Download AOS Mini Vignette

Astronaut Mini-Vignette
Calibrating Weather Instruments on the Weather Pole
The Meteorology Station (or PAM-IV, the weather pole) inside the diorama is a multipurpose
instrument station, containing its own power supply, rechargeable batteries, two antennae (for linking
to other PAM stations and to satellites) and numerous sensors for detecting Mars conditions. (For the
specifics of the environmental variable measured, typical values recorded at CCBS, the image of the
instrument and a brief explanation of how it works, see chart below.) PAM stands for Portable
Automated Mesonet, a compact design patterned after similar robotic weather stations placed in remote
sites on Earth. According to the backstory, there are many other PAM stations deployed at numerous
locations on the Martian surface, and connected together via microwave transmitters. These stations,
including the site where the dusting vignette laser is located, are PAM-I, PAM-II and PAM-III.
Mesoscale refers to regional sized events such as windstorms as opposed to global weather or strictly
local changes.
What the AOS does
Equipment needed:
DCD, OCC, temperature probe (AKA the omni-probe)
Activity:
(Note: This is not a stand alone vignette; it is a short activity that you can tack onto any vignette.)
The stage business for this mini-vignette.
1. AOS goes down to the meteorology station (weather pole) on the side nearest the glass.
2. AOS removes the coiled gray cord (located behind the large solar panel) which is wrapped
around two cleats on the vertical support pole.
3. AOS inserts the plug attached to the gray cord into one of the dummy ports on the DCD.
(DON’T use the first port, the one highlighted in red; it will short out the DCD!)
4. AOS explains that he/she is either downloading data from the instruments or calibrating one
of them. Be sure to use specifics and acronyms of the weather instruments. For these details,
see below.
5. AOS discusses the network of connected weather stations, of which this is one. AOS then
uses the laser button on the OCC to illustrate where the outlying station is. For consistency,
let’s call this one PAM-III.
Reminder about the purpose of the jargon and acronyms:
The AOS needs to incorporate just enough technical jargon and acronyms to make the stage business
seem realistic, but not so much that it confuses or overwhelms the audience. It might be a good
strategy to pick one instrument on the pole and concentrate on it, so that you will not overdo the
technical bit, but can still use the specifics that support realism.
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Calibrating Weather Instruments on the Weather Pole
Integrating this activity into vignettes.
TRY THIS:
Have the AOS BUDDY break into the conversation near the beginning or at a lull and say,
“Magoo, this is base station. I’m going to have to reboot PAM-IV. Can you retrieve the data
from the Tavis barometer for me before I take it off line?” AOS says yes, and does the above
stage business. As data is downloading into the DCD, this is a good opportunity to talk about
weather and environmental conditions on Mars.
OR TRY THIS:
AOS starts the vignette by saying something like, “Nikko asked me to re-calibrate this digital
hygrometer. It’s been giving some us weird data this morning, and he thinks that dust storm last
night may have damaged it.” AOS says that the DCD has a probe for that he/she can use to
check it against. AOS holds up omni-probe and “checks its reading” against the corresponding
instrument on the PAM-IV. AOS communicates with base station about the need to bring the
instrument in, or else says, it’s fine.
Scientific background
The visible sensors on the PAM-IV measure these variables:
Environmen
tal Variable
measured
Temperature
Typical Values
Image on PAM-IV Inside
Diorama
highs tend to be about +8
o
F, lows: minus 110 oF
Measures both Temperature
and pressure
How this instrument
works
Temperature is measured
by thin wire
thermocouples.
Thermocouples work
because when two
different metals are joined
together they produce a
characteristic electrical
signal (voltage) as their
temperature varies. The
two metals used are
chromel and constantan.
Each one degree
(centigrade) variation
produces a change of 60
millionths of a volt.
Calibrating Weather Instruments on the Weather Pole
Wind speed
and
direction
Barometric
pressure
Wind direction– winds
tend to blow mainly from
northwest to southeast
through Candor Chamsa.
(This is from stage left to
stage right.) This is
consistent with the wind
tails that you see upstage
flowing behind the rocks on
the ground.
Wind speed– Winds are
typically just a few miles
per hour in the morning,
rising to perhaps 10 to 15
m.p.h. (16 to 24 kms.) at
night Winds have been
strongest in the early
morning hours and
relatively strong around
noon. The lightest winds
have been seen in late
afternoon and early evening.
As on Earth, solar heating
causes the atmosphere of
Mars to expand during the
day and contract at night.
But there are also seasonal
variations. Pressure on Mars
averages 6.75 millibars: sealevel pressures on Earth are
about 150 times greater
(1013.25 millibars.)
Pressure changes on a daily
cycle: minimums are found
near 4:00 a.m. and 6:00
p.m., and maximums near
Measures both Temperature
midnight and 10:00 a.m.
and pressure
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The wind sensor uses six
hot wire elements. The
differential cooling and
heating effects of wind
blowing over these
detectors, as well as
variations from side to
side, are transformed into
measurements of speed
and direction.
Pressure is measured by a
Tavis magnetic reluctance
diaphragm sensor, just as
on Viking. This sensor is
similar to an eardrum,
which is a very sensitive
device to detect minute
changes in air pressure.
The difference here is that
movement of the
membrane disturbs a
magnetic field which can
be detected as electric
current.
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Calibrating Weather Instruments on the Weather Pole
H2O
(Relative
Humidity)
and CO2
levels
Martian humidity varies
daily as on Earth, but
Martian air is 100 to 1000
times drier than Earth’s
atmosphere. Even the
Sahara desert on Earth has
more humidity than Mars.
As on Earth the cause of
humidity changes is changes
in temperature and
movement of air masses
from one locale on Mars to
another.
CO2 levels change by a
range of 30% overnight due
to frosting out of CO2 in the
form of dry ice in as
overnight temperatures
plunge below minus 78 oC,
the freezing point of CO2.
measured
spectroscopically, that is,
with beams of well
selected light at certain
wavelengths. The amount
of absorption of the preselected beams indicates
the amount of a target gas.
Other measurements and instruments not on the visible part of the MET that would likely be used on
Mars.
Environment
-al Variable
measured
Airborne
Magnetic
Dust
Collection
Typical Values
DCD
antenna
Data from the AOS’s DCD
is sent to this antenna
where it can be relayed to
the Hablab main frame
computer.
Dust particles have been
found from local rocks as
well as from sources
1000’s of km away.
Image on PAM-IV (or elsewhere)
Inside Diorama
How this instrument
works
Dust particles are
collected by magnets
for microscopic
analysis to determine
how wind erosion
works on Mars. By
examining the
chemical composition
of the dust grains, we
can learn where on
Mars they originated
Sends data via the
microwave region as
cell phones do on
Earth.
Calibrating Weather Instruments on the Weather Pole
LAN &
MET
antenna
(LAN –
Local Area
Navigation.
MET –
Meteorologic
al Station)
Solar panel
Rechargeable
batteries
This forked antenna
electronically links the
outlying meteorological
stations MET-2, MET-3
and MET-4 on the low hills
in the mid ground between
the CCBS and the high
butte 12 miles away.
Must have 3.4 times more
surface area as an
equivalent solar panel on
Earth because Mars, being
father from the sun,
receives only 42% of the
light that the Earth does.
Also, the extinction
coefficient (a measure of
the light scattering ability
of air) is 1.4 times higher
on Mars due to chronic
suspended dust.
On each mission, new
technologies are constantly
being tested under
operational conditions on
Mars. The batteries seen in
the diorama are being
tested for future use in the
field.
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Also uses microwaves,
but a different
frequency that the
DCD.
“PAM” on the
batteries stands for
“Portable Automated
Mesonet”
Mesoscale refers to
regional sized events
such as windstorms as
opposed to global
weather or strictly
local changes.
In addition to the above instruments, the top of the mast above the eave of the Hablab contains more
instruments for measuring these variables.
Atmospheric
opacity
(local)
Atmospheric
opacity
(high altitude)
UV radiation
level
Varies due to wind. High opacity means less
light. Typical values are 70% of a clear day on
earth.
On a clear Martian day, only 70% of the sunlight
arriving at the top of the Martian atmosphere
reaches the ground.
Measured by extinction of a laser
beam through a measured path of
air.
This number varies greatly due to
high level clouds and dust driven
by the strong seasonal winds. PIC
is targeted on the sun during the
day and on Phobos at night.
Without an ozone layer, the Martian atmosphere
Photocells specific to a prelets in harmful UVB (280-315 nm) and UVC
determined wavelength record UV
(200-280nm). The DNA damage potential is 1000 intensity by converting it to a
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Calibrating Weather Instruments on the Weather Pole
Galactic
cosmic
radiation
(GCR)
Solar
energetic
particle
events (SEP)
Cloud cover
Wind
turbulence
x that of Earth.
Galactic cosmic rays (GCRs) come from outside
the solar system but generally from within our
Milky Way galaxy. GCR levels on Mars are
higher than Earth because Mars lacks a magnetic
field and has a thinner atmosphere than Earth.
The magnetic fields deflect GCR towards Earth’s
pole. The thicker terrestrial atmosphere absorbs
some GCR before it reaches the ground.
Solar flares release high speed particles that reach
the Martian surface more easily than the same
particles can reach Earth because Earth’s thicker
atmosphere serves as a natural shield.
voltage difference.
GCRs are atomic nuclei from
which all of the surrounding
electrons have been stripped away
during their high-speed passage
through the galaxy.
Martian skies often have morning and evening
clouds. The dramatic sunset images are
impressive, but to scientists the high, early
morning wispiness is just as fascinating. These
may be carbon dioxide clouds, formed overnight
when temperatures plummet and dispersing as the
atmosphere warms up.
Martian wind varies, but wind near the station
tends to be broken up by the Hablabs, so we see
more turbulence here than in flatter areas.
Imaged with the PIC*.
Sources
NASA’s Mars Exploration Program
http://mpfwww.jpl.nasa.gov/
Pathfinder as a Martian Weather Stationhttp://wwwk12.atmos.washington.edu/k12/mars/MPF_short_facts.html#pip40
Description of Mars Pathfinder weather instruments
http://mars.jpl.nasa.gov/MPF/mpf/sci_desc.html
Ultraviolet Radiation on the Surface of Mars
http://mars.jpl.nasa.gov/mgs/sci/fifthconf99/6128.pdf
When traveling outside the Earth’s
magnetic field, astronauts in space,
including a 6 month trip to Mars,
would have to be shielded from
SEP’s
*PIC is the Primary Imaging
Camera)
Three wind socks are located at
various heights on the
meteorology mast to determine the
speed and direction of winds. The
wind socks are imaged repeatedly
by the PIC. The orientations of the
wind socks are measured in the
images to determine the wind
velocity at three heights above the
surface.