Comet! (an Ell Donsaii story #5 ) (30 page)

Emma’s eyes narrowed, “What if you break it up into ‘cosmic buckshot’?”

“Yeah, that’s a problem. So, first we hit it with this little five kilo rocket at 22 kps and watch to make sure we aren’t breaking it up. Then we gradually increase the power of our strikes, checking the stability of the comet after each one.” Ell put up a finger, “Sorry, I’ve got a call I need to take.”

Emma’s eyes defocused as Ell wander
ed away.
Roger
pulled over a screen to start running some numbers of
his
own.

Ell said, “
Wilson
, how are you? What did your wife say?”

“I’m OK. Taking a lot of Rolaids. My wife is OK with us moving but it will take us a while to get there.”

“If we’re going to do this, I want you
here
this afternoon. My AI says you can catch a commercial flight out of
Sky
Harbor
at…
10:37
and be here by late afternoon.”

“But
…
but, I have
…
have
to
give notice at my job. Help my wife get started on packing our house and selling it, and, and…”

“Those are problems money can solve and D5R is willing to spend it. We’ll double any penalty clauses in your contract for leaving without notice and
reimburse
your company three months of your salary. We’ll pay for high end movers to do
everything
related to
moving you
. Your wife will only have to say ‘pack that, move this
.
’
We’ll pay all real estate fees and cover any reasonable losses you think you have incurred from selling
your home
in a hurry. We’ll cover your wife’s salary from her last day there for six months or until she finds a job here whichever is first.”

“But, but…”

“
Wilson
! Do you think
human
civilization is at risk or not?”

“Uh, I, I, I do, but…”

“Then, pack a bag and get out here. The rest of this stuff is trivia
l,
isn’t it?”

Daster audibly swallowed, then
practically gasped
, “Uh, yes.” With more resolve he said, “I’ll be on that plan
e and see you at your facility ASAP this afternoon.”

“
All right!
My
AI has made you a reservation for the plane and for a car rental when you get here, charged directly to D5R.”

“All right.” Daster broke the connection, head
wh
irling
. He
turned, “Hey Em?”

Ell walked back over to Emma
and Roger
, “OK, tell me what you’re thinking?”

Emma said,
“You’re right, we should be able to bump it using weighted rockets as long as we don’t blow it apart. But remember, there ain’t no free lunch. Accelerating a 25 kilo rocket up to 150 kps so that it has 134 of
TNT
energy will take a
t least
that
much
energy put into the rocket to accelerate it. I’m figuring a minimum of 6500 liters of RP-1 rocket fuel and corresponding amounts of oxygen.”

“Oh yeah. We’ll have to have delivery trucks coming out here all the time huh?
”

“Well,” Emma grinned at her, “I suggest using natural gas instead of RP-1. It isn’t quite as good a
rocket
fuel but it’s good enough
when you’re using ports
.
Even though PHMSA won’t let us install a port at the distributor we already have a real pipe for natural gas here.
A
nd the
United States
has
lots
of natural gas.
Then we’d only need to have LOX trucked in here.
”

Ell said, “I wonder if we could just use compressed air. We’ve been thinking of LOX for our oxidizer because that’s what rockets use. But they use it because they don’t want to transport the weight of the nitrogen that’s in air. We don’t care, the nitrogen actually adds to the impulse
of the rocket
like the extra air a turbofan jet throws out the back.”

Emma’s eyes widened, “Yeah! You’re right. We might not get quite as much impulse out of our rocket but we can just back it up
some
to let it accelerate longer if we have to.”

Ell had been staring off into space, “Hmm, we’re limited by the 22 meters per second velocity that
fuel
can flow through a port. It’ll take
…
over 50 hours to put enough natural gas and air through a seven centimeter port to the rocket on the pusher to get a five kilogram rocket up to 150kps. If we use liquid natural gas and LOX we can fly it pretty much as fast as we want. Five gravities of acceleration would be pretty easy and would get the impactor up to 150kps in 51 minutes.

“Ouch, 50 hours would mean we wouldn’t be able to launch many missions per day.”

Ell shrugged,
“OK, Allan, ask Braun if there is a problem using
liquid
natural gas and
LOX
for our rockets that we’re not
aware of
?
And for that matter plain natural gas and air, which we could still use for low acceleration missions.
If not, ask Sheila to arrange
with the
distributor
to provide us with bigger
LNG and LOX tanks
.
We’re going to need several thousand liters of each
per
impactor rocket.” She stared off into space again, “Wow we can only fly about 5 impactors with an entire tanker truck of LOX!”

Emma said, “That’s a problem. First of all, a tanker of LOX is over $
2
0,000 and even if Quantum Research can afford it, our supplier has been having trouble providing us with as much LOX as we’ve
been
using. I think they’ll just say they can’t do it if we ask for that much.”

Ell grinned, “OK, back to ‘Plan A.’ We’ll just fly them with natural gas and air and do it from as far away as it takes to get them up to speed. It isn’t as if we don’t have time to move the comet with about two impactors per day.”
Ell turned to Emma, “Let’s toss this five kilogram rocket through the port to the comet and see what the comet does when we hit it.”

Roger
said, “Wait a minute, why aren’t we just landing a rocket nozzle on the comet and pushing it directly?”

Ell frowned, “
Several
reasons. One, it’s rotating at about one revolution every 5 and a half hours. So, either we’d have to stop the rotation
first
or our rocket would be pointing the wrong direction
most
of the time. We could of course land a lot of rocket motors
on it and fire each one when it’
s pointing the correct direction.
But, t
wo,
it’s
probably
to
some
extent a slushy snowball and we might have a hard time getting a good foundation for the rockets to push on
. Instead they’ll sink
into the slush
until they
hit one of the big fragments in the middle. Three,
it’s a jumble of big fragments that might shift when our rocket started pushing on one of them, then
the rocket
would be pointing the wrong way and have to be moved.
It could even get buried.
Four,
if we hit the comet hard and blow small fragments away
from it
at high enough velocities that they escape
,
the comet’s
mass
’ll be getting smaller and
it’ll be
easier to push.

“But you may be right and it might be better to push it constantly with a series of motors instead of hitting it hard every so often. I think we need to find out through some trial and error. If we whack it with this five kilo rocket we’ll be able to more accurately judge its mass
by measuring
how much it deflects
from
its current orbit
. If it looks like the nucleus is unstable from a small whack like this we may
have
to
work on
plan B.”

Emma’s eyes had narrowed as she considered. “OK,” she said, picking up the rocket. “Let’s launch this bad
boy
.”

Ell said, “Allan, which direction is the comet currently most likely to miss the Earth?”

In her ear she heard him say, “The center of its currently projected course ‘leads’ the earth in its orbit by 12,238 kilometers and
is 5
,
0
69 kilometers
north
.”

First they sent a
“
port rocket
”
through the port on the rocket
that they were using to observe the comet. They had Allan move
the “port rocket”
6
0,000 kilometers
from the comet
the opposite direction
from
the direction
they wanted the comet to be moved
. Next they
popped the five kilogram impactor rocket through. It
happened
to be
that the rocket they had observing the comet at present was already well placed to observe the impact site
so it didn’t have to be moved
.

Accelerating at 5 G
,
it took seven and a half minutes for the rocket to get to 22 kps so Ell called Manuel to talk to him about making more impactors while they waited.

When the impactor hit
,
a huge plume of material burst away from the side of the comet.
Ell said, “Wow, that looked a lot bigger than wh
en the guys hit their asteroid!” She frowned, “
Of course
a metal rich
asteroid is a lot harder than an icy
comet
…
Wait, the asteroid could have been farther away. Allan, display the two impacts
to us again
as if they are being seen from the same distance.”

Displayed at the same magnification the asteroid
was
smaller than the comet and the comet impact plume
was
much bigger, presumably due to the softer material.

“Allan, can you measure deflection yet? If so what is the mass of the comet?”

“Best estimate at present is 298 million metric tons. The estimate will be improved with a longer baseline.”

“Any evidence of instability in the comet nucleus?”

“No.”

“OK,” Ell turned to Emma
and Roger
who’d been patched in to Allan’s responses. “Let’s build some 150 kps impactor rockets.”

Soon she and Emma were working on improving Ell’s circuit for the 150 kps ports and programming the circuit fabricator to build
them
.

Chapter
Ten

As
Epaulding
got up to go to the meeting with the comet team his AI said, “You have an urgent call from Joseph Stein, leader of the team building the motors for the comet rocket.”

He sighed, grabbing his coat, “Put them on.”

“D5R refuses to sell us the ports!” Stein said in a panicked tone.

“Calm down,” Epaulding said soothingly, “Did they say why?”

“Something about new regulations and that they weren’t allowed to sell any until they had the proper permits… They think that will be
months
!”

“Take a deep breath. I’m sure that this is something that can be fixed. I’ll see you at the meeting in about 10 minutes.”

Epaulding
frowned around the room. There was no doubt Candela had assembled some really smart people for this most critical of all projects. Unfortunately, Epaulding thought, they were
all
idiot savants with seriously impaired people skills. No wonder Candela had had a stroke! Their anxiety about the critical importance of the project had them working incredibly long hours and
engaging in “flight of ideas” discussions when together but they weren’t getting much done. They
certainly
weren’t a team. Worse, these geniuses had
been oblivious to
some basic changes brought to their world by Donsaii’s inventions.

The rocket engine people, originally tasked to create a nozzle that would tolerate
extremely
long burns for constant acceleration were still working on that
,
even though the ports
’
22 kps limitation
meant that they would only be firing a short period before they were in danger of going too fast and ruining their ports
. To his dismay they still didn’t have working rocket motors for the craft.