Starship Asterisk*

JohnD wrote: ↑Wed Jun 26, 2019 8:56 am See: http://spaceweathergallery.com/indiv_up ... _id=154744

BDanielMayfield wrote: ↑Wed Jun 26, 2019 7:23 pm The vid John linked to showed that the bolide exploded above the cloud deck. Even so, I wonder if this event was noticed and reported by any people on watercraft in that part of the Caribbean Sea. Chris, do you think much remains made it clear to the sea's surface?

https://www.nesdis.noaa.gov/content/flashes-sky-how-lightning-sensor-weather-satellite-can-also-track-meteoroids wrote:
Flashes in the Sky: How the Lightning Sensor on a Weather Satellite Can Also Track Meteoroids

Recorded incidents of fireballs around the world, 1988-2018. Brighter colors denote larger impacts. (Credit: NASA Jet Propulsion Laboratory)

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Click to play embedded YouTube video.

What do lightning strikes and meteoroids zipping through space have in common? It turns out they both can be tracked from a weather satellite. Scientists have discovered that the Geostationary Lightning Mapper on NOAA’s GOES-16 and GOES-17 satellites sees more than just lightning flashes in our skies.

Meteoroids routinely bombard Earth's atmosphere from outer space. These small rock fragments, which come from comets or asteroids orbiting the sun, hurtle through space at speeds reaching 100,000 mph or more. When they enter our atmosphere as meteors, their resistance with the surrounding air creates intense heat, which in most cases vaporizes them to dust long before they reach the ground.

The brightest meteors, called bolides, make quite a flash when they explode in the Earth’s atmosphere. Commonly known as fireballs, these large meteoroids can measure several feet in diameter and appear as bright, or sometimes even brighter, than the full moon. While several thousand large meteors enter (and burn up in) Earth’s atmosphere each day, the vast majority of them occur over the oceans and uninhabited regions, leaving them undetected.

Until recently, tracking bolides has largely been the work of U.S. military satellites in geostationary orbit. Now, however, an instrument on-board NOAA’s two newest geostationary weather satellites (GOES-16 and GOES-17) designed to detect a different type of flash – lightning – has also observed these spectacularly bright meteors flying through our atmosphere.

In 2017, the Geostationary Lightning Mapper on-board NOAA’s GOES East (GOES-16) satellite, detected several bolides throughout the Western Hemisphere. The brightest and most energetic meteor occurred over the western Atlantic Ocean on March 11, about 300 miles southeast of Bermuda. Data from other U.S. government satellites showed the resulting explosion in Earth’s atmosphere could be traced to an asteroid about 2 to 3 meters in diameter, an event that happens only about once per year around the entire globe.

The Geostationary Lightning Mapper (GLM) also tracked several smaller bolides in other parts of North and South America, from western Canada to southern Argentina. One of these even left behind tangible evidence: Two months after the GLM detected a bolide in British Columbia, Canada, researchers confirmed that they had discovered several meteorites, the name given to fragments of meteoroids that survive their journey through the Earth’s atmosphere and land on the ground.

While designed for mapping lightning flashes, the Geostationary Lightning Mapper can observe large meteors anywhere throughout its coverage area. The instrument takes 500 images of Earth every second, allowing it to measure the shape of a meteor “light curve,” or the change in brightness of a meteor with time, with millisecond precision. In order for the GLM to detect these flashes, the bolides need an apparent visual magnitude of minus 14 at night, which is slightly brighter than the full moon.

Unlike most individual lightning flashes, which are shorter than a millisecond, the light signature of bolides lasts slightly longer. The flash is similar to what the GLM sees in lightning with continuing current, in which the cloud continues to glow (for tens of milliseconds) while lightning transfers charge to the ground. To make sure that the flashes were from large meteors, and not lightning, researchers checked that the GLM’s sensors had registered the flashes as “non-lightning” events.

Of course, the number of bolides pale in comparison to the millions of lightning flashes that occur across Earth each year. That means the GLM’s main job will be to monitor lightning activity and help us forecast severe thunderstorms. Nonetheless, the GLM’s ability to detect meteoroids means that NOAA weather satellites may eventually provide an open source of information about how and when these small asteroids from outer space impact the Earth’s atmosphere.>>

Asteroid 2019MO impact prediction and actual location
A map of the predicted trajectory and final impact location for
asteroid 2019MO. The predicted path is based on observations from
the University of Hawaiʻi's ATLAS and Pan-STARRS survey telescopes.
Credit: Larry Denneau (IfA/ATLAS), Brooks Bays (SOEST)

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For the first time, astronomers at the University of Hawaiʻi have demonstrated that their ATLAS and Pan-STARRS survey telescopes can provide sufficient warning to move people away from the impact site of an incoming asteroid. They detected a small asteroid prior to its entering the Earth's atmosphere near Puerto Rico on the morning of June 22, 2019.

The 4-meter diameter asteroid, named 2019 MO, was observed four times in a span of 30 minutes by the ATLAS Maunaloa facility, just after midnight Hawaiʻi time on the morning of Saturday, June 22. At that time, the asteroid was only 500,000 km from Earth - or 1.3 times the distance to the Moon. These initial observations were assessed by the NASA Jet Propulsion Laboratory's (JPL) Scout impact analysis software, and the asteroid was given a modest impact rating of 2 (a rating of 4 is "likely"). However, JPL's Davide Farnocchia noted a possible match with an atmospheric infrasound detection near Puerto Rico about 12 hours later, and he asked if the community could search for additional observations.

Luckily, the Pan-STARRS 2 (PS2) telescope on Haleakalā was operating at the same time, and two hours prior to the ATLAS observations had imaged the part of the sky where 2019 MO should have been seen. The asteroid was located on a part of the PS2 camera that is not fully operational, but PS2 scientists Robert Weryk and Mark Huber, at the University of Hawai'i Institute for Astronomy (IfA) and Marco Micheli at the European Space Agency (ESA), were able to analyze these PS2 images and find the asteroid.

With these additional PS2 observations, the asteroid's entry path prediction improved significantly, and new calculations by the Scout software increased the impact rating to 4, or "likely." The improved orbit calculation also matched the infrasound detection with very high likelihood. The Nexrad weather radar in San Juan, Puerto Rico also detected 2019 MO as it burnt up in the atmosphere, and pinpointed the entry location over the ocean, about 380 km south of San Juan, closely corresponding to the infrasound location. ...

• http://rammb.cira.colostate.edu/ramsdis ... _barry.gif