Over the Edge
The solar system exists inside a giant plasma bubble blown out by the solar wind and shaped by its interaction with the surrounding space of the Milky Way galaxy that we call the heliosphere. The bubble shields us from interstellar gas and, to a degree, from the penetrating space radiation known as cosmic rays. In September of 2012 a robotic NASA probe has crossed the boundary of the heliosphere and entered interstellar space. For my fellow space scientists this event is as significant as the first landing of a spacecraft on another planet. I will explain how scientists learn about the shape and properties of the heliosphere from remote observations and how the missing pieces are reconstructed through computer simulations. Exploring such remote regions of space is extremely challenging, not least because the twin Voyager spacecraft are now more than 35 years old and were built with computer technology that was state of the art in the 1970s. Hardware breakdowns and apparent discrepancies between different instruments were the reasons NASA only confirmed the crossing a year an a half later. The Voyagers made a bounty of discoveries while inside the heliosphere, and we expect to learn much more about interstellar space over the next 10 years, until the probes runs out of power. For now, it appears that interstellar space is just really, really quiet..
Transient Luminous Events (TLEs) are naturally-occurring electrical discharges in the upper atmosphere above thunderclouds and can extend in altitude to the base of the E-region ionosphere (Altitude ~ 90km). In particular, sprites are a class of TLEs triggered by the mesospheric electric fields the exceed the breakdown threshold for air - a configuration often resulting from cloud-to-ground (CG) strikes of tropospheric lightning. The primary emissions of sprite-generated flashes are in the visible spectrum, but because they are short-lived (up to 10s of ms) and relatively unpredictable, several decades of anecdotal reports (e.g. by pilots) went unexplained - that is, until in 1989 when a TLE was serendipitously captured by a low light level TV camera undergoing tests for sounding rocket integration. Since then, dozens of campaigns and hundreds of papers have been completed on the topic. This seminar will cover the progress in understanding the physical mechanisms of sprites and the features that distinguishes them from other forms of TLEs.
HAL5 double feature! Space Shuttle history talk featuring David Hitt on "Bold They Rise: The Space Shuttle Early Years, 1972-1986" and Scott Phillips on "Remove before flight. Memoir of a Space Shuttle Team Member". Book sale and signing will follow before and after the talk.
For a second year in a row, HAL5 was awarded the NSS Chapter Excellence Award for Education Outreach. Special thanks to our members, supporters and attendees of our monthly programs to HAL5 one of the most active chapter in NSS! Thank you!
Once again, we are the best chapter in NSS! At the 2011 ISDC in Huntsville, HAL5 was awarded
the NSS Chapter of the Year award for 2010! Thank you, our
members and guests, and HAL5 officers for making this possible.
Would you like to give a talk to HAL5 on subjects related to space,
space exploration, space science, space tourism,
technology, aerospace technologies, planetary defense,
and STEM? If you do, please
Members and general public are welcome to attend the HAL5 Executive Officers' meetings. Second Thursday of each month, except for holidays, at 6 pm at Newk's on University Drive.
Open to all current HAL5 members. We meet on Wednesday from 7 PM to 9:30 PM at Steve's except for holidays and other conflicts. If you are interested, please .