howitloops

009 The endless landing

Philae reached a comet. Staying there was the hard part. Its first rebound lasted about 1 hour and 50 minutes; it still returned science before its initial battery ran out.

Published
Length
37.5 s
Claims
11
Sources
5

Claims 11

Each claim as said or shown in the video, with the value it states, its source and the date it was checked.

  1. November 2014; screen 12 NOV 2014; Philae lands on comet 67P

    Value
    12 November 2014, 67P/Churyumov–Gerasimenko
    Source
    A, C
    Checked
    . A reports confirmation on 12 November and three contacts with 67P; C describes separation and touchdown on that date.
    Simplified
    Comet shape and lander pictogram are schematic.

  2. Harpoons did not fire

    Value
    Anchoring failed
    Source
    A
    Checked
    . A explicitly reports failure of the harpoons.
    Simplified
    Two simplified anchor tips represent the anchoring system; no deployment is shown.

  3. Hold-down thruster was not working

    Value
    No downward thruster during landing
    Source
    B
    Checked
    . B describes the landing without a downward thruster and with failed automated harpoons.
    Simplified
    Diagram shows the intended downward force, crossed out; it does not suggest a working exhaust.

  4. Comet gravity is very weak; a small rebound lasts much longer than on Earth

    Value
    Qualitative comparison
    Source
    C, D
    Checked
    . C relates the rebound to low gravity; D gives projectile motion under gravity. For fixed upward speed, return time T = 2v/g in the constant-g approximation.
    Simplified
    Earth/comet comparison is illustrative, not the real trajectory or a measured gravity ratio. Actual comet field varies spatially and the comet rotates.

  5. First flight lasts about 1 h 50 min

    Value
    Approximate duration
    Source
    A
    Checked
    . A gives 1 hour 50 minutes; its rounded touchdown times 15:34 and 17:25 differ by 111 minutes, consistent with an approximate 110-minute statement.
    Simplified
    Flight time and distance compressed independently.

  6. Another touchdown followed by a smaller hop; three principal touchdown locations

    Value
    3 major sites
    Source
    A, C
    Checked
    . A describes a smaller second hop; C reconstructs the second site and additional contacts.
    Simplified
    The drawing omits a cliff collision and smaller scrapes at the second site; three sites does not mean only three physical contacts.

  7. Final stop in shadow

    Value
    Poorly lit final site
    Source
    B, C
    Checked
    . B reports the shadow of a cliff; C describes an unfavourable site with insufficient sunlight.
    Simplified
    Cliff, solar rays and final pose are schematic.

  8. Instruments return science despite the landing

    Value
    Science data returned
    Source
    B
    Checked
    . B confirms returned science data and completion of the final experiment block.
    Simplified
    A single radio pulse represents data return. No claim that every planned measurement succeeded.

  9. Too little sunlight to sustain operation; battery runs out

    Value
    Power depleted, hibernation
    Source
    B, C
    Checked
    . B reports depleted batteries, insufficient solar energy and idle mode. C confirms the primary battery ran out.
    Simplified
    Battery icon is qualitative. The primary battery was finite; shadow limited continued solar-powered operation rather than causing the primary battery to expire. This is the initial November 2014 mission; later brief communications in 2015 are outside the story.

  10. Touchdown alone does not ensure remaining on a tiny world

    Value
    Synthesis of failed anchoring + rebound
    Source
    A, B, C
    Checked
    . supported by the actual Philae sequence described above.
    Simplified
    A story conclusion, not a general claim that landing is easy.

  11. Final site named Abydos; later brief communications in June and July 2015

    Value
    Abydos, 2015
    Source
    E
    Checked
    . E identifies Abydos and confirms brief contact in June and July 2015.
    Simplified
    Later recovery is disclosed in the caption, outside this initial-landing story.

Simplifications

As stated in the post’s caption.

The flight, terrain and lander are schematic; time and distance are compressed independently. The Earth comparison illustrates weak gravity, not a measured ratio. Three principal touchdown sites are shown; a cliff collision and smaller scrapes are omitted. The battery icon is qualitative. This follows the initial November 2014 mission, before later brief communications in 2015.

Sources 5

  1. ESA, “Three touchdowns for Rosetta’s lander” (14 November 2014). https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Three_touchdowns_for_Rosetta_s_lander

    Claims 1, 2, 5, 6, 10

  2. ESA, “Pioneering Philae completes main mission before hibernation” (15 November 2014). https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Pioneering_Philae_completes_main_mission_before_hibernation

    Claims 3, 7, 8, 9, 10

  3. DLR, “4.5-billion-year-old ice on comet ‘fluffier than cappuccino froth’” (28 October 2020). https://www.dlr.de/en/latest/news/2020/04/20201028_4_5-billion-year-old-ice-on-comet-fluffier-than-cappuccino-froth

    Claims 1, 4, 6, 7, 9, 10

  4. OpenStax, University Physics Volume 1, §4.3 Projectile Motion. https://openstax.org/books/university-physics-volume-1/pages/4-3-projectile-motion

    Claims 4

  5. ESA, “Philae found!” (5 September 2016). https://www.esa.int/Science_Exploration/Space_Science/Rosetta/Philae_found

    Claims 11

Transcript

November twenty fourteen. A spacecraft lands on a comet — and bounces.

Philae’s harpoons don’t fire, and its hold-down thruster isn’t working.

On Earth, a little bounce ends quickly. But this comet’s gravity is incredibly weak.

Philae stays airborne for about an hour and fifty minutes.

It hits the surface again, then makes one more hop.

Finally, it stops in shadow. Its instruments still send back science.

But too little sunlight reaches its solar panels. Its battery runs out.

On a tiny world, touching down can be just the beginning.

Fig. 1 Video 009 as a dial: one turn is 37.5 s. Heavy arcs are the narration. The last word ends 1.0 s before the seam, where the video starts again.