Mro On Approach, TCM-3 not required |
Mro On Approach, TCM-3 not required |
Feb 3 2006, 11:06 PM
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#1
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Member Group: Members Posts: 134 Joined: 13-March 05 Member No.: 191 |
MRO has shifted from the cruise phase to Approach phase. Apparently, the trajectory is so good that TCM-3 was cancelled. This is good news for the prospects for a long life for MRO supporting future missions. TCM-4 is on Feb 28, and MOI on March 10. Only 5 weeks away!
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Feb 15 2006, 02:35 PM
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#2
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Founder Group: Chairman Posts: 14434 Joined: 8-February 04 Member No.: 1 |
http://bookstore.spie.org/index.cfm?fuseac...d=619857&coden=
QUOTE Abstract The Optical Navigation Camera (ONC) is part of NASA's Mars Reconnaissance Orbiter (MRO) scheduled for an August 2005 launch. The design is a 500 mm focal length, F/8.3 Ritchey-Chretien with a refractive field corrector. Prior to flight, the off-axis performance of the ONC was measured at visible wavelengths in the off-axis scatter facility at the Space Dynamics Laboratory (SDL). This unique facility is designed to minimize scatter from the test setup to prevent data corruption. Testing was conducted in a clean room environment, and the results indicate that no detectable contamination of the optics occurred during testing. Measurements were taken in two time frames to correct an unanticipated stray light path, which occurred just outside of the sensor's field-of-view. The source of the offending path was identified as scatter from the edges of the field corrector lenses. Specifically, scatter from the interface between the flat ground glass and polished surfaces resulted in significant "humps" in the off-axis response centered at ± 1.5°. Retesting showed the removal of the humps, and an overall satisfactory performance of the ONC. The troubleshooting, correction, and lessons learned regarding the above stray light path was reported on in an earlier paper. This paper discusses the measurement process, results, and a comparison to a software prediction and other planetary sensors. The measurement validated the final stray light design and complemented the software analysis. Very little info out there though. That's about all I could find. |
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Feb 15 2006, 03:52 PM
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#3
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Senior Member Group: Members Posts: 1465 Joined: 9-February 04 From: Columbus OH USA Member No.: 13 |
http://bookstore.spie.org/index.cfm?fuseac...d=619857&coden= Very little info out there though. That's about all I could find. Thanks! That paper states that the FOV is 2.8 degrees (+/- 1.4 degees from the optical axis). I can see from the pointing (CK) SPICE kernels for the last few days that they are indeed periodically slewing the ONC across the position of Mars and Phobos/Deimos. Here's one predicted view from a few days ago: The targets are in the FOV for about a minute. I gather from the paper that the intent is to have Mars outside the FOV for the science observations. -------------------- |
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Feb 15 2006, 07:29 PM
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#4
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Senior Member Group: Members Posts: 2488 Joined: 17-April 05 From: Glasgow, Scotland, UK Member No.: 239 |
From the MRO website:
http://mars.jpl.nasa.gov/mro/mission/sc_instru_optical.html "Optical Navigation Camera This camera is being tested for improved navigation capability for future missions. If it performs well, similar cameras placed on orbiters of the future would be able to serve as high-precision interplanetary "eyes" to guide incoming spacecraft as they near Mars. From 30 days to 2 days prior to Mars Orbit Insertion, the spacecraft will collect a series of images of Mars' moons Phobos and Deimos. By comparing the observed position of the moons to their predicted positions, relative to the background stars, the mission team will accurately determine the position of the orbiter in relation to Mars. While not needed by Mars Reconnaissance Orbiter to navigate to Mars, the data from this experiment will be used to demonstrate that this technique can be used by future spacecraft to ensure their accurate arrival. Accuracy is important to some future landers and rovers that will need extremely precise navigation at Mars arrival to get to their landing sites safely." So, some interesting images of the moons, perhaps? Bob Shaw -------------------- Remember: Time Flies like the wind - but Fruit Flies like bananas!
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