- 3854
- MARS WEATHER
- reports sent back? Mars' weather is proving to be turbulent
and diverse over the Perseverance rover's landing site in Jezero Crater. NASA's Perseverance rover is dotted with
various weather sensors, collectively called the Mars Environmental Dynamics
Analyzer (MEDA), which cover the rover's neck and deck; some are also housed in its interior.
-------------------- 3854 - MARS WEATHER - reports sent back?
- Scientists have now released MEDA's weather
report for the project's first 250 sols (Martian days, which are each about 40
minutes longer than an Earth day), and the findings describe a surprisingly
dynamic atmosphere near the Red Planet's surface.
-
- MEDA includes five button-sized sensors
that routinely measure the Martian air temperature at four different altitudes
to create a vertical temperature profile; two wind-speed sensors; and
additional sensors to measure radiation, dust, humidity and air pressure.
-
- Spanning the Red Planet's northern
hemisphere spring into early summer, the results focus on the "atmospheric
surface layer (ASL)", the lower layer of Mars' atmosphere that is in
contact with the planet's surface. Heat and mass in the form of dust are
exchanged between the surface and the ASL, with each region affecting the
other.
-
- Perseverance measured the average air
temperature at Jezero to be minus 67 degrees Fahrenheit, but this can vary by
as much as 90 to 110 degrees F, particularly between day and night.
-
- Air pressure also fluctuated, both daily
and more noticeably on a seasonal basis as the carbon dioxide frost at the
poles sublimated in the early summer "heat," bolstering the thin
atmosphere.
-
- The pressure and temperature of Mars' atmosphere
oscillate with periods of the Martian solar day … following the daily cycle of
sunshine greatly influenced by the amount of dust and the presence of clouds in
the atmosphere.
-
- As the daytime sun warms the surface and
lower atmosphere, pockets of air begin to rise, creating gentle turbulence that
leads to some of the observed temperature fluctuations. The turbulence stops in
the evening as the sun sinks down toward the horizon and solar heating drops
off, allowing the air to settle, at least for a short time.
-
- Then, Perseverance often measured
instability returning to the ASL at the equivalent of about 2 a.m. local time
on Mars. Similar returning instability was also witnessed by NASA's InSight
lander, which ended its mission in December after four years on the Red Planet.
-
- MEDA has now confirmed that this is the
result of the warm surface of the local terrain, enhanced by winds with gentle
speeds to 6.5 to 13 feet per second driven by differences in the temperature of
the surface.
-
- MEDA measured a daily wind cycle, with
strong south-easterly gusts of 82 feet per second around midday, weaker winds
of 23 feet per second in the afternoon, a wind-direction reversal at night, and
no winds at all between 4 a.m. and 6 a.m. local time. Seems funny to have local time on another
planet.
-
- Previous findings have shown how
Perseverance has detected dust devils passing over the rover and the
accompanying change in air pressure.
-
- The dust devils are more abundant at Jezero
than elsewhere on Mars, and can be very large, forming whirlwinds more than 100
meters in diameter. With MEDA we have been able to characterize not only their
general aspects their size and abundance but also to unravel how these
whirlwinds function.
-
- Understanding Mars' present-day atmosphere
is important not just because of scientific curiosity. It can also affect
missions landing on the planet. In addition, the 10 sample canisters left on
the ground by Perseverance as it trundles around Jezero Crater will be
constantly exposed to the atmospheric conditions for many years; the future
mission meant to retrieve them is currently scheduled to land on the Red Planet
in 2031.
-
January 30, 2022 MARS WEATHER
- reports sent back? 3854
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“Jim Detrick” -----------
--------------------- --- Wednesday, February 1, 2023 ---------------------------
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