- 3862 - NEW SCIENCE - in “weather” balloons? - Our scientists have so many new capabilities. A new propulsion system could levitate vehicles in the Earth’s upper a atmosphere. This could be a more modern technology to do the same thing as a weather balloon.
------------- 3862 - NEW SCIENCE - in “weather” balloons?
- The
Russians have a helium balloon over our heads today. It can carry much more instrumentation than
our sartellites normally carry. It could
cover much of the electromagnetic spectrum reserved for only military use. And,it could be set to explode if tampered
with.
-
- Meanwhile
our President is dithering!
-
- Sometimes
it’s hard to remember that NASA also does atmospheric research too. While
typically thought of as the province of the “National Oceanic and Atmospheric
Administration” (NOAA), America’s space agency also has a vested interest in
exploring our atmosphere and in the technologies that enable us to do so.
-
- “NASA Institute for Advanced Concepts” (NIAC)
program provided a grant to a team from
the University of Pennsylvania to develop a novel type of propulsion using only
light to collect data in the Earth’s challenging-to-explore mesosphere.
-
- The “mesosphere”
is the part of the atmosphere that ranges from 50 km to 80 km, and it has
several disadvantages for current exploration technologies. It’s too high for
balloons or typical aircraft to reach, making standard high-altitude
exploration technologies impractical.
-
- It’s also
too low for satellites, as their orbit would degrade too quickly in its
relatively thick soup of molecules, making the other typical space-based
sensing platform impractical as well. The only way researchers have been able
to explore it so far is through research rockets that only traverse it for a
few minutes before falling back to Earth.
-
- Enter this
new technology that takes advantage of a phenomenon known as “photophoretic
levitation” to float devices simply by hitting them with light. That propulsion
technology might sound similar to that used on a solar sail, but the delicate
layers of foil used on solar sails would die a horrible death in the Earth’s
atmosphere.
-
- The
photophoretic effect, which has been known for almost a century, uses the
heating of a solid compared to the ambient gas as a lifting force. The photophoretic force creates lift in
structures that absorb light on the bottom yet stay cool on the top.
-
- The new
design relies heavily on the pressure its plates operate in, and it just so
happens that the mesosphere, which ranges in pressure from 1-100 pascals, hits
right in the sweet spot where the lifting action is most effective, creating
enough lift to hold a centimeter-scaled probe in the air, potentially
indefinitely.
-
- Even with
only a few centimeters, there are plenty of miniaturized sensors that could be
packed onto that platform to relay data that had before been accessible only by
research rockets. In fact, those
microfliers could potentially stay aloft indefinitely if the technology was
modified to utilize solar energy and have a day/night cycle where it would
shift from ascending in the day to descending in the night.
-
- The
technology could be modified slightly to enable horizontal thrust, allowing the
sensing platform to travel to any point in the mesosphere using only light as a
propulsion source. Until the Russians
shoot it down.
-
- Did you
know the Earth’s atmosphere extends beyond the orbit of the Moon? Strictly speaking, there aren’t strict
boundaries between Earth and space. Our atmosphere doesn’t just end at a
certain altitude; it peters out gradually.
Our atmosphere extends out to 630,000 km into space. (391,000 miles)
-
- The
“geocorona” is a vast cloud of hydrogen atoms that’s situated where Earth’s
atmosphere merges with space. SOHO has 12 science instruments onboard, and one
of them is called SWAN, (Solar Wind Anisotropies.) SWAN was able to trace the
hydrogen signal from the geocorona and detect its outer boundaries more
precisely than ever before.
-
- Apollo 16
astronauts actually took pictures of the geocorona with the first camera on the
lunar surface, in 1972. But at the time, they didn’t know they were actually
still inside Earth’s atmosphere.
-
- This study
is also all about what’s known as “Lyman-alpha light”. It’s a particular
wavelength of ultraviolet that interacts with hydrogen atoms. The atoms can
both absorb and emit this light. The problem is that inside Earth’s atmosphere,
this light is absorbed. The only way to see the extent of the corona is from
space.
-
- SWAN’s
design allows it to measure the hydrogen atoms in the geocorona, and filter out
or discard the hydrogen atoms in space.
The scientists found that sunlight compresses hydrogen atoms on Earth’s
dayside, and it also produces enhanced density on the night side.
-
- However,
that density is only relative; the dayside dense region has only 70 atoms per
cubic centimeter at 60,000 km above Earth. At the distance of the Moon, there
are only about 0.2 atoms per cc.
-
- The Moon
flies through Earth’s atmosphere. We
were not aware of it until we dusted off observations made over two decades ago
by the SOHO spacecraft. Even though the
geocorona extends far enough to encompass the Moon, it doesn’t mean it would
help space exploration in any way. Though the hydrogen is an extension of the
atmosphere, the density of hydrogen atoms is still so low that it’s pretty much
a vacuum.
-
- On Earth we
would call it vacuum, so this extra source of hydrogen is not significant
enough to facilitate space exploration.
But , it is significant when it comes to exoplanets. For planets with
hydrogen in their exospheres, water vapur is often seen closer to their
surface. That is the case for Earth, Mars and Venus. That fact could be helpful
when trying to determine which exoplanets might have water.
-
- This
extended atmosphere and the ultraviolet in it don’t pose any danger to
astronauts on missions in this region of space. There is also ultraviolet
radiation associated to the geocorona, as the hydrogen atoms scatter sunlight
in all directions, but the impact on astronauts in lunar orbit would be
negligible compared to the main source of radiation – the Sun.
-
- But, there
is always a but, it’s possible that the
geocorona could interfere with astronomical observations performed near the
Moon. This is something that any lunar telescope would have to consider. Space telescopes observing the sky in
ultraviolet wavelengths to study the chemical composition of stars and galaxies
would need to take this into account.
-
- SOHO was
launched in 1995, and has been studying the Sun for over 20 years. It’s still
up there orbiting L1, even though it was designed for a two-year mission. Over
its lifetime so far it has a number of “firsts” under its belt.
-
- SOHO’s SWAN
instrument observed Earth’s geocorona three times between 1996 and 1998. The
team decided to retrieve this data from the SOHO archives and to analyze it
further. This discovery makes us wonder what other discoveries are hidden in
its archives.
-
- New
discoveries in data on the ground with instruments that can not be easily
launched into space.
-
February 4, 2023 NEW SCIENCE
- in “weather” balloons? 3862
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--- Saturday, February 4, 2023 ---------------------------
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