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Abstract.Solar active regions are known to be brighter in Lyman (• radiation than the quiet sun. Accordingly, they illuminate more H atoms in interplanetary space through resonance scattering. As we show here, this excess of illumination related to active regions is clearly seen in full-sky Lyman a maps recorded by the SWAN instrument on board SOHO, including those excesses resulting from active regions which are on the far side of the Sun. Since solar activity is most often connected to solar active regions, this technique could be used in the future to improve the quality of Space Weather forecast , by earlier detection of the birth of a new active region on the far side of the sun, before it comes into Earth's view at the East limb.

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Abstract-a real options framework for use in space mission design is presented. Such a framework has potential application in architecting flexibility in certain mission designs with the objective of maximizing mission utility. It integrates economic principles of cost, return, risk, flexibility, and other concepts from Black-Scholes option pricing theory and the multiplicative binomial process. Options pricing theory provides an objective method for valuing flexibility in making future investment decisions based on new information becoming available; such flexibility may have great value in certain risky ventures. This flexibility in the future may or may not exist without additional investment. The development of investment strategies to create flexibility must include answering the question "how much can be invested to create the desired flexibility?" The answer must include a priori estimation of the value that the flexibility provides; in this application the real options framework becomes a powerful tool. The utility of this tool will be demonstrated through conceptual examples; these examples will also illustrate some limitations of the method. This work is by no means a comprehensive study. At best it attempts to demonstrate that there are techniques and ways of thinking -frameworks -that offer benefits for the complex process of mission design for an uncertain and often risky future.