Programmatic systems engineering (space systems)

Programmatic systems engineering as it pertains to space systems, focusing on its temporal dimension, including flexibility, obsolescence, space responsiveness, and schedule risk. These topics are also important beyond the space industry and for any complex engineering system. Research in this area addresses a cluster of closely related topics:

    • Value-informed design and acquisition

    • Flexibility in system design

    • System technology portfolio, schedule risk, and obsolescence

One anchor for these related topics is the important problem of schedule slippage of space programs, which plagues the space industry. NASA and the Department of Defense (DOD) have repeatedly struggled to keep the development of their space capabilities on schedule, and many programs have experienced several months, sometime years of delays.

The repeated pattern of these schedule slippages suggests deep-seated flaws in handling spacecraft design and delivery times, and an inadequate understanding of the drivers of schedule risk and slippage (this observation is applicable to other complex engineering systems, not just spacecraft).

Furthermore, due to their long development time and physical inaccessibility after launch, space systems are exposed to a peculiar risk of obsolescence, which can result in loss of value or competitive advantage over time. The perception of this particular risk has driven space agencies or organizations to adopt design choices that are (inadvertently) contributing to these schedule slippages, and jeopardizing what is increasingly recognized as critical, namely space responsiveness.

My research in this area tackles fundamental causes of, and contributing factors to, risks of schedule slippage and obsolescence of space systems; its end objective is to guide spacecraft design choices that will result in better control of delivery schedule and eliminate/mitigate these “temporal risks”.

To address these issues at a fundamental level, my students and I have developed novel ideas, frameworks, and analytics for:

    • Value-informed design and acquisition
    • Flexibility in system design
    • System technology portfolio, schedule risk, and obsolescence

Contributions in this area include (i) identification and analysis the levers of responsiveness and schedule slippage; (ii) adapting the concept of a technology portfolio from the macro- or company level to the micro-level of a single complex engineering system, and analyzing a space system as a portfolio of technologies and instruments, each with its distinct stochastic maturation path and exposure to obsolescence; the characteristics of this portfolio were quantitatively shown to be key determinants of schedule risk, and a trade-off was identified between mitigating the risks of on-orbit obsolescence and schedule slippage.

Finally a more fundamental contribution to this area consisted in (iii) the identification of the current and pervasive clock-based design optimization paradigm as a major underlying driver of the recurrent issues of schedule slippage. In its stead, I have proposed a paradigm shift towards a calendar-based design approach, in which for example the delivery time of the spacecraft is accounted for and becomes an intrinsic design parameter of the system itself. The calendar-based paradigm leads to different design choices, which are more likely to prevent schedule slippage and/or enhance responsiveness and ultimately result in a larger cumulative utility or value delivered by the system—value analysis being an important pillar of my research (see publications for more details).


Specific focus areas: the titles below provide a first guide into this body of work

Value-Informed Design and Acquisition

1. Gen, F. Saleh, J.H., Tien, A. Herd, R. A.

“Beyond cost tools: spacecraft net present value and the hosted payload paradigm”

IEEE Transactions on Aerospace and Electronic Systems, Vol. 51, No. 4, 2015, pp. 3348–3363

2. Brathwaite, J., Saleh, J. H.

Bayesian Framework for Assessing the Value of Scientific Space Systems: Value of Information Approach

Acta Astronautica, Vol. 84, 2013, pp.24–35

3. Saleh, J. H.

Perspectives in Design: the deacon’s masterpiece and the hundred-year aircraft, spacecraft, and other complex engineering systems

Journal of Mechanical Design, Vol. 127, September 2005, p. 845–850

4. Brathwaite, J., Saleh, J. H.

Value-Centric Framework and Pareto Optimality for Design and Acquisition of Communication Satellites

International Journal of Satellite Communications and Networking, Vol. 27, Issue 6, 2009, pp. 330–348)

5. Saleh, J. H.

Flawed metrics*: satellite cost per transponder and cost per day (*for guiding design decisions)

IEEE Transactions on Aerospace and Electronic Systems, Vol. 44, No. 1, 2008, pp. 147–156

6. Dubos, G.F., Saleh, J.H.

Comparative Cost and Utility Analysis of Monolith and Fractionated Spacecraft Using Failure and Replacement Markov models

Acta Astronautica, Vol. 68, Issue 1–2, 2011, pp. 172–184


Flexibility in System Design

7. Saleh, J. H., Mark, G. T., Jordan, N. C.

Flexibility: a multi-disciplinary literature review and a research agenda for designing flexible systems

Journal of Engineering Design, >Vol. 20, No. 3, 2009, pp. 307–323

8. Lafleur, J. M., Saleh, J. H.

Survey of Intra- and Inter-Mission Flexibility in Space Exploration Systems

Acta Astronautica, Vol. 67, Issue 1-2, 2010, pp. 97–107

9. Saleh, J. H., Lamassoure, E., Hastings, D. E., Newman, D. J.

Flexibility and the Value of On-Orbit Servicing: A New Customer-Centric Perspective

Journal of Spacecraft and Rockets, Volume 40, No. 1, 2003, p. 279–291


System Technology Portfolio, Schedule Risk, and Obsolescence

10. Dubos, G. F., Saleh, J. H.

Spacecraft Technology Portfolio: Probabilistic Modeling and Implications for Responsiveness and Schedule Slippage

Acta Astronautica, Vol. 68, Issues 7-8, 2011, pp. 1126–1146

11. Saleh, J. H., Dubos, G. F.

Responsive Space: Concept Analysis, Critical Review, and Theoretical Framework

Acta Astronautica, Vol. 65, No. 3, 2009, pp. 376–398

12. Dubos, G. F., Saleh, J. H., Braun, R.

Technology Readiness Level, Schedule Risk and Slippage in Spacecraft Design: Data Analysis and Modeling

Journal of Spacecraft and Rockets, Vol. 45, No. 4, 2008, pp. 836–842

13. Dubos, G. F., Saleh, J. H.

Risk of Spacecraft On-Orbit Obsolescence: New Framework, Stochastic Modeling, and Implications

Acta Astronautica, Vol. 67, Issue 1-2, 2010, pp. 155–172