Historian’s Corner (Jan. 2010)
By: Ben Clark
(BENCLARK@COMCAST.NET)
MGS is Dead. Long Live MGS !
Our Mars Global Surveyor (MGS) mission was born out of the ashes of a
failed mission, the Mars Observer (M.O.) spacecraft, which went silent
before reaching Mars in the summer of 1993. M.O. was built by GE
Astro Space and launched just as Martin Marietta bought that division
from General Electric. NASA and JPL quickly initiated studies
seeking an affordable path forward. Fortunately, some science
instruments had significant residual hardware, and most of the
spacecraft’s black boxes existed as flight spares. Contracts were
awarded to eight aerospace institutions, and from feasibility studies a
low-cost approach was crafted. All but two instruments would be
hosted on a new spacecraft, using a streamlined “Faster, Better,
Cheaper” approach. We competed and we won. MGS was to be
developed on a fast-track and launched in October 1996, only slightly
more than 3 years after the sudden demise of M.O.
Our team succeeded in designing a spacecraft which could squeeze out
the maximum science by switching from an aluminum body to
graphite-epoxy honeycomb structure; saving more mass by
accomplishing the first aerobraking at Mars; by instituting dual-mode
propulsion; and by providing the capability to point simultaneously in
three directions – solar arrays toward the sun, instruments looking
down at Mars, and antenna tracking Earth. The failure of a damper
caused an excessive deployment force and structural damage to one of
the solar wings after launch. An innovative method of flying the
mission saved the day.
The magnetometer
experiment not only verified that Mars’ magnetic field is virtually
non-existent now, but revealed evidence for an ancient field stronger
than ours, preserved as “magnetic stripes” in crustal rocks. This
discovery was announced by the Vice-President of the United States, Al
Gore, in a press conference on Sept. 17, 1997, in which he stated "Mars
Global Surveyor has been in orbit for only a few days, yet it already
has returned an important discovery about the red planet. This is
another example of NASA's commitment to faster, better, cheaper Mars
exploration . . .”
The TES mapping spectrometer
discovered deposits of crystalline hematite mineral in the plains of
Meridiani. As a result, the MER rover “Opportunity” was targeted
to land there. Only weeks after landing, Opportunity accomplished
the primary goal of both rover missions. A press conference held
in March 2004 revealed to the world that the MGS/TES discovery was
indeed the smoking gun evidence for pools of actual liquid H2O in
previous times on Mars. Amazingly, the gray hematite is in the
form of trillions of BB-sized spheres, called “blueberries” by the
rover team.
The MOC camera on MGS has
discovered incredible amounts of layering in various terrains and
thousands of “gullies” that occur on steep slopes of crater
walls. Overall, MOC returned more than 240,000 high-resolution
images.
The MOLA laser altimeter generated a
topographic map of the surface of Mars more detailed, comprehensive,
and accurate than for any other body in the solar system. It aso
discovered a huge expanse of the northern hemisphere that has some of
the flattest terrain in the solar system. Although still
controversial, the possibility of a former martian ocean remains under
study. All four discoveries have great significance --
mind-bending new knowledge about the red planet.
Our first study of a successor to refly instruments from M.O. was led
by Terry Gamber in my Advanced Missions group. Ed Dorrah was the
original Proposal Manager for the RFP, but Jim McAnally as head of
Denver Space Systems designated Bud McAnally under Noel Hinners as the
program manager, telling the JPL customer during Orals this program was
so important that he was assigning his own brother to lead it.
The heroes of MGS, of course, are not only all of the above and our JPL
partners but most of all the several hundred employees in Denver who
brought to the program intense levels of dedication and talent.
MGS was developed in a record 26 month time period, with miniscule
growth in cost and mass. Almost exactly 10 yrs after launch but
far beyond its design life, MGS finally ceased operations in November
2006, due to a ground command error, after persistent decreases in
budgets while attempting to maintain complex operations. MGS
discoveries are still being folded into the results of other Mars
missions, providing a scientific legacy for decades to come.