Mercury Read Free Page A

smallest planet in the solar system, except for distant-most Pluto. Jupiter and Saturn have moons that are larger than Mercury. The planet is slightly more than one-third larger than Earth’s own Moon.
    Yet Mercury is a dense planet, with a large iron core and a relatively thin overlay of silicon-based rock. This may be because the planet formed so close to the Sun that most of the silicate material in the region was too hot to condense and solidify; it remained gaseous and was blown away on the solar wind, leaving little material for the planet to build on except iron and other metals.
    Another possibility, though, is that most of Mercury’s rocky crust was blasted away into space by the impact of a mammoth asteroid early in the solar system’s history. Mercury’s battered, airless surface looks much like the Moon’s, testimony to the pitiless barrage of asteroids and larger planetesimals that hurtled through the solar system more than three billion years ago. Caloris Basin is a huge bullseye of circular mountain ridges some 3700 kilometers in diameter. This gigantic impact crater is the center of fault lines that run for hundreds of kilometers across the planet’s rocky surface.
    An asteroid roughly one hundred kilometers wide smashed into Mercury nearly four billion years ago, gouging out Caloris Basin and perhaps blasting away most of the planet’s rocky crust.
    Despite the blazing heat from the nearby Sun, water ice exists at Mercury’s polar regions. Ice from comets that crashed into the planet has been cached in deep craters near the poles, where sunlight never reaches. Just as on the Moon, ice is an invaluable resource for humans and their machines.

Dante’s Inferno

    Yamagata rode the small shuttle down to the planet’s airless surface in his shirtsleeves, strapped into an ergonomically cushioned chair directly behind the pilot and co-pilot. Both the humans were redundancies: the shuttle could have flown perfectly well on its internal computer guidance, but the Himawari ’s captain had insisted that not merely one, but two humans should accompany their illustrious employer.
    The shuttle itself was little more than an eggshell of ceramic-coated metal with a propulsion rocket and steering jets attached, together with three spindly landing legs. Yamagata hardly felt any acceleration forces at all. Separation from the Himawari was gentle, and landing in Mercury’s light gravity was easy.
    As soon as the landing struts touched down and the propulsion system automatically cut off, the pilot turned in his chair and said to Yamagata, ‘Gravity here is only one-third of Earth’s, sir.’
    The co-pilot, a handsome European woman with pouty lips, added, ‘About the same as Mars.’
    The Japanese pilot glared at her.
    Yamagata smiled good-naturedly at them both. ‘I have never been to Mars. My son once thought of moving me to the Moon, but I was dead then.’
    Both pilots gaped at him as he unstrapped his safety harness and stood up, his head a bare centimeter from the cabin’s metal overhead. Their warning about the Mercurian gravity was strictly pro forma , of course. Yamagata had instructed the Himawari ’s captain to spin the fusion-torch vessel at one-third normal gravity once it reached Mercury after its four-day flight from Earth. He felt quite comfortable at one-third g .
    Leaning between the two pilots’ chairs, Yamagata peered out the cockpit window. Even through the window’s tinting, it looked glaring and hot out there. Pitiless. Sun-baked. The stony surface of Mercury was bleak, barren, pockmarked with craters and cracked with meandering gullies. He saw the long shadow of their shuttle craft stretched out across the bare, rocky ground before them like an elongated oval.
    ‘The Sun is behind us, then,’ Yamagata muttered.
    ‘Yes, sir,’ said the pilot. ‘It will set in four hours.’
    The co-pilot, who still had not learned that she was supposed to be subordinate to the pilot, added, ‘Then