Green Mars by 2060? Imposible! Or is there a way?
It is almost taken for granted that humans will set foot on Mars sooner or later this century. However, we don’t want just to visit it or to build some underground settlements. Assuming we will not find life on Mars, we want to terraform it and introduce Earth’s flora and fauna. How fast we can turn Mars into a green planet?
Earth can turn from sterile land to jungle in decades
Mars looks like an empty desert nowadays. Probably no life at all. It is like a piece of fresh frozen vulcanic rock. I am a fan of vulcanos and I have visited multiple locations like Mount Etna in Italy, Mauna Kea in Hawaii, Vanuatu island, and the national park Craters of the Moon in Idaho in the USA. Typically, it is a bit like walking on the Moon. Sharp black rocks are everywhere. The volcanic ash is for the barest, just a few lichens or moss on some rocks.
However, it is a striking difference, compared to other locations I have been such as Azory or the Canary Islands. Where there is enough water, sun, and warm weather, it takes only a few years to notice the first pioneer species. And about ten-twenty years later there is a bush and trees everywhere. It is obvious that with the right conditions, Mars could turn green in a few years or decades. So how we can fastrack Mars terraforming?
Step 1: Let’s start with genetic engineering
Firstly, genetic engineering would be required. Our Mother Nature had billions of years to engineer the best pioneering plants like cushion plants. It is a compact, low-growing, mat-forming plant that is found in alpine, subalpine, arctic, or subarctic environments around the world. They live as high as 6150 meters above sea level.
Let's say, we could do our best genetic modifications to adopt these for Mars conditions. So these plants could do at least as good as in harsh conditions on Earth — cold, dry areas on the top of the Mountains.
However, we will need to adjust the current conditions at Mars to allow forming of at least some moisture in the air. So the prerequisite is to increase the atmospheric pressure and temperature.
What are the options besides using nuclear bombs at poles to melt frozen CO2, as once jokingly mentioned by Elon Musk? I have once already argued to use ice-rich asteroids. Their kinetic energy would convert much of CO2 into gas, but it could convert some of the ice into water gas. Unfortunately, to create an atmosphere suitable for humans from asteroids, we would need about 1000 asteroids of the size that wipe out the dinosaurs. We don’t have the technology to do that, but we could perhaps start with something at a smaller scale.
Step 2: What about fetching some asteroids
We could bombard polar caps and kick the positive greenhouse effect. So we at least create sufficient conditions for our pioneering plants & gradually create an atmosphere using the resource available on the planet. Can we use rockets to bring some asteroids?
The diagram below shows DeltaV required to transit between the different objects in our Solar system. We will need DeltaV about 2000 m/s to get from Mars orbit of 200 km to Mars transfer orbit and another 1000m/s to reach the asteroids using the optimal trajectory called Hohmann transfer.
What about instead of sending SpaceX Starship rocket back to Earth, we would send some to the asteroid belt to fetch some pieces of ice?
Option a) Starship as a transport ship
Let's say, we have already the ability to fully refuel the Starship in Mars orbit. Starship will likely have a total propellant capacity of 1,200 t giving its 100t payload DeltaV of 6900 m/s. Starship will be launched empty, we could have enough fuel to be able to drag to Mars a relatively small asteroid (300-400.000 kg of dimensions of 5x5x10 m assuming ~1500 kg/m3).
We will reach the transfer orbit and hit the planet. The collision speed will be around 6–7km/s. Despite its size is rather small, the kinetic energy (Ek= (mass * velocity^2)/2) will be equivalent to 2300t of TNT.
Not bad, but that is enough energy to boil just about 17.000 t (or 10.000 m3) of frozen CO2 for each Starship journey. That is a very tiny fraction of the estimated deposit of 12,500,000,000,000 m3 of CO2 available.
So we need much larger and faster asteroids than we can get by using Starship. Unfortunately, one of the key aspects of Space astronavigation is the Rocket equation. Accelerating fuel just takes a lot of fuel. With more efficient ion thrust engines, better DeltaV can be achieved. Unfortunately, we don’t have such technology as Epstein drive presented in the Amazon Prime TV show The Expanse. On the other hand, we have already the skills to modify the asteroid trajectory by laser ablation.
Option b) Using An Asteroid Anti-Collision System
It works by heating up a small area of the asteroids to allow gaseous material to eject, either through sublimation (solid to gas) or vaporization (liquid to gas). The ejecting material creates a thrust, which over an extended period of time can change the trajectory of the asteroid. Many industries use affordable highly efficient laser systems. They can operate continuously and they are used for cutting materials, etc.
The laser power input is about 3x power output. So we will need about 90kW electric power input per laser to get a 30kW laser beam. We can use solar panels to power it. The solar irradiance at 2AU (astronomical unit), where we will use it, is about 340 W per m2. Current state of art solar panels would provide almost 100W per m2. So we will need a 30m x 30m solar array for each such laser. That sounds reasonable. The total weight of such a space probe shooting laser would be a few tons. We might be able to fit 50–100 probes into a single Starship.
So how much push acceleration we will get for our 300.000 kg asteroid from a single laser beam? The specific heat of the sublimation of ice is approximately 2,680,000 J/kg. The laser will provide about 30,000 J /s of power. So we could sublimate up-to ≈ 0.0112 kg (11 grams) of ice every second. The estimated average speed of water vapor molecules in a vacuum is approximately 500–600 m/s (given the gas formula v=√(γRT/M) ). So the force would be close to 6 N. This is close to the performance of Steam Thruster One, which provides 6 mN for 20W (6N for 20kW) of power using water as a propellant.
Even in this ideal scenario, the force of 6N will give our 300.000 kg of asteroid acceleration of just 0.00002 m/s2 (F = m * a, where F = force, m = mass of an object, a = acceleration). The asteroid velocity will change by 1.728 m/s per day and we will vapourize almost 1000 kg of the ice. So about 80% of the asteroid would need to be resolved before we achieve the required delta V to hit Mars. That would not be worth it.
Option c) Optimized Laser Propulsion
An alternative laser propulsion technology was developed and tested by a startup Lightcraft Technologies 20 years ago. They used a 10 kW Carbon-dioxide pulsed laser and demonstrated (low-resolution video here) the ability of the system to power the test device. The light beam is focused by the parabolic mirror on the bottom of the conical light craft, which heats the air to between 10.000–30.000 degrees Celsius (18,000 and 54,000 degrees Fahrenheit). That’s several times hotter than the surface of the Sun. So the air is converted to a plasma state — this plasma then explodes to propel the craft upward. The company doesn’t exist anymore, but the detailed report can be downloaded.
So by concentrating the laser beam in short pulses and in very small caveats in the asteroid, we could convert the material into plasma and achieve much higher particles escape velocity. Using the kinetic theory of gases as in the previous case, we should get to the speed of 200–300 km/s. That is in the same order of magnitude as the solar wind with a speed between 250 to 750 km/s. That will create up to 1000x higher momentum from the same mass of the ice. To evaluate the feasibility further, the essential parameter is to estimate how much energy will be converted into the thrust. I found a review study of the Laser Lightcraft, where engine efficiency is estimated to be γ = 0.7. Considering the high reflectivity and spike nozzle, I think that it could be achievable. For our case, let's set γ = 0.33 to be safe and use 3 additional beam lasers of each 30kW power on average.
So we will convert about 30 000 J into the kinetic energy of the plasma every second. Hence slowly accelerating the asteroid. It would take about 2 months to achieve the DeltaV required to hit Mars.
Step 3: Impact and effect
A single probe with 4x 30kW lasers might allow redirecting the 300-ton icy asteroid into a collision course every ~2 months.
As close to the Mars surface, the ice asteroid will need to be scattered into thousands of small pieces of tens of kilograms each. A small railgun located at one of the Mars moons would do the job. The pieces of ice would quickly penetrate the thin atmosphere and hit an area of 10–100 km2 maximizing the conversion into heat and vapor.
A single Starship will be able to deploy about 50 probes, which will be able to divert about 250 asteroids per year, vaporizing 2.500.000 m3 of dry ice. If we would be serious about the planet terraforming, we would need at least 1000 probes (20 Starships fully loaded) to start with. That is 50.000.000 m3 of dry ice converted into gas and 1.500.000 m3 of water vapor every year.
We want to focus the bombardment timing into the short period of time in Mars summer when the polar dry ice cap can naturally undergo sublimation. So the combined release the CO2 back into the atmosphere could make a dint and tip the scale toward global warming. So the atmosphere gets thicker and warmer and after a few Mars revelations will provide some moisture for our genetically adapted cushion plants.
If we would gradually deploy 10.000 probes, during the next 20 years of operation, about 10,000,000,000 m3 of dry ice and 300,000,000 m3 of water will be released into the atmosphere just by the asteroid impacts.
The positive warming loop should be created allowing humidity in the low altitude areas and perhaps liquid water on the Mars surface during the summer. Humanity will slowly witness the change of the planet’s color from red to brown and eventually green with blue dots. We will start the next phase of Mars terraforming — building up its ecosystem.
