If space colonies were built at the Lagrange Points, would life be able to survive?
Short answer: yes.
Long answer: Lagrange Points are totally awesome places to hang out!
What’s a Lagrange Point you might ask? A Lagrange Point is an area between two orbiting bodies where the gravitational pull between the bodies are balanced along with the centripetal forces of the objects in orbit.
In other words, they’re places between two orbiting bodies where a satellite will maintain a stable relation with the other two bodies.
Here’s a diagram showing the five Lagrange Points between Earth and the Sun. Any two orbiting bodies will have these same five Lagrange Points between them.
L1, L2, and L3 are all in a line intersecting the center of mass of the two bodies. They are also the least stable off the five points. Satellites parked in these three places have a tendency to wander off after a while and require the occasional rocket burn to stay.
L4 and L5 are 60 degrees ahead and behind the Earth and are much more stable. L4 precedes it’s planet in orbit, while L5 trails. Satellites there will kinda drift around a bit but stay in the general area.
Because L4 and L5 are stable, cosmic dust and debris tend to gather and stay there. Asteroids that hang out at a planet’s L4 or L5 points are called Trojans by astronomers. Jupiter has a number of Trojans in it’s L4 and L5 points. And by ‘a number’, I mean a cosmic truckload.
Even Earth has at least one trojan in it’s L4 point. There’s probably a few more, we just haven’t seen them yet.
Asteroids are classified into three broad types - C, S, and X. Each type has a number of subtypes, but in general C-types are carbonaceous and include asteroids with a lots of ices, S-types are primarily stone or rock, while X-types include asteroids with high amounts of metals and other stuff.
So, not only are the L4 and L5 points stable places for your space colony, they’re also a good source of asteroids to mine for the metals you need to build the colony and the and ices (for water and other gasses) you need to survive.
Closer to home, there are also five Lagrange points between the Earth and our Moon.
These L4 and L5 points with our Moon are also very stable places to put your closer-to-Earth space colonies.
Edit: I attached the wrong graphic for the Earth-Moon Lagrange points. I fixed it.
The Solar and Heliospheric Observatory (SOHO) has been watching the Sun for almost 20 years. In that time it has seen solar activity ramp up and die down repeatedly. Its Extreme ultraviolet Imaging Telescope has taken images of the resulting waxing and waning of the Sun’s corona – its atmosphere – that are impossible to record from the ground.
Brighter images show times when there was more activity on the Sun. This activity is driven by the Sun’s magnetic field and follows a cycle of about 11 years.
20 Years of the Solar and Heliospheric Observatory
The Solar and Heliospheric Observatory, SOHO for short, has captured the imagination of scientists and the public alike for two decades now. We teamed up with the European Space Agency (ESA) on SOHO, which observes the sun from space. It was launched 20 years ago this week, on Dec. 2, 1995, with the mission to study the internal structure of our neighborhood star, its atmosphere and the origin of the solar wind. SOHO sends spectacular data daily, and has led scientists to a wealth of understanding.
Here are the top 5 things you need to know about SOHO, the sun and other solar observation missions:
1. SOHO Set Out for Space with an Ambitious Mission
SOHO was designed to answer three fundamental scientific questions about the sun: What are the structure and dynamics of the solar interior? Why does the solar corona exist and how is it heated to such an extremely high temperature? Where is the solar wind produced and how is it accelerated? Clues about the solar interior come from studying seismic waves that appear as ripples on the sun’s surface, a technique called helioseismology.
2. SOHO Enjoys a Great View
SOHO commands an uninterrupted view of the sun, while always staying within easy communication range of controllers at home. The space-based observatory moves around the sun in step with the Earth, by slowly orbiting around a unique point in space called the First Lagrangian Point (L1). There, the combined gravity of the Earth and sun keep SOHO in a position that’s always between the sun and the Earth. The L1 point is about 1 million miles (about 1.5 million kilometers) away from Earth (about four times the distance to the Moon).
3. Bonus Discoveries: Lots of Comets
Besides watching the sun, SOHO has become the most prolific discoverer of comets in astronomical history. In September 2015, SOHO found its 3000th comet. Sometimes the spacecraft’s instruments capture comets plunging to their death as they collide with the sun.
4. Extra Innings
SOHO was meant to operate until 1998, but it was so successful that ESA and NASA decided to prolong its life several times and endorsed several mission extensions. Because of this, the mission has been able to observe an entire 11-year solar cycle and much of the next.
5. Keep Your Eye (Safely) on the Sun
You can see what SOHO sees, almost in real time. The latest images from the spacecraft, updated several times daily, are available online. Take a look HERE.
It took 10 years to create this image of our changing Sun. Taken from space by the Solar and Heliospheric Observatory (SOHO), it shows a dramatically different picture than the one we receive on Earth.
From Earth’s surface, we are treated to a biased view. Every day our world is bathed in the Sun’s light and heat, and at these visible and infrared wavelengths our luminary shines to within a fraction of a percent of the same energy every day.
At ultraviolet and X-ray wavelengths, this is not true. Launched in 1995, SOHO has been continuously monitoring the Sun since then, in part to study this variation. Back in 2006, one image for each year of the mission until then was chosen and displayed in this montage.
The bright parts of these images correspond to gas in the Sun’s atmosphere at a temperature of about 2 million degrees Celsius.
Unlike visible light, the intensity of the ultraviolet radiation from the Sun varies greatly. This variation becomes more pronounced the shorter the wavelength, especially in the X-ray region of the spectrum. This is governed by solar activity, which runs in an approximately 11-year cycle. It is linked to the generation of the Sun’s magnetic field although our precise understanding of this mechanism remains elusive.
The waxing and waning of cycle-23, counted since 1755 when systematic record-taking began, can be seen clearly in this image. At its peak in 2001, the Sun was a maelstrom of activity, releasing about 10 times more ultraviolet light than at the minimum periods that can be seen in 1996 and 2006.