Mission Planners
Mission Planners compare different strategies for meeting goals and
analyze the costs and benefits of each approach. One approach may
be faster and cheaper-but more risky! Another may be very reliable
but much more expensive. Yet another may be cheap and safe but take
too long. Once a basic strategy has been chosen (such as the innovative
new MGS aerobraking maneuver) more detailed planning begins. This
includes schedules for design, construction, launch and operation
of the spacecraft; detailed planning for the package of science instruments;
discussions about the inevitable trade-offs between competing requirements.
What will be required to make the best use of each instrument? What
are the most important observations? The most difficult? How will
information be returned to Earth and analyzed? Every aspect of the
mission must be studied, understood and incorporated in a Mission
Plan.
Project Managers
These specialists create budgets and schedules for the entire project.
How many people are required for each task? How long will it take?
Where will the spacecraft be built? (MPF is built at JPL, but MGS
at Lockheed Martin Astronautics (in Denver). Who will be responsible
for the launch vehicle? (McDonell Douglas builds the Delta IIs,
the Air Force is responsible for launching them from Cape Canaveral,
and then handing off control to JPL, which communicates with the
spacecraft via the Deep Space Network, which has huge radio dishes
in the Mojave desert, California, Spain and Australia.) How will
components be tested? Who will monitor the "health and safety" of
the spacecraft? Many of these are engineering questions, but all
have cost and schedule implications and each issue is just a small
part of a far larger puzzle that must ultimately fit together perfectly.
Managers must choose particular people and personalities for each
task, ensure that the required equipment is available at the right
time, and monitor progress in each activity area.
The Science Team
This team will have specific detailed science objectives and a "wish
list" for the types of instruments that will precisely answer their
questions. Some will study radiation, the fields and particles that
permeate space. Others will call for images of different wavelengths
in the electromagnetic spectrum (visible light, infrared, ultraviolet,
etc.)
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Engineering Teams
These teams will be concerned with how much power each instrument
needs, and how much it weighs. Is the device sensitive to heat or
cold? Will radiation affect the measurements? How precisely will the
device need to be aimed? Does its operation affect other spacecraft
systems? What if some component fails? Can there be a backup or alternative
procedure?
The Navigation Team
This team must precisely calculate the position and movement of
the spacecraft and its target, then specify changes in attitude
via thruster firings. In the case of Pathfinder, navigation also
includes remotely "driving" a roving vehicle that is millions of
miles away and up to 19 minutes in the past! It takes that long
for a radio signal, traveling at the speed of light, to get from
Mars to Earth, so the "Nav" team has to be sure they're not going
to drive over a cliff before they can order the rover to stop or
turn.
"OPS" Team
Specialists responsible for Flight Operations and Spacecraft Systems
formulate the coded electronic commands that tell the spacecraft
exactly what to do and when to do it. They also monitor each subsystem:
propulsion, power, communications, guidance and control. All operations
are controlled by computers that may receive pre-programmed commands
months in advance. But complex systems often behave in surprising
ways and the "Ops" Team must be prepared to respond immediately
to unexpected developments.
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