The livestream below is from one of the four commercial, off-the-shelf high-definition cameras, which take turns streaming a live video feed of Earth for online viewing.
As NASA says, "The cameras are enclosed in a temperature specific housing and are exposed to the harsh radiation of space."
"Analysis of the effect of space on the video quality, over the time HDEV is operational, may help engineers decide which cameras are the best types to use on future missions."
The system is operated one camera at a time on an automated repeating cycle so that the video follows a location on Earth as the ISS passes over, all with no intervention from human operators. It also drops out relatively frequently due to loss of Ku-band transmission, and it goes completely dark while in the night sections.
It's fascinating to watch and is strangely relaxing. Enjoy!
Broadcast live streaming video on Ustream
Black Scenes = Night side of the Earth
The live video feed from HDEV will occasionally be unavailable due to loss of Ku-band transmission from the International Space Station. Please check the site again in approximately 30 minutes
Total Lab Supplies - Everything for your laboratory
Our Head Office in St Helens
Showing posts with label ISS. Show all posts
Showing posts with label ISS. Show all posts
Friday, 28 November 2014
Friday, 26 July 2013
Sprites!
Sprites are a fleeting, ethereal and a relatively unknown aspect of lightning storms.
Since the 1960s, and probably before then, pilots have been seeing but seldom reporting what have become known as sprites and elves above the clouds. Sprites are electrically-charged lightning funnels which shoot up from the top of a cloud as much as 60 miles into the atmosphere. These charges are vivid red and usually occur in clusters of three or more but are only visible for nanoseconds. They are sometimes preceded by lower altitude red flashes known as elves, and can have striking blue tendrils which are easily mistaken for blue jets. While they are a similar visual phenomenon, blue jets are less powerful than the sprites and travel neither as quickly nor as far.
Because 'everyone knows' lightning goes to ground, pilots were naturally
reluctant to report this phenomenon in case they found themselves grounded for
hallucinating. As a result, serious research was delayed until the last 15 years
or so.
While sprites are more common during positively-charged lightning storms, this is not due to any preference on the part of the sprite, but rather due to the greater internal energy of a positively charged storm. It was not until 1999 that the first sprites of a negatively-charged storm were recorded.
During a powerful storm it is possible to see red sprites, elves and blue
jets, but the exact atmospheric conditions which create such a show are
uncertain.
As sprites are relatively new to the science world there is still a lot more to learn about them.
It is only with the advent of high speed photography that the existence of these light shows could be confirmed, and even with that they were first photographed by accident in 1989. Amazingly, there have since been more than 10,000 confirmed sightings. They are also known to create a very low-frequency thunder which was only recently captured with the use of specialist listening equipment.
As their energy is spread more thinly than the traditional thunderbolt due to
the cone like dispersal from cloud to atmosphere, they are thought to be
relatively weak. Sprites are cold plasma phenomena that lack the hot channel temperatures of tropospheric lightning, so they are more akin to fluorescent tube discharges than to lightning discharges.
The effects of sprites are currently being investigated by various agencies including NASA who seriously addressed them as a possible cause for the tragic loss of the space shuttle Columbia, which was, incidentally, on a mission to record data about the very same sprite phenomenon.
The link below shows footage from the ISS and shows a red sprite over East Asia at around 0:06.
http://upload.wikimedia.org/wikipedia/commons/f/f8/Red_Sprite.ogv
Sprite Halos
Sprites are sometimes preceded, by about 1 millisecond, by a sprite halo, a pancake-shaped region of weak, transient optical emissions approximately 50 kilometres (31 mi) across and 10 kilometres (6.2 mi) thick. The halo is centred at about 70 kilometres (43 mi) altitude above the initiating lightning strike. These halos are thought to be produced by the same physical process that produces sprites, but for which the ionization is too weak to cross the threshold required for streamer formation.
Recent research carried out at the University of Houston in 2002 indicates that some normal (negative) lightning discharges produce a sprite halo, and that every lightning bolt between cloud and ground attempts to produce a sprite or a sprite halo.
For more information visit:-
http://en.wikipedia.org/wiki/Sprite_(lightning)
http://h2g2.com/approved_entry/A13492398
http://apod.nasa.gov/apod/ap990616.html
Since the 1960s, and probably before then, pilots have been seeing but seldom reporting what have become known as sprites and elves above the clouds. Sprites are electrically-charged lightning funnels which shoot up from the top of a cloud as much as 60 miles into the atmosphere. These charges are vivid red and usually occur in clusters of three or more but are only visible for nanoseconds. They are sometimes preceded by lower altitude red flashes known as elves, and can have striking blue tendrils which are easily mistaken for blue jets. While they are a similar visual phenomenon, blue jets are less powerful than the sprites and travel neither as quickly nor as far.
While sprites are more common during positively-charged lightning storms, this is not due to any preference on the part of the sprite, but rather due to the greater internal energy of a positively charged storm. It was not until 1999 that the first sprites of a negatively-charged storm were recorded.
As sprites are relatively new to the science world there is still a lot more to learn about them.
It is only with the advent of high speed photography that the existence of these light shows could be confirmed, and even with that they were first photographed by accident in 1989. Amazingly, there have since been more than 10,000 confirmed sightings. They are also known to create a very low-frequency thunder which was only recently captured with the use of specialist listening equipment.
The effects of sprites are currently being investigated by various agencies including NASA who seriously addressed them as a possible cause for the tragic loss of the space shuttle Columbia, which was, incidentally, on a mission to record data about the very same sprite phenomenon.
The link below shows footage from the ISS and shows a red sprite over East Asia at around 0:06.
http://upload.wikimedia.org/wikipedia/commons/f/f8/Red_Sprite.ogv
Sprite Halos
Sprites are sometimes preceded, by about 1 millisecond, by a sprite halo, a pancake-shaped region of weak, transient optical emissions approximately 50 kilometres (31 mi) across and 10 kilometres (6.2 mi) thick. The halo is centred at about 70 kilometres (43 mi) altitude above the initiating lightning strike. These halos are thought to be produced by the same physical process that produces sprites, but for which the ionization is too weak to cross the threshold required for streamer formation.
Recent research carried out at the University of Houston in 2002 indicates that some normal (negative) lightning discharges produce a sprite halo, and that every lightning bolt between cloud and ground attempts to produce a sprite or a sprite halo.
For more information visit:-
http://en.wikipedia.org/wiki/Sprite_(lightning)
http://h2g2.com/approved_entry/A13492398
http://apod.nasa.gov/apod/ap990616.html
Subscribe to:
Posts (Atom)