Systematic ranging and late warning asteroid impacts

We describe systematic ranging, an orbit determination technique especially suitable to assess the near-term Earth impact hazard posed by newly discovered asteroids. For these late warning cases, the time interval covered by the observations is generally short, perhaps a few hours or even less, which leads to severe degeneracies in the orbit estimation process. The systematic ranging approach gets around these degeneracies by performing a raster scan in the poorly-constrained space of topocentric range and range rate, while the plane of sky position and motion are directly tied to the recorded observations. This scan allows us to identify regions corresponding to collision solutions, as well as potential impact times and locations. From the probability distribution of the observation errors, we obtain a probability distribution in the orbital space and then estimate the probability of an Earth impact. We show how this technique is effective for a number of examples, including 2008 TC3 and 2014 AA, the only two asteroids to date discovered prior to impact

Workplace technology use may increase both employees’ distress and productivity

As technology has become an inescapable part of most workplaces, it has become ever more important to understand its impact on employees. Using data from two surveys of U.S. workers, Noelle Chesley examines the effects of both personal and job-related technology use. She finds that increased technology use, especially when it extends work into personal life, is linked with higher levels of worker distress. However, it is also associated with gains in productivity, and personal technology use at work may help employees to manage work-related stress

Alien Registration- Crouse, Chesley (Allagash, Aroostook County)

https://digitalmaine.com/alien_docs/32805/thumbnail.jp

Chesley Morri to Dr. Howerton, 18 November 1960

Professional correspondenc