# Monthly Archives: April 2016

## Recent Asteroid Impacts on Mars and Jupiter

I liked this picture of the recent impact of a small asteroid on Mars. This impact crater is about 100 feet across and was not seen in NASA photographs prior to 2010 and was first seen in a photograph in 2012. The blue color is an artifact of the image enhancement process, which removed the red dust. Continue reading

Posted in Astronomy | 5 Comments

## A Little Heat Sink Math

I am conducting a seminar next week on cooling electronics. One of the topics I will cover involves basic heat sink usage. Most of the products that are designed by my team do not use heat sinks because we are not allowed to use fans in our designs – fan-based cooling systems generally have air filters that require regular maintenance that is unacceptable for optical hardware deep in the network (example deployment). Continue reading

Posted in Electronics | 1 Comment

## MTBF, Failure Rate, and Annualized Failure Rate Again

I just had another meeting where folks thought that specifications for Annualized Failure Rate (AFR), failure rate (λ), and Mean Time Between Failures (MTBF) were three different things – they are mathematically equivalent. I have given up writing the formulas down as a way to explain the concept. Maybe a graphic will illustrate the relationship better? I have tried this approach before – the most successful was about component temperatures. That graphic has saved me hours. Continue reading

Posted in Electronics | 2 Comments

## Unfortunate Satellite Launch Problem Allows Test of Relativistic Time Dilation

In November 2015, the European Space Agency (ESA) had a launch problem with two of its Galileo navigational satellites that resulted in both satellites being placed into highly elliptical orbits. ESA can burn some of the satellites' station-keeping fuel to bring these orbits back to standard, but this will take some time. While the orbit adjustments are occurring, ESA will use the satellites to provide another test of Einstein's general theory of relativity. Specifically, they will test the prediction that clocks will run slower the closer they approach a massive object. Continue reading

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