Since Isaac Newton was hit by his apple back in 1666, scientists have been trying to get their heads around the forces that shape our planet.
While Earth’s gravitational pull and magnetic field should be fairly familiar, scientists now say they have found a third field which is ‘just as fundamental’.
NASA researchers have found the first evidence of a subtle, almost undetectable electric field surrounding the planet.
This ‘ambipolar electric field’ could be responsible for the mysterious winds of supersonic particles that constantly shoot out from the Earth’s poles.
What’s more, the researchers claim the discovery could even help explain why life formed here on Earth and nowhere else.
NASA researchers have discovered a hidden field of energy surrounding our planet which is ‘just as important as gravity’
The field was discovered by launching the rocket Endurance (pictured) from the remote island of Svalbard
In the 1960s, as the first spacecraft began to orbit the Earth, space agencies began to notice strange phenomena over the poles.
As the spaceships passed overhead, they would be blasted by a sudden supersonic wind of charged particles erupting from the atmosphere.
But while scientists have known for more than 50 years that these ‘polar winds’ exist, no one has yet been able to explain what causes them.
Some of the particles may just be heated by unfiltered sunlight and escape like steam from a boiling pot.
But others were more mysterious, as scientists also found a constant flow of hydrogen ions which were completely cool – despite travelling at supersonic speeds.
Lead author Dr Glyn Collinson, of NASA’s Goddard Space Flight Center, says: ‘Something had to be drawing these particles out of the atmosphere.’
Since the 1960s scientists have known that there are streams of particles leaving the atmosphere over the poles but only now do they have the technology required (pictured) to detect the ambipolar electrical field responsible for this
Researchers hypothesised that the particles could be pulled out of the atmosphere by a planet-wide electrical charge somewhere around 150 miles (250 km) above the surface.
At this altitude, the atoms in our atmosphere begin to break apart into negatively charged electrons and positively charged ions.
Since the ions are 1,836 heavier than electrons, they should sink towards the Earth under the influence of gravity.
But since they have opposite charges, the electrons and ions are tethered together by an electric field which pulls in both directions – hence the name ambipolar.
Like a dog pulling on its lead, the electrons drag their ions upwards against the force of gravity and lift them out of the atmosphere.
However, until very recently, the technology to measure this field simply did not exist.
Over the 322 miles (518 km) travelled (illustrated left), the rocket detected an electrical potential difference of just half a volt. Although weak, this is exactly what scientists had predicted
Starting in 2016, researchers began to develop a rocket capable of measuring what they believed to be a very small voltage difference across hundreds of miles.
This culminated in NASA’s Endurance Mission, which launched from the remote Norwegian island of Svalbard – just a few hundred miles south of the North Pole.
The researchers needed to make the journey to this distant island because it is the only place in the world where detecting the ambipolar electric field is possible.
Around the poles, the Earth’s magnetic field produces ‘open field lines’ which shoot outwards into space rather than forming closed loops.
Co-author Professor Suzanne Imber, a space physicist at the University of Leicester, UK, told the MailOnline: ‘The field is generated by electrons, which have some thermal pressure that allows them to rise to higher altitudes on open field lines.
The rocket had to be launched from the island of Svalbard (pictured) which is close to the North Pole since it is home to the only rocket launch station far enough North to detect the field
‘The electrons are tied to the magnetic field, so this is only detectable over the poles because high magnetic latitudes are where the field lines go from the surface out to space.’
This was made even more challenging by the fact that these field lines don’t stay in the same place but rather move continuously.
‘It’s a bit of a disaster if you get that wrong and launch your rocket at the wrong moment – you only get one shot at the experiment,’ Professor Imber says.
Despite shifting field lines and white-out blizzards, the team managed to launch their rocket into a suborbital flight on May 11, 2022.
Endurance, named after Ernest Shackleton’s polar expeditions, flew to an altitude of 477.23 miles (768.03 km), splashing down 19 minutes later in the Greenland Sea.
Across the 322 miles (518 km) of altitude across which Endurance gathered data, it found an electrical charge potential of just 0.55 volts.
The rocket had to be launched between open magnetic field lines (blue) otherwise the mission would be a failure. It is only between these lines that the ambipolar electric field can lift particles out of the atmosphere into space
Dr Collinson says: ‘A half a volt is almost nothing — it’s only about as strong as a watch battery, but that’s just the right amount to explain the polar wind.’
Even though this force is very small, across such a vast area the researchers believe it is responsible for boosting the height of the ionosphere, a layer of the atmosphere, by 271 per cent.
‘It’s like this conveyor belt, lifting the atmosphere up into space,’ Dr Collinson says.
Since this field has only just been discovered, the researchers are still not sure what effect it might have had on the Earth’s development, but the consequences could be huge.
Critically, there is some suggestion that it might be part of the reason why Earth still has water while planets like Venus and Mars have dried up.
In 2016, the European Space Agency’s Venus Express mission found that Venus’ ionosphere generates a 10-volt potential around the entire planet.
As intense sunlight split positively charged oxygen ions from the hydrogen in water, this charge could have sucked them into space like a planet-sized vacuum cleaner.
Over time, this process might have emptied all of Venus’ water into space and left it as the barren wasteland we now see.
Since the Earth’s ambipolar electric field is much weaker, this could be part of the set of factors which determine whether a planet is habitable in the long term.
Dr Collinson says: ‘Any planet with an atmosphere should have an ambipolar field.
‘Now that we’ve finally measured it, we can begin learning how it’s shaped our planet as well as others over time.’
