Since 1972 seven orbiting Landsat satellites have taken turns to photograph the Earth’s surface. Needless to say if they could talk they’d be able to tell a few stories, as seen by this series of then and now photos, showing how cities such as Tokyo, Chicago, Istanbul, and Santiago have changed over the last forty years.
The image of Santiago (move the centre dividing slider back and forth to see the contrasts) is especially interesting. Note the presence of what looks to be snow/ice in the bottom right-hand corner of the 1985 image and then compare the same region with the 2010 photo.
Place a satellite into a geosynchronous orbit above the Earth, being 36,000 kilometres or so up, and it will, all things remaining equal (a big ask at the best of times, but that’s another story), remain there perpetually. As it is there are hundreds of such probes, many no longer functioning, floating in this zone, giving rise to the term “graveyard orbit”.
What better place then to store a record of artworks created on Earth that will still be about long, long, after life on the surface has disappeared?
That’s the thinking of behind US artist Trevor Paglen’s “The Last Pictures” project, that will see trillions of images depicting artworks from across the globe, stored on very long life discs, aboard a satellite that will be launched into a permanent graveyard orbit this September.
Life would be: Migratory and on shorter day-night cycles, if existent at all. Huge tides generated by the moon – which orbited much closer to Earth when it formed – washed the chemical building blocks for life from land into the oceans and helped “stir up the primordial soup,” said Neil Comins, a professor of physics at the University of Maine.
Everyone knows that alien spaceships don’t have to clumsily lumber down a runway before takeoff – they lift off vertically with perfect balance and then propel in whatever direction they choose. Helicopters have the vertical takeoff aspect down, but even the best designs can be foiled by ground landings, as was the stealthy MH-60 Black Hawk helicopter used in the raid that killed Osama bin Laden. A Discrotor helicopter is actually a helicopter/airplane blend that can take off and land vertically, but also enter into high-speed flying mode by retracting its rotating blades and relying on fixed wings, allowing it to move like a plane. Will that help against aliens? We certainly hope so.
A difficult question to address really, considering we’d likely have no idea at all as to what we were up against.
Geologists have long known that Earth’s core, some 1,800 miles beneath our feet, is a dense, chemically doped ball of iron roughly the size of Mars and every bit as alien. It’s a place where pressures bear down with the weight of 3.5 million atmospheres, like 3.5 million skies falling at once on your head, and where temperatures reach 10,000 degrees Fahrenheit – as hot as the surface of the Sun. It’s a place where the term “ironclad agreement” has no meaning, since iron can’t even agree with itself on what form to take. It’s a fluid, it’s a solid, it’s twisting and spiraling like liquid confetti.
Just over 70 per cent of the Earth’s surface is covered with water, yet if that were amassed – together with every last drop on the planet, lakes, rivers, plants, etc, even the water that makes up us – into a single body, it would form a sphere with a diameter of almost 1,400 kilometres, which is about 40 percent of the Moon’s diameter.
Migrating to Mars, then certain moons of Jupiter and Saturn, may extend humanity’s stay in the solar system once the Sun begins to heat up and expand, forcing us from our home on Earth, in about a billion years time. Once the Sun enters its red giant phase however we will have to completely bail.
A next stop could be Proxima Centauri, a red dwarf star, about four light years away, if it happens to host a suitable planet that is. While red dwarfs present a few problems, they have life spans of trillions of years, and would give us plenty of time to figure out our next great escape, the demise of the universe itself.
When Proxima Centauri perishes, humanity can relocate to another red dwarf and then another, but that strategy won’t work forever. Stars need fuel, and as vast as the universe is, there is only so much to go around. Newly forming stars are gradually depleting the cosmic supply of hydrogen. Roughly 100 trillion years into the future, they will have exhausted the universe’s hydrogen stockpile. As existing stars consume their last drops of fuel, they will wink out one by one, and the light of the universe will almost entirely disappear.
And on the subject of high attitude – to be precise, very high attitude – photography, Blue Marble is a composite image of the Earth, made up of many photos taken by the “Suomi NPP” satellite, a few days ago. See the also the full size version (warning: this is massive).
The latest results suggest LUCA was the result of early life’s fight to survive, attempts at which turned the ocean into a global genetic swap shop for hundreds of millions of years. Cells struggling to survive on their own exchanged useful parts with each other without competition – effectively creating a global mega-organism.