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

[Ron Baalke]

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