Slingship Sam: Chapter 2

     “Not 33, Sam, it’s 32 years, seven mon–“

     “Yeah, yeah. When will we make our closest approach to Hilco?”

     “Five hours and twenty one minutes.” They were about one and a half million miles away–at the edge of detection for Fling’s radar. Maybe the iron was there, but outside Fling’s range. The iron was only a mile wide.

     “Let’s talk to Patroclus,” Sam said. “How far out of Now are they?”

     “We are thirty six million miles from Patroclus. Speed-of-light time lag is 387 seconds, round-trip. It will take 97 seconds to rotate the antenna into proper position.”

617 Patroclus is a double asteroid 68 miles wide, orbiting in synch with 617 Menoetius, almost the same size, 493 miles apart, faces locked toward each other the way the Moon is locked toward Earth.

     “Hold off on the rotation,” Sam said. “If we’re breaking the link I want to let them know back at the Roost.” The antenna was locked onto 704 Interamnia, his former home, and the link might be difficult to re-establish. Regaining contact when they’re 482 million miles away is a tricky thing that could take days of trial and error until Fling locked it in because they were 90 minutes out of now with Interamnia. Extremely fine tuning would be necessary to find it again. He would be out of touch with his only friends in the solar system.

     “Hi, guys, this is Sam. I might be off the air for a while, I’ve got to reposition the antenna for an emergency. One of my sling rocks has vanished.”

     Sam heard Fling’s big dish antenna cranking around to aim at Patroclus. He couldn’t wait for a reply from Interamnia: that would have taken an hour and a half.

     Space is a lonely place and not just because you’re alone. Sam was trapped in his own solitary Now. Every human-occupied asteroid is at the center of its own bubble of Now. Distances in the Belt were too far for real-time contact. Earth’s moon is about at the outer edge of Earth’s Now–it is possible to have a phone conversation between Luna City and New York, and the 3-second lag is merely annoying. In the Belt, a 3-second lag is stripped-naked intimacy. Sam was 6 minutes and 27 seconds out of Now with Patroclus.

     “Focused on Patroclus Station,” Fling said. Patroclus’s site sprang into view on the screen, a standard format.   

     “Okay. Start message: Hello, Patroclus, mayday, mayday, this is Sam Flandern–I’m two weeks away from arriving. I’m your new splinter jockey. I’ve encountered 1303247 Hilco A way out of position, and I can’t find Hilco B. Can you locate the iron companion for me? Thanks.”  

     “Our orbital parameters have been attached to your message,” Fling said.              

     It would be at least six and a half minutes before he could expect an answer, even if they responded instantly. Six and a half minutes Out of Now. Meanwhile, what was Sam going to do if Patroclus couldn’t help locate the iron?

     “Look, why can’t we use the mag drive on the carb?” Sam gestured at the carbonaceous chondrite in the windshield.

     “Carbs don’t have enough magnetic moment.”

     “We’ve been swinging on carbs all the way up to now.”

     “We approached very close to nine carbonaceous chondrites and used maximum gravito-magnetic power to increase our speed at each encounter. Our speed of 52 miles per second cannot be offset and re-vectorized except by the stronger connection to an iron asteroid. Which is no longer there.”

     Three months ago he’d been on Interamnia on the other side of the Sun when he heard about the Patroclus job. Interamnia is one of the largest asteroids near the outer edge of the main belt, about 286,000,000 miles from the sun. The slow, easy way to get to Patroclus was to accelerate into a Hohmann transfer orbit and drop outward from the sun.

     The fast slingship method is to speed up. Sam travelled in fast, tight orbits, slinging outward from rock to rock like a kid swinging on playground monkeybars, gaining speed and heading further outward toward his destination in Jupiter’s orbit, until there weren’t any more rocks to sling off of until the other side of the Kirkwood Gap.

     Slinging. That’s how the early space probes were able to get to Saturn, Uranus, Neptune, and Pluto. They used gravitational slingshots at Jupiter to get to Saturn, and used Saturn to get to Uranus, and Uranus to get to Neptune.

     The asteroids are far too gravitationally feeble for that kind of slinging; but you can do the same thing electromagnetically if you have a corium-powered mag drive. The Great Corium Boom led to the most accelerated advancement in rocket technology in history. It was no longer just governments launching probes for intellectual and scientific reasons. Then rockets were discarded in favor of corium-powered mag drives. And Earth’s insatiable demand for corium has never let up. 

     He was crossing the big 4:3 Kirkwood gap, which Jupiter’s gravity had long since swept clean–for a hundred million miles the only available asteroids were 279 Thule, which was far out of position, and 1303247 Hilco.

     It had been a big risk to take this cometary orbit. Usually your computer can plan an orbit so that if something goes wrong on your planned interaction, you’ll encounter another rock fairly soon afterward.

     Sam didn’t know anything about orbital mechanics. Back on Interamnia, Sam had asked “How can I get to Patroclus?” and Fling had displayed a map showing an optimax orbit. 219 days. 31 weeks–more than 7 months! No way. “I’ve got to get there faster than that.”

      Fling had displayed a new orbit. “Faster, I have to get there in just a couple of months,” Sam said. Eventually Fling displayed a cometary orbit that decelerated at Hilco B while changing vector to aim precisely at Patroclus.

     You could shed any amount of speed at a big iron asteroid (not to mention Earth). Hilco was Sam’s last acceleration, and a drastic course change.

     But now the iron wasn’t there. “What about this,” Sam said. “Let’s get in close to that carb and use a giant pulse of energy at closest approach and see if we can grab enough momentum to sling us to Patroclus . Heck, we only need, what–” he looked at the charts–“a delta V of…”

     “Our current trajectory takes us no closer than 5,000 miles, much too far away.” Although the mag drive’s electromagnetic field can easily interact over such distances, the pseudo-gravitic aspect of corium works only at very short range. Real gravity has an infinite range and its strength diminishes as the square of the distance. Corium’s pseudo-gravity field diminishes as the fourth power of the distance. 

     “Well, use the mag drive against the solar field. Jam us in on a near collision course with that carb and we’ll use whatever it’s got.”

     “Sam, that is possibly an overload power demand.”

     “That’s the way I want to do it.”

     There was a long pause, but eventually Fling said, “Yes, Sam. But it won’t work. You need iron, not a carb.” But Sam heard the change in the subsonic hum of the mag drive as Fling began tacking the ship’s orbit closer to Hilco.

     “Besides,” Sam said, “do you have an assay report for Hilco A?”


     “So it could be anything. It can’t hurt to try. Maybe we can swing into an orbit toward some other iron. Anything is better than zooming out past the Kuiper Belt.”

     The escape velocity of the Sun is 26.15 miles per second. That’s the local speed limit, because anything going that fast will never come back again. The slingship’s speed was twice as fast. Sam would be in danger of leaving the solar system forever if the close approach to Hilco failed.

     The job on Patroclus was going to be the worst kind of vacuum-suit work. Patroclus and Menoetius formed from re-condensing rubble after two massive asteroids slammed into each other millions of years ago. Among the debris is a lot of corium. All you have to do is sift through the surface rocks for it.

     The job awaiting Sam? Sifting rocks. After the big slow-speed collision, all the tumbling rocks gradually drifted back into two clumps again under the mild gravitational pull.  

     Fling said, “A message has arrived from Patroclus  Control.”

     “Play it.”