[meteorite-list] Prolific Mars Orbiter Completes 50, 000 Orbits (MRO)

[Ron Baalke]

https://www.jpl.nasa.gov/news/news.php?feature=6800

Prolific Mars Orbiter Completes 50,000 Orbits
Jet Propulsion Laboratory
March 29, 2017

The most data-productive spacecraft yet at Mars swept past its 50,000th 
orbit this week, continuing to compile the most sharp-eyed global coverage 
ever accomplished by a camera at the Red Planet.

In addition, the spacecraft -- NASA's Mars Reconnaissance Orbiter (MRO) 
-- recently aided preparations for NASA's next mission to Mars, the InSight 
lander. Insight will launch next year on a mission to study the planet's 
deep interior. Meanwhile, the orbiter continues diverse science observations 
of Mars and communications-relay service for two active Mars rovers, Curiosity 
and Opportunity.

MRO's Context Camera (CTX) exploits a sweet spot in the balance between 
resolution and image file size. With a resolution of about 20 feet (6 
meters) per pixel in images of the Martian surface, it has provided a 
library of images now covering 99.1 percent of Mars. That is approximately 
equivalent to the land area of Earth. No other camera ever sent to Mars 
has photographed so much of the planet in such high resolution.

The Context Camera has taken about 90,000 images since the spacecraft 
began examining Mars from orbit in late 2006. Each one reveals shapes 
of features down to sizes smaller than a tennis court, in a swath of ground 
about 18.6 miles (30 kilometers) wide.

"Reaching 99.1-percent coverage has been tricky because a number of factors, 
including weather conditions, coordination with other instruments, downlink 
limitations, and orbital constraints, tend to limit where we can image 
and when," said Context Camera Team Leader Michael Malin of Malin Space 
Science Systems, San Diego.

In addition to observing nearly the entire planet at least once, the Context 
Camera has observed 60.4 percent of the planet more than once. These observations 
aid science directly and also certify the safety of future landing sites.

Malin said, "Single coverage provides a baseline we can use for comparison 
with future observations, as we look for changes. Re-imaging areas serves 
two functions: looking for changes and acquiring stereoscopic views from 
which we can make topographic maps."

A dramatic type of change the Context Camera has documented more than 
200 times is a fresh impact crater appearing between the times of two 
observations. These images enabled scientists to calculate the rate at 
which small asteroids, or bits of comets, are colliding with Mars. Some 
of the fresh impacts reveal white material interpreted as water ice. The 
latitudes and estimated depths of the ice-exposing craters provide evidence 
about the distribution of buried ice near the surface. MRO's Shallow Radar 
has found ice farther underground, but this very shallow ice would go 
undetected if not for its exposure by impacts.

One of MRO's other cameras, the High Resolution Imaging Science Experiment 
(HiRISE), can zoom in on the new impact craters found by the Context Camera. 
For some of these craters, HiRISE and MRO's Compact Reconnaissance Imaging 
Spectrometer for Mars have confirmed the presence of water ice. However, 
even though MRO has returned more than 300 terabits of science data, the 
much higher spatial resolution of HiRISE has limited its coverage of Mars' 
surface to about three percent. A third MRO camera, the Mars Color Imager, 
observes almost the entire planet every day to track weather change. Another 
instrument, the Mars Climate Sounder, records vertical profiles of the 
atmosphere's temperatures and suspended particles.

The spacecraft was launched Aug. 12, 2005. It entered an elongated orbit 
of Mars in March 2006, then spent several months using friction with Mars' 
upper atmosphere to revise its orbit. Since beginning its science operations 
in November 2006, MRO has been flying near-polar orbits lasting about 
two hours, at altitudes from 155 to 196 miles (250 to 316 kilometers). 
The mission completed its 50,000th orbit on Monday, March 27.

"After 11 and a half years in flight, the spacecraft is healthy and remains 
fully functional," said MRO Project Manager Dan Johnston at NASA's Jet 
Propulsion Laboratory, Pasadena, California. "It's a marvelous vehicle 
that we expect will serve the Mars Exploration Program and Mars science 
for many more years to come."

On March 22, the mission made the latest adjustment to the orbit, with 
a 45.1-second burn of six intermediate-size rocket engines, each of which 
provides 5 pounds (22 newtons) of thrust. This maneuver revised the orbit 
orientation, so that the spacecraft can be at the right place at the right 
time, on Nov. 26, 2018, to receive critical radio transmissions from NASA's 
InSight Mars lander as it descends to the surface.

MRO has already provided more than 60 images from HiRISE for advance analysis 
of the landing region for InSight. In a broad plain of the Elysium Planitia 
region of equatorial Mars, InSight will use a seismometer and heat probe 
to examine the interior of Mars to better understand the formation process 
of rocky planets like Earth. The final MRO image for assessment of this 
landing area will be taken Thursday, March 30.

For additional information about Mars Reconnaissance Orbiter, visit:

http://nasa.gov/mro

For additional information about InSight, visit:

http://www.nasa.gov/insight

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

Laurie Cantillo / Dwayne Brown
NASA Headquarters, Washington
202-358-1077 / 202-358-1726
laura.l.cantillo at nasa.gov / dwayne.c.brown at nasa.gov

2017-094