Orbiters Allow Us to Understand the Planet as a Whole
Orbiters circling Mars have shown us that Mars, though hostile, has
many similarities to Earth: canyons, volcanoes, craters, gullies and runoff
channels, clouds, weather patterns, rocks, hills, polar ice caps, eclipses,
and more. They've revealed a wealth of information about the red
planet's atmosphere, landforms, gravity, magnetic fields, elemental and
mineral composition, internal structure, and weather.
Orbiters on future missions will examine the planet's environment
even more precisely. They will search for evidence of water's existence
both now and in the past, on the surface and underground. The history
of water is key to all four science themes
of the Mars Exploration Program: climate, geology, life, and preparation
for human exploration.
Orbiters will also help identify scientifically interesting sites on the
surface for further investigation and provide a knowledge of large
rocks and other hazards at landing sites to be avoided.
Orbiters Can Assist in Communications and Navigation
Orbiters will also play a key role as communications relays for
rovers, landers,
balloons, and airplanes.
For instance, it won't be practical for rovers, busy navigating hazardous
terrain, to point their small antennas towards faraway Earth and transmit
information. Instead, it will be easier for the rover to send data to a
Mars orbiter, which in turn will precisely point a large antenna at Earth and
communicate large volumes of images and other data.
Orbiters can also assist with navigation of other spacecraft approaching
Mars. For example, Mars Reconnaissance Orbiter
will carry a test camera that pinpoints the position of approaching
spacecraft, helping navigators back on Earth know exactly how to direct
the spacecraft for precision orbit insertion and landing.
Orbiters Can Assist with Sample Returns
Orbiters may also play a vital role in returning samples
from the surface of Mars. Just as it is not efficient to communicate large
volumes of science data directly from the Martian surface to Earth, it is
not practical to launch a rocket containing samples from the Martian
surface and expect it to navigate itself back to Earth and land safely.
Instead, the preferred solution is to launch a small canister containing
samples into orbit around Mars, have an orbiter rendezvous with and
capture the canister, and then eject the spacecraft from Mars orbit
back towards Earth.
See the technology section for information
on technologies that will expand the capabilities of orbiters in the future,
including propulsion and remote sensing.
