Ancient ices sublimed under the growing warmth. First carbon monoxide, as the core swept in past the orbit of Jupiter, and later carbon dioxide. The escaping vapors lifted black, powdery dust to meet the growing sunshine. A thin haze began to form.

The rendering was vivid. Virginia watched the faint, glimmering dust and ion tails begin to take shape, like ghostly banners unfurling in the growing light.

On at least ten score occasions the spinning ball of ice had fallen this way, since that time when it had passed too close to Jupiter and been snared into the middle solar system. Since then it had been tethered to the sun on a shorter leash than most comets.

Space was roomy, vast, and since that one near-brush with the giant planet’s gravity the comet had never met another physical object it could not absorb. Dust grains, little bits of rocky flotsam, they all had blundered into Halley’s streaking path and paid the price.

But the Nudge had seen to it that there would be another meeting. Something smaller than Jupiter, but much too large to absorb, would pass improbably close this time, while Halley Core hurtled inward.

And there it was! A pinprick of reddish light, just ahead.

Mars, Virginia thought. Right on time. Ready for a little carom action?

JonVon recognized a rhetorical question. Anyway, the machine was too busy to answer as the close encounter drew near.

This was Earth Control’s compromise, its plan to rescue them without risking infection to the homeworld.

I must admit, I didn’t expect even this much out of them.

Sure, public pressure, Earthside, was a major reason for the Care Package, which was now only months away from rendezvous with their little isolated outpost of humanity. Nevertheless, after all these years Virginia had grown cynical over just how much Earth Control really cared.

I’d have expected them to order us to commit suicide “honorably” and quietly, like good little plague carriers should.

The red planet loomed. Virginia asked JonVon to zoom in on the details, slowing the action as she and the comet approached rendezvous.

She swept ahead of Halley to look over the planet. The icy south pole of the dead world came into view first.

Red sands blew over Cydonia. The long-dormant Shield Volcanoes were pimples that poked nearly through the thin atmosphere, tufted on their flanks by thin, dry clouds.

Phobos rose around the small world’s limb. The little moonlet was a pockmarked stone, aglitter with lights, that rolled by Virginia and then set over the sharp, ocher horizon.

Nice people, she thought of the folk of Phobos Station. Toobad they’ve never been allowed to become a real colony. Maybe we can help them, there.

She looked back and saw the comet nearing, as the men and women on Phobos would see it thirty-eight years from now.

It ought to be quite a show for those folks… Halley sweeping by almost close enough to touch. Mars has to pass through the thick of the tail for its faint gravity to catch our aeroshell lifeboats. And yet the planet and comet can’t be allowed to come so close to each other that the turbulence will knock our boats off course.

In the simulation, Halley was putting up a grand display. Nothing like the spectacle would show closer to the sun, of course; but the twin tails had started to unfurl, and the coma glowed like a fuzzy cloud of fireflies.

The simulation was excellent. JonVon even depicted the lights of Phobos winking off as workers battened down and covered up.

For a few days there would be too many meteoroids to risk venturing out into the open. A small price to pay, though, for a chance to rescue three hundred souls. At least Virginia hoped they would feel that way.

Three hundred people quarantined on Mars… that really might be enough to start a colony. Ithad never been one of her dreams to settle a rust-red desert, but the plan beat the alternatives. And it’ll be nice to,feel gravity again, to walk, and maybe even swim in a dome-covered pool.

It’s not Maui, but I could get used to the idea of being a Martian.

The separation narrowed. Halley’s surface seemed to fizz as hot spots threw fountains of gas and dust into space, adding to the coma’s brilliance.

Is it a trick of perspective? Or are we really going to pass as near as it looks?

Sparks flew off as tiny objects separated from the comet’s head in soundless explosions.

The life rafts. Armored against the dust and heat, the aeroshell-covered sleep slots would split way from Halley. Tiny, mech-controlled rockets increased the spacing, guiding the hibernating colonists toward their first fiery encounter with the red planet’s atmosphere.

Virginia backed away further, giving the simulation space.

All Earth will be watching this. The folks on Phobos won’t be the only ones having quite a show.

Halley’s cloudy coma seemed to touch the planet. Virginia blinked.

Something’s wrong. How can it…

The coma began to warp out of shape, compressed by sonic shock waves as the globe of gas encountered the planet’s sparse atmosphere. Ionized gas bowed outward and away from the weak Martian magnetic field.

The sparkling dot of the core itself, a trillion tons of ice, pulled forward, unimpeded by anything so tenuous as gas or magnetism. It fell ahead of its cloud, and began to glow still brighter.

NO…

Gaseous bow shock waves multiplied into expanding cones. Sensing that she wanted to follow the action, JonVon slowed the encounter as Halley Core scattered the tiny lifeboats like pollen grains and sped on toward closest passage.

Closest passage…

The nucleus split apart! Then again. Four chunks streaked inward at an angle, their path through the Martian atmosphere now incandescent. Then they struck the little world.

One piece seemed to glance off the limb of the planet, like a hammer striking glowing sparks off into space. Plumes of dust roiled where the mile-wide bit had briefly touched down.

A large fragment scored a direct hit on Olympus Mons, shearing off the left side of the great volcano in a titanic, blinding explosion.

Simulation or not, Virginia blinked away the afterimage from that flash. By the time she could watch again, the series of searing blasts had turned into spreading orange clouds. The thin atmosphere rippled and swirled like a shallow pond into which bullets had been fired.

Quakes shook the ancient sands. Under Mars the permafrost buckled and melted. Virginia imagined she could sense magma stirring.

She was too stunned to do more than watch, unbelieving. She sought out the little aeroshells and found one, two, tumbling away toward the sun. Others glowed briefly as they hit the rolling dust clouds, flared, and went out.

Some had simply disappeared.

It was supposed to be a gravity carom! A near passage! Earth Control never said anything about this!

Carlnever said anything about this.

Unconsciously she willed her simulated self away from light— away from the burning, sunlit face of the rocky crucible.

Mars fell back as she fled outward along its shadow. Seen from dark-face, the planet was a thin crescent of red wind, tinged in fire. From one side of the crescent, a rosy pyre bloomed: the god of war answering heaven’s violence in reawakened volcanoes.

Unbeckoned, unwelcome, a line from Shelley came to mind.

Look on my Works, ye Mighty, and despair!

Virginia disengaged, her hands shaking as she tore off the contact disk. In her mind, though, the scene continued. Imagination went on simulating what was intended for thirty-eight years hence, picturing the sun as it would rise on the morning following this encounter, to shine over a steamy, cloudy day on Mars.