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Thread: Rosetta and 67P/Churyumov-Gerasimenko

  1. #31
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    From ESA's pre-landing media briefing today:

    • Philae will start warming up and fully activating this evening; landing instructions already uploaded, all pre-landing instrument tests done
    • exact timeline for pre-delivery burn on wednesday morning will be decided on tomorrow
    • surface material is dusty, verging between cigarette ash and hard-packed snow in hardness; possible problem is that harpoons might not anchor
    • "If we see the comet break up, then we have a NOGO :-)" (smiley (c) ESA)


    ESA TV will stream the landing live from the control room at Rosetta #CometLanding webcast on Livestream and broadcast it over Eutelsat in Europe. Countdown to begin of stream at that link.

  2. #32
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    Apparently comets are the whales of the solar system:

    The singing comet | Rosetta - ESA's comet chaser (with audio!)

    Also, in the upcoming hours to the landing ESA has been publishing a ton of things on the Rosetta Blog, including:


    24-hour livestream starts in about 80 minutes btw.
    Last edited by kato; 11 Nov 14, at 17:42.

  3. #33
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    Three GO/NOGO decisions to go until separation.

    If we get a NOGO, they'll try again in two weeks after one full orbit.

    Attachment 38437
    Last edited by kato; 11 Nov 14, at 19:45.

  4. #34
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    Pre-separation maneuver should begin in a couple minutes. That's the one where Rosetta takes a sharp turn towards the comet so it can throw Philae directly at it. Separation comes about an hour later, basically in just enough time for Rosetta to take that turn, wait 28 minutes for confirmation to arrive on Earth, and have about five minutes for the final GO/NOGO decision, before it has to be broadcast to arrive in time before separation.

    Attachment 38438

  5. #35
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    Tuning in from work:

    - Separation successful
    - touchdown in about one hour
    - 360000+ viewing People on the livestream right now (!!)

  6. #36
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    Media briefing for the landing just concluded.

    The good news: Philae has landed, and it landed on the right comet. It even hit almost exactly the center of its kilometer-wide landing ellipse, which is quite a feat.

    The detailed, somewhat worse news:
    - the hold-down thruster failed to fire; this was already identified as a problem before separation
    - the harpoons fired but did either did not penetrate or the surface was too brittle to hold them; they were fully rewound, and could be fired again in theory
    - according to estimations based on data received, it's likely that Philae bounced off on the first landing, started turning off the surface because the flywheel was shut off, and then came down again in a slightly different position
    - according to various sources, it seems the lander may be anchored with the ice screws on two of its legs; a lack of anchoring may interfere with some science operations, in particular the two drilling systems (SD2 and MUPUS)
    - the first science sequence started automatically 15 seconds after touchdown
    - they do have science data received from COSAC, PTOLEMY, ROLIS, SESAME, MUPUS, ROMAP.
    - Rosetta is now behind the horizon of the comet, so no news on Philae's situation until she gets back into position to act as a data relay

    Released ROLIS (descent camera) image from 3 km distance - the other six ROLIS pics taken haven't been released so far:

    Attachment 38440

  7. #37
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    Brief update, so far it looks like:

    [ Landing Site ]

    - Philae bounced twice; first time 112 minutes "airborne", second time 7 minutes.
    - Philae is located somewhere around 1 km from Agilkia, after hitting it right on in the first landing - this means Philae is in an entirely different place, 1 km is one quarter of the comet
    - Philae might have entered a crater, cave or similar
    - Philae is sitting on a boulder or something similar, with the main body up to 30cm off the ground
    - Philae is sitting inclined at more than 30 degrees tilt
    - the lander rotated in the z-axis after the first bounce
    - the exact location of the landing is not yet known

    Initial fears were that the lander might be laying on its side.

    [ Systems ]

    - none of the anchoring mechanism worked; Philae hence is not anchored
    - despite all this, all onboard systems are working fine
    - surrounding terrain apparently interfers with radio communication, only giving Rosetta a clear link in a limited angle
    - only one side of the lander got sunlight so far
    - there's somewhere around 50 hours remaining on the initial battery

    We do have a picture taken by Philae from the ground: Welcome to a comet! | Rosetta - ESA's comet chaser

    Media briefing in 30 minutes streamed live here: Rosetta #CometLanding webcast on Livestream
    Last edited by kato; 13 Nov 14, at 12:50.

  8. #38
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    Currently looks like they might have landed just inside the "mouth" to the right (which is actually a far more shallow crater than it looks like here).

    Attachment 38446

  9. #39
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    The blue quadrangle gives an approximation of the landing position compared to where Agilkia is (the red square)

    Attachment 38448

    This is the overhang Philae has apparently slid under:

    Attachment 38447

  10. #40
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    Fantastic achievement


    Trust gets you killed, love gets you hurt, and being REAL gets you hated.

  11. #41
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    Sounds like there is discussion of using either deployable instruments or reconfiguring the landing gear to bounce Philae up and to a better location with more sunlight. Is it worth the risk or better to get what data they can before the battery discharges?

  12. #42
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    Quote Originally Posted by tankie View Post
    Fantastic achievement
    Attachment 38454

  13. #43
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    Quote Originally Posted by SteveDaPirate View Post
    Sounds like there is discussion of using either deployable instruments or reconfiguring the landing gear to bounce Philae up and to a better location with more sunlight. Is it worth the risk or better to get what data they can before the battery discharges?
    BBC is saying most of the data req is in ?


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  14. #44
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    Quote Originally Posted by SteveDaPirate View Post
    Sounds like there is discussion of using either deployable instruments or reconfiguring the landing gear to bounce Philae up and to a better location with more sunlight. Is it worth the risk or better to get what data they can before the battery discharges?
    They'd need a lot more detailed information before they try that - both on how the legs are exactly situated and on which way Philae is facing right now, as well as whether a more advantageous position is even remotely attainable.

    By best estimate, the deployable instruments are currently on the downhill left side of the lander - deploying them would probably at best tilt Philae slightly uphill. Using the - entirely theoretical, untested and unintended - hopping ability to move places by basically bouncing Philae on its landing gear would be a full gamble.

    It's not really like the extended science phase - after the primary battery drains - would have been all that exhaustive. Maximum Philae could have gotten from the solar panels was 30 minutes of operating its instruments per (earth) day. For that it'd need at least around four times as much sunlight per (comet) day as it gets now. Unless a bouncing would move Philae entirely free of the cliff or whatever it's stuck at, the potential gain is not particularly high.

    Optimal right now would probably be if they could get the harpoons to fire to anchor themselves so they could deploy MUPUS and SD2.

  15. #45
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    Quote Originally Posted by tankie View Post
    BBC is saying most of the data req is in ?
    Out of 10 instruments on Philae, 5 are working suboptimal from their position or can't operate (the CONSERT radio sounding experiment's antennae are touching the ground, the APXS alpha-particle spectrometer is limited to operations without moving parts, MUPUS should only get information from two of the leg sensors, and PTOLEMY isn't getting any surface material fed to it from SD2, and SD2 can't drill at all).

    ---

    Apparently the MUPUS crew has a GO on deploying its primary sensor at midnight tonight. Boom will set the probe at two thirds of the maximum distance from Philae (i.e. at about 70cm), and the sensor will then hammer itself into the ground.

    MUPUS crew even has selected a soundtrack for the entire next science phase:



    No SD2 deployment during this phase. Planning meeting for next science phase concluded half an hour ago, commands for Philae are being prepped for uploading via Rosetta.
    Last edited by kato; 13 Nov 14, at 19:33.

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