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Old 02-18-2011, 08:23 AM   #76
Notebook
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More news.
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MESSENGER Mission News
http://messenger.jhuapl.edu/

February 17, 2011

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One Month Until Mercury Orbit Insertion


After more than a dozen laps through the inner solar system, NASA's MESSENGER spacecraft will move into orbit around Mercury on March 17, 2011. The durable spacecraft — carrying seven science instruments and fortified against the blistering environs near the Sun — will be the first to orbit the innermost planet.



At 8:45 p.m. EDT, MESSENGER — having pointed its largest thruster very close to the direction of travel — will fire that thruster for nearly 14 minutes, with other thrusters firing for an additional minute, slowing the spacecraft by 862 meters per second (1,929 miles per hour) and consuming 31% of the propellant that the spacecraft carried at launch. Less than 9.5% of the usable propellant at the start of the mission will remain after completing the orbit insertion maneuver, but the spacecraft will still have plenty of propellant for future orbit correction maneuvers.



The orbit insertion will place the spacecraft into an initial orbit about Mercury that has a 200 kilometer (124 mile) minimum altitude and a period of 12 hours. At the time of orbit insertion, MESSENGER will be 46.14 million kilometers (28.67 million miles) from the Sun and 155.06 million kilometers (96.35 million miles) from Earth.



“The journey since launch, more than six and a half years ago, has been a long one,” says MESSENGER Principal Investigator Sean Solomon, of the Carnegie Institution of Washington. “But we have rounded the last turn, and the finish line for the mission’s cruise phase is in sight. The team is ready for orbital operations to begin.”



Engineers recently tested the arrayed-antenna configuration that will be used during the Mercury orbit insertion. During the maneuver, MESSENGER’s orientation will be optimized to support the burn, not to support communications with the team on the ground. As a result, the signal home will be weaker than usual. To boost the signal, communications engineers will use four antennas at the Goldstone Deep Space Communications Complex — one 70-meter dish and three 34-meter dishes.



“This arrangement is not typical for a maneuver, so we wanted to do a few dry runs before orbit insertion,” says MESSENGER Communications Engineer Dipak Srinivasan, of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md. “We are still analyzing the data, but everything went as expected.”



Since the last deep-space maneuver (DSM) almost a year and a half ago, the primary focus of the team has been on preparing for the orbit insertion maneuver and for orbital operations. Detailed plans have been developed and vetted through an extensive series of meetings ranging from internal peer reviews of each subsystem to formal reviews with external experts assessing overall readiness. Three of the major reviews were dedicated specifically to the activities associated with the MOI maneuver itself.

In addition to taking advantage of planned DSMs to practice aspects of the orbit insertion maneuver, the team has conducted a number of flight tests to characterize key subsystem behavior and to confirm the proper operation of various spacecraft components. Three full-team rehearsals using the hardware simulator have been conducted to practice all activities to be followed during the upcoming maneuver. The first of these exercises mimicked a nominal orbit insertion, and the following two presented anomalies for the team to recognize, analyze, and address.

“Although we feel that the preparations to date – and those scheduled for the next month – have been well thought-out, that the decisions made to define the specific activities were sound, and that the level of review and rehearsal has been more than adequate, we recognize the extraordinary complexity and unique nature of this endeavor,” says APL’s Peter Bedini, MESSENGER’s project manager. “But at this point, four weeks out, we are well positioned for success. The spacecraft is healthy, continues to operate nominally, and is on course to be at the right place at the right time at 8:45 P.M. ET on the evening of March 17.”



For an overview of Mercury Orbit Insertion and planned orbital observations, go online to http://messenger.jhuapl.edu/mer_orbit.html.




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MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.




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"The spacecraft is healthy, continues to operate nominally, and is on course to be at the right place at the right time at 8:45 P.M. ET on the evening of March 17.”

Well, I know where I'll be. Not every day a spacecraft goes into orbit.

N.

Last edited by Notebook; 02-18-2011 at 08:28 AM.
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Old 02-18-2011, 04:07 PM   #77
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and some more
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MESSENGER Mission News

February 18, 2011

http://messenger.jhuapl.edu

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A Solar System Family Portrait, from the Inside Out

The MESSENGER spacecraft has captured the first portrait of our Solar System from the inside looking out. Comprised of 34 images, the mosaic provides a complement to the Solar System portrait – that one from the outside looking in – taken by Voyager 1 in 1990.

http://messenger.jhuapl.edu/gallery/...p?image_id=399


“Obtaining this portrait was a terrific feat by the MESSENGER team,” says MESSENGER Principal Investigator Sean Solomon, of the Carnegie Institution of Washington. “This snapshot of our neighborhood also reminds us that Earth is a member of a planetary family that was formed by common processes four and a half billion years ago. Our spacecraft is soon to orbit the innermost member of the family, one that holds many new answers to how Earth-like planets are assembled and evolve.”



MESSENGER’s Wide Angle Camera (WAC) captured the images on November 3 and 16, 2010. In the mosaic, all of the planets are visible except for Uranus and Neptune, which – at distances of 3.0 and 4.4 billion kilometers – were too faint to detect. Earth’s Moon and Jupiter’s Galilean satellites (Callisto, Ganymede, Europa, and Io) can be seen in the NAC image insets. The Solar System’s perch on a spiral arm of the Milky Way galaxy also afforded a beautiful view of a portion of the galaxy in the bottom center.



“The curved shape of the mosaic is due to the inclination of MESSENGER’s orbit from the ecliptic, the plane in which Earth and most planets orbit, which means that the cameras must point up to see some planets and down to see others,” explains MESSENGER imaging team member Brett Denevi of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md. “ The images are stretched to make it easier to detect the planets, though this stretch also highlights light scattered off of the planet limbs, and in some cases creates artifacts such as the non-spherical shape of some planets.”



Assembling this portrait was no easy feat, says Solomon. “It’s not easy to find a moment when many of the planets are within a single field of view from that perspective, and we have strong Sun-pointing constraints on our ability to image in some directions.”



APL’s Hong Kang, from MESSENGER’s guidance and control team, used the Jet Propulsion Laboratory’s Solar System Simulator to pinpoint the relative positions of MESSENGER and the planets to determine if it was possible to see the planets from MESSENGER at any given time. “I then used the celestial coordinates of the planets at the time I wanted to observe them to verify with simulations that MESSSENGER could see each of the planets,” Kang explains. “I also used a satellite tool kit to verify that we had the planets in the field of view of MESSENGER’s Mercury Dual Imaging System.”



The MESSENGER team then had to determine how long the exposures needed to be for each planet. “From exposure times that worked for previous imaging of stars with visual magnitudes similar to those of the planets, we chose exposure times that would allow us to obtain the appropriate number of counts (i.e., amount of light) in each planet image,” explains APL’s Nori Laslo, the mission’s Operations Lead and Instrument Sequencer for MDIS.



“We decided to take images using both the Narrow Angle Camera and the Wide Angle Camera for each planet so that we would cover the sky surrounding the planets and also image the planets themselves at as high a resolution as possible,” she adds. “I took all of these parameters, along with a variety of related settings, and began building the command sequence with the library of MDIS commands that we have to configure and control the camera system.”



Robin Vaughan, who worked with Kang to coordinate the pointing and timing of the MDIS, also played a role in Voyager’s portrait.



“I was working as an optical navigation analyst at JPL for the Voyager Neptune encounter,” says Vaughan, the lead engineer for MESSENGER's guidance and control (attitude control) subsystem at APL. “I had to plan and generate the pointing commands for pictures of Neptune and its satellites against background stars that we used to improve our estimate of the spacecraft’s trajectory leading up to the Neptune encounter. Voyager’s solar system portrait was done a few years after that flyby and was coordinated by the imaging team. Our optical navigation image planning software was used to double check the pointing commands they had designed and confirm what they expected to see in each image.”



Vaughan did the same thing for MESSENGER’s portrait, using Kang’s designs. “I used the SPICE trajectory files for the spacecraft generated by MESSENGER’s navigation team, as well as routines in the SPICE toolkit, to write a software program that would identify windows when each of the planets would be visible to MDIS given the constraints on pivot angle and Sun keep-in zone for spacecraft attitude,” she says.



From a technical standpoint, the MESSENGER portrait was a little more complicated than what was done for Voyager because scientists had to stay within the Sun keep-in constraints. “With Voyager so far out in the solar system, the Sun is much fainter and there were no constraints on the overall spacecraft attitude as far as the Sun was concerned,” Vaughan says. “Being in the inner solar system, MESSENGER has to constantly keep the sunshade pointing toward the Sun, which limits the periods when the different planets can be viewed even with the extra degree of freedom that MDIS has with its pivot capability.”



Denevi says the experiment was humbling. “Seeing our solar system as just these little specks of light, it reminds you of how lucky we are that we've had the chance, through so many missions, to get up close and explore the incredible diversity and geology that each planet and moon displays,” she says. “Mercury has been just a dot on the horizon for most of history, and we get to fill in the details and know it as a real world. What an amazing opportunity!”




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MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.




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Last edited by Notebook; 02-18-2011 at 04:23 PM. Reason: added portrait link.
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Old 02-21-2011, 02:50 AM   #78
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I think the portrait is awesome enough to show it directly here:
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Old 02-21-2011, 08:11 AM   #79
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Remarkable image, like to see it on a large scale diarama type display in a museum or similar.

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Old 02-21-2011, 04:20 PM   #80
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Where is Uranus and Neptune?
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Old 02-21-2011, 04:41 PM   #81
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All of the planets are visible except for Uranus and Neptune, which at distances of 3.0 and 4.4 billion kilometers were too faint to detect with even the longest camera exposure time of 10 seconds, though their positions are indicated. (The dwarf-planet Pluto, smaller and farther away, would have been even more difficult to observe).
They are on this graphic, showing postions when made.

http://messenger.jhuapl.edu/images/1...orbits-all.png

and a hires version to compensate(22MB)
http://messenger.jhuapl.edu/images/f...rtrait_wac.png

N..

Last edited by Notebook; 02-21-2011 at 04:46 PM.
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Old 02-23-2011, 04:54 AM   #82
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Thanks Notebook!

I didn't read the original carefully enough and missed the part about Uranus and Neptune. And then wondered how it could be called a "family" portrait with those two not in the photos.
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Old 03-05-2011, 03:21 PM   #83
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Animations of MOI (Mercury Orbit Insertion) from the MESSENGER Web Site:

http://messenger.jhuapl.edu/the_miss...it%2053sec.mov


http://messenger.jhuapl.edu/the_miss...final_best.mov
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Old 03-08-2011, 07:46 PM   #84
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MESSENGER Mission News

March 7, 2011

http://messenger.jhuapl.edu




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Ten Days from Orbit Insertion



Ten days from now – on March 17 EDT – the MESSENGER spacecraft will execute a 15-minute maneuver that will place it into orbit about Mercury, making it the first craft ever to do so, and initiating a one-year science campaign to understand the innermost planet.



Starting today, antennas from each of the three Deep Space Network (DSN) ground stations will begin a round-the-clock vigil, allowing flight control engineers at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., to monitor MESSENGER on its final approach to Mercury.



At 10:40 a.m. this morning, the spacecraft began executing the last cruise command sequence of the mission. This command load will execute until next Monday, when the command sequence containing the orbit-insertion burn will start.



“This is a milestone event for our small, but highly experienced, operations team, marking the end of six and one half years of successfully shepherding the spacecraft through six planetary flybys, five major propulsive maneuvers, and sixteen trajectory-correction maneuvers, all while simultaneously preparing for orbit injection and primary mission operations,” says MESSENGER Systems Engineer Eric Finnegan. “Whatever the future holds, this team of highly dedicated engineers (http://messenger.jhuapl.edu/moc/index.html) has done a phenomenal job methodically generating, testing, and verifying commands to the spacecraft, getting MESSENGER where it is today.”



The mission operations team now turns its attention to the final preparations for the insertion burn next week and establishing nominal operations for the primary mission. As with the last three approaches to Mercury, the navigation team and the guidance and control team have been successfully using the solar radiation of the Sun to carefully adjust the trajectory of the spacecraft toward the optimum point in space and time to start the orbit-insertion maneuver.



As of the most recent navigation report on February 22, the spacecraft was less than 5 kilometers and less than three seconds from the target arrival point.



“These figures place the spacecraft well within the target corridor for successful orbit insertion,” Finnegan says. “Over the next week, additional body and solar-array attitude alternations will further refine this approach and nudge the spacecraft closer to the optimum target location. This approach will require the spacecraft to spend extended amounts of time at attitudes that do not support transmission of telemetry from the spacecraft, so monitoring of the spacecraft over the next week will be conducted with both telemetry and carrier signals.”



The in-flight preparations for this historic injection maneuver began on February 8, when several heaters on the spacecraft were configured to condition the bi-propellant used during the maneuver.



“Similar to pre-heating the diesel engine of a truck or car prior to starting in cold weather to allow ignition and prevent damage to the engine, the MESSENGER team turns on and off different heaters on the spacecraft so that the pressures for each of the two propellant species (hydrazine and nitrogen tetroxide) are at the optimum ratio for safe and efficient maneuver execution,” Finnegan explains.



Last Wednesday, the engineering and operations teams convened the last detailed review of the injection command sequence. After three iterations of this command sequence, countless Monte-Carlo simulations by the guidance and control team, numerous propulsion modeling simulations, and more than 30 hardware simulations covering all manner of nominal and anomalous operating configurations, the sequence and the associated fault protection configuration have been given the green light to start final preparations for upload to the spacecraft this week.



”The cruise phase of the MESSENGER mission has reached the end game,” adds MESSENGER Principal investigator Sean Solomon, of the Carnegie Institution of Washington. “Orbit insertion is the last hurdle to a new game level, operation of the first spacecraft in orbit about the solar system’s innermost planet. The MESSENGER team is ready and eager for orbital operations to begin.”




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Upcoming Mercury Orbit Insertion Events



March 15, 1 p.m. EDT. NASA Media Teleconference to preview the orbit insertion.
March 17, 8:00 p.m. EDT. APL and The Planetary Society co-host a public lecture in APL’s Kossiakoff Center, featuring MESSENGER Project Scientist Ralph L. McNutt, Jr. RSVP online at http://messenger.jhuapl.edu/RSVP/.
March 17, 8:45 p.m. EDT MESSENGER's Mercury Orbit Insertion maneuver begins.
May 10, 1 p.m. EDT. NASA Press Conference to present early science findings from Mercury’s primary orbital mission. NASA Headquarters.


Details on all these events will be posted as they become available on the MESSENGER Mercury Orbit Insertion Web site at http://messenger.jhuapl.edu/mer_orbit.html.




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Geologist Enjoys Finding the Story in MESSENGER's Features



Carolyn Ernst, the instrument sequencer for the Mercury Laser Altimeter and an instrument team associate for the Mercury Dual Imaging System, loves looking at planetary surfaces that have never been seen before, so the long-neglected innermost planet is right up her alley. To read more about her work on the MESSENGER mission, go online to http://messenger.jhuapl.edu/who_we_a...ber_focus.html.




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MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.




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Old 03-09-2011, 05:02 AM   #85
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Default MOI Scenario

As mentioned in this thread, http://www.orbiter-forum.com/showthr...ight=MESSENGER here is a scenario for Mercury Orbit Insertion.

It uses the stock DG in place of the actual spacecraft and starts about 1 hour before MOI.

I recommend installing Mercury level 8 (found here:
Planet Mercury Level 8 High Resolution Surface
) as it is the best one can get until MESSENGER is commissioned in its orbit and starts the science...especially with its cameras. Not to say it hasn't taken outstanding photos so far...it's just that eventually someone will have enough data to generate a texture of 100% of Mercury's surface.

Code:
BEGIN_DESC
Begins about 1 hour before orbit insertion.  Uses a DeltaGlider in place of the actual spacecraft.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 55637.988817314
END_ENVIRONMENT

BEGIN_FOCUS
  Ship GL-01
END_FOCUS

BEGIN_CAMERA
  TARGET GL-01
  MODE Extern
  POS 6.49 77.74 50.72
  TRACKMODE GlobalFrame
  FOV 30.00
END_CAMERA

BEGIN_HUD
END_HUD

BEGIN_MFD Left
END_MFD

BEGIN_MFD Right
END_MFD

BEGIN_PANEL
END_PANEL

BEGIN_SHIPS
GL-01:DeltaGlider
  STATUS Orbiting Mercury
  RPOS 12191415.6552744 3625829.82746938 299211.840761222
  RVEL -2876.81397869585 164.272654338043 -20.8182957958074
  AROT 62.90 -0.99 -93.92
  VROT 0.00 0.00 13.11
  PRPLEVEL 0:0.553 1:0.999
  IDS 0:528
  NAVFREQ 588 0 0 0
  NOSECONE 1 1.0000
  GEAR 0 0.0000
  AIRLOCK 0 0.0000
END
END_SHIPS
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Old 03-10-2011, 04:10 AM   #86
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Quote:
Originally Posted by NukeET View Post
 I recommend installing Mercury level 8 (found here: Planet Mercury Level 8 High Resolution Surface) as it is the best one can get until MESSENGER is commissioned in its orbit and starts the science...especially with its cameras. Not to say it hasn't taken outstanding photos so far...it's just that eventually someone will have enough data to generate a texture of 100% of Mercury's surface.
There is an image available that combines Mariner 10's images with MESSENGER's images so far if you want to make some near-global textures. I mentioned it here: http://www.orbiter-forum.com/showthr...4&postcount=61
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Old 03-10-2011, 06:58 PM   #87
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Originally Posted by tblaxland View Post
 There is an image available that combines Mariner 10's images with MESSENGER's images so far if you want to make some near-global textures. I mentioned it here: http://www.orbiter-forum.com/showthr...4&postcount=61
Thanks for the link and the suggestion. Since I have a new PC, making a new texture of Mercury won't be a problem...except I've never done that before with planets.

Maybe you could provide better RPOS and RVEL numbers for the scenario...using the actual MESSENGER add-on instead of the stock DG results in really accurate numbers on the MOI...except the burn start / end times are about 5 minutes early...everything else is really close.

Almost like being there...

EDIT:

Try this "scenario pack". It uses portions of the MESSENGER add-on found on O-H. See the doc for details.
Attached Files
File Type: zip MESSENGER MOI.zip (480.5 KB, 7 views)

Last edited by NukeET; 03-10-2011 at 08:37 PM.
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Old 03-10-2011, 07:30 PM   #88
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Wonder if using SPICE data for Mercury will fix the difference. And yes, beverages will be of help this close to the Sun...
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Old 03-10-2011, 08:42 PM   #89
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Originally Posted by Wishbone View Post
 Wonder if using SPICE data for Mercury will fix the difference. And yes, beverages will be of help this close to the Sun...
A PM from tblaxland to me some time ago recommended using SPICE data for more accurate results...I think he was referring to SPICE. I wasn't able to extract meaningful data from it in order to use it. I used data from JPL Horizons.

OBTW, see post #87 in this thread, as I've uploaded a zip file containing a "scenario" pack.
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Old 03-11-2011, 04:25 AM   #90
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Quote:
Originally Posted by NukeET View Post
 I used data from JPL Horizons.
I haven't had a chance to check your scenario file yet but, on the subject of using JPL Horizons, if you use Mercury relative state vectors they will be more accurate than the Sun relative ones (in my experience).
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