A Human Migration to Space is NOT so Inevitable, says New Research

Artist's depiction of a pair of O'Neill cylinders. Credit: Rick Guidice/NASA Ames Research Center

“It is possible even with existing technology, if done in the most efficient ways. New methods are needed, but none goes beyond the range of present-day knowledge. The challenge is to bring the goal of space colonization into economic feasibility now, and the key is to treat the region beyond Earth not as a void but as a culture medium, rich in matter and energy. Then, in a time short enough to be useful, the exponential growth of colonies can reach the point at which the colonies can be of great benefit to the entire human race.”

-Gerard K. O’Neill, The Colonization of Space, 1974

During the 1960s and 70s, coinciding with the height of the Space Age, scientists pondered how human beings could one day live in space. Among the many benefits, the migration of humans and industry to other celestial bodies and orbiting habitats presented a possible solution to overpopulation and environmental degradation. As O’Neill suggested in his writings, the key was to make this migration an economically feasible venture. Given the renewed efforts to explore space that are now underway and the rise of commercial space (NewSpace), there is a growing sense that humanity’s migration to space is within reach – and even inevitable.

But to paraphrase famed British historian AJP Taylor, “nothing is inevitable until it happens.” In a new study, Cornell graduate researcher Morgan A. Irons and Norfolk Institute co-founder and executive director Lee G. Irons reviewed a century of scientific studies to develop the Pancosmorio (“World Limit”) theory. They concluded that specific life-sustaining conditions on Earth that are available nowhere else in the Solar System could be the very thing that inhibits our expansion into space. Without an Earth-like “self-restoring order, capacity, and organization,” they argue, space settlements would fail to be sustainable and collapse before long.

Continue reading “A Human Migration to Space is NOT so Inevitable, says New Research”

A Habitat at Ceres Could be the Gateway to the Outer Solar System

Artist's impression of the interior of an O'Neill Cylinder. Credit: Don Davis/NASA

In the near future, humanity stands a good chance of expanding its presence beyond Earth. This includes establishing infrastructure in Low Earth Orbit (LEO), on the surface of (and in orbit around) the Moon, and on Mars. This presents numerous challenges, as living in space and on other celestial bodies entails all kinds of potential risks and health hazards – not the least of which are radiation and long-term exposure to low gravity.

These issues demand innovative solutions; and over the years, several have been proposed! A good example is Dr. Pekka Janhunen‘s concept for a megasatellite settlement in orbit around the dwarf planet Ceres, the largest object in the Main Asteroid Belt. This settlement would provide artificial gravity for its residents while the local resources would allow for a closed-loop ecosystem to created inside – effectively bringing “terraforming” to a space settlement.

Continue reading “A Habitat at Ceres Could be the Gateway to the Outer Solar System”

What Are The Lagrange Points?

What Are The Lagrange Points?

Being stuck here on Earth, at the bottom of this enormous gravity well really sucks. The amount of energy it takes to escape into the black would make even Captain Reynolds curse up a gorram storm.

But gravity has a funny way of evening the score, giving and taking in equal measure.

There are special places in the Universe, where the forces of gravity nicely balance out. Places that a clever and ambitious Solar System spanning civilization could use to get a toehold on the exploration of the Universe.

The five Sun-Earth Lagrange points. Credit: NOAA
The five Sun-Earth Lagrange points. Credit: NOAA

These are known as the Lagrange Points, or Lagrangian Points, or libration points, or just L-Points. They’re named after the French mathematician Joseph-Louis Lagrange, who wrote an “Essay on the Three Body Problem” in 1772. He was actually extending the mathematics of Leonhard Euler.

Euler discovered the first three Lagrangian Points, even though they’re not named after him, and then Lagrange turned up the next two.

But what are they?

When you consider the gravitational interaction between two massive objects, like the Earth and the Sun, or the Earth and the Moon, or the Death Star and Alderaan. Actually, strike that last example…

As I was saying, when you’ve got two massive objects, their gravitational forces balance out perfectly in 5 places. In each of these 5 places you could position a relatively low mass satellite, and maintain its position with very little effort.

Sun-Earth Lagrange Points. Credit: Xander89/Wikimedia Commons
Sun-Earth Lagrange Points. Credit: Xander89/Wikimedia Commons

For example, you could park a space telescope or an orbital colony, and you’d need very little, or even zero energy to maintain its position.

The most famous and obvious of these is L1. This is the point that’s balanced between the gravitational pull of the two objects. For example, you could position a satellite a little above the surface of the Moon. The Earth’s gravity is pulling it towards the Moon, but the Moon’s gravity is counteracting the pull of the Earth, and the satellite doesn’t need to use much fuel to maintain position.

There’s an L1 point between the Earth and the Moon, and a different spot between the Earth and the Sun, and a different spot between the Sun and Jupiter, etc. There are L1 points everywhere.

L2 is located on the same line as the mass but on the far side. So, you’d get Sun, Earth, L2 point. At this point, you’re probably wondering why the combined gravity of the two massive objects doesn’t just pull that poor satellite down to Earth.

It’s important to think about orbital trajectories. The satellite at that L2 point will be in a higher orbit and would be expected to fall behind the Earth, as it’s moving more slowly around the Sun. But the gravitational pull of the Earth pulls it forward, helping to keep it in this stable position.

Animation showing the relationship between the five Lagrangian points (red) of a planet (blue) orbiting a star (yellow), and the gravitational potential in the plane containing the orbit (grey surface with purple contours of equal potential). Credit: cmglee (CC-SA 3.0)
Animation showing the relationship between the Lagrangian points (red) of a planet (blue) orbiting a star (yellow), and the gravitational potential in the plane containing the orbit (grey surface with purple contours of equal potential). Credit: cmglee (CC-SA 3.0)

You’ll want to play a lot of Kerbal Space Program to really wrap your head around it. Sadly, your No Man’s Sky time isn’t helping you at all, except to teach you that hyperdrives are notoriously finicky and you’ll never have enough inventory space.

L3 is located on the direct opposite side of the system. Again, the forces of gravity between the two masses balance out so that the third object maintains the same orbital velocity. For example, a satellite in the L3 point would always remain exactly hidden by the Sun.

Hold on, hold on, I know there are a million thoughts going through your brain right now, but bear with me.

There are two more points, the L4 and L5 points. These are located ahead and behind the lower mass object in orbit. You form an equilateral triangle between the two masses, and the third point of the triangle is the L4 point, flip the triangle upside down and there’s L5.

Now, it’s important to note that the first 3 Lagrange points are gravitationally unstable. Any satellite positioned there will eventually drift away from stability. So they need some kind of thrusters to maintain this position.

Imagine a tall smooth mountain, with a sharp peak. Put a bowling ball at the very top and you’re not going to need a lot of energy to keep it in that location. But the blowing wind will eventually knock it out of place, and down the mountain. That’s L1, L2 and L3, and it’s why we don’t see any natural objects located in those places.

But L4 and L5 are actually stable. It’s the opposite situation, a deep valley where a bowling ball will tend to fall down into. And we find asteroids in the natural L4 and L5 positions in the larger planets, like Jupiter. These are the Trojan asteroids, trapped in these natural gravity wells though the gravitational interaction of Jupiter and the Sun.

Artist's diagram of Jupiter and some Trojan asteroids nearby the gas giant. Credit: NASA/JPL-Caltech
Artist’s diagram of Jupiter and some Trojan asteroids nearby the gas giant. Credit: NASA/JPL-Caltech

So what can we use Lagrange points for? There are all kinds of space exploration applications, and there are already a handful of satellites in the various Earth-Sun and Earth-Moon points.

Sun-Earth L1 is a great place to station a solar telescope, where it’s a little closer to the Sun, but can always communicate with us back on Earth.

The James Webb Space Telescope is destined for Sun-Earth L2, located about 1.5 million km from Earth. From here, the bright Sun, Earth and Moon are huddled up in a tiny location in the sky, leaving the rest of the Universe free for observation.

Image: James Webb Space Telescope
NASA’s James Webb Telescope, shown in this artist’s conception, will provide more information about previously detected exoplanets. It will be at Sun-Earth L2.

Earth-Moon L1 is a perfect place to put a lunar refueling station, a place that can get to either the Earth or the Moon with minimal fuel.

Perhaps the most science fictiony idea is to put huge rotating O’Neill Cylinder space stations at the L4 and L5 points. They’d be perfectly stable in orbit, and relatively easy to get to. They’d be the perfect places to begin the colonization of the Solar System.

Thanks gravity. Thanks for interacting in all the strange ways that you do, and creating these stepping stones that we can use as we reach up and out from our planet to become a true Solar System spanning civilization.