Chapter 9: Once We Get There, How Do We Get Back?

I discussed my primitive 'peek, shoot and scoot' navigation technique with Earl, which I used to return my first star drive test bed to the Sol system.

He disappeared for a while before requesting a staff meeting. He started out with a solid right cross. "Once we're out there I don't know how we're going to find our way home. We don't have any telescopes on board with enough resolving power to locate Cephid variables or radio beacons. Hell, I can't find any telescopes at all. I'm going to need some help from science and engineering."

"I expected this to rear up and bite us. I actually did a little research on the problem when I was designing the sensor system."

I lowered the lights and brought up an image that I'd captured during my mass sensor tests. " One entire wall of the bridge is a high-resolution display for the gravitic sensor system. This is what our sensors can detect when the star drive fields are operating. Note the heavy concentrations. I compared this image to a photographic image and a star catalog. These correlate to other galaxies and this huge thing is the galactic center, obviously a black hole by the gravitational density. I believe that by recording 360 degree images as we travel we'll at least be able to locate ourselves close enough to resolve some of the brightest stars in our home locus, such as Deneb, Cygnus X-1, the Canis Majoris stars and others. I believe that by careful measurement of the observed distance between the Milky Way's central black hole and several marker galaxies we can determine where we are located around the galaxy's circumference. From that point I know that I can hack together a four meter reflector for you to do a local catalog of the brightest objects. How's that?"

"Quite good, actually. I'll want to do some correlation work with a good star atlas to your sensor images before we do anything drastic, but it's certainly a useable technique."

"I wouldn't get too bent out of shape If I were you. At our top speed my testbed traveled almost eight light years over four hours. We can't get too far out of our back yard in any hurry." He nodded and smiled, pacified for the moment.

After the meeting the captain said to me, "I'd get busy on that telescope if I were you. He looked like a man with a mission."

That evening I used a browser to find a telescope builder's supply site. I didn't want to have to recreate the final optics. That was a mature science that I'd never approached before. Then I set about building extremely heavy steerable telescope mounts to bolt down near each landing bay entrance. I'd need a lot of stability to get a low-jitter image on a four-meter mirror. The stepper motors used were huge. Invar was used for the frames and ULE (ultra low expansion) glass was purchased for the mirror blanks. A 28 meter barrel was required to accommodate the focal length of a four meter reflector. After a CAM station had done most of the work shaping the lenses in a micro-gravity environment the polishing stage began. After eleven months spent polishing both mirrors, they were moved to vacuum and their planned operating temperature of 13 degrees Kelvin to normalize and were re-tested for optical trueness. A little remedial polishing was required, then a bare angel's breath of aluminum ions was plated to the working surfaces using an electrical ion doping process. Then we made another pair and put them into space-normal storage at the closest to zero G that I could arrange.

[Ed. Hubble's telescope mirror is 2.4 meters in diameter and can resolve objects down to an apparent magnitude of about 28.]

I had elevators constructed to retract and cover the telescopes when they weren't in use. They were too delicate to leave hanging out in the big empty like that. I also made damned sure that the controlling program would never try to bring one up in direct solar illumination. I set the maximum apparent magnitude of the brightest observable object to -12 to enable the telescopes' elevators. The full moon from Earth has an apparent magnitude of -12.92.