The solar panel?
Technical information.
Data transmission speed
What happened to Mars Observer?
Surveyor instruments.
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Mission to Mars. The solar panel? Technical information. Data transmission speed What happened to Mars Observer? Surveyor instruments. |
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Mars Global Surveyor entered Mars orbit with a small propulsion maneuver which made Surveyor orbit Mars in an elliptical capture orbit. Surveyor will aerobrake into the Mars atmosphere using its solar arrays with drag flaps on them, to reach mapping orbit. This will decrease Surveyors speed and lower its orbit.
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During aerobraking in october 1997 the solar panel that was not fully deployed moved past what would have been its fully deployed and latched position. This occured on october 6 when the martian atmosphere unexpectedly doubled in density. The solar panel showed signs of even further movement. This meant that mapping orbit would be delayed, it would no be reached until March 1999, one year behind schedule.
In its new elliptical orbit, the craft flew much closer to Mars surface than originally intended, coming within 75 miles of the surface instead of the planned 250 miles. "The redesigned flight gives us some very significant science that we couldn't have gotten in the normal design", a scientist said. "We have canyons which are hardly named which are steeper and deeper than the Grand Canyon." he said. "We'd never have been gutsy enough to design the mission this way."
Each array consists of two panels, an inner and outer panel comprised of gallium arsenide and silicon solar cells,
respectively. During mapping operations at Mars, the amount of power produced by the arrays will vary from a high of 980 Watts to a low of about 660 Watts depending on how far away Mars is from the sun.
While in orbit around Mars, the solar arrays will provide power as Surveyor flies over the day side of the planet. When the spacecraft passes over the night side, energy will flow from two nickel-hydrogen (NiH2) batteries to compensate for the temporary loss of power from the solar arrays. These two batteries can provide power for over an hour before requiring a recharge from the solar arrays.
Mapping operations began in March 1999, one year behind schedule and will continue until January 2000. During those two years, transmission rates as fast as 85,333 bits per second will allow Mars Global Surveyor's six main scientific instruments to send nearly 83 gigabytes of data back to Earth. The enormous amount of data, will contribute to an extremely comprehensive study of the Martian atmosphere, surface features, mineral distribution, and magnetic properties.
The answer depends on Surveyor's distance to the Earth. When Mars
is farthest from the Earth (summer 1998), the maximum data rate will drop
as low as 21,333 bits per second. When Mars is closest to the Earth
(summer 1999), Surveyor will use a data rate of 85,333 bits per second.
At times in between those two extremes, Surveyor will use a medium data
rate of 42,667 bits per second. In contrast, modems on home computers
transmit data at an average speed of 28,800 bits per second.
Mars Observer was a spacecraft that NASA launched in September 1992 with the same scientific instruments carried by Mars Global Surveyor. On August 21, 1993, several days before arriving at Mars, contact was lost with the craft.
Because there were no indications of problems aboard the spacecraft prior to loss of contact, nobody knows for certain what happened. The most plausible theory was that a critical failure in the propulsion system disabled Mars Observer. The board recommended changes to the design to prevent such an occurrence from happening on Mars Global Surveyor. Mars Observer most likely flew past Mars and is now in an orbit around the Sun with an orbital period of approximately 500 days.
The camera will produce a daily wide-angle image of Mars similar to weather photographs of the Earth. The narrow-angle lens will capture images of objects as small as 1.5 meters across.
The laser altimeter will bounce beams of light off of the surface to measure the heights of mountains and depths of valleys.
The thermal emission spectrometer will scan for heat emitted from Mars to study the atmosphere and to map the mineral composition of the surface.
The magnetometer will study the magnetic properties of Mars to gain insight into the interior of the planet.
The relay antenna will receive data transmitted to Surveyor from future NASA spacecraft that will land on the Martian surface.
An analysis of radio signals sent to Earth from Surveyor will reveal the precise shape of the planet and structure of the
atmosphere.
| Module | Mass (Kg) | Fuel (Kg) | Science payload | Body Length | Solar panel length | Power Output W |
|---|---|---|---|---|---|---|
| Surveyor | 1062 Kg | 387,7 Kg | 75,8 Kg | 3m | 12m tip to tip | 980 W(max) |
