By Manickavasagam Thiruchitrambalam
Lagrange Points are positions in space where the gravitational forces of a two-body system like the Sun-Earth, Earth-Moon produce enhanced regions of attraction and repulsion. These can be used by spacecraft to reduce fuel consumption needed to remain in position. All major planets have their own Lagrange points. Other than spacecrafts, large concentration of asteroids and dust can also be found in these points.
Simply put, the forces that act on the satellites that are stationed at these Lagrange points are balanced and hence it is the perfect spot for positioning these satellites. When they are stationed at these points, they stay in the same orbit and do not move away. Leaving satellites in space other than Lagrange points would result in those satellites moving millions of miles from where you initially stationed it.
There are five special Lagrange points (L1, L2, L3, L4, L5) where a small mass can orbit in a constant pattern with two larger masses. Of all the planets in the solar system, Jupiter has large clusters of asteroids in these points. Out of these five points, L1, L2, L3 are unstable. The points L4 and L5 are the stable points. This means when the satellites in L1, L2, L3 moves little off from the point, it’s orbit will move farther and farther away in a matter of time. When the satellites are in L4 and L5 move a little off from these points, it’s orbit will shift little but not as that of those in the L1, L2 and L3.
Various spacecrafts have been positioned at various Lagrange points by various space agencies. NASA for example, at L1 point of the Sun-Earth system has placed the Solar and Heliospheric Observatory Satellite (SOHO), The Advanced Composition Explorer (ACE). India and China have future plans to position Aditya-L1, Kuafu at L1.
At the L2 point of the Sun-Earth system it has placed WMAP spacecraft and Planck. NASA, ESA, CSA plan to place James Webb Space Telescope, JAXA has planned LiteBIRD mission at L2 in the future. L2 is ideal for astronomy because a spacecraft is close enough to readily communicate with Earth, can keep Sun, Earth and Moon behind the spacecraft for solar power and provides a clear view of deep space for the telescopes. Since the L1 and L2 points are unstable, satellites orbiting these positions undergo regular course and attitude corrections once in 23 days. The point L3, always remains hidden behind the Sun hence positioning a space craft at L3 is difficult.
The L4 and L5 of the Sun-Earth system have few space crafts namely STEREO, OSIRIS-REx in L4 and Spitzer Space Telescope, Hayabusa2 in L5. They are perfectly suitable for positioning space colonies, refueling stations which would be of large help for the inter planetary and future intergalactic travel.
Similarly in the Earth-Moon system, L1, L2, L3 are unstable and L4, L5 are stable Lagrange points. For the future missions to moon and beyond, we can make use of L4 and L5 points and have an actual spaceship refueling outpost. Very few spacecrafts are now stationed in Lagrange points in the Earth-Moon system. ARTEMIS is the first mission ever to orbit the moon’s Lagrange points – points on either side of the moon where the moon and Earth’s gravity balance perfectly. The Chinese Chang’e-4 mission has a relay satellite at L2.
While militarization of space is not being advocated by any country, all major countries have some form of militarized presence in space, be it satellites for surveillance or communication.
In the near future many space agencies have planned inter-planetary travel. Some of those include establishing human colonies in Moon and Mars. The key to reach moon, mars and return back to the earth is that you need to have fuel. We cannot place the space-based fuel stations as we like in space as they can change their orbit anytime. Therefore, it is important to place these space-based fuel stations in Lagrange points L4 and L5.
Although nobody owns the space and beyond, it always does not work that way. Let us consider the Earth-Moon system and a human travel to the moon. The country that has control over the L4 and L5 points in the Earth-Moon system will control what happens in the moon, meaning – that country controls the moon. Obviously, when one country has control over the L4 and L5 points there will always be a country that would want to take over those points. This means despite occupying key L4 and L5 points, all assets are vulnerable when there is a direct view of the space asset to the adversary. To prevent any adversary attack and save crucial assets, space based “Anti-spacecraft weapons” are required.
Conventional explosives with oxygen supply will be effective only to a certain extent in space warfare and the destructive shockwave will diminish in vacuum. Space guns, shrapnel explosion can be effective in a close combat space war, although the shrapnel’s presence in space after the space war will always be vulnerable to all space assets.
Deploying space based ballistic missile defense system might not be a viable option. An Atomic blast would generate electric pulse of sufficient voltage to disable satellites and space stations, but it would make both aggressor and defender vulnerable to huge loss.
Hence the only effective weapons in space warfare will be Direct energy Weapons (DEW), LASER, Particle beam weapons, Electromagnetic Pulse Weapons (EMP) and effective jammers. Deploying such weapons in the Lagrange points L4 and L5 would be more effectively. The moon will become a contested area for humans in the future because of the presence of certain rare and valuable minerals. Hence the country that first establishes such a “Space base” in Lagrange points will dominate both the Moon and the Earth.
Similarly, for inter planetary human space travel, L4 and L5 of other two-body systems will remain a hotly contested area. Having some presence in all Lagrange points is another strategy but the stability of those respective points should be taken into consideration. Major private space companies around the world are also in the same race to establish colonies in the space and inter planetary travel. It is yet to be seen if “private companies” originating from certain countries are “truly private companies”.