Mercury Read Free

creased with laugh lines. In his first life Yamagata had laughed a lot, although during those years of remorse and penance he had spent with the lamas in their stone fortress high in the Himalayas there was precious little laughter.
    Freshly showered and dressed in a crisply clean open-necked shirt and fashionable dark trousers, Yamagata made his way to the ship’s bridge. He thought about dropping in on his two guests, but he would see them later at dinner, he knew. As soon as he stepped through the open hatch into the bridge the Japanese crew, including the captain, snapped to respectful attention.
    Waving a hand to show they should return to their duties, Yamagata asked the captain, ‘Are we ready to send the landing craft to the planet?’
    The captain tried to keep his face expressionless, but it was clear to Yamagata that he did not like the idea.
    ‘It is not necessary for you to go down to the surface, sir,’ he said, almost in a whisper. ‘We have all the necessary facilities here on the ship—’
    ‘I understand that,’ said Yamagata, smiling to show that he was not offended by the captain’s reluctance. ‘Still, I wish to see the surface installation for myself. It’s near the north pole, I understand.’
    ‘Yes, sir. Borealis Planitia.’
    ‘Near the crater Goethe,’ said Yamagata.
    The captain dipped his chin to acknowledge Yamagata’s understanding of the geography. But he murmured, ‘It is very rugged down there, sir.’
    ‘So I have been told. But personal comfort is not everything, you know. My son, Nobuhiko, enjoys skiing. I cannot for the life of me understand why he would risk his life and limbs for the joy of sliding down a snowy mountain in all that cold and wet, but still he loves it.’
    The captain bowed his head. But then he added one final warning. ‘Er . . . They call it “Dante’s Inferno” down there. Sir.’

Data Bank

    The closest planet to the Sun, Mercury is a small, rocky, barren, dense, airless, heat-scorched world.
    For centuries astronomers believed that Mercury’s rotation was ‘locked,’ so that one side of the planet always faced the Sun while the other side always looked away. They reasoned that the sunward side of Mercury must be the hottest planetary surface in the solar system, while the side facing away from the Sun must be frozen down almost to absolute zero.
    But this is not so. Mercury turns slowly on its axis, taking 58.6 Earth days to make one revolution. Its year – the time it takes to complete one orbit around the Sun – is 87.97 Earth days.
    This leads to a strange situation. Mercury’s rotation rate of nearly fifty-nine Earth days is precisely two-thirds of the planet’s year. A person standing on the surface of the planet would see the huge Sun move from east to west across the dark airless sky, but it would slow down noticeably, then reverse its course and head back east for a while before resuming its westerly motion. At some locations on Mercury, the Sun rises briefly, then dips down below the horizon before finally rising again for the rest of the Mercurian day. After sunset the Sun peeks back up above the horizon before setting for the length of the night.
    Counting the Mercurian day from the time the Sun appears directly overhead (local noon) to the next time it reaches that point, it measures 176 Earth days. From the standpoint of noon-to-noon, then, the Mercurian day is twice as long as its year!
    The Sun looms large in Mercury’s sky. It appears twice as big as we see it from Earth when Mercury is at the farthest point from the Sun in its lopsided orbit and three times larger at the closest point.
    And it is  hot.  Daytime temperatures soar to more than 400° Celsius, four times higher than the boiling point of water, hot enough to melt zinc. At night the temperature drops to –135°C because there is no atmosphere to retain the day’s heat; it radiates away into space.
    With a diameter of only 4879 kilometers, Mercury is the