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Science: Planetary Formation, Proteins, SkyLab

By Bob Snodgrass
Posted: 02/08/2021

Present: Howard, Leni, Barbara, Bruce, Sally A, Sharon, Dick, Bob

We had a small, cordial meeting beginning with an attempt to find a new leader. Nobody
wanted the job, so after some debate I said that I could continue my role from Oakland for
the next few months, but certainly not once the village resumes in person gatherings. I can
probably control the scheduling of my medical visits – if something intrudes, Howard
agreed to step in.

Howard presented a list of things that happened on February 8th in previous years,
including Skylab 4’ s return to Earth. The Skylab program began in 1973 and sought to
show that humans could live and work in space for extended periods, and to expand our
knowledge of solar astronomy beyond Earth-based observations. The program was
successful despite mistakes and mechanical difficulties. It was launched May 14, 1973,
sustaining severe damage including loss of function of most of its solar panels. The first
crewed mission, Skylab 2, Launched on May 25th and was able to repair most of the
damage, making the station habitable. Three different 3 man crews, named Skylab 2, 3 & 4
visited the station, Skylab 4 staying the longest, 84 days. That crew returned to Earth on
Feb 8, 1974. There were some difficulties with the space station losing altitude with loss of
the use of one gyroscope, so further human missions were cancelled, even though the
Skylab 5 crew had been assembled. NASA planned to have it available to be pushed or
towed to a higher altitude by one of the first space shuttles in the early 1980s.

However, greater than usual solar activity heated the outer atmospheric layers and
increased drag on Skylab- this had been predicted back in 1973 by a British mathematician,
knowing the sunspot cycle, who predicted a 1979 demise. NASA stuck to its original
predictions and was criticized in 1977 by NOAA for using an inaccurate model for the 2nd
most intense sunspot cycle in 100 years. NASA didn’t give up until December 1978 as it
became certain no shuttle would be ready in time. As the station dipped lower and lower
NASA attempted to have it land in the Indian ocean, but, due to a calculation error, debris
landed in Western Australia in a sparsely populated are between Esperance and Rawlinna
with most debris around Balladonia on July 16, 1979. No human was injured.

This mission had 2 computers, versions of the IBM System/4 Pi, the second for back up.
Each crew member had an HP 35 calculator and multiple slide rules were available
including a circular one at the workstation. Slide rules were extensively used by the Apollo
astronauts, including Moon landings. Most of the slide rules were made by Pickett in Santa
Barbara. The space shuttle had five computers, similar to those on Skylab, and a 2
Honeywell HDC-601computers as engine controllers. Some crew members brought slide
rules on the early Shuttle flights, but no astronaut has admitted using them. Those of us
who used slide rules will remember the superior accuracy but limited portability of the
circular ones.

Howard also brought up the first Trans-Atlantic transmission of Television signals by Baird
Television Development Company in 1928. Scotsman John Logie Baird was a pioneer of
early television. Many other inventors worked on early television. He later brought up
interesting studies of composting wood with urine, from an article in the Economist.

After Howard, Leni brought us much information about owls and had many nice pictures of
owls, but had problems showing them by screen sharing. She mailed those of us in
attendance these nice pictures afterwards.

Barbara brought information about transcription factors which are regulatory proteins
binding to DNA sites either to enhance or reduce gene activity. The default status of
eukaryotic genes is mostly off, hence most TFs activate genes. In prokaryotes, most genes
on, so TFs are typically suppressors. All have DNA binding domains, there are 1500-1800
such proteins produced by humans plus a few dozen noncoding RNAs transcribed from
‘junk DNA’. TFs are significant in gene regulation, but there are additional levels of
regulation, making gene regulation an increasingly complex topic Bruce came in to tell us how he has subscribed to science News Magazine for many years and enjoyed their wide coverage of almost all areas of science. He held up some to show us and his comments on protoplanetary discs were spot on.

I brought a topic new to most people, the details of planetary formation The first exoplanet
was reported in 1988 and only a few were generally accepted in 2000. Now over 5000 are
established, all from nearby galaxies. Because of this, astronomers now believe that almost
all stars have at least one planet. Stars form from a. protoplanetary disc and it seems that
there is always material left over. Stars form from clouds of dust and gas; Supernovae add
enriching elements to space clouds of dust and gas, increase interstellar diversity, and
produce shock waves that compresses clouds of gas to aid new star formation. The
question addressed by recent articles is how and why the different types of planets (rocky,
terrestrial vs gas giants) are formed. My article, emailed to everybody, could not be shown
unfortunately. Here I reproduce the single most informative figure, which is a simulation
supported by spectroscopic and other data from actual protoplanetary discs.

The idea is that the snow line moves in closer to the protosun after about 1 million years,
leaving two very different reservoirs of growing protoplanets. Although our solar system
was born 4.58 bn years ago, other stars with planetary systems were born earlier or later.

Sally, Sharon and Dick joined in with worthwhile comments, but presented no topic.
Our next meeting will be Monday March 8th at 4 PM. We can do better with screen sharing
next time.