8/1/2001:
Tonight, for the August 2 science news, I'm
going to change the format once again to a layout that I think
will improve it for everyone. I have been stockpiling news items
so that on the weekends, I could present 50 new articles a day
when nothing was coming in. I've also squirreled away what seemed
to me to be some of the more interesting articles so that the
weekends wouldn't be a letdown. The problems are
(1) I'm accumulating articles faster than I can I can publish
them, including some of the more interesting articles that never
see the light of day;
(3) some of the news becomes stale before it"s presented;
and
(2) I'm making more work for myself by copying articles to a backlog
page and then re-copying them to the Science News page.
Consequently, what I'm going to do, beginning
tonight, is to present all the articles I collect each day, however
many that may be, and then issue on weekends whatever I find.
There are some weekend updates, and I'll publish those, but it
means that the number of articles won't be fixed, but will fluctuate
from day to day, depending upon how much is available. This should
have the benefit of providing you with more, and more timely news.
Anyway, we can try it and see how it works.
Tonight, I'm including a part of my backlog,
so there will be a greater number of articles in tonight's news
than usual. Hope you enjoy them!
7/31/2001: The "Word(s)
of the Day" have been modified to make them multiple choice
so that over time, they can contribute to vocabulary quizzes..
7/30/2001:
On the 24th
of June, I mentioned,
" 6/24/2001:
"A couple of years ago, NASA's Marshall Flight Center conducted
a "tethered satellite" experiment employing a 20-kilometer-long
wire to generate electricity using the Earth's magnetic field.
Before the wire was fully deployed, it mysteriously snapped in
two. Tonight, I ran into Dr, Nobie Stone, the scientific principal
investigator for the project, and my former co-worker. Nobie told
me that the reason the tether broke was because of the 3,500 volts
it had generated.. Although the Earth's magnetic field is small---0.5
gauss---the tether is so long---2,000,000 centimeters---and the
satellite moves so fast---8 kilometers or 800,000 centimeters---per
second, that high voltages, and kilowatts of power can be generated.
The wire was about 1/16th of an inch in diameter, and was insulated
with teflon. At some point, as the onboard winch was unreeling
the wire, a spot on the wire with a nick in its teflon insulation
passed through the eye of the cross-feeder that was paying out
the wire. With 3,500 volts on the wire, a dielectric breakdown
occurred. An arc formed, with about 1 ampere of current flowing
from the wire back to the satellite. The teflon vaporized and
formed a plasma, which finished the job of melting the wire.
"At that point, our conversation was interrupted. As he turned
away, Nobie mentioned that you could run current the other way,
into the wire, and use it as an electric motor to propel the wire
(and presumably, the satellite). I didn't get a chance to ask
about the logisitcs of the situation, but I will the next time
I see him. How practical is this for spacecraft propulsion, and
if it's very practical, what are NASA's plans for employing it?
(It would transfer momentum to the Earth through the Earth's magnetic
field.) "
I called Nobie that night
but didn't hear back from him. Last week, his wife, Margaret,
explained that they had had to rush Nobie's 90-year-old aunt to
the Emergency Room that night, and that's why he didn't call me
back. Tonight, I asked him about using a tether as an electric
motor in the Earth's one-half gauss magnetic field to accelerate
a satellite out of Earth orbit. Nobie explained that it can possibly
be done. It requires hanging weights on both ends of the wire
so that it will remain upright and taut during the acceleration,
with the lower weight feelng a slight net-gravitational- orce
and the upper weight responding to a slight net-centrifugal force.
He said that it's not one of the most hotly-pursued propulsion
technologies, but that it is in the running.
Sorry.
Haven't had time for additional "Colonizing
Mars" updates
today.
Dan Thompson has finished his "Sherlock
Holmes Adventures on the Red Planet" story. As you'll soon see, Dan is an accomplished
author, illustrator, and much more. His stories on his "Mars"
website are only the tip of the iceberg.
7/29/2001:
Tonight's updates to "Colonizing
Mars" are shown in green.