Our Classtronauts visits aren’t just about launching balloons. We teach all kinds of lessons about the troposphere, the stratosphere and the other layers of the atmosphere. It presents a great opportunity to tie in other topics like climate change, electromagnetism and even the weather. But amongst the different layers that make up our atmosphere is one which we know surprisingly little about: the mesosphere.
Known colloquially among scientists as the ‘ignorosphere’, the mesophere is relatively difficult to study in depth. Why? Well, we can’t actually get there long enough to get a good look around. There are a limited number of methods of transport that allow us to approach the region, which is roughly between 60km and 100km above the Earth’s surface. These are high altitude ballooning (our speciality), rockets, aeroplanes and satellites.
The world record altitude achieved with a helium balloon flight is 53km, set by a team of collaborators from NASA and JAXA, the Japan Aerospace (e)Xploration Agency. The problem with lighter-than-air flight is that it only continues to rise as long as there’s air – and at 53km the atmospheric pressure is less than 0.1% of normal pressure at sea level.
Aeroplanes do even worse. The highest you can get with a jet aeroplane is just shy of 38km, and don’t even think about using a propellor, for the same reasons. Aeronautics relies on the presence of an atmosphere, where the shape of the wings combined with forward momentum cause a difference in pressure underneath and above the aircraft, which is balanced out by the aircraft moving upwards. Take away the air and you can’t go very far.
What about rockets? Well, we use rockets to get into space, so they can definitely reach the mesosphere. Unfortunately, they can only do so at very high speeds and by burning huge amounts of fuel. In the short time that a rocket passes through the mesosphere, the powerful reactions which propel it cause enough interference that any measurements or sensor readings taken are of little or no value.
So we’re left with satellites, which orbit high above the mesosphere in the exosphere. Even from here, what we can learn often raises more questions than answers. Consider lightning: a difference in electrical charge between the clouds and earth resolves in a sudden discharge of enormous power in a blinding moment of light. Very pretty, very dangerous. But did you know that lightning also strikes upwards?
‘Blue jets’ have been observed by lucky pilots and astronauts many times since the dawn of human flight, but information about them is scarce, and imagery even scarcer. In fact, they belong to a family of electromagnetic phenomena whose existence is hotly debated, so much so that other examples bear the names of fantastical creatures of legend and folklore: the sprite, the elf, the pixie.
That’s why it’s so exciting that this week, the ESA have unveiled new images taken from the ISS by astronaut Andreas Mogensen of a blue jet in action. The images of storms from above are stunning as it is, but this rare capture of a blue jet in its natural habitat represents an advancement of our understanding about the world we live in. Also, it’s really cool!
We tend to think of space exploration and research as focusing on the stars above us and the other planets in our solar system, but human curiosity is remarkably self-absorbed and much of the work done by astronauts and space scientists is learning more about ourselves and our home.