-systems in the satellite for

housekeeping. Rechargeable battery is used for

supplying electrical power during eclipse of the

satellite spacecraft. Telemetry, tracking and

command (TTC) system of the satellite works along

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with its counterparts located in the satellite control

earth station. The telemetry system collects data

from sensors on board the satellite and sends these

data via telemetry link to the satellite control centre

which monitors the health of the satellite. Tracking

and ranging system located in the earth station

provides the information related to the range and

location of the satellite in its orbit. The command

system is used for switching on/off of different sub-

systems in the satellite based on the telemetry and

tracking data.

The thermal control system maintains the

temperature of different parts of the satellite within

the operating temperature limits and thus protects

the satellite sub-systems from the extreme

temperature conditions of the outer space.

4 SPACE ENVIRONMENT

Space environment consists of zero gravity

condition, vacuum with thermal cycling (high and

low) and diverse solar radiation. Zero gravity

condition does not impose considerable effects on

space hardware except loose conductive and non

conductive particles entrapped in the spacecraft.

These particles can move freely inside creating

blockage or shorting of sensitive electrical circuits

resulting damage in few sub-systems. Precautions

are taken to prevent such entrapment during

hardware fabrication using clean room fabrication

and associated protection.

Vacuum of the order of 10

-13

Torr or higher

exists at geosynchronous orbit. Any sliding and

rubbing of surfaces as in bearing and for rotating

movements tend to get vacuum welded. Use of dry

lubricant material is a solution to this problem.

Outgassing of polymeric substances, sealing and

potting compound etc create total weight loss and

condensable volatile mass in thermo vacuum

environment in space.

The outgassing products can cause low voltage

corona of the electrical circuit and change the

physical properties of optical surfaces inside

spacecraft. It is a practice to screen these materials

before using in space hardware so that total mass

loss (TML) and collection volatile condensable mass

(CVCM) are less than a predetermined level.

5 SELF-AWARE AND

ADAPTIVE ISSUES

This section describes the potential self-aware and

adaptive issues which need to be considering while

designing a spacecraft. The most prominent issue is

to supply a regulated electrical power to each of the

sub-systems of the spacecraft. Embedded solar cells

are the primary source of energy during the mission

life of a satellite. During eclipse period the

electrochemical batteries are the most appropriate

means of secondary energy source. Nickel-cadmium

and Nickel-hydrogen cells have been normally used

for the storage of electrical energy since the advent

of communication satellites. A number of self-aware

and adaptive issues have been devised in electrical

power supply sub-system of the spacecraft. They are

as follows:

• The solar generator consists of small groups

of cells arranged in series or in parallel. The

choice of combination is such that it

maximizes the relative adaptability and

reliability, taking into account of failure rates

of the cells.

• The solar generator wings of the satellite are

rotated in order to maintain the apparent

movement of the sun. Hence it must employ

self-aware solar sensors and adaptive control

circuits so as to check out the proper

dimensioning of the power at the time of

summer solstice and equinoxes.

• The design of secondary energy sources must

be adaptable in varying temperature

conditions. The key issues for battery energy

sources are dimensioning, depth of discharge

(DOD), protection against overcharging and

several battery technologies.



In the same way the potential self-aware and

adaptive designs are required in attitude control of

the satellite spacecraft. Maintaining attitude is

fundamental for the satellite to fulﬁll its function.

The embedded self-aware sensors measure the

orientation of the satellite axes with respect to

external references. Embedded sun, earth, star, radio

frequency and laser detector sensors should be

adequately designed so as to adapt in adverse space

environment and to provide the accurate orbit

attitude and alignment errors.

Telemetry, Tracking and Command (TTC) and

On Board Data Handling (OBDH) are another two

important mutual sub-systems in satellite spacecraft.

Adaptive electronic systems should be employed in

TTC and OBDH sub-systems so that they ensure

enduring availability of the links with the ground

stations. One of the important characteristics of the

command link is security. Hence the embedded sub-

systems are not only supposed to be self-aware and

INSIGHT INTO THE REQUIREMENTS OF SELF-AWARE, ADAPTIVE AND RELIABLE EMBEDDED

SUB-SYSTEMS OF SATELLITE SPACECRAFT

605

adaptive but also adequately secured so that the

system is insensitive to the signals transmitted by

intruders.

The purpose of the thermal control is to maintain

the sub-systems and equipments within the

temperature ranges which enable it to operate

reasonably. A self-aware temperature sensor adjusts

the thermal conductivities among various parts of

the satellite. The thermal reliability of the on-board

equipments and sub-systems depend on adaptability

of the components in different temperature

conditions.

6 ADAPTIVE ANTENNA- A

CASE STUDY

The payload is one of the most important sub-

systems of satellite spacecraft. Antenna is a part of

the payload. We have chosen development of an

adaptive multi-layered antenna as a case study. Here

the emphasis has been given to explore the self-

aware and adaptability issues of the developed dual

band, self-tunable and sierpinski based fractal

antenna. The detail design methodologies, result

analysis and development mechanisms are

demonstrated in (Kanth et al, 2010), (Kanth et al.,

2010), (Kanth et al., 2009). The major challenges

during the development of this adaptable antenna

were selection of space qualiﬁed materials and meet

the required speciﬁcations. The work was performed

satisfactorily using the materials copper, duroid,

foam, glass epoxy and coaxial probe to achieve the

required speciﬁcations in terms of return loss, gain

radiation and coverage area. The multi-layered

layout of the proposed adaptive antenna is shown in

Fig. 1.

Figure 1: Multi-Layered Layout.

The adaptive nature (dual band self-tunable) of

the proposed antenna has been described in (Kanth

et al., 2009). The adaptability of the on-board sub-

systems must qualify space adverse ranges of the

temperatures, outgassing properties in vacuum, zero

gravity and random vibration resistance. The

selection of the materials for fabricating this antenna

is such that it surpasses all the space qualiﬁcation

tests and ensures the required performance as per the

speciﬁcations. The return loss of the developed

adaptive dual band self tunable antenna is presented

in Fig. 2. Several iterations and new optimizations

techniques were involved to achieve the desired

performance. The developed multi-layered,

sierpinski based adaptable dual band antenna is

shown in Fig. 3.

Figure 2: Return Loss Diagram- Adaptive Nature.

Figure 3: Dual Band Adaptive Satellite Navigational

Antenna.

7 CONCLUSIONS AND FUTURE

WORKS

This position paper explicitly introduces, analyzes

and reflects on important issues and problems

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related to the topic. Obvious practical implications

of these investigations illustrate that adaptive and

self-aware issues are the potential research areas for

outer space communication technology. We have

developed a space qualiﬁed payload antenna which

is adaptive in nature. Undoubtedly, the realization of

adaptive, self-aware and reconﬁgurable sub-systems

of the spacecraft not only enhances the reliability but

also lengthen the mission life of spacecraft. The list

of self-aware and adaptive issues of the embedded

sub-systems of satellite spacecraft, mentioned in this

paper gives guidelines to a designer to ensure

corrective actions before it is launched. Here we

conclude that self-aware and adaptive designs are

the most important issues in developing a successful

satellite spacecraft.

There are many avenues for further research.

The ﬁrst important future work is to measure the

degree of reliability considering the self-aware and

adaptive design issues for the embedded sub-

systems of the spacecraft. One should focus on

related parameters of these issues and explore the

significances in terms of reliability and mission life

enhancement. Another imperative future work is to

consider the adaptive designs in realization of high

power ampliﬁer, attitude control systems, TTC,

propulsion sub-system and on-board processing

systems. Finally, it would be worthwhile to examine

the role of self-aware and adaptive designs in

minimization of failure rate of the sub-system in its

mission life.

ACKNOWLEDGEMENTS

The authors would like to thank Indian Space

Research Organization (ISRO) satellite centre, India

and Computer System Laboratory, University of

Turku, Finland for providing necessary support to

carry out these investigations.

REFERENCES

Gerard Maral, Michel Bousquet, Satellite Communications

Systems Systems, Techniques and Technology, Fourth

Edition, ISBN-13 978-0-471-49654-0, John Willy and

Sons Ltd. pp-551-643

Vassev, Emil; Hinchey, Mike; Nixon, Paddy, A formal

approach toself-conﬁgurable swarm-based space-

exploration systems, A Conference on Adaptive

Hardware and Systems (AHS), 2010 NASA/ESA,

Digital Object Identiﬁer: 10.1109/AHS.2010.5546276,

Publication Year: 2010, Page(s): 83 - 90

Striemer, Gregory M.; Akoglu, Ali, An adaptable low

density parity check (LDPC) engine for space based

communication systems, A Conference on Adaptive

Hardware and Systems (AHS), 2010 NASA/ESA,

Digital Object Identiﬁer: 10.1109/AHS.2010.5546275,

Publication Year: 2010, Page(s): 105 - 112

Kang, Dong-Soo; Jhang, Kyoung-Son; Oh, Dae-Soo,

Design and implementation of a radiation tolerant on-

board computer for science technology satellite-3, A

Conference on Adaptive Hardware and Systems

(AHS), 2010 NASA/ESA, Digital Object Identiﬁer:

10.1109/AHS.2010.5546260, Publication Year: 2010,

Page(s): 17 - 23

Lee, Ganghee; Choi, Kiyoung, Thermal-aware fault-

tolerant system design with coarse-grained

reconﬁgurable array architecture, A Conference on

Adaptive Hardware and Systems (AHS), 2010

NASA/ESA, Digital Object Identiﬁer:

10.1109/AHS.2010.5546249, Publication Year: 2010,

Page(s): 265 - 272

Jung, Yong-Kyu, An emerging adaptive architecture and

compilation techniques, A Conference on Adaptive

Hardware and Systems (AHS), 2010 NASA/ESA

Digital Object Identiﬁer: 10.1109/AHS.2010.5546268,

Publication Year: 2010, Page(s): 134 - 141

Santambrogio, M. D.; Hoffmann, H.; Eastep, J.; Agarwal,

A., Enabling technologies for self-aware adaptive

systems, A Conference on Adaptive Hardware and

Systems (AHS), 2010 NASA/ESA,Digital Object

Identiﬁer: 1109/AHS, 2010.5546266, Publication

Year: 2010 , Page(s): 149 - 156

Cheng, Kevin; Zarezadeh, Ali Akbar; Muhlbauer, Felix;

Tanougast, Camel; Bobda, Christophe, Auto-

reconﬁguration on self-organized intelligent platform,

A Conference on Adaptive Hardware and Systems

(AHS), 2010 NASA/ESA, Digital Object Identiﬁer:

1109/AHS.2010.5546243 ,Publication Year: 2010 ,

Page(s): 309 – 316

Stauffer, A.; Rossier, J.; Self-Testable and Self-Repairable

Bio-Inspired Conﬁgurable Circuits, A Conference on

Adaptive Hardware and Systems, 2009. AHS 2009.

NASA/ESA, Digital Object Identiﬁer:

10.1109/AHS.2009.19 Publication Year: 2009,

Page(s): 155 - 162

Hyungjoo Yoon, Panagiotis Tsiotras, Spacecraft Adaptive

Attitude and Power Tracking with Variable Speed

Control Moment Gyroscopes Journal of Guidance,

Control and Dynamics, Vol. 25, No. 6 December

2002, Page(s): 1081 - 1090

W. Mackunis, K. Dupree, N. Fitz-coy, W. E. DIxon,

Adaptive Satellite Attitude Control in the Presence of

Inertia and CMG Gimbal Friction Uncertainties, The

Journal of the Astronautical Services, Vol. 56, No. 1

March 2008, Page(s) 121-134.

Rajeev Kumar Kanth, Waqar Ahmad, Yasar Amin, Pasi

Liljeberg, Li-Rong Zheng, Hannu Tenhunen, Analysis,

Design and Development Novel, Low Proﬁ

le 2.487

GHz Microstrip Antenna Conference proceedings of

14th International Symposium on Antenna

Technology and Applied Electromagnetics and the

INSIGHT INTO THE REQUIREMENTS OF SELF-AWARE, ADAPTIVE AND RELIABLE EMBEDDED

SUB-SYSTEMS OF SATELLITE SPACECRAFT

607

American Electromagnetics Conference

(ANTEM/AMEREM) 2010, ISBN: 978-1-4244-5049-

7, Page(s): 1 - 4

Rajeev Kumar Kanth, Waqar Ahmad, Subarna Shakya,

Pasi Liljeberg, Li-Rong Zheng, Hannu Tenhunen,

Autonomous Use of Fractal Structure in Low Cost,

Multiband and Compact Navigatinal Antenna

Conference proceedings of 10th Mediterranean

Microwave Symposium (MMS) 2010, Northern

Cyprus, ISBN: 978-1-4244-7243-7, Page(s): 135 - 138

Rajeev Kumar Kanth, Alok Kumar Singhal, Pasi

Liljeberg, Hannu Tenhunen, Analysis, Design and

Development Novel, Low Proﬁle Microstrip Antenna

for Satellite Navigation Conference proceedings of

NORCHIP 2009, Trondheim, Norway, ISBN: 978-1-

4244-4311-6/09/, Page(s): 1 -4

Rajeev Kumar Kanth, Alok Kumar Singhal, Pasi

Liljeberg, Hannu Tenhunen, Design of Multiband

Fractal Antenna for Mobile and Hand-held Terminals

Conference proceedings of Asian Himalayan First

International Conference on Internet (AH-ICI, 2009),

Kathmandu Nepal, ISBN:978-1-4244-4570-7/09/,

Page(s): 1 - 4

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