back to article Huge ice blades on Jupiter’s Europa will make it a right pain in the ASCII to land on

Exploring Jupiter’s moon Europa will be a treacherous task, it seems: scientists reckon its surface is covered in sharp towering icy daggers. The menacing shards are known as penitentes, according to a paper published in Nature Geoscience this week. They normally form in dry cold climates, where sunlight melts snow and it …

  1. frank ly Silver badge

    Penitentes

    So called because of how you'd feel if you fell/landed on them.

    1. Anonymous Coward
      Anonymous Coward

      Re: Penitentes

      Pointed structures standing upright suggests an etymological root shared with penis. Is that Latin for "sword"?

      1. Steve the Cynic Silver badge

        Re: Penitentes

        No, it's the Spanish word for, well, "penitents", people doing penance. See also the robes and hoods worn by penitents during Spanish Holy Week.

        https://en.wikipedia.org/wiki/Capirote

        1. TRT Silver badge

          Re: Penitentes

          So nothing to do with eating pasta on a camping holiday, then?

          1. Mycho Silver badge

            Re: Penitentes

            It's from the Latin for sorry, because if you land on it you will be.

            1. Crisp Silver badge
              Coat

              Re: Penitentes

              Icy what you did there.

      2. Anonymous Coward
        Anonymous Coward

        Re: Penitentes

        " Is that Latin for "sword"?"

        Apparently old Latin for "tail".

  2. Anonymous Coward
    Anonymous Coward

    So they haven't discovered anything. they've assumed.

    1. A.P. Veening

      Assumptions

      True, they haven't directly observed them, but this theory explains the observed data and is consistemt with some other information as well, so I'll take this at face value until something better comes along.

    2. Anonymous Coward
      Anonymous Coward

      They've assumed

      It's more of a proposed explanation than an assumption, but I think there are better explanations.

      Penitentes are formed by ablative erosion so the peak of the penitente is indicative of an older and higher surface level - the penitentes are not built up from the original surface but are what's left.after the surrounding material has been removed (by the aforesaid erosion). If we have 15m high penitentes then we need to know where that 15m of eroded material came from and where it subsequently went.

      More likely, imo, is that the 'roughness' is due to either compression fractures, similar to what we see in the Arctic ice sheets, or the presence of cryovolcanic 'spines', similar in mechanism to those we see being erupted from lava domes. Neither of these explanations require the now missing eroded material.

      1. Muscleguy Silver badge

        Re: They've assumed

        That might be true with earth penitentes but on Europa the ground surface is all ice (with pink bits) so a source of ablative ice is not a problem. I also strongly suspect the physics is a mite different when the sublimating ice is in a vacuum.

        But then I'm only a Stamp Collector so what do I know but I do suspect your assumptions are wanting.

  3. malle-herbert Silver badge
    Joke

    No wonder...

    The aliens told us to "Attempt no landing there"....

    1. DJV Silver badge

      Attempt no landing there...

      ...unless you fancy [a close shave / a Brazilian / castration without anesthetic] or all three on the way in!

  4. Voyna i Mor Silver badge

    Obvious A C Clarke reference

    Now we know why we're not allowed to land on Europa.

  5. Neil Barnes Silver badge

    According to Mirriam Webster

    Penitente noun

    Pen·i·ten·te | \ˌpenəˈtentā, -tē\

    plural Penitentes\-ās, -ēz \

    Definition of Penitente

    : a member of a religious society of Flagellants in Spanish-American communities of the southwestern U.S. (as New Mexico) who practice self-whipping and other forms of penitential torture particularly during Holy Week

    1. John Brown (no body) Silver badge

      Re: According to Mirriam Webster

      Is that Merriam Websters younger sister?

  6. Giovani Tapini

    In the UK we would just say

    Its the wrong sort of snow...

    Although it does make me wonder if any lander would have to be called a "blade runner"

  7. Aladdin Sane Silver badge

    Has anybody mentioned Arthur C. Clarke yet?

    1. TRT Silver badge
      1. Aladdin Sane Silver badge

        Are you sure?

        1. Voyna i Mor Silver badge

          Yes

          It's in my headline from two and three quarter hours before your post, though I was beaten to the reference by seconds.

    2. HelpfulJohn

      Not Clarke, more like a Hugh Walters book, "Journey to Jupiter".

      https://en.wikipedia.org/wiki/Journey_to_Jupiter

      Okay, so that one has the spiky bits set on a different moon and made of rock but he did have the "here be dragons" sentiment fairly well.

      There's an entire series of these. Fun reads if you're not too fussy about what we now consider to be scientific accuracy.

  8. Tessier-Ashpool

    Does nobody ever read Larry Niven?

    Just head there with your personal fusion drive and tickle the surface for a few seconds.

    1. JetSetJim Silver badge
      Mushroom

      Re: Does nobody ever read Larry Niven?

      > Just head there with your personal fusion drive and tickle the surface for a few seconds.

      Requires managing fuel carefully. Just have the host spacecraft drop a small nuke from orbit. It's the only way to be sure...

      1. Simon Harris Silver badge

        Re: Does nobody ever read Larry Niven?

        I thought the idea was to look for life on the moon, not to turn it into a ready-meal.

        1. MacroRodent Silver badge

          Re: Does nobody ever read Larry Niven?

          Besides, the locals would consider this a hostile act, and respond with a psychic attack (see Niven's "Handicapped").

          1. TRT Silver badge

            Re: Does nobody ever read Larry Niven?

            David Niven, perhaps.

            Well, his early memoirs.

            1. $till$kint

              Re: Does nobody ever read Larry Niven?

              Ah, the moon's a balloon. A most entertaining read.

        2. Muscleguy Silver badge

          Re: Does nobody ever read Larry Niven?

          Don't nukes fail to work very well in a vacuum? Also Europa is already bathed in very hard radiation whipped up to relativistic speeds by the local gas giant. Hardening the electronics of any lander so it survives long enough to take samples from the pink crevasses let alone drill through kilometres of likely very hard ice (cf the measurements of comet ice hardness) is very live issue.

          The radiation pretty much precludes a manned presence on the surface any time soon barring some very sci-fi levels of technology advancement. But even so, think humans staying in shielded craft and sending the robots out into the radiation storm.

  9. Simon Harris Silver badge

    NASA is planning to send Europa Clipper spacecraft

    They're sending a clipper?

    Maybe they should be sending an ice-breaker.

    ... and shouldn't ESA get first dibs on a moon called Europa?

    1. Anonymous Coward
      Anonymous Coward

      Re: NASA is planning to send Europa Clipper spacecraft

      Maybe they should be sending an ice-breaker.

      Let the European Space Agency send a lander first. Then NASA can come along afterwards and land in the relatively smooth crater.

      1. Phil O'Sophical Silver badge
        Coat

        Re: NASA is planning to send Europa Clipper spacecraft

        Then NASA can come along afterwards and land in the relatively smooth crater

        With their 36 inch lander, in the 36 cm crater?

    2. Anonymous Coward
      Anonymous Coward

      Re: NASA is planning to send Europa Clipper spacecraft

      > They're sending a clipper?

      Is it windy? Probably need a zippo

  10. Conundrum1885

    Re. Icebreaker

    Actually they may well send a nuclear powered submarine probe there once all the bugs are worked out/etc.

    In order to melt the ice it would need to get up to some 200C for several hours and the best way to do this would be something like a small plutonium source (238Pu) and a heat exchanger.

    1. Giovani Tapini
      Coat

      Re: Re. Icebreaker

      This method of propulsion would be called the "Astroglide" drive

    2. aks Bronze badge

      Re: Re. Icebreaker

      More than a few hours, if the ice crust is as thick as projected. The same concept was suggested as a way to go deep into the Earth. Pressure is another major issue.

  11. Nick Kew Silver badge
    Coat

    Nanny Ogg's space travels

    Her favourite song captures the essence of this planet's defence against alien (e.g. human) interference.

    1. Voyna i Mor Silver badge

      Re: Nanny Ogg's space travels

      Are you sure that you don't mean the product of various researches by Darwin and Huxley and Hall that conclusively proved that the hedgehog has an ingenious first line of defence?

    2. Alister Silver badge

      Re: Nanny Ogg's space travels

      Her favourite song captures the essence of this planet's defence against alien (e.g. human) interference.

      A Wizard's staff has a knob on the end?

      Shirley not?

      :)

  12. Bigbadbod
    Happy

    RE: Icebreaker

    Spacey McSpaceface?

    1. hplasm Silver badge
      Happy

      Re: RE: Icebreaker

      "Spacey McSpaceface?"

      Spikey McSpikearse.

      Oh sorry, that's the hedgehog again.

  13. AndrueC Silver badge
    Facepalm

    ASCII

    Or as we used to refer to it several years ago 'Arthur's Code'.

    This came about because early versions of The Sphere by Michael Crichton spelt it that way.

    One of several mistakes in the text, actually. Another was a transmission of a block of digits they receive (and it was only digits in the text) that one character identifies as a hex dump. Shortly after another character claims it can't coming from a 68000 processor "because the 68000 doesn't work in hex".

    The film was better. Just.

    1. This post has been deleted by its author

  14. Jim84

    Duke Nukem

    Not if you send in a small tactical nuke to the landing zone first.

  15. choleric

    It's not ROCKET science

    So we need to invent something that sprays copious volumes of very hot gases out of its underside as it comes in to land, thereby melting any ice spears and creating a smooth surface for eventual touchdown? It'll transform space-flight when that's invented.

    1. Geoff May (no relation)

      Re: It's not ROCKET science

      I'll nominate our entire government strapped to the underside of some suitable vessel. The advantage of politicians is that you do not need to worry about their orientation as they spray copious volumes of very hot gasses out of both orifices.

    2. Saruman the White
      Flame

      Re: It's not ROCKET science

      Sounds like me the day after a really good vindaloo

  16. eric halfabe

    Shirley this is wrong

    "They found that the regions near the equator reflect radar waves more readily than its poles, and the reflection patterns are best explained by the existence of these icy blades."

    If the surface was smooth you would get more reflection at the equator than the poles.

    If the surface is covered in penitentes to almost 15 metres or 50 feet in height, with a spacing of 7.5 metres there would be more reflections near the poles than the equator. All those surfaces perpendicular to the radar beam and all.

    1. Francis Boyle Silver badge

      You're making a lot of assumptions there

      As I read it the penitentes are near the equator (warmer environment aiding sublimation, presumably). So, at the poles the radar signal just disappears into space unless it's pointing straight down. At the equator there are vertical and horizontal surfaces forming cavities which reflect the signal randomly creating a more or less omnidirectional return signal.

  17. Stevie Silver badge

    Bah!

    Nonsense!

    These "ice blades" will flash into steam when bathed in the superheated gasses of the lander's mighty descent stage engine.

    The astronauts may then safely walk about on the re-frozen ice-plain with the aid of non-slip space-crampons.

    What?

    1. Saruman the White

      Re: Bah!

      I can't help but think of the short story "Wait it Out" by Larry Niven. Granted the short story was set on Pluto (a long while before we knew anything about that frozen wasteland) but the say events could happen.

  18. Gene Cash Silver badge

    Pol

    Looks like the spiky rocks you see on Jool's moon Pol in KSP when you turn terrain scatters all the way up...

  19. Anonymous Coward
    Anonymous Coward

    Ouch!

    That would hurt if you landed on your icehole.

  20. richard mullens

    Sublimes not sublimates.

  21. Claptrap314 Bronze badge

    Lunar lander?

    I don't know why anyone thinks that landing in such an environment would be hard. We've had an entire generation preparing for just this scenario.

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