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The Tale of Two Images

Last week, I gave a talk at a local astronomy club on the topic of my latest book: the evolution of space mission cameras and instruments (which you can find here). Trying to cover the content of a three-hundred-page book into a forty-five-minute talk is, of course, a self-defeating task. So, whenever I do this talk, I tend to focus on the basics of imaging technology, accompanied by a few examples I cherry-pick amongst the hundred missions I cover throughout my book.

This month, I am sharing with you an insight that I include at the end of my presentations. It covers an aspect of space exploration we forget all too easily and starts with the image below.

Credit: National Geographic Magazine

We are in November 11, 1935. It is a cold autumn day in the Black Hills, a small mountain range in America’s Midwestern state of South Dakota, and two brave men from the US Army Air Corps, Captain Stevens and Captain Anderson, are getting ready to be lifted off from a giant helium balloon, named Explorer II. Their daring mission was to reach the stratosphere, the unconquered territory above the troposphere, and study it with the help of 64 scientific instruments. Luckily for us, they bring a film camera as well. A few hours after the launch, they successfully reach the stratosphere putting them above 96% of Earth’s atmosphere. It is there, amidst the low temperatures and the high winds, that they immortalise their adventure and take the grainy picture.

Taken at 22 km in altitude, it is the first high-altitude photograph ever taken and shows the curvature of the Earth. As it stands, it is not the first image taken from space - you would need to go above the Kármán line to do so - but it is the first image that shows our planet as a sphere, a truly remarkable feat for these two brave men. After the record-breaking balloon flight, Captain Stevens was asked by a journalist about the feasibility of flying into outer space one day. At the time, he thought such a feat impossible.

Fast forward to January 1, 2019, and this image below was sent to us by New Horizons, a medium-sized planetary mission class from NASA.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

The image shows us Arrokoth, a Kuiper Belt object. It is a ball of ice and rocks lost within the immensity of space, lying at an average distance of 43.6 astronomical units (AU) from Earth. That’s 6.522.467.162 kilometres.

One of the cameras that helped take this image is LORRI, an advanced 20.8-cm optical instrument coupled with a digital sensor capable of taking the highest resolution images of Arrokoth at 33 m/pixel. When you consider the breath-taking speed New Horizons was going at (the spacecraft is the fastest ever to be sent to the outskirts of our Solar System, and is currently flying at over 84,000 km/h), the relatively small dimensions of Arrokoth at 36 x 20 x 10 km, the low-light situation at 44.6 AU and the fact that the spacecraft had already spent 13 years in deep space, this image on its own is an incredible feat of science and engineering.

And yet, between the image showing the plains of South Dakota from 22 km in altitude and the one showing Arrokoth 43.6 AU away, only 84 years have passed. That’s an average human lifespan. How incredible that in one lifetime, the scale of scientific and technological progress has been so immense as to take us from the limits of the troposphere to the furthest end of the Kuiper Belt and that we have striking images to prove it.

Looking forward, what amazing space-related image do you think we will look at in 84 years from now? I’m putting my money on a picture showing the underwater oceans of Europa and Enceladus, revealing the potential alien life swarming within them. How about you? What do you think we will be looking at in 84 years? Surface features on Proxima Centauri b? An alien spaceship adrift within the Oort cloud? Share your thoughts on this.

As always, onwards and upwards.

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