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Dario Izzo

Optimal Control Probem in the CR3BP solved!!! - 7 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 :)
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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 _

OpenLuna Picks Up Where NASA's Moon Mission Leaves Off - 0 views

  • The ambitious project will tap the resources of private enterprise to build several small scout rovers that will be shipped to the south pole of the moon via a single lander. Rock and earth samples will be returned to Earth for testing, then auctioned off to secure funding for the next phase of the plan
Ma Ru

Scientists who rock - 3 views

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    I'll just leave this here... Found them through a recent publication of LeDoux in Trends in Cognitive Sciences
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    Ah, and if there are no strong objections, from now on every brainstorming session shall commence with this: http://thebeautifulbrain.com/2010/10/ledoux-amygdaloids-brainstorm/2/
Lionel Jacques

» Kamikaze Satellite Could Be Earth's Last Defense Against Asteroid - 5 views

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    Does ESA really want to sent 2 S/C to this rock ?
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    Isn't there a bit of confusion there - Don Quijote will actually not fly, is it? Isn't it just an old buzz that has been misquoted...
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    indeed the article is a bit too upbeat - DQ is a concept and brain child of Andrés! and chances are indeed good that ESA will do something on NEO missions, if it will be don quijote, nobody knows of course ... but in my view it's a nice concept ...
Francesco Biscani

BBC NEWS | Science & Environment | Space rock yields carbon bounty - 0 views

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    All we are is stardust.
ESA ACT

Sleep like a rock, wake up like Iron Man with Sleep.fm | Webware : Cool ... - 0 views

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    A good example of sci-fi inspiration...
Marion Nachon

NASA research offers new prospect of water on Mars - 4 views

NASA scientists are seeing new evidence that suggests traces of water on Mars are under a thin varnish of iron oxide, or rust, similar to conditions found on desert rocks in California's Mojave Des...

started by Marion Nachon on 02 Jul 11 no follow-up yet
LeopoldS liked it
Christophe Praz

The 10 warmest years: Not exactly forever ago - 1 views

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    Last week NASA and NOAA announced that 2014 topped the list of hottest years ever recorded. Yikes! What's worse, the ten warmest years ever recorded have all occurred since 1998. Yikes again! In the meantime, the ACT is skiing on stones and rocks in Switzerland ^^
Alexander Wittig

The Effort to Turn Martian Soil Into Rock Solid Concrete - 4 views

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    Sounds like an interesting building material. Unlike concrete, after use it can simply be molten down (at seemingly reasonable temperatures) and used again to build different parts. Crack in the wall? Just iron it out (literally)! A group at Northwestern University wants to solve an engineering challenge now to prepare for the future: it's turning Mars-like soil into concrete. And, in turn, that concrete requires very little (if any) water. It's just the thing we may need to make life on Mars sustainable.
derekaranguren

Scientists release first analysis of rocks plucked from speeding asteroid - 0 views

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    On the topic of asteroid composition :)
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