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  1. #1
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    The Great All Encompasing Interesting stuff happening in Space thread

    As with the Climate Change thread i like to keep abreast of space stuff, and a quick look around did not show any specific thread for us to post things about that, so i'll kick this one off with an arstechnica article:

    'NASA’s Dawn ends primary mission, may not be done with asteroids yet':

    http://arstechnica.co.uk/science/201...ther-asteroid/

    UPDATE: In a new release put out today, NASA announced that it had ultimately decided against plans to send the Dawn spacecraft to visit an additional asteroid. Apparently whoever posted yesterday's Dawn journal was not informed of this decision. "The long-term monitoring of Ceres, particularly as it gets closer to perihelion—the part of its orbit with the shortest distance to the Sun—has the potential to provide more significant science discoveries than a flyby of Adeona,” said NASA Director of Planetary Science Jim Green.

    The announcement does come with good news for fans of the unknown: New Horizons has been approved for a visit to a Kuiper Belt object known as 2014 MU69. That rendezvous will take place in 2019. Given the unexpected nature of Pluto, visiting a second body in the Kuiper Belt will provide some much-needed perspective on these worlds.

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    A nice story sort of showing why NASA (and organisations like it) are inspirationally important for us all:

    'Adam Savage thinks NASA should get working on a backup plan for Earth':

    http://arstechnica.co.uk/science/201...lan-for-earth/

    Although NASA enjoys widespread public support, that hasn’t translated to increased funding for the space agency, which receives slightly less than 0.5 percent of the federal budget. Surveys regularly show that the public thinks the federal government spends about the right amount, balanced against the government’s other priorities.

    "It’s a fantastic question," he said. "But I really don't have a good answer because I've never really thought about that." Savage then said, in his view, NASA furthers the human condition because it feeds our desires to explore and learn the nature of things. The space agency helps us understand the universe around us, our place in it, and, through activities on board the International Space Station, how to use space to do stuff. But most importantly, he said, NASA and private spaceflight companies are laying the groundwork for a backup plan. “While the chances of our extermination are infinitesimal, they are zero if we manage to colonize a second sphere in this solar system,” he said.

  3. #3
    Lesser Hivemind Node Matt_W's Avatar
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    Biggest space news right now is that by tomorrow (July 4) we should have a spacecraft in orbit around Jupiter for the first time in nearly 13 years. We won't get to see images until probably August, but still pretty exciting that we're going to learn a bunch about the awesome magnetic, gravitation and radiation fields surrounding our giant neighbor.


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    What a pic! Sadly your first link did not work, it seems to be missing something?

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    http://www.planetary.org/blogs/emily...nos-orbit.html

    I did find that one though via examining your links, is that what you were going to post?

  6. #6
    Lesser Hivemind Node Matt_W's Avatar
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    Weird. The link works for me. Basically Juno's insertion will be complete this evening at around 4am UTC (9pm my time.) NASA will do a live broadcast (probably of the control room and NASA PR folks) starting at 0230 UTC.

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    And now it works for me too! Earlier it took me to the planetary.org site but said the page could not be found? Still all working and awesome now :)

  8. #8
    Lesser Hivemind Node Matt_W's Avatar
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    Juno's capture burn performed perfectly. Juno is now in an elongated 50-some day orbit around Jupiter. Space engineers are the best! This thing has to operate largely autonomously in the harsh magnetic, radiation, and vacuum environment around Jupiter after 5 years of travelling through the solar system, contending with a 49 minute command delay. It's like trying to program a robot to thread a needle 5 years from now while someone's throwing pillows at it and someone else is trying to set it on fire. It's amazing what we do, and what we take for granted.

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    When you see stuff like that, you know the human race can have an incredible future! :)

    -------------------------------

    And a bit on Mars' Moons:

    'Mars may have once had lots of moons, but soon it will be down to just one':

    http://arstechnica.co.uk/science/201...he-red-planet/

  10. #10
    Secondary Hivemind Nexus Zephro's Avatar
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    Quote Originally Posted by Matt_W View Post
    Juno's capture burn performed perfectly. Juno is now in an elongated 50-some day orbit around Jupiter. Space engineers are the best! This thing has to operate largely autonomously in the harsh magnetic, radiation, and vacuum environment around Jupiter after 5 years of travelling through the solar system, contending with a 49 minute command delay. It's like trying to program a robot to thread a needle 5 years from now while someone's throwing pillows at it and someone else is trying to set it on fire. It's amazing what we do, and what we take for granted.
    OK it is amazing but it's also not that amazing because of the maths involved. I mean we've been putting stuff in orbit around these things since the 70s or to the moon since the 60s and that was mostly without computers, as the maths isn't all that hard (it's hard but not super computer hard). Orbits work in predictable ways, there's no wind or environmental factors really, the distances are large but incredibly accurately measured. Self driving cars are genuinely more technically impressive. This is impressive in a whole different way, because it's in orbit around another fucking planet.

  11. #11
    Secondary Hivemind Nexus Gus_Smedstad's Avatar
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    Well, it both is and it isn't hard.

    It's hard because the 3 body problem is impossible to solve for the general case. There are solutions for specific cases, i.e. identical planets in identical planets, but no exact solutions for Hohmann transfers in the real solar system. The issue is that every object in the solar system pulls on your spacecraft, and the result is so complex that it's essentially chaotic.

    It's not so hard because most of those pulls are very small, and make very small changes to the course of the spacecraft. Your spacecraft can make a few small correction burns, and you can overcome all this tiny little influences from remote objects. It's like driving - we're all capable of adjusting the course of a car around a complex curve, because we're making tiny little adjustments to the wheel in response to visual feedback. We're not doing any internal math, it's just a matter of moving the wheel until the car remains centered, and we do it so quickly we don't even notice we're doing it.

    For the most part, you can do this remotely. It's better and safer if the spacecraft computes it, but the 49 minute command delay isn't important because you don't have to respond in real time. Unless the spacecraft takes a significant impact from a micrometeorite, something big enough to transfer momentum, you can measure the spacecraft's position and vector accurately enough remotely to compute correctional burns days before you need them.

    The hard part of self-driving cars, the basic bits I mean, is that recognizing "this is a road" and "this is a lane" and "that is another car" are computationally difficult problems. Image recognition isn't easy. By contrast, it's really quite easy to write software to recognize a planet's disc. It's just the bright circle in the middle of your image. I've got telescope autoguiding software that does essentially that, only with stars, and it's freeware that's about 12mb. Which is gigantic by Apollo era standards (the Apollo flight computer had 72kb of ROM, and 4kb of RAM), but not by today's.

  12. #12
    Lesser Hivemind Node Matt_W's Avatar
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    I'm not generally referring to navigation, though I think you're both trivializing somewhat the difficulty of determining the spacecraft's own position and velocity in space with the precision necessary to calculate burns. I'm referring to the design for vacuum, design for radiation, design for magnetic fields, all of which are relatively hard problems. I work at a plasma physics facility where we design for all three, and the constraints they provide comprise the bulk of the engineering problem. Spacecraft have to be designed with redundancy, they can't fail, they have to be autonomous, they have to make very precise measurements in difficult environments. It's phenomenal. It's easy to say "oh yeah, that's easy to do conceptually", but much more difficult to actually imagine and design real systems that can really do it.

  13. #13
    Secondary Hivemind Nexus Gus_Smedstad's Avatar
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    Quote Originally Posted by Matt_W View Post
    I think you're both trivializing somewhat the difficulty of determining the spacecraft's own position and velocity in space with the precision necessary to calculate burns.
    Position and velocity are the same problem, since you determine vector by determining position at differing times.

    There's a page discussing how NASA does it. These days, it's done primarily by a technique that's at the root of how GPS's work. They can get a very accurate read on the spacecraft distance by pinging it - they send out a signal, they spacecraft replies, and the time delay gives you the distance. Because we're routinely measuring time in nanoseconds now, the distance is accurate within 10 meters or so.

    To get an angle, you use two different, widely separated ground stations. The page mentions using ground stations on different continents.

    I honestly don't know how they did this in the 70's. They'd be stuck with optical methods, which aren't very accurate.

  14. #14
    Secondary Hivemind Nexus Zephro's Avatar
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    I may have over stated that, not knocking it, it is amazing. Especially the engineering of the actual things. My masters and phd programmes were in Machine Learning/Computer Hardware, so was thinking of this in terms of stuff that was possible but really hard in the 70s versus things that are fundamentally impossible without modern computers. It's not to say they aren't hard, but that popular imagination tends to misplace which is which. Self driving cars remain computationally insanely more complex, yet it's less astonishing than a probe around Jupiter. Though that's just the computational effort involved rather than the sheer astonishment of being there or the engineering involved in building the thing.

  15. #15
    Secondary Hivemind Nexus Gus_Smedstad's Avatar
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    I was somewhat dismissive of the Apollo guidance computer, but the truth is you can do a lot with that much memory. I did a lot of work in the 80's on Apple II's which had 48k of RAM. 72k of ROM would have been a lot by my standards then. 4k RAM is pretty small, but it's purely for scratch variables, not for your program.

    Reading the Wikipedia article on the computer, it reminds a bit of the 6502 architecture, only a bit more powerful. Most stuff uses memory operands, and there's only a single accumulator register for doing math. On the other hand it has built-in multiply and divide, which I didn't see until I started working with Intel x86 CPUs.

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    Secondary Hivemind Nexus karaquazian's Avatar
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    What I would like with space stuff is to remove the nationalism. It's for the future of all mankind, and scientists general are more globally thinking / cooperative people.

    The usa, Russia, China, India & eu should get together and make a global space agency, pool their resources, take advantage of the best talent.

  17. #17
    Secondary Hivemind Nexus karaquazian's Avatar
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    Quote Originally Posted by Gus_Smedstad View Post
    I was somewhat dismissive of the Apollo guidance computer, but the truth is you can do a lot with that much memory. I did a lot of work in the 80's on Apple II's which had 48k of RAM. 72k of ROM would have been a lot by my standards then. 4k RAM is pretty small, but it's purely for scratch variables, not for your program.

    Reading the Wikipedia article on the computer, it reminds a bit of the 6502 architecture, only a bit more powerful. Most stuff uses memory operands, and there's only a single accumulator register for doing math. On the other hand it has built-in multiply and divide, which I didn't see until I started working with Intel x86 CPUs.
    Yes without fancy user interfaces you can do a lot with limited resources.

  18. #18
    Lesser Hivemind Node Matt_W's Avatar
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    Quote Originally Posted by karaquazian View Post
    What I would like with space stuff is to remove the nationalism. It's for the future of all mankind, and scientists general are more globally thinking / cooperative people.

    The usa, Russia, China, India & eu should get together and make a global space agency, pool their resources, take advantage of the best talent.
    Maybe they should jointly create a semi-permanent station in low Earth orbit that can be used for science research, continuously crewed by an international team, with a variety of different modules developed by the various national agencies. Or an international conglomeration of agencies should develop a flagship mission to study Saturn and its moons over the course of 13 years. :)

    Many large space projects are international projects and have been since the 70's. Science is usually done this way. I work at a pure science facility and probably 70% of the scientists doing research there are international. I don't get any sense of national triumphalism from watching live feeds of space projects. There's no question that the United States funds more space science by far than any other country, but there's also a sense that the accomplishments of the science teams are for all of humanity.
    Last edited by Matt_W; 06-07-2016 at 04:44 AM.

  19. #19
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    I agree. So far Space has been pretty polite in terms of the earth side politics, science does seem to be the winner (so overall humanity) rather than a specific nation so far. That is not to say it did not start out as a nationalistic endeavour, the Cold War being what it was back then, but in general it has been bloody awesome to see the unity space exploration has helped to foster :)

    -------------------------

    ' Future missions to Venus need tough new technologies – and an old one.':

    http://www.bbc.com/future/story/2016...eve-ever-built

    It’s been a long time since anyone tried landing on Venus, one of the most hostile environments in the Solar System. Covered in sulphuric acid clouds, the surface temperatures approach 460 C (860 F) with atmospheric pressure 90 times that of Earth. Lead, zinc and tin are liquids, and the weight of the carbon dioxide air is roughly equal to that found a kilometre under the ocean – enough to crush a submarine.

    Yet the planet is getting renewed attention – Japan’s Akatsuki mission successfully entered orbit in December 2015 and there are new missions planned from Nasa and Esa in the 2020s. Even Russia plans a follow up to their highly successful Venera and Vega missions of the 1970s and 80s. All of these missions involve orbiters, and will study the planet's atmosphere, magnetic field, and geography.

  20. #20
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    This is a bit theoretical in nature, but fun stuff non the less :)

    'Another good reason to sail the seas of Titan—life may exist there':

    http://arstechnica.co.uk/science/201...cientists-say/

    Citing experimental and observational data, the researchers note the abundance of hydrogen cyanide in Titan's atmosphere. This is a hydrogen-bonding molecule that may combine with other molecules on the surface to form polymers, including polyimine. Using quantum mechanical calculations, the scientists demonstrated that polyimine has electronic and structural properties at very cold temperatures that could potentially facilitate prebiotic chemistry in conditions like those on the surface of Titan, especially in tidal pools near the large seas.

    "Possibilities like this... are very speculative and intended as a suggestion of the kinds of structures that might occur, rather than a specific prediction," the authors wrote in their paper, published this week in the early edition of Proceedings of the National Academy of Sciences. "Because they are impossible to form naturally in a warmer world containing water and oxygen, only future exploratory missions to Titan can test the hypothesis that natural chemical systems evolve chemical complexity in almost any circumstance."
    I personally think we are more likely to find life (or dead remnants of it) on Mars, or even Europa, but i'm not a space biologist ;)

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