planet Mars

[See also Mars' erstwhile 'twin' Astrus]

Mars has virtually no atmosphere; its equatorial surface temperature is well below freezing; its eon-early atmosphere froze-out onto its polar caps: by some estimates an Earth-equivalent atmosphere of very cold gravel-hard water-ice and frosty carbon-dioxide ice, a clathrate of raw 'greenhouse' gases; unready, unusable for air-plants even at higher partial pressures --maybe hydroponic diatoms, in deep underground liquid water.

During Martian summers, twice per longyear, 687.0 Earth-days (1.881 Earth-years), the summer polar cap transports to the opposite winter pole-- the atmospheric pressure is too low to sustain liquid water.

POSSIBLE TERRAFORMING SCENARIOS:

• Under a thin-film canopy, a powder-seeded surface, the water-vapor pressure is raised; vast regions of the poles may become diatom-summer resorts, by vaporizing selected powderable Mars-herded asteroids deep in the thin atmosphere over the poles.
• At the equator the deep permafrosts may be liquified by impinging comets and asteroids, medium-large enough to gouge the surface. [Nuclear 'mini-nukes' would be more costly, and less overall effectual]
• Underground, Mars being not a large planet, its temperature, while moderated year round, is shy of melted water, save at sufficient depth, internal pressure and temperature may melt it.

The GNSCruiser with nuclear authority can:

• Put 'ion' vernier-thrusters on many asteroid/comets, and drop them on the poles of Mars, to vaporize significant portions of the ice caps, to replenish the atmosphere, which will hold more solar heat and keep Mars warmer for more than the longyear
• Supply the nuclear power generators for building fields of pole-cap-heaters, to maintain the H₂O and CO₂ atmospheric for decades, to warm the planet and recover the vegetation cycle.