How to make the Earth red again?

Question

An alien entity fell in love with Earth a long time ago. When he came back to her, she looked different. He would like to return Earth to her Hadean eon when she was much hotter.

This entity has abilities that are comparable to what we suspect a Kardashev Type 2 civilization would be capable of.

The entity would like to return Earth to the Hadean eon without having to throw tons of rocks at her or changing her composition. And he doesn't want to use a Mega bomb if it isn't necessary. A bomb can be used, but he wants to make sure that Earth doesn't lose too much weight in the process. Any loss bigger than 1% will be noticed.

The time and energy spent to bring her back is irrevelant, but the sooner the better.

How can I make the Earth red again?

Answer 1

Buy a lot of paint. Presumably a Type 2 Kardashev civilization entity can lift a bucket that large...

Answer 2

Actually a very interesting premise - a type 2 Kardashev civilisation entity would have command over significant assets, but I believe also in the nano scale as well as the macro scale.

Hence it would probably be a good bet that it has an unbelievablely large arsenal of nanobots at his command.

The cloud of nanobots would be able to make large structures as well as small, and change the configuration of the environment too. Indeed, to capture the energy of the sun, one needs means to create large structures without the need to think, design, or manually make them - hence AI controlled nanorobots would be one of the likely scenarios, ones which could manipulate large amounts of material.

These nanobots can then be sent to earth, to 'reconfigure it into a new matrix'. Basically, the Hadean Earth has high temperatures, high atmospheric pressure, and high levels of C02 - these can be achieved by the nanobots by first self-replicating, then disassembling the crust, ejecting the material into the atmosphere, boiling the oceans, and releasing the magma.

The entity can then blissfully come down and admire his handiwork.

Answer 3

Impacts are your friends

Step 1:

Push the moon towards the Earth. Once the moon gets to ~20,000 km from the Earth, Earth's gravity will cause it to disintegrate into a ring.

Step 2:

Perturb the ring. I think that many of the moon particles will end up impacting Earth anyways, but a little perturbation won't hurt. Get those particles into nice elliptical orbits and then atmospheric drag will eventually get most of them to impact the Earth's surface. Remember, as the oceans vaporize, you will only get more atmosphere to help drag down moon particles!

Step 3:

Wait for the Earth to heat up. There is over 7e22 kg of moon. The potential energy of dropping those from ~20,000 km is something on the order of 1e30 J. That is a million years of sunlight energy that strikes the Earth. If you can deliver all that energy within few hundred years, it should be not problem to vaporize the oceans and get the Earth's crust nice and glowing again.

Note: The best part about this is that there is no way you will lose 1% of the Earth's mass, since by tossing a moon down there, you will be gaining about 1% of Earth's mass! Even if you blast a few impact particles off into deep space, they will be more than made up for.

Answer 4

Spread a lot of Fe2O3 (iron oxide) all over the planet.

Where there is no water it will give a nice red appearance, while where there is water it will make it red.

At the end Mars is known as the red planet just for the rust it has on it.

Answer 5

Hadean Earth was Hadean Earth because it was still cooling down. All the entity has to do is reheating the planet.

A K2 civilization should be able to harness the energy output of a star. The entity can make something akin to a dyson sphere and redirect the energy to Earth.

The atmosphere might be lost to space. But the atmosphere weights only around 5x10¹⁸ kg according to the heavier estimates. That is less than one millionth of the mass of the Earth (approximately 6x10²⁴ kg). Surface water will also be lost, but according to Wikipedia, the whole mass of Earth's hydrosphere is around 1.4x10²¹ kg, which is about 0.023% of the mass of the planet, so your "no more than 1% mass loss" requirement is accounted for.

Answer 6

Which end of the Hadean are you going for? There was the early Hadean with molten surface and a rock vapor atmosphere, and there was the late Hadean with liquid water oceans at a balmy 230C with an atmosphere at around 27kPa.

Early Hadean requires lots of surface heating so the bombardment and radiation ideas are the way to go. A more subtle method of creating the late Hadean would be interior heating.

A Kinder, Gentler Planet Cooker

Alexander already suggested infusing the earth with radioactive elements. If you could deliver a large dose to the core, conduction and convection would take care of the rest. A large critical mass of dense fissile material (and what fissile material isn't dense?) placed on the Earth's surface would naturally find its way to the core with local scarring to the crust and mantle.

Another way to heat from the inside out would be akin to a microwave, or to a Bubblegram. Normal radiation wouldn't make it though the atmosphere very effectively, but bombardment by a focused neutrino emitter could warm the core via Cherenkov radiation and trigger nuclear changes within heavy elements, infusing radioactive material directly into the core. This would require some unknown technologies, like aimable neutrino emitters, and probably neutrino reflectors to get enough interactions.

So, a large high energy neutrino emitter bombarding the planet from a 60 degree spherical cone converging on the core, so that there is relatively low neutrino density on the surface but a small area of extreme bombardment in the core, combined with a reflector reflecting back the same 60 degree cone to increase interactions would bias heat toward the core, gently warming the planet from the inside.

Answer 7

Infuse Earth with radioactive elements.

This is much less invasive than Dyson spheres, mega-bombs or celestial calamities. Radioactive elements will undergo fission, which will heat up the Earth's mantle and lead to massive volcanism (think Siberian Traps). With half-life of the elements being long enough, this volcanism will turn the Earth back into Hadean era.

However, the whole process will take centuries and millennia to unfold. The idea is actually similar to Asimov's "Robots and Empire". And, even "Kardashev II" level is not needed for it.

Answer 8

The Greenhouse Effect

There is little chance of modern society turning Earths atmosphere into something like Venus. However, a powerful alien entity would probably be able to do this.

The main ingredient in the Venusian atmosphere is carbon dioxide, not the mere 0.04% concentration that climate change scientists seem so worried about, but 96.5%. The Venusian atmosphere is much heavier too, being 93 times the mass of Earths atmosphere on a slightly smaller planet.

Our strategy is simple. Pick a greenhouse gas, or a combination of greenhouse gasses, and release enormous quantities on Earth.

The amount of solar energy hitting Earth is 174 PW, enough to heat the entire mass of the planet by 1 degree Kelvin in a year or two. So once we set up the correct atmospheric conditions, we can expect the appropriate surface temperature in a reasonable period of time.

Of course, this will heat up the crust but not the core or mantle, as they are already hotter than the temperature you are likely to achieve.

Another issue is that you may as well just enjoy Venus, which already resembles what this would do to Earth, and is not far away.

Answer 9

Move Earth's Orbit

Switch orbits of Earth and Mercury would probably do the trick. It wouldn't be quick for us (well, our deaths would be fairly quick), but for an entity that visited so long ago, what's a few million more years.