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Aurelie Heritier

Why NASA Should Nab an Asteroid - 2 views

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    In his last dispatch from the recent AIAA Global Space Exploration Conference, veteran astronaut and PM contributor Tom Jones argues for NASA to undertake a mission to snare a nearby small asteroid and tow it into the orbit of the moon.
Thijs Versloot

Most Amazing Exoplanets #ifls - 1 views

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    The most astounding fact about Kepler-78b is that it shouldn't even exist, according to our current knowledge of planetary formation. It is extremely close to its star at only 550,000 miles (900,000 kilometers). As a comparison, Mercury only gets within 28.5 million miles (45.9 million kilometers) of the sun in the nearest point of orbit. With that proximity, it isn't clear how the planet could have formed as the star was much larger when the planet formed. With its current distance, that would mean it formed inside the star, which is impossible as far as we know.
Thijs Versloot

Walking droplets (video) - 2 views

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    Wow, the two droplets that orbit each other are really cool - as is the explanation!
Nicholas Lan

Kerbal Space Program | Media - 2 views

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    what seems to be an impressively detailed space game
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    Yeah... 2011 called with the greetings. However, there was quite an interesting news about KSP recently... Perhaps it's been ACT's small failure to spot this opportunity? Considering we wrote space missions games ourselves...
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    This guy actually makes very detailed video tutorials about how to master the orbital dynamics in Kerbal. I think the level of detail (and sometimes realism) is quite impressive: https://www.youtube.com/channel/UCxzC4EngIsMrPmbm6Nxvb-A
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    I will have to try this definitely, looks like a lot of fun.. I also saw some crazy 'Insane Rocket Division' videos.. :)
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    @Marek: true, old news. But "opportunity"? For what? The games we write are always games with a scientific purpose (not training not educational) Kerbal Space programme is cool, but it is a game just like Microsoft Flight Simulator (but less accurate). Having ESA mission simulated in it is also cool but is it what we should or could do? Even more is it want we want to do? My personal opinion: No-No-No
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    > The games we write are always games with a scientific purpose (not training not educational) I'd say investigating how to get the crowd may be an important part of "science of crowdsourcing". So, an obvious example would be comparing how many participants the original ACT space mission game attracted versus a variant implemented in Kerbal and why. Easily made and easily publishable I think. But that's just an obvious example I can give on the spot. I think there is more potential than that, so would not dismiss the idea so definitively. But then, correct me if I'm wrong, social sciences are still not represented in the ACT... Perhaps an idea to revive during the upcoming retreat? ;-)
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    it's on sale on steam til tomorrow by the way if anyone's interested
johannessimon81

Solar Power Satellites: overview of NASA's former plans - 1 views

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    Nice link and clear overview! I like the point raised about 1000 man in space, even when including automation (as far as they could envision at the time). Now that is a future of the space industry and permanent habitation of near-earth orbits! In fact, I can envision just two reasons maybe, power and the hotel industry
Thijs Versloot

ISEE-3 Reboot Project - Recovering an satellite from deep space by crowdsourcing @Spac... - 3 views

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    "A band of space hackers and engineers are trying to do something never done before - recover a 36 year old NASA spacecraft from the grips of deep space and time. With old NASA documents and Rockethub crowdfunding, a team led by Dennis Wingo and Keith Cowing is attempting to steer ISEE-3, later rechristened ICE, the International Cometary Explorer, back into an Earth orbit and return it to scientific operations. Dennis says, 'ISEE-3 can become a great teaching tool for future engineers and scientists helping with design and travel to Mars'. Only 40 days remain before the spacecraft will be out of range for recovery. A radio telescope is available, propulsion designs are in hand and the team is hoping for public support to provide the small amount needed to accomplish a very unique milestone in space exploration
Nina Nadine Ridder

Testing shows using microwaves to propel a craft into space might work - 4 views

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    A team of researchers at Colorado based Escape Dynamics is reporting that initial tests indicate that it might really be possible to launch space-planes into space using microwaves sent from the ground, to allow for a single stage spacecraft. If the idea pans out, the cost savings for sending satellites (or perhaps humans) into orbit could be considerable.
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    Not very new, but a very slick video nonetheless! Will it work? I am not so sure whether "just engineering" applies in this case. The array of antenna's required is quite significant to compensate for beam losses. Wall plug efficiency is not that high therefore, then again.. solar energy is for free almost in the future so who cares.. let's go for it! :)
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 ...
Nina Nadine Ridder

Sentinel-2 catches eye of algal storm - 0 views

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    The Sentinel-2A satellite has been in orbit for only a matter of weeks, but new images of an algal bloom in the Baltic Sea show that it is already exceeding expectations. Built essentially as a land monitoring mission, Sentinel-2 will also certainly find its way into marine applications.
Joris _

Spaceflight Now | Falcon Launch Report | Falcon rocket meets fiery end after three week... - 1 views

  • the truck-sized vehicle would have streaked back into the atmosphere and burned up over Iraq and Syria
Juxi Leitner

Obama declares war on space junk - space - 29 June 2010 - New Scientist - 2 views

  • The US will also fund research into cleaning up the space junk that's already there.
  • Obama administration also calls for research into technologies that could remove space debris already in orbit, such as laser tractor beams.
pacome delva

Planets 'Sing' in Three-Part Harmony - 0 views

  • this is the first three-planet resonance ever seen.
  • The three planets are in a 4:2:1 resonance: the innermost giant completes four orbits in the time the middle one completes two and the newfound outermost world completes one.
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    for Francesco!
pacome delva

Radiation fears stalk stellar mission - 0 views

  • Concern over ESA's handling of the radiation issue caused Michael Perryman, former GAIA project scientist, to resign from the agency in 2008. But GAIA science-team member Lennart Lindegren, an astronomer at Lund Observatory in Sweden, is confident that GAIA's unprecedented accuracy will be feasible. GAIA researchers will continue to perform tests and calibrations until at least 2011, which will include irradiating the CCDs at space-like temperatures. Lindegren admits, however, that they can never be certain of success until the spacecraft is in orbit and starts sending back data.
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    metamaterials to stop radiations?
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    hmm ... in the optical range it is already a bit tricky .... lets brainstorm a bit about it ... anything in the literature? Luzi?
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    the components of the metamaterial need to have a size inversely proportional to the wavelenght, but here we are talking about high energy protons. So the idea was: is there metamaterials that change the electrical properties to solve this problem of holes in the material... but i dont have a clue !
Joris _

NASA Set to Launch Solar NanoSail into Space | Inhabitat - Green Design Will Save the W... - 0 views

  • 100 square feet;
  • NASA is, rather, testing the deployment mechanism.
  • In 2008, engineers were given just four months to devise a solar sail. They pulled it off, but the rocket carrying the sail experienced launch failure.
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  • to learn more about how best to bring older satellites out of space rather than allowing them to become that much more space junk
Joris _

Spaceflight Now | Breaking News | Sweden's Prisma satellites go their separate ways - 1 views

  • exotic green propellant maneuvering systems
  • In the two months since launch, controllers have powered up the satellites' navigation and formation flying equipment, tested its green propellant thruster, and successfully navigated around orbital debris threats.
  • a smorgasbord of payloads
Juxi Leitner

The Associated Press: Launch set for US satellite to monitor space junk - 0 views

  • It's designed to give the Air Force its first full-time, space-based surveillance of satellites and debris in Earth's orbit. It monitors them for possible collisions.
Ma Ru

A free and realistic space flight simulation program - 4 views

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    Have a nice gaming :-)
Joris _

KodiakDailyMirror.com :: Daily newspaper of Kodiak, Alaska - 0 views

  • The NanoSailD is a solar sail designed to use light particles to accelerate. If all goes well it will be the first solar sail deployed by NASA.
  • It instead uses the sail for the humble but important mission of testing a potential orbit-cleaning tool.
Joris _

FASTSAT performing well; launch of small satellite coming next week | al.com - 0 views

  • Being able to launch a satellite from a satellite has numerous potential benefits to the military and scientists, but those benefits depend on the smaller satellite not hitting the mother ship when it launches and going where it needs to go.If the sail can deploy as planned to its 100-square-foot size - about as big as a six-person camping tent - and can guide the smaller satellite to its planned re-entry, it would also illustrate a new way to bring satellites back to Earth and reduce orbiting space junk.
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