Earth, Mars, solar shades, space mirrors, and Enyo. (Patreon)

Geo-engineering

Earth phased out first the building of, then the use of, coal and gas power stations in the mid 21st century. Renewables, especially wind and tidal took up the slack and, as Nuclear Fusion became a reality at last, the concentration of CO2 in the atmosphere stopped rising. Warming didn’t level off at this point, in fact for a number of years things got worse. Some pollutants and particulates in the atmosphere had actually been cooling the earth, off-setting a small proportion of the greenhouse effect. Carbon capture and storage technology was accelerated, finally capturing more than the output of the power facilities they were attached to. When Rasmussen’s breakthrough in carbon capture became the main industrial method, humanity finally got a hold on the climate emergency. CO2 in the atmosphere dropped 50ppm in just two years. Within a decade the Earth’s atmosphere was back to levels not seen since the late 1700s.

Geo-engineering projects had started in the 2020s when it became obvious that efforts to restrict pollution were going to be too little too late. Solar shades in LEO had protected the polar regions from the worst of the warming, in some cases reversing the melting of ice sheets and preventing catastrophic sea level rise. Huge water dispersal schemes in the polar seas created ice particles in the high atmosphere that reflected more sunlight, adding to the cooling effect.

Areo-engineering

On Mars, climate problems were of a similar magnitude, but a very different type. Atmospheric pressure on Mars was around 1% of Earth’s, and less than 1/6 of the pressure that would allow humans to walk on the surface without full pressure suits. The average temperature at the Martian equator was -20ºC, and could drop to -120ºC. Temperature and atmospheric composition were less of a problem than pressure. Blood boils under normal Martian atmospheric pressure, making it almost as inhospitable as the hard vacuum of space.

What could be done? A major issue was Mars’s lack of a magnetosphere. Unprotected from the solar wind, atmospheric gases on Mars were stripped off in to space faster than they could be replenished.

Moroccan physicist Latifa Elouadrhiri was the first to propose modifying a Weird-Field drive to produce a strong enough magnetic field to act as a shield for Mars from the Solar Wind. The dipole, the most powerful magnet ever produced at the time, was positioned in orbit around the sun, so that it was always between the Mars and Sun, at a distance of just over 1 million km from the Martian surface. As the Solar Wind hit the magnetic field it produced a shockwave that bent the high energy particles away from Mars. This alone led to an increase year on year of 4% in the atmospheric pressure on Mars. It also reduced the amount of radiation shielding needed on the surface to protect humans.

During the next thirty years a range of different projects were initiated, including: 

Solar mirrors were installed in orbit, initially to simply prolong daylight by a few minutes each Martian day, the projects were expanded - particularly in the polar regions - to rapidly increase the release of gases from the permafrost.

Moholes were dug deep in to the Martian surface. Digging down over 2km reached a warmer section of the planet, releasing heat in to the atmosphere. The moholes, often over 500m in diameter were used as habitations in the early days of colonisation, before the dipole was installed.

The most radical areo-engineering project, and the most controversial, was the plan to crash comets in to the surface. Although no evidence of any lifeforms had been found on Mars, scientists insisted that the search should go on. The UN moratorium prohibited such dramatic interventions, and the idea was shelved. Only to be picked up by a splinter group of the NuMars movement. NM advocated for the rapid areo-forming of the planet, stating that humanity needed a second planet as backup for the Earth (which at the time was struggling through the worst of the climate emergency). NM was largely a peaceful lobby group, its splinter group, simply known as NMX, was less so. In 2123, NMX hijacked the freighter WF Maxwell-Fyfe which was carrying WF drive components to the L5 Station. Escaping with such a valuable cargo, and a working WF ship, was a huge coup for the group and support grew for them over the next few years. After the highjack they largely disappeared from view, broadcasting only an increasingly fanatical series of monologues from their leader Emma Broadhead. It wasn’t until 2126 that they dramatically showed their hand. Short period comet P/2019 F17 had been detected back in the summer of 2019, it was large, having an approximate diameter of 19km and a mass of 4.2 x 1015kg. NMX managed to use WF Drives to turn the comet into a projectile. Moving at well over one million kph the comet wasn’t detected early enough to divert it using nuclear rockets (the tactic had worked to divert a small asteroid in 2078 that would have struck near the Philippines). As soon as the comet was detected, NMX declared it was guiding it to a collision at a point near the northern polar region of Mars. Several scientific outposts were hastily evacuated, and larger settlements were abandoned. NMX, for all their ingenuity had neglected one thing. They had forgotten to account for the orbits of Phobos and Deimos, the two small moons of Mars. Comet P/2019 F17, which had by now been nicknamed Enyo (after the Greek lover of Ares) crashed in to Diemos, shattering the slightly smaller moon. The debris from the collision, including fragments several kilometres in size rained down on Mars over a period of days and weeks. Many large pieces struck the polar region that NMX had originally targeted. The impacts were devastating, causing huge upheavals of Martian regolith, liberating much of the gas, ice and water trapped in the permafrost. 

Over the next three years, during which material continued to enter the atmosphere (usually, but not always, to burn up), NMX evaded capture. Their action had resulted in the deaths of almost 1700 people - who weren’t evacuated as they were nowhere near the intended impact site. Scientists returned to work, and began to study the changes to Mars the impact had wrought. What they found astonished them. Much more volatile material had been released than had previously been thought possible. The atmosphere had thickened by a significant factor (not enough to make the wearing of pressure suits a thing of the past), and the composition changed with much more water vapour present. The dust that had been thrown up by the impact had covered the planet in a thin layer of dark red material which absorbed much more heat that either the standard regolith or the polar ice caps. This led to even more heating of the surface and a greater liberation of water and carbon dioxide - which led to even more heating. Since the installation of the Martian Dipole, the increase in the atmosphere was no longer stripped away by the solar wind and continued to build. 

Thirty years after the Enyo Impact, the atmosphere of Mars had increased so much that the pressure at mean Mars elevation was now almost 30kPa, approximately the same pressure as the summit of Everest. While this obviously was far too thin for humans to live in unprotected, it did mean that surface operations on Mars could now be conducted in much more lightweight suits, predominantly geared for heating (the average temperature on Mars was still barely above freezing). Breathing apparatus was still required to convert the CO2 heavy atmosphere in to something more suitable for humans.

The terrorists had achieved their aim. They had showed that intentional impact of cometary bodies on the surface of Mars could radically change the atmosphere. Within three decades scientific thinking (and economic pressure) had changed. More comets, this time more closely controlled, were headed for Mars.