Microsatellites And Improved Acquisition Of Space Systems

Traditional practices of the United States Department of Defense (DoD) in the acquisition of space systems have focused on advanced versions of proven technology, meaning large satellites. This paradigm contributes to dependence on a handful of satellites, program schedules measured in decades, and the expensive oversight and program management functions which must be applied to systems which, since there are so few assets, cannot countenance failures. The escape from this paradigm is offered by Microsatellites (Microsats). Microsats are not only useful technology, but technology which enables a different approach to acquisition. What the authors call the Microsat Acquisition Paradigm (MAP) is partly modeled on NASA's Faster, Better, Cheaper approach and takes lessons from NASA's successes and failures. Now that some space functions can be undertaken by low-cost Microsats, the advantages of mass production, reduced government oversight, and acceptance of a reasonable failure rate can be applied to space system acquisition. This paper explores the three pillars of the MAP approach: requirements, technology, and acquisition, which together support the Holy Grail of space system affordability. Understanding the military's space requirements is the first pillar of this approach. The second pillar is the ability to correlate the requirements to the current and projected state of Microsat technology and explain what space functions can be accomplished with Microsats. Finally, historical examples, as well as recent studies. demonstrate that streamlined, cost-effective acquisition is a reality for Microsats, enabling savings in time and money compared to the acquisition system used for traditional space systems.     

ROSAT-WFC detection of the Lyman continuum flux of β CMa (B1 II–III)

We report the first detection of Lyman continuum (≈ 600Å) emission from a non-degenerate star. The WFC on-board ROSAT detected emission from β CMa (B1 II–III) which has a very low interstellar column. Both Kurucz LTE line-blanketed and Mihalas NLTE un-blanketed model atmospheres can match the observed count rate within the very considerable absolute calibration errors. We also find very marginal evidence for variability, although not at the dominant period of the known optical pulsations.