From NASA Science News: Firefly Mission to Study Terrestrial Gamma-ray Flashes
High-energy bursts of gamma rays typically occur far out in space, perhaps near black holes or other high-energy cosmic phenomena. So imagine scientists’ surprise in the mid-1990s when they found these powerful gamma ray flashes happening right here on Earth, in the skies overhead.
They’re called Terrestrial Gamma-ray Flashes, or TGFs, and very little is known about them. They seem to have a connection with lightning, but TGFs themselves are something entirely different.
Right: An artist’s concept of TGFs. Credit: NASA/Robert Kilgore [more]
“In fact,” says Doug Rowland of NASA’s Goddard Space Flight Center, “before the 1990s nobody knew they even existed. And yet they’re the most potent natural particle accelerators on Earth.”
Individual particles in a TGF acquire a huge amount of energy, sometimes in excess of 20 mega-electron volts (MeV). In contrast, the colorful auroras that light up the skies at high latitudes are powered by particles with less than one thousandth as much energy.
At this stage, there are more questions about TGFs than answers. What causes these high-energy flashes? Do they help trigger lightning–or does lightning trigger them? Could they be responsible for some of the high-energy particles in the Van Allen radiation belts, which can damage satellites?
To investigate, Rowland and his colleagues at GSFC, Siena College, Universities Space Research Association, and the Hawk Institute for Space Sciences are planning to launch a tiny, football-sized satellite called Firefly in 2010 or 2011. Because of its small size, Firefly will cost less than $1 million — about 100 times cheaper than what satellite missions normally cost. Part of the cost savings comes from launching Firefly under the National Science Foundation’s CubeSat program, which launches small satellites as “stowaways” aboard rockets carrying larger satellites into space, rather than requiring dedicated rocket launches.
Below: An artist’s concept of Firefly on the lookout for TGFs above a thunderstorm. Firefly will make simultaneous measurements of energetic electrons, gamma rays, and the radio and optical signatures of the lightning discharge. [more]
If successful, Firefly will return the first simultaneous measurements of TGFs and lightning. Most of what’s known about TGFs to date has been learned from missions meant to observe gamma rays coming from deep space, such as NASA’s Compton Gamma Ray Observatory, which discovered TGFs in 1994. As it stared out into space, Compton caught fleeting glimpses of gamma rays out of the corner of its eye, so to speak. The powerful flashes were coming–surprise!–from Earth’s atmosphere.
Subsequent data from Compton and other space telescopes have provided a tantalizingly incomplete picture of how TGFs occur:
In the skies above a thunderstorm, powerful electric fields generated by the storm stretch upward for many miles into the upper atmosphere. These electric fields accelerate free electrons, whisking them to speeds approaching the speed of light. When these ultra-high speed electrons collide with molecules in the air, the collisions release high-energy gamma rays as well as more electrons, setting up a cascade of collisions and perhaps more TGFs.
Right: Doug Rowland, principal investigator for Firefly stands next to the a life-sized model of the tiny satellite. Credit: NASA/Pat Izzo
To the eye, a TGF probably wouldn’t look like much. Unlike lightning, most of a TGF’s energy is released as invisible gamma rays, not visible light. They don’t produce colorful bursts of light like sprites and other lightning-related phenomena. Nevertheless, these unseen eruptions could help explain why brilliant lightning strikes occur.
A longstanding mystery about lightning is how a strike gets started. Scientists know that the turbulence inside a thundercloud separates electric charge, building up enormous voltages. But the voltage needed to ionize air and generate a spark is about 10 times greater than the voltage typically found inside storm clouds.
“We know how the clouds charge up,” Rowland says, “we just don’t know how they discharge. That is the mystery.”
TGFs could provide that spark. By generating a quick burst of electron flow, TGFs might help lightning strikes get started, Rowland suggests. “Perhaps this phenomenon is why we have lightning,” he says.
If so, there ought to be many more TGFs each day than currently known. Observations by Compton and other space telescopes indicate that there may be fewer than 100 TGFs worldwide each day. Lightning strikes millions of times per day worldwide. That’s quite a gap.
Then again, Compton and other space telescopes before Firefly weren’t actually looking for TGFs. So perhaps it’s not surprising that they didn’t find many. Firefly will specifically look for gamma ray flashes coming from the atmosphere, not space, conducting the first focused survey of TGF activity. Firefly’s sensors will even be able to detect flashes that are mostly obscured by the intervening air, which is a strong absorber of gamma rays (a fact that protects people on the ground from the energy in these flashes). Firefly’s survey will give scientists much better estimates of the number of TGFs worldwide and help determine if the link to lightning is real.
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Sören (11:42:04)
“The author saw atmospheric spots caught on satellite pictures and interpreted them as impacts of small watery comets. These would account for the water necessary to fill up the expanding earth’s oceans.”
Sounds like Louis Frank’s mini-comets…
Pretty much what I was thinking too.
It’s likely as simple as pinch instabilities along the discharge filament (lightning). Plasma pinches are well known for producing radiation across the entire EM spectrum, including gamma rays.
http://en.wikipedia.org/wiki/Pinch_%28plasma_physics%29
Neutron generation in lightning bolts
http://www.nature.com/nature/journal/v313/n6005/abs/313773a0.html
We know that gamma rays and neutrons can be created in high energy plasma pinches and that these have also been detected in lightning, which as an electric arc is a long cylindrical column of plasma, with all manner of kinks and twists. The TGF’s also seem to occur more preferentially along an equatorial band, which would indicate a denser population of free charge carriers, ions and electrons, available to the ionosphere and injected into the charged lower atomosphere, likely due to the Earth’s equaotrial ring current and/or radiation belts. More bang for the buck, so to speak.
Anyways, I think it’s pretty straightforward like that.
peace,
Tim
JonesII (06:43:54) :
BTW, the other day, someone said that any progress in science must be the exclusive outcome of a long mathematical elaboration even involving one´s elbow wear solving a lot of differential equations.
You are misquoting me. My meaning was that unless one has the tools of mathematics at one’s finger tips, one cannot do modern day physics. Pontification no longer works. And the tools of mathematics are differential equations and functional integrals.
.Such a person forgot that computers compute and solve mathematical problems using simple arithmetics..and that mathematical computations should be done AFTER not before experiments, and if complicated or if needing rounding, adjusting or massaging, something is wrong
Computers are as good as their programmers, otherwise one gets GIGO. And it is the AGW cabal that has been using computers par excellence to massage and round and adjust reality.
Mathematical computations from theories predict experimental results. If the results do not fit, the theory is either scrapped or changed.
Data is gathered, as with the above satellite experiment, and the fitting theory will be proposed to explain the data. It will not be a theory based on a verbal composition, but one mathematically based on the known physics.
Wade, I don’t think there’s enough room in there for hauling cattle. . .
GV, you may have had a gamma-ray impact on your eye. Astronauts experience that fairly often, but if you were looking at a flash. . .
Jupiter and Saturn, and possibly Uranus and Neptune have lightening, as well as do Venus and Mars. Whether or not Triton and Titan have lightening, I do not know.
Dr. Anthony Peratt of Los Alamos National Laboratory has writtten of gamma ray production in the plasma physics laboratory, Physics of the Plasma Universe pp 34,35:
Dr. Peratt’s biography:
http://www.ieee.org/organizations/pubs/newsletters/npss/0306/peratt.html
“Gamma Ray and X ray.”
“Most emissions at these wavelengths [infrared to gamma] is likely to be produced by electrons with energies in excess of 100 eV. We know that processes in magnetized plasmas, especially concerning electric fields aligned by magnetic fields, accelerate auroral electrons to keV energies. Similar plasma processes in solar flares produce energies of 1-10 GeV. Under cosmic conditions, relativistic double layers (Chapter 5) may generate even higher energies in magnetized cosmic plasmas.”
“Therefore we can assume with some confidence that the X rays and gamma rays we observe derive mainly from magnetized plasmas with energies in excess of 100 eV. Therefore, we call the picture we get from these wavelengths the high-energy plasma universe, or simply the plasma universe.”
“The energy densities of radiation in the gamma ray and X ray bands are approximately 10^(-18) J per cubic meter and 10^(-16) J per cubic meter respectively, and may arise from the total contribution of discrete sources (Section 6.7.5).”
Possibly the ionosphere acts as one plate in a “leaky” capacitor and the surface of the Earth acts as the other plate and the atmosphere acts as an “insulating” medium in between.
The medium’s insulating qualities breakdown and an electric discharge is released in the electric field between the two plates of the “capacitor” and lightning is the result.
It has been observed & measured that on the earth’s surface, the electric field can be as strong as 100 to 300 Volts/meter.
From the instant post:
“In the skies above a thunderstorm, powerful electric fields generated by the storm stretch upward for many miles into the upper atmosphere. These electric fields accelerate free electrons, whisking them to speeds approaching the speed of light. When these ultra-high speed electrons collide with molecules in the air, the collisions release high-energy gamma rays as well as more electrons, setting up a cascade of collisions and perhaps more TGFs”
With all due respect to the author, it maybe that there is a charge differential between the ionosphere and the Earth’s surface that generates the electric field. Electric fields have been observed & measured at the Earth’s surface on a clear day.
“What length is a 1/2 Lamda dipole for 2.4 GHz? (A little under 2.5 inches)”
Each half (1/4 wave) of the dipole, perhaps. A half wave is about 4.9 inches.
Ain’t gonna do it with one dipole from space. Adding a reflector might give you 3db. Most satellites use dishes, and those generally below 2.4 Ghz (which has quite a few terrestrial users). A dinky satellite will have dinky solar panels, which will produce dinky amounts of electricity. Can’t power much of a transmitter.
The point was micro-sats have been talked about for years. Faster, cheaper, all that. But, like flying cars and supersonic personal airplanes, far more is said than done. I’d like to see a real study, with real satellites. As we learned from a few of the “faster and cheaper” missions to Mars (which failed) smaller is not always better.
AndrewWH (11:14:11) : Said “I often wonder why we go out racing in thunderstorms.”
The same risks apply to aircraft – Glider pilots often seek out thunderstorms for the considerable up-draughts. However a strike on an all composite glider will usually blow it apart – that’s why they wear parachutes! Metal skins conduct the charge, and don’t usually suffer serious damage. Boeing have spent lots of time & money incorporating conductive materials in the new Dreamliner to get it certified.
They’ve been launching real, functional micro/nano-sats for several years.
http://www.surrey.ac.uk/news/releases/10-0100sstl.html
http://www.prlog.org/10351303-isro-launches-nano-satellites-from-sriharikota.html
btw, those little mars rovers, spirit and opportunity, are still operational after far exceeding their expected lifetimes. The couple of “faster/cheaper” failures really had nothing to do with the faster/cheaper design concept. Mistakes happen regardless of the design paradigm.
peace,
Tim
They THINK they know how the charge is generated.
Got the cart before the horse. Kinda like the CO2 driver!!
Looking at the GRB as the initiator is pretty dumb, but, what do you expect of people who believe in Blackholes, Evolution, and AGW!!
Poor education WILL affect later performance!
HAHAHAHAHAHAHAHAHAHAHAHAHA
Having a heavy cable from mast to metal or keel is what I was referring. Of course lightning does really like turning corners much.
Believe it or not, normal currents one experiences in their house have the electric wave traveling close to the speed of light in a vacuum but the actual motion of the electrons may be 0.5mm / second.
A typical lightning strike may have a rise time of 10 or 20 microsecnds and a tail of 100 microseconds (and typically a significant number of repeats) so it it doesn’t have tremendous amount of really high frequency energy being that 10 microseconds is around 100khz and the sizing of a mast for a 30-40ft sailboat is going to be more like 1/4 wave in the low mhz, well over 2mhz and under 14mhz. Consequently, It’s going to go the path of least resistance unless that makes too significant an angle.
Considering that it was stated that potential differences reached 20 million volts, accelerating particles by that much should be more than enough to generate electron positiron pairs which can then combine and generate half mev gamma rays.
One needs to distinguish between gamma rays and cosmic rays. cosmic rays are not rays but high energy particles, typically protons. What caused the flashes inside the astronauts eyeballs were actually iron nuclei cosmic rays-a small subset. Cosmic rays are occaisionally seen to reach horrifically high energies creating bursts of particles covering square kms with showers of secondary particles. These are thought to be originating not nearly so far away as the other side of the universe because they will lose energy in collisions with the microwave background radiation. And of course, none of this has anything to do with gamma ray bursts, grb s where huge amounts of energy or released in the gamma ray spectrum – evidently due to supernovae blowing out high speed particles from the dying star’s poles that encounter gas clouds blown out earlier and at slower velocities.
cosmic rays, especially lower energy ones can come from the Sun and there’s tons of these. They’re what causes the old geiger counter to ‘click’ randomly but frequently – even when not around radioactive materials – and that is something less than a square inch of sensor. Something the size of a human body is being hit continually by the secondary particles at rates far to fast for a human to actually distinguish one event from another or to count them (of course assuming there was something detecting them that flashed or clicked so a person could try to count the events).
correction,
lightning doesn’t like turning corners.
The video associated with this exposition confuses Planck’s 1900 quantum theory of electromagnetic radiation per “black box” spectra, where energy E = hv (h is Planck’s Constant of Proportionality, v –Greek “nu”– represents photon frequency), with Einstein’s 1905 Special Theory of Relativity where E = mc^2 [physical mass is proportional to Energy converted to an equation by means of a universal constant c, the “speed of light”]. The “Annals of Physics” article that won Einstein the Nobel Prize for 1922 explicated Planck in terms of quantized photons, not atoms (the topic of his second article, dealing with molecules’ random Brownian Motion) which are not germane to Special or General Relativity (1916).
Any popular presentation so utterly ignorant of Planck has no awareness of classical Newtonian as distinct from quantum physics. No-one neglecting Planck in toto while egregiously misrepresenting Einstein has any business producing science documentaries.
G. Varros (12:06:00) :
“Sounds like Louis Frank’s mini-comets…”
Indeed, clearly it was – I remember now, thanks! 🙂
(emph added)
This logic seems a bit quirky to me. Perhaps they don’t know how the charge accumulation takes place in the clouds at all.
Well if they are just looking for a patch on their current lightning theory, then a million dollars is all they deserve to get!
Or maybe the electrons are accelerated to near light speeds in the usual way: by magnetic reconnection! Above the clouds!
http://www.spacedaily.com/news/stellar-02d.html
anna v (12:31:58)
but one mathematically based on the known physics
You just said it. And I would add, proved and tested in the lab, if it is not, it is like any “New Age” phantasy, perhaps more elaborated and more difficult to unravel.
The artist’s rendering of the gamma-ray interaction is incorrect.
As a result of the cascade of interactions that follow the initial gamma-ray interaction in the upper atmosphere (principally in the ionosphere), the location of the source of the gamma rays cannot be specified exactly from a terrestrial observation- the location in the sky of the source can only be (somewhat) inferred
Any increase in resolution of the location of gamma-ray sources would be of value
Zeke the Sneak (07:38:21) :…funny. Some people should wear a big magnet on their heads to promote reconnection with reality☺
Zeke the Sneak (07:38:21) wrote: “Or maybe the electrons are accelerated to near light speeds in the usual way: by magnetic reconnection! Above the clouds!”
http://www.spacedaily.com/news/stellar-02d.html
Dr. Leif Svalgaard (19:42:08), January 27, 2010: “This is where reconnection takes place [no field line needs to be ‘cut’ as there is no field there]”
Dr. Svalgaard’s quoted description and the SpaceDaily.com article contradict each other.
From the ScienceDaily.com article: “Magnetic reconnection should occur wherever magnetic fields clash. As the fields try to bend around one another, the field lines break and recombine…”
According to Dr. Svalgaard supposed “magnetic reconnection” does not involve magnetic field lines being “cut” or “break” as the SpaceDaily.com article puts it.
Actually, supposed “magnetic reconnection” is an Electric Double Layer where a flow of plasma, charged particles, streams perpendicularly into a magnetic field.
There are severe theoretical difficulties with the “magnetic reconnection” hypothesis and in situ satellite probe observations & measurement of so-called “magnetic reconnection” events have revealed physical processes and relationships consistent with Electric Double Layer processes such as electric fields, acceleration in opposite directions of free electrons & ions, and potentially even parallel electric fields, along with rows of electrons & ions across from each other causing the electric field in between:
http://en.wikipedia.org/wiki/Double_layer_(plasma)
More germane to this post is that no scientist researching these high altitude Gamma Ray emissions has suggested so-called “magnetic reconnection” has anything to do with it, maybe you were just being sarcastic 🙂
It’s true, no one said anything about magnetic reconnection being responsible for these relativistic electrons; the em fields above the clouds are said to be the particle accelerators in this case. But I thought it would be fun to add a bit of cosmological perspective on how NASA explains this intriguing and fundamental problem:
But this is for you and JonesII:
You all be sure to mark that day on the calender, and celebrate this and many more of NASA’s amazing discoveries! 🙂
Yes, regarding so-called “magnetic reconnection” (really Electric Double Layers), April Fool’s day is about right 🙂
It’s strange why “modern” astronomy clings to so many ideas from the pre-space age, even after in situ satellite probes’ observations & measurements contradict these ideas.
Humor (irony) is a good way to go 🙂