[meteorite-list] Mars Missions to Pause Commanding in June, Due to Sun

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 3 Jun 2015 16:58:13 -0700 (PDT)
Message-ID: <201506032358.t53NwDpD006172_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?feature=4611

Mars Missions to Pause Commanding in June, Due to Sun
Jet Propulsion Laboratory
June 3, 2015

Fast Facts:

* In June 2015, Mars will pass almost directly behind the sun from Earth's
perspective, a geometry called Mars solar conjunction.

* Mars solar conjunction happens about every 26 months.

* Because the sun disrupts radio transmissions between Earth and Mars
during conjunction, communications are curtailed.

In June 2015, Mars will swing almost directly behind the sun from Earth's
perspective, and this celestial geometry will lead to diminished communications
with spacecraft at Mars.

The arrangement of the sun between Earth and Mars is called Mars solar
conjunction. It occurs about every 26 months as the two planets travel
in their sun-centered orbits. The sun disrupts radio communications between
the planets during the conjunction period. To prevent spacecraft at Mars
from receiving garbled commands that could be misinterpreted or even harmful,
the operators of Mars orbiters and rovers temporarily stop sending any
commands.

The teams running NASA's three active Mars orbiters and two Mars rovers
will refrain from sending commands to their spacecraft from about June
7 to June 21. During that period, the sun will be within two degrees of
Mars in Earth's sky. (Don't try to look, though, because looking at the
sun is dangerous to the eyes.) The operators also will put restrictions
on commanding -- such as using only reduced data rates or communicating
only in an emergency -- during the days before and after that period.

Spacecraft will continue making some science observations during the conjunction
period, though rovers will not do any driving or arm movements.

"Our overall approach is based on what we did for the solar conjunction
two years ago, which worked well," said Nagin Cox, a systems engineer
at NASA's Jet Propulsion Laboratory, Pasadena, California, who is leading
conjunction planning for NASA's Curiosity Mars rover. "It is really helpful
to have been through this before."

NASA's MAVEN spacecraft, which arrived in Mars orbit last September, will
be experiencing its first solar conjunction. Its team has prepared thoroughly.
MAVEN -- short for Mars Atmosphere and Volatile Evolution -- will continue
monitoring the solar wind reaching Mars and making other measurements.
"The data will be stored and transmitted back to us after communications
are reestablished at the end of the solar conjunction period," said James
Morrissey, MAVEN deputy project manager at NASA's Goddard Space Flight
Center, Greenbelt, Maryland.

Transmissions from NASA's two other Mars orbiters -- Mars Odyssey and
Mars Reconnaissance Orbiter -- will continue through the conjunction period,
but some of those transmissions are not expected to reach Earth. Science
data transmitted during conjunction will also remain stored aboard the
orbiters, for reliable retransmission in late June. The active Mars rovers
-- Curiosity and Opportunity -- will send limited data to orbiters throughout
conjunction for relay to Earth during and after conjunction.

Mars Odyssey, which reached Mars in 2001, will be in its seventh solar
conjunction. For Opportunity and Mars Reconnaissance Orbiter, the 2015
solar conjunction is the sixth and fifth, respectively.

In preparation for conjunction, orbiter and Curiosity mission teams have
been clearing some science data from spacecraft memories to optimize availability
of memory for storing science data during the conjunction period. Data
that Opportunity collects and sends daily to orbiters will be kept on
the orbiters for replay after conjunction. No conjunction-period data
from Opportunity will be kept on the rover. Opportunity will operate during
conjunction in a mode avoiding use of non-volatile flash memory, the type
of memory that can retain data when the rover powers down overnight.

A video showing Mars solar conjunction geometry is at:

http://mars.nasa.gov/allaboutmars/nightsky/solar-conjunction

NASA's five current missions at Mars are preparing the way for human-crewed
missions there in the 2030s and later, in NASA's Journey to Mars strategy.

NASA's Goddard Space Flight Center manages the MAVEN project for the principal
investigator at the University of Colorado, Boulder, and for the NASA
Science Mission Directorate, Washington. JPL, a division of the California
Institute of Technology in Pasadena, manages the Odyssey, Reconnaissance
Orbiter, Opportunity and Curiosity projects, and NASA's Mars Exploration
Program, for the Science Mission Directorate. Lockheed Martin Space Systems,
Denver, built all three NASA Mars orbiters. For more about NASA's Mars
Exploration Program, visit:

http://mars.jpl.nasa.gov

http://www.nasa.gov/mars


Media Contact

Guy Webster
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278
guy.webster at jpl.nasa.gov

2015-190
Received on Wed 03 Jun 2015 07:58:13 PM PDT