A rocket team reports the first successful detection of Earth's ambipolar electric field:
Using observations from a NASA suborbital rocket, an international team of scientists has, for the first time, successfully measured a planet-wide electric field thought to be as fundamental to Earth as its gravity and magnetic fields. Known as the ambipolar electric field, scientists first hypothesized over 60 years ago that it drove how our planet's atmosphere can escape above Earth's North and South Poles. Measurements from the rocket, NASA's Endurance mission, have confirmed the existence of the ambipolar field and quantified its strength, revealing its role in driving atmospheric escape and shaping our ionosphere — a layer of the upper atmosphere — more broadly.
[...] Since the late 1960s, spacecraft flying over Earth's poles have detected a stream of particles flowing from our atmosphere into space. Theorists predicted this outflow, which they dubbed the "polar wind," spurring research to understand its causes.
Some amount of outflow from our atmosphere was expected. Intense, unfiltered sunlight should cause some particles from our air to escape into space, like steam evaporating from a pot of water. But the observed polar wind was more mysterious. Many particles within it were cold, with no signs they had been heated — yet they were traveling at supersonic speeds.
[...] The hypothesized electric field, generated at the subatomic scale, was expected to be incredibly weak, with its effects felt only over hundreds of miles. For decades, detecting it was beyond the limits of existing technology. In 2016, Collinson and his team got to work inventing a new instrument they thought was up to the task of measuring Earth's ambipolar field.
[...] Endurance's discovery has opened many new paths for exploration. The ambipolar field, as a fundamental energy field of our planet alongside gravity and magnetism, may have continuously shaped the evolution of our atmosphere in ways we can now begin to explore. Because it's created by the internal dynamics of an atmosphere, similar electric fields are expected to exist on other planets, including Venus and Mars.
Journal Reference: Collinson, G.A., Glocer, A., Pfaff, R. et al. Earth's ambipolar electrostatic field and its role in ion escape to space. Nature 632, 1021–1025 (2024). https://doi.org/10.1038/s41586-024-07480-3
(Score: 5, Interesting) by mhajicek on Tuesday September 03, @04:06AM
I doubt this is the case, but it would be nice if Polaris Dawn had instruments to take more readings on this.
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 5, Interesting) by VLM on Tuesday September 03, @10:08PM
Well, what was it, don't keep us in suspense.
IF you're bored go look up field mills. Its barely within the ability of an amateur to make one and its been on my "infinite spare time" list for a very long time so I assumed these dudes invented a field mill where the rotary part won't wear out or contaminate in a high vacuum which might be tricky or they used some whacky ultra-low current sensor that measures picoamps or whatever somehow.
They look like: https://en.wikipedia.org/wiki/Field_mill [wikipedia.org]
Naah they did something else, a "photoelectron spectrometer"
https://en.wikipedia.org/wiki/Photoemission_spectroscopy [wikipedia.org]
However plain old PES dates back to the 50s.
Thanks for naming the mission "Endurance" that only has like ninty zillion other unrelated hits. However this seems related:
Before:
https://ui.adsabs.harvard.edu/abs/2022SSRv..218...39C/abstract [harvard.edu]
After:
https://ui.adsabs.harvard.edu/abs/2022AGUFM.P45B..02C/abstract [harvard.edu]
Although my tax money paid for it all, I don't have access to any of it.
Probably an interesting story, although functionally secret by being behind enough paywalls.
I found what seems a pretty interesting paper from the evil Springer and Embry-Riddle U which is probably pirated so I won't link to it. However, section 2.3 "2.3 Basic Concept:How to Measure Planetary Ambipolar Electric Potentials" is pretty interesting.
As near as I can tell and poorly paraphrase, they know the spectrum of glowing oxygen from the ground, and the small E field messes with the peaks in a detectable manner by energizing the entire rocket to a known voltage (how?) and then when the rocket is non-interactive then it must be at the voltage of its surroundings (more or less. much handwaving here)
Again massive hand waving and generalization, but they turned the entire rocket into a Langmuir probe. Cool idea.
Langmuir probe... how do I explain one of those. Well, we have oscopes that directly show voltage over time. But IF as a thought experiment we did not, I guess you could connect a function generator or plain old power supply thru a resistor to the thingy you're trying to test and slap a sensitive ammeter in line with the resistor and presumably when you set your function generator or power supply to the exact same voltage as what you're trying to measure then the current would drop to zero, so you can use some mixture of ohms law and the known resistance and the applied voltage and measured current to determine all kinds of things about whatever the probe is touching. Normally Langmuir probes touch fusion plasma, which is approximately nothing, a pretty good approximation to a vacuum most of the time, its a long story.
Extending the analogy the whole thing is kind of a Whetstone bridge on crack. Or my analogy is on crack. But its at least not entirely wrong.
I have to admit, huh, that's pretty creative to charge the entire rocket to a certain voltage as part of the test instrument itself... Hope the pyros were already safed before they lit her up LOL.