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Luís F. Simões

Evolution of AI Interplanetary Trajectories Reaches Human-Competitive Levels - Slashdot - 4 views

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    We made it to Slashdot's frontpage !!! :)
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    Congratulations, gentlemen!
jmlloren

Shark Wheel - the SQUARE skateboarding wheel that shreds! by SharkWheel.com and SharkWh... - 2 views

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    The square wheel!
jmlloren

COPENHAGEN SUBORBITALS - OPEN SOURCE AND NON PROFIT SPACE - 1 views

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    Our mission is very simple. We are working towards launching a human being into space. 
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    Nicholas this is project I mentioned while G&T-ing in Madrid.
Luís F. Simões

Physicists Discover a Whopping 13 New Solutions to Three-Body Problem - ScienceNOW - 1 views

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    They search numerically for initial conditions resulting in periodic orbits. Reminds to me the methods we employed for the "search for invariant relative motion" and which brought us to discover the magic inclinations (47.9 degrees).

    I wonder what are the implications. In any case nice plots :)
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    Haven't read in detail, but it's not clear to me what it means exactly. If they were discovered numerically (I assume it means via numerical integration), how can they be sure the orbits are truly periodic?
Joris _

NASA International Space Station Longeron Marathon Challenge - 1 views

shared by Joris _ on 18 Jan 13 - No Cached
LeopoldS liked it
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    nice - did not know about it. GTOC on steroids and with loads of cash. concerning this specific challenge and especially the last condition: doesn't this hint towards a flawed design?

    In addition to maximizing the total power output there are some constraints on the possible movements:
    Each SARJ and BGA is limited to a maximum angular velocity and to a maximum angular acceleration.
    Each SAW must produce at least some minimum average power over the orbit (which is different for each SAW).
    The sequence of positions must be cyclic, so it can be repeated on the next orbit.
    The maximum amount of BGA rotation is not limited, but exceeding a threshold will result in a score penalty.
    Some structural members of the SAW mast (called Longerons) have restrictions on how they can be shadowed.
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    The longerons will expand and contract with exposition to sun (I think whatever the material they are made of). Because you have 4 longerons in a mast, you just need to be carefull that the mast is well balanced, and that the 4 longerons support each other, basically, you need an even number of shadowed longerons, possibly 0 too. I would call this an operational constraint.
Joris _

SpaceCamera on Apophis - 1 views

shared by Joris _ on 09 Jan 13 - No Cached
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    Apophis is back! You can watch its close approach live.
    Announcement: http://images.slooh.com/files/press_release/asteroid_apophis2013.pdf
Joris _

Out of this world! Student takes stunning snaps of space using only a £30 sec... - 2 views

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    Boh....
Dario Izzo

TETRIS - 5 views

shared by Dario Izzo on 27 May 12 - No Cached
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    Connected to asteroid deflection? :)
Joris _

video of the short hop test flight - 4 views

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    Have you seen this?!
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    no! quite impressive indeed!
    thanks for sharing it here
Joris _

ATV docks with the ISS | Bad Astronomy | Discover Magazine - 4 views

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    On March 28, ATV-3, named Edoardo Amaldi, docked with the ISS. Astronauts on the station took this unbelievable picture of it as it approached
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    More pics here: http://www.flickr.com/photos/europeanspaceagency/
    ATV docking is a bit further down the photostream.
Joris _

New DARPA challenge wants unique algorithms for space applications - 4 views

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    "On March 28, the Defense Advanced Research Projects Agency will kick of another one of its highly successful challenges this time looking for teams or individuals to develop unique algorithms to control small satellites on-board the International Space Station. "

    Will the ACT participate?
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    That would be wrong on so many levels...
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    Could not find out what the prize money is? Also does not seem clear to me how three cubes can catch an object "flying" in the opposite direction... But the approach is nice to see
jmlloren

A Swarm of Nano Quadrotors - YouTube - 3 views

shared by jmlloren on 01 Feb 12 - No Cached
LeopoldS liked it
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    Nice formation flying, though I still prefer Dario's 3D animation
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    very nice indeed!!
Joris _

DARPA Aims to Repurpose Retired Satellites - 2 views

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    Agency wants to send mini robots into space to recycle and reuse antennas from more than 1,300 dormant satellites in geostationary orbit above the earth.
Joris _

Domino's plans pizza on the Moon - Telegraph - 0 views

jmlloren

Designer lattices - 5 views

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    Perhaps interesting for the SPS self-assembling
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    nice, read only the abstract so far but looks to me like a bit of 19th century crystallography reinvented ...
Joris _

Asteroid Deflection Research Center - 5 views

shared by Joris _ on 16 Jul 11 - No Cached
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    lol
Dario Izzo

Optimal Control Probem in the CR3BP solved!!! - 6 views

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    This guy solved a problem many people are trying to solve!!! The optimal control problem for the three body problem (restricted, circular) can be solved using continuation of the secondary gravity parameter and some clever adaptation of the boundary conditions!! His presentation was an eye opener ... making the work of many pretty useless now :)
  • ...13 more comments...
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    Riemann hypothesis should be next...
    Which paper on the linked website is this exactly?
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    hmmm, last year at the AIAA conference in Toronto I presented a continuation approach to design a DRO (three-body problem). Nothing new here unfortunately. I know the work of Caillau, although interesting what is presented was solved 10 years ago by others. The interest of his work is not in the applications (CR3BP), but in the research of particular regularity conditions that unfortunately make the problem limited practically.
    Look also at the work of Mingotti, Russel, Topputo and other for the (C)RTBP. Smart-One inspired a bunch of researchers :)
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    Topputo and some of the others 'inspired' researchers you mention are actually here at the conference and they are all quite depressed :) Caillau really solves the problem: as a one single phase transfer, no tricks, no misconvergence, in general and using none of the usual cheats.

    What was produced so far by other were only local solutions valid for the particular case considered.

    In any case I will give him your paper, so that he knows he is working on already solved stuff :)
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    Answer to Marek: the paper you may look at is: Discrete and differential homotopy in circular restricted three-body control
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    Ah! with one single phase and a first order method then it is amazing (but it is still just the very particular CRTBP case).
    The trick is however the homotopy map he selected! Why this one? Any conjugate point?

    Did I misunderstood the title ?
    I solved in one phase with second order methods for the less restrictive problem RTBP or simply 3-body... but as a strict answer to your title the problem has been solved before.

    Nota:
    In "Russell, R. P., "Primer Vector Theory Applied to Global Low-Thrust Trade Studies," JGCD, Vol. 30, No. 2", he does solve the RTBP with a first order method in one phase.
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    I think what is interesting is not what he solved, but how he solved the problem. But, are means more important than end ... I dunno
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    I also loved his method, and it looked to me that is far more general than the CRTBP. As for the title of this post, OK maybe it is an exageration as it suggests that no solution was ever given before, on the other end, as Marek would say "come on guys!!!!!"
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    The generality has to be checked. Don't you think his choice of mapping is too specific? he doesn't really demonstrate it works better than other. In addition, the minimum time choice make the problem very regular (i guess you've experienced that solving min time is much easier than mass max, optimality-wise). There is still a long way before maximum mass+RTBP, Topputo et al should be re-assured :p
    Did you give him my paper, he may find it interesting since I mention the homotopy on mu but for max mass:)
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    Joris, that is the point I was excited abut, at the conference HE DID present solutions to the maximum mass problem!! One phase, from LEO to an orbit around the moon .. amazing :)

    You will find his presentation on line.... (according to the organizers)

    I gave him the reference to you paper anyway, but no pdf though as you did not upload it on our web pages and I could not find it in the web. So I gave him some bibliography I had with be from the russians, and from Russell, Petropoulos and Howell, As far as I know these are the only ones that can hope to compete with this guy!!
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    for info only, my phd, in one phase: http://pdf.aiaa.org/preview/CDReadyMAST08_1856/PV2008_7363.pdf
    I prefered Mars than the dead rock Moon though!
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    If you send me the pdf I can give it to the guy .. the link you gave contains only the first page ... (I have no access till monday to the AIAA thingy)
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    this is why I like this Diigo thingy so much more than delicious ...
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    What do you mean by this comment, Leopold? ;-)

    Jokes apart: I am following the Diigo thingy with Google Reader (rss). Obviously, I am getting the new postings. But if someone later on adds a comment to a post, then I can miss it, because the rss doesn't get updated.
    Not that it's a big problem, but do you guys have a better solution for this? How are you following these comments?

    (I know that if you have commented an entry, then you get the later updates in email.)

    (For example, in google reader I can see only the first 5 comments in this entry.)
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    I like when there are discussions evolving around entries
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    and on your problem with the RSS Tamas: its the same for me, you get the comments only for entries that you have posted or that you have commented on ...
Joris _

DARPA Solicits Ideas For Its Hundred-Year Starship Project | Popular Science - 4 views

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    I just can't see how their way of finding non-state funding for a 100 year project could work but would be happy to be surprised positively ...
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