Skip to main content

Home/ Advanced Concepts Team/ Group items tagged entry

Rss Feed Group items tagged

Filter: All | Bookmarks | Topics Simple Middle
Marcus Maertens

Everything You Wanted to Know about Space Tourism but Were Afraid to Ask | Space Safety... - 3 views

www.spacesafetymagazine.com/...wanted-space-tourism-afraid

space

shared by Marcus Maertens on 04 Feb 13 - No Cached
  • Marcus Maertens on 04 Feb 13
     
    "chances are that if 700 passengers are flown annually, up to 10 of them might not survive the flight in the first years of the operations." most remarkable also the question who is to blame if a dead and burned space tourist corps comes crashing down from the sky into your car.
  • ...3 more comments...
  • dejanpetkow on 07 Feb 13
     
    How sure is the information that a human body would not completely burn / ablate during atmospheric re-entry? I am not aware of any material ground tests in a plasma wind tunnel confirming that human tissue would survive re-entry from LEO.
  • Marcus Maertens on 07 Feb 13
     
    Since a steak would not even be cooked by dropping it from very high altitudes (http://what-if.xkcd.com/28/) I would doubt that a space tourists body would desintegrate by atmospheric re-entry.
  • dejanpetkow on 07 Feb 13
     
    Funny link, however, some things are not clear enough: 1. Ablation rate is unknown 2. What are the entry conditions? The link suggests that the steak is just dropped (no initial velocity). 3. What about the ballistic coefficient? 4. How would the entry body orientation? It would be a quite non-steady state configuration I guess with heavy accelerations. 5. How would vacuum exposure impact on the water in the body/steak and what would be the consequence for ablation behaviour? 6. Does surface chemistry play a role (not ablation, but catalysis)? My conclusion: the example with the steak is a funny and not so bad exercise, not more.
  • LeopoldS on 09 Feb 13
     
    This calls for some we serious simulations by the Petkow code it seems to me ...
  • dejanpetkow on 09 Feb 13
     
    I still would need some serious input data...
Dario Izzo

Optimal Control Probem in the CR3BP solved!!! - 7 views

math.u-bourgogne.fr/...research

OCP CR3BP trajectory MAD

shared by Dario Izzo on 07 Jun 11 - No Cached
  • Dario Izzo on 07 Jun 11
     
    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...
  • Ma Ru on 08 Jun 11
     
    Riemann hypothesis should be next... Which paper on the linked website is this exactly?
  • Joris _ on 08 Jun 11
     
    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 :)
  • Dario Izzo on 08 Jun 11
     
    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 :)
  • Dario Izzo on 08 Jun 11
     
    Answer to Marek: the paper you may look at is: Discrete and differential homotopy in circular restricted three-body control
  • Joris _ on 08 Jun 11
     
    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.
  • Joris _ on 08 Jun 11
     
    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
  • Dario Izzo on 08 Jun 11
     
    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!!!!!"
  • Joris _ on 09 Jun 11
     
    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:)
  • Dario Izzo on 09 Jun 11
     
    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!!
  • Joris _ on 09 Jun 11
     
    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!
  • Dario Izzo on 09 Jun 11
     
    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)
  • LeopoldS on 11 Jun 11
     
    this is why I like this Diigo thingy so much more than delicious ...
  • tvinko on 17 Jun 11
     
    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.)
  • LeopoldS on 18 Jun 11
     
    I like when there are discussions evolving around entries
  • LeopoldS on 18 Jun 11
     
    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 ...
Juxi Leitner

Hayabusa Sample Return Capsule Entry - Airborne Observing Campaign - 0 views

airborne.seti.org/hayabusa

re-entry mission live video jaxa nasa

shared by Juxi Leitner on 10 Jun 10 - Cached
  • An attempt will be made to provide a live video feed of the Hayabusa Re-Entry in the minutes around the re-entry at 13:51 UT, Sunday June 13. The video will be chosen from cameras operated onboard NASA's DC-8 Airborne Laboratory
  • Ma Ru on 10 Jun 10
     
    After reading the Hayabusa's story posted by Joris a while ago, I think that the only adequately epic final to conclude this awesome mission is that the capsule will land safely. And empty.
LeopoldS

Meteorite Crashes In Russia, Panic Spreads (Updating) - 5 views

gizmodo.com/...rashes-in-russia-panic-spreads

shared by LeopoldS on 15 Feb 13 - No Cached
  • Joris _ on 15 Feb 13
     
    Latest update: the European Space Agency says their experts "confirm there is no link between the meteor incidents in Russia and asteroid 2012DA14 flyby tonight". How did they find this? As they did not see this one coming, how could they come to that conclusion that early!
  • ...5 more comments...
  • johannessimon81 on 15 Feb 13
     
    As you can see from the videos of this meteorite it is coming in from an east to south-east direction (i.e. the direction of the sunrise, more or less). 2012DA14 is coming from due south as you can see here: http://www.wired.com/wiredscience/2013/02/how-to-watch-asteroid-2012-da14/ So the two objects seem to be coming from different directions - at least that would be my explanation.
  • Joris _ on 15 Feb 13
     
    My point is, that if you want to come to such a conclusion (that it is not rubble) you need to be able to construct back the orbits of both objects. 2012DA14 has been observed for one year only, but it is well enough. When the meteor has been observed for the first time, such that we knew its orbit? has it been observed before? if yes, why the impact has not been predicted?
  • johannessimon81 on 15 Feb 13
     
    If you can show that they come from different directions you know that they are not associated, even if you don't reconstruct their orbits.
  • Joris _ on 15 Feb 13
     
    I don't think so. If both objects were part of the same, they would be on different but intersecting orbits anyway, hence different directions. Anyway, I am not knowledgeable in atmospheric entry ... But, with so few information about the object, I am surprised they are 100% certain it is not related to DA14. I think science requires more cautions ... With only the direction they are 100% sure, while the probability of such event is itself extremely small, I am amazed... They can't even predict with 100% certainty where a space debris will fall... plus, nobody consider the object being part of a bigger one that broke up during early entry (which has not been observed) ... so many uncertainties and possible hypothesis... and i am not the only one :) http://www.infowars.com/russian-meteor-linked-to-da14-asteroid/
  • LeopoldS on 17 Feb 13
     
    was not that evident to me also but apparently with the right understanding it was quite clear; was amazed also how quickly NASA has published the likely trajectory of the russian object - have a look at it: quite evident that these are not coming from the same body
  • Joris _ on 17 Feb 13
     
    yes, now i get my 100% certainty with the reconstructed orbits nothing else (http://wiki.nasa.gov/cm/blog/Watch%20the%20Skies/posts/post_1361037562855.html) ... I still think that esa anouncemement was highly premature but with a high probability of being right...
  • Ma Ru on 26 Feb 13
     
    Some more results on the topic (link to an arxiv article inside): http://www.bbc.co.uk/news/science-environment-21579422
Luís F. Simões

The Amazing Trajectories of Life-Bearing Meteorites from Earth - Technology Review - 0 views

www.technologyreview.com/...27720

BIO life meteorite microbes

shared by Luís F. Simões on 11 Apr 12 - No Cached
  • That raises another interesting question: how quickly could life-bearing ejecta from Earth (or anywhere else) seed the entire galaxy? Hara and co calculate that it would take some 10^12 years for ejecta to spread through a volume of space the size of the Milky Way. But since our galaxy is only 10^10 years old, a single ejection event could not have done the trick. However, they say that if life evolved at 25 different sites in the galaxy 10^10 years ago, then the combined ejecta from these places would now fill the Milky Way.
  • Ref: arxiv.org/abs/1204.1719: Transfer of Life-Bearing Meteorites from Earth to Other Planets
Thijs Versloot

Magnetic bubble may give space probes a soft landing - 4 views

www.newscientist.com/article/mg22329763.100-magnetic-bubble-may-give-space-probes-a-soft-landing.html?cmpid=RSS|NSNS|2012-GLOBAL|physics-math#.U7aeTnWSzmE

magnetoshell aerocapture plasma entry

shared by Thijs Versloot on 04 Jul 14 - No Cached
  • Thijs Versloot on 04 Jul 14
     
    I am also looking into this idea since some time and it seems NASA is already ahead, awarding two contract to investigate magnetoshell aerocapture. This could be interesting for probes that want to enter eg Marsian atmospheres at relatively high velocity. Or for multiple re-entry s/c at Earth. The idea of the experiment, The satellite will carry a copper coil, powered by a lithium-ion battery, that generates a magnetic field around the probe. As it descends, the spacecraft will eject a small amount of plasma. This gets trapped in the magnetic field, creating a protective bubble that stops air molecules colliding with the craft and producing heat.
  • LeopoldS on 05 Jul 14
     
    A few years back Mimmo has worked on this, rather from the theory side if I remember well ...
  • Paul N on 11 Jul 14
     
    The power requirements for such a thing must be HUGE!
Thijs Versloot

Communicate through the plasma sheath during re-entry - 1 views

scitation.aip.org/...1.4921751

technology plasma hypersonic

shared by Thijs Versloot on 10 Jul 15 - No Cached
  • Thijs Versloot on 10 Jul 15
     
    In order to overcome the communication blackout problem suffered by hypersonic vehicles, a matching approach has been proposed for the first time in this paper. It utilizes a double-positive (DPS) material layer surrounding a hypersonic vehicle antenna to match with the plasma sheath enclosing the vehicle. Or in more easy language, basically one provides an antenna as capacitor, in combination with the plasma sheath (an inductor), they form an electrical circuit which becomes transparent for long wavelength radiation (the communication signal). The reasons is that fluctuations are balanced by the twin system, preventing absorption/reflection of the incoming radiation. Elegant solution, but will only work on long wavelength communication, plus I am not sure whether the antenna needs active control (as the plasma sheath conditions change during the re-entry phase).
LeopoldS

Crypto-Gram: October 15, 2013 - 2 views

www.schneier.com/crypto-gram-1310.html

security internet

shared by LeopoldS on 07 Nov 13 - No Cached
Nicholas Lan liked it
  • LeopoldS on 07 Nov 13
     
    interesting blog entry on TOR and the NSA
  • Nicholas Lan on 08 Nov 13
     
    on a somewhat related note. court document from the fbi agent that was chasing that silk road guy a friend sent me the other week. an interesting read if only because i found the content quite unexpected e.g. 2 pages of login instructions http://www1.icsi.berkeley.edu/~nweaver/UlbrichtCriminalComplaint.pdf
LeopoldS

Open innovation and Apple .... - 6 views

www.linkedin.com/news

open innovation IT

shared by LeopoldS on 14 Jun 10 - No Cached
  • LeopoldS on 14 Jun 10
     
    interesting blog entry
  • ...3 more comments...
  • Francesco Biscani on 14 Jun 10
     
    Your link points to a restricted LinkedIn page... Here's the original link: http://www.15inno.com/2010/06/07/apple/
  • Francesco Biscani on 14 Jun 10
     
    A pretty standard Apple-o-getic (ah ah) blog post. How many times does the guy say 'I like Apple'? Anyway, I'm having a hard time understanding the point he is trying to make. Apple should open up its innovation? It shouldn't because they are so hip, cool, a 'unique company' and an 'exception to the rule'? Mah..
  • Ma Ru on 14 Jun 10
     
    I think the point is the guy bashes the "open innovation theory" (whatever the theory is) with his main argument being that Apple is not open and at the same time very successful.
  • LeopoldS on 14 Jun 10
     
    this guy is actually one of the most fervent supporters of open innovation and tries to promote it whereever he can ... his problem is that at least at first view Apple does not confirm his theory ...
  • Francesco Biscani on 15 Jun 10
     
    lol, the 'about' page is priceless bullshit: http://www.15inno.com/about-15inno/ "Corporate Mind Exchange (CMX) events in which corporate innovation leaders discuss relevant challenges and issues. No academics, consultants or start-ups; just corporate practitioners." We are doing it wrong, Leo. We don't need no stinking Universities! "Network groups in which 12-20 innovation leaders from different companies meet 4-6 times annually to discuss challenges and issues. Workshops and events with thought leaders and practitioners." What the hell are "innovation/thought leaders"?
Dario Izzo

World's Strangest | A Glass Bottle Will Disappear… - 4 views

www.worldsstrangest.com/...a-glass-bottle-will-disappear

NAN optics

shared by Dario Izzo on 15 Dec 09 - Cached
  • Dario Izzo on 15 Dec 09
     
    Here is a first entry for our canweuseitforspace database. Jose, apparently this invisibility cloack is not that difficult after all!!!! Watch the youtube video.....
nikolas smyrlakis

UNITED KINGDOM SPACE AGENCY UKSA (fake website) - 3 views

www.uk-space.com

space united kingdom fun

shared by nikolas smyrlakis on 24 Mar 10 - Cached
  • nikolas smyrlakis on 24 Mar 10
     
    according to the normal website (http://www.bnsc.gov.uk/): "The UK Space Agency website will officially launch on 1 April 2010. Until then, the BNSC website will be in a state of transition " the guys above i think just take the piss coz theres no official website. Mission statement: TOGETHER WE ARE GOING TO EMBARK ON A JOURNEY INTO SPACE. ..........................THE MISSION IS......MARS................................."
  • Ma Ru on 24 Mar 10
     
    I've just read a blog entry about this on New Scientist, and while the entry itself is not interesting, I learned from it where the UKSA and ESA's UK establishment are going to be based. Answer: it's even more in the middle of nowhere than Plymouth! BTW does anyone (Leo?) know what is the basis on which new ESA establishments locations are chosen (if this info is classified, you can send it on priv ;) [Edit] Esa has released a news item about it... Whatever one can say about the British Space Agency, they certainly have a fantastic logo!
LeopoldS

Three-Dimensional Invisibility Cloak at Optical Wavelengths - 4 views

www.sciencemag.org/...337.abstract

technology phy science nan

shared by LeopoldS on 16 May 11 - No Cached
  • LeopoldS on 16 May 11
     
    more transformation optics ... 
  • dejanpetkow on 17 May 11
     
    I still believe that it is worth to check the thermal, mechanical and chemical properties of the developed metamaterials. For hyperbolic re-entries the radiation is still the dominating heat load source and a dominating bandwith may be indentified. A resistive metamaterial should be placed on the nose cap of the entry body in order to reduce local radiation heat load.
ESA ACT

Gallery of NSS Space Settlement Art Contest - 0 views

www.nss.org/...gallery.htm

MAD art technology

shared by ESA ACT on 24 Apr 09 - Cached
  • ESA ACT on 24 Apr 09
     
    The following images have been accepted by the NSS Space Settlement Calendar Committee as entries in the NSS Space Settlement 2009 Calendar Art Contest.
ESA ACT

Slashdot | Cutting-Edge AI Projects? - 0 views

tech.slashdot.org/article.pl

AI INF fun

shared by ESA ACT on 24 Apr 09 - Cached
  • ESA ACT on 24 Apr 09
     
    Read the first entries, are really funny. The ones tagged as "Informative" contain references that might be useful for us.
ESA ACT

What are the greatest challenges to the advancement of science and research? - 0 views

www.publicservice.co.uk/article.asp

science research future

shared by ESA ACT on 24 Apr 09 - Cached
  • ESA ACT on 24 Apr 09
     
    Our entry may not have made it to the publication but perhaps the other opinions will give some food for thought
pablo_gomez

How AI could help make Wikipedia entries more accurate - 0 views

tech.fb.com/...ikipedia-entries-more-accurate

technology AI

shared by pablo_gomez on 31 Jul 22 - No Cached
  • pablo_gomez on 31 Jul 22
     
    Now this sounds pretty useful
LeopoldS

ExtremeTech - USAF Flying saucer document from the 1960s - 1 views

m.extremetech.com/extremetech

Advanced aircraft

shared by LeopoldS on 09 Oct 12 - No Cached
  • LeopoldS on 09 Oct 12
     
    Funny ...
johannessimon81

Frozen Water and Organic Material Discovered on Mercury - 1 views

www.wired.com/...water-ice-organics-mercury

shared by johannessimon81 on 30 Nov 12 - No Cached
  • LeopoldS on 01 Dec 12
     
    Sorry, did not see your entry when posting mine ...
Juxi Leitner

Spaceflight Now | Breaking News | Private spaceflight gets new contender with Stratolaunch - 1 views

spaceflightnow.com/...13stratolaunch

private spaceflight launcher technology

shared by Juxi Leitner on 13 Dec 11 - No Cached
  • LeopoldS on 14 Dec 11
     
    sorry - have not seen your entry before posting mine today ...
Lionel Jacques

Russian Craft Fails to Head to Mars Moon - 1 views

www.thestar.com/...t-toxic-falling-satellite-ever

space technology science

shared by Lionel Jacques on 09 Nov 11 - No Cached
  • Lionel Jacques on 09 Nov 11
     
    Out-of-control Russian space probe may be 'most toxic falling satellite ever: A Russian space probe aiming to land on a Mars moon was stuck circling the Earth after equipment failure Wednesday, and scientists raced to fire up its engines before the whole thing came crashing down.
  • Ma Ru on 09 Nov 11
     
    Is it just me, or is uncontrolled space junk re-entry becoming trendy?
  • LeopoldS on 12 Nov 11
     
    this was a fantastic mission - ... what a pity!
1 - 20 of 42 Next › Last »
Showing 20▼ items per page