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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
LeopoldS

Effective Space Solutions Ltd - YouTube - 3 views

www.youtube.com/watch

debris

shared by LeopoldS on 21 Sep 14 - No Cached
  • LeopoldS on 21 Sep 14
     
    israeli startup betting on an orbital tug to put telecom sats into graveyard orbit ...
Juxi Leitner

Rogue satellites to be cleared from Earth's orbit by German robots | Science | The Obse... - 1 views

www.guardian.co.uk/...-robots-clear-rogue-satellites

satellites orbital debris security technology

shared by Juxi Leitner on 14 Oct 09 - Cached
  • Their robots will dock with failing satellites to carry out repairs or push them into "graveyard orbits", freeing vital space in geostationary orbit.
  • meant that the German robots will be "ready to be used on any satellite, whether it's designed to be docked or not".
  • Juxi Leitner on 14 Oct 09
     
    I am not sure the military will like this...
jmlloren

Experimental verification of the feasibility of a quantum channel between space and Earth - 0 views

www.iop.org/...njp8_3_033038.html

NAN MAD technology

shared by jmlloren on 14 Jul 09 - Cached
  • jmlloren on 14 Jul 09
     
    Extending quantum communication to space environments would enable us to perform fundamental experiments on quantum physics as well as applications of quantum information at planetary and interplanetary scales. Here, we report on the first experimental study of the conditions for the implementation of the single-photon exchange between a satellite and an Earth-based station. We built an experiment that mimics a single photon source on a satellite, exploiting the telescope at the Matera Laser Ranging Observatory of the Italian Space Agency to detect the transmitted photons. Weak laser pulses, emitted by the ground-based station, are directed toward a satellite equipped with cube-corner retroreflectors. These reflect a small portion of the pulse, with an average of less-than-one photon per pulse directed to our receiver, as required for faint-pulse quantum communication. We were able to detect returns from satellite Ajisai, a low-Earth orbit geodetic satellite, whose orbit has a perigee height of 1485 km.
  • pacome delva on 16 Jul 09
     
    hello Jose! Interesting it was proposed to do the same with the ISS as part of the ACES experiment. I don't remember the paper but i can look if you're interested
Juxi Leitner

DARPA Orbital Debris Removal (ODR) - Federal Business Opportunities: Opportunities - 0 views

www.fbo.gov/index

orbital debris removal darpa

shared by Juxi Leitner on 18 Sep 09 - No Cached
  • Juxi Leitner on 18 Sep 09
     
    DARPA in search for orbit debris removal ideas
santecarloni

[1101.6015] Radio beam vorticity and orbital angular momentum - 1 views

arxiv.org/1101.6015

radio light antennas technology

shared by santecarloni on 20 Oct 11 - No Cached
  • It has been known for a century that electromagnetic fields can transport not only energy and linear momentum but also angular momentum. However, it was not until twenty years ago, with the discovery in laser optics of experimental techniques for the generation, detection and manipulation of photons in well-defined, pure orbital angular momentum (OAM) states, that twisted light and its pertinent optical vorticity and phase singularities began to come into widespread use in science and technology. We have now shown experimentally how OAM and vorticity can be readily imparted onto radio beams. Our results extend those of earlier experiments on angular momentum and vorticity in radio in that we used a single antenna and reflector to directly generate twisted radio beams and verified that their topological properties agree with theoretical predictions. This opens the possibility to work with photon OAM at frequencies low enough to allow the use of antennas and digital signal processing, thus enabling software controlled experimentation also with first-order quantities, and not only second (and higher) order quantities as in optics-type experiments. Since the OAM state space is infinite, our findings provide new tools for achieving high efficiency in radio communications and radar technology.
  • santecarloni on 20 Oct 11
     
    It has been known for a century that electromagnetic fields can transport not only energy and linear momentum but also angular momentum. However, it was not until twenty years ago, with the discovery in laser optics of experimental techniques for the generation, detection and manipulation of photons in well-defined, pure orbital angular momentum (OAM) states, that twisted light and its pertinent optical vorticity and phase singularities began to come into widespread use in science and technology. We have now shown experimentally how OAM and vorticity can be readily imparted onto radio beams. Our results extend those of earlier experiments on angular momentum and vorticity in radio in that we used a single antenna and reflector to directly generate twisted radio beams and verified that their topological properties agree with theoretical predictions. This opens the possibility to work with photon OAM at frequencies low enough to allow the use of antennas and digital signal processing, thus enabling software controlled experimentation also with first-order quantities, and not only second (and higher) order quantities as in optics-type experiments. Since the OAM state space is infinite, our findings provide new tools for achieving high efficiency in radio communications and radar technology.
  • LeopoldS on 20 Oct 11
     
    and how can we use this?
LeopoldS

Testing Continues for Satellite Servicing Capabilities | NASA - 0 views

www.nasa.gov/...tellite-servicing-capabilities

orbit maintenance

shared by LeopoldS on 13 Dec 13 - No Cached
  • LeopoldS on 13 Dec 13
     
    Engineers at NASA's Kennedy Space Center in Florida are partnering with counterparts at the agency's Goddard Space Flight Center in Maryland to develop systems to bring potential future robotic "service tow trucks" to orbiting spacecraft in need of aid
Nina Nadine Ridder

NASA discovers Earth-like planet orbiting 'cousin' of Sun - 1 views

phys.org/...ke-planet-orbiting-cousin.html

exoplanets science ESS earth-like habitable_zone

shared by Nina Nadine Ridder on 24 Jul 15 - No Cached
  • Nina Nadine Ridder on 24 Jul 15
     
    Astronomers hunting for another Earth have found what may be the closest match yet, a potentially rocky planet circling its star at the same distance as the Earth orbits the Sun, NASA said Thursday.
Luís F. Simões

Timelapse video of asteroid discoveries in our solar system from 1980-2010 (watch in 10... - 5 views

www.youtube.com/watch

asteroid detection solar system WISE

shared by Luís F. Simões on 13 Sep 10 - No Cached
Joris _ liked it
  • Ma Ru on 14 Sep 10
     
    Nice... Now I have a lame question: after you have discovered ~500k asteroids, all moving (I assume more or less) chaotically in that asteroid belt, how do you tell one from another?
  • ...1 more comment...
  • Joris _ on 14 Sep 10
     
    hmm, not very chaotic indeed - laws of Kepler plus some perturbations.
  • Ma Ru on 15 Sep 10
     
    That's what I thought but when presented as a green "goo" in the video, it appears rather unordered... so I guess this is just an impression evoked by a not-to-scale presentation?
  • Francesco Biscani on 19 Sep 10
     
    It depends... orbits can be chaotic if the orbital period is in a resonance with Jupiter, although such orbits are not stable. Such configurations tend to get disrupted pretty quickly (in cosmic terms :P) http://en.wikipedia.org/wiki/Kirkwood_gap
Joris _

Japan probe overshoots Venus, heads toward sun - 0 views

www.washingtonpost.com/...AR2010120701077.html

MAD venus robust

shared by Joris _ on 08 Dec 10 - No Cached
sreejanag liked it
  • A Japanese probe to Venus failed to reach orbit Wednesday and was captured by the sun's gravitational pull
  • Akatsuki's engines did not fire long enough to attain the proper orbiting position
  • may be able to try again when it passes by Venus six years from now.
  • Joris _ on 08 Dec 10
     
    The usefulness of having a robust trajectory :) ... They have to wait 6 more years for another date with Venus ...
  • ...2 more comments...
  • Joris _ on 09 Dec 10
  • LeopoldS on 11 Dec 10
     
    I agree in general but just out of the stomach: is there really an optimised trajectory that would be able to avoid this kind of scenarios when main thrusters don't perform properly? Wouldn't you in any case end up in a sun-orbiting trajectory and have to come back after years??
  • Joris _ on 11 Dec 10
     
    "optimised trajectory" of course not, robust definitely! It was the subject of my paper presented at the AAS (the one in San Diego) "Designing robust interplanetary trajectories subject to one temporary engine failure". The problem here is that they do not have enough fuel for a correction maneuver that would allow to come back to Venus earlier, and break for a VOI. A robust scenario could have alloted the best amount of fuel and time to be able to recover from almost all possible unplanned events. In the paper, I introduce some confidence regions such that I get the robust control for p% chance of mission success in case m% chance of problem with the propulsion system.
  • Dario Izzo on 12 Dec 10
     
    You should run your method on this scenario and see if you could get a trajectory with a shorter come back time using the same spacecraft.... would be a big selling point for a new trajectory design approach
Luís F. Simões

Boeing probes international market for human spacecraft - 1 views

spaceflightnow.com/...10cst100

human spaceflight commercial spaceflight

shared by Luís F. Simões on 11 Feb 11 - No Cached
  • The aerospace powerhouse is designing and testing systems for its CST-100 space capsule, a craft the company says could begin flying astronauts to low Earth orbit by 2015. It will launch on existing rockets to lessen development risk and costs.
  • "The spacecraft that we're designing is rocket-agnostic. It would be possible to sell this like a commercial airplane to countries who perhaps have a launch vehicle who would like to launch it in their own country."
  • Luís F. Simões on 11 Feb 11
     
    ...and hitting the news in the same day: A Rocket Built from U.S. and European Parts "A new rocket that would combine parts from NASA's canceled Ares I rocket as well as the Ariane 5 , a well-proven European satellite launcher, could provide a low-cost option for taking crew and cargo to the space station. The rocket proposal was announced this week by ATK, an aerospace and defense company that manufactures the solid rocket motors for NASA's space shuttles, and Astrium, the European company that makes the Ariane 5. They say the rocket, called Liberty, would be ready for flight by 2015." "Other commercial companies, including Boeing and Orbital Sciences Corporation, are looking to use low-end versions of the Atlas V to carry the capsules they are building. Liberty could carry any capsule at a cost less than that of the Atlas V, according to ATK." Look! Competition! :)
Dario Izzo

Black Holes play drums - 8 views

www.jannalevin.com/science.html

shared by Dario Izzo on 08 Jun 11 - No Cached
  • Dario Izzo on 08 Jun 11
     
    Another great presentation at this conference!! Plus I always wanted to enter the numerical computations of orbit around black holes.... with Luzi we had a project on formation flying around black holes .... revolutionary idea (of course we did not do it!!!)
  • ...1 more comment...
  • Ma Ru on 08 Jun 11
     
    formation flying around black holes... so practical...
  • pacome delva on 08 Jun 11
     
    nice movie, and song :) we should definitely implement GR orbits in pagmo !
  • Dario Izzo on 08 Jun 11
     
    I agree Marek, yet was it practical for Apollonio to study conic sections more than 1500 years before Kepler found his three laws? And here is a good paper to start with: http://prd.aps.org/abstract/PRD/v77/i10/e103005, making an analogy between the periodic table and the taxomony of all orbits around a black hole.
ESA ACT

Utilization of Photon Orbital Angular Momentum in the Low-Frequency Radio Domain - 0 views

scitation.aip.org/...GetabsServlet

NAN

shared by ESA ACT on 24 Apr 09 - No Cached
  • ESA ACT on 24 Apr 09
     
    We show numerically that vector antenna arrays can generate radio beams that exhibit spin and orbital angular momentum characteristics similar to those of helical Laguerre-Gauss laser beams in paraxial optics. For low frequencies (<~1 GHz), digital techni
Nina Nadine Ridder

To save on weight, a detour to the moon is the best route to Mars - 1 views

phys.org/...ht-detour-moon-route-mars.html

technology space lunar_base fuel Mars_missions

shared by Nina Nadine Ridder on 15 Oct 15 - No Cached
Ethan Evan liked it
  • Nina Nadine Ridder on 15 Oct 15
     
    More arguments for a lunar base? "They found the most mass-efficient path involves launching a crew from Earth with just enough fuel to get into orbit around the Earth. A fuel-producing plant on the surface of the moon would then launch tankers of fuel into space, where they would enter gravitational orbit. The tankers would eventually be picked up by the Mars-bound crew, which would then head to a nearby fueling station to gas up before ultimately heading to Mars."
  • Alexander Wittig on 16 Oct 15
     
    There was a paper with a very similar concept (reaching Mars via DRO) at the AAS meeting in January by Conte et al. First, the total Delta V required for a trip Earth -> LLO -> MLO is higher than Earth -> MLO. The trick is that Earth -> LLO requires less Delta V than Earth -> MLO and hence less mass has to be carried along *from Earth*. Essentially what both approaches have in common is that they say "if there's a free gas station orbiting the moon, it's cheaper to fly empty and fill up there on the way". The AAS paper actually does a decent job at estimating the "real" cost by also including estimates of the cost of a lunar base. https://pure.strath.ac.uk/portal/files/44275737/Conte_etal_AAS2015_Earth_Mars_transfers_through_Moon_distant_retrograde_orbit.pdf
joergmueller

Caltech Researchers Find Evidence of a Real Ninth Planet | Caltech - 0 views

www.caltech.edu/...idence-real-ninth-planet-49523

PHY space science

shared by joergmueller on 21 Jan 16 - No Cached
  • joergmueller on 21 Jan 16
     
    Caltech researchers have found evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer solar system. The object, which the researchers have nicknamed Planet Nine, has a mass about 10 times that of Earth and orbits about 20 times farther from the sun on average than does Neptune (which orbits the sun at an average distance of 2.8 billion miles).
LeopoldS

Orbit Fab to launch first fuel tanker in 2021 with Spaceflight - SpaceNews - 1 views

spacenews.com/fab-to-launch-with-spaceflight

in orbit servicing

shared by LeopoldS on 19 Nov 20 - No Cached
  • LeopoldS on 19 Nov 20
     
    interesting approach, quite a gamble in my view but moving in the right direction
santecarloni

The Colour Of Alien Earths - Technology Review - 0 views

www.technologyreview.com/...the-colour-of-alien-earths

space technology

shared by santecarloni on 25 Sep 12 - No Cached
  • santecarloni on 25 Sep 12
     
    Earth is a pale blue dot when viewed from space. Now astrobiologists have worked out the likely colours of Earth-like planets orbiting other stars
Joris _

NASA International Space Station Longeron Marathon Challenge - 1 views

www.topcoder.com/iss

MAD optimization

shared by Joris _ on 18 Jan 13 - No Cached
LeopoldS liked it
  • LeopoldS on 19 Jan 13
     
    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.
  • Joris _ on 26 Jan 13
     
    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.
Luís F. Simões

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

news.sciencemag.org/...cists-discover-a-whopping.html

MAD

shared by Luís F. Simões on 10 Mar 13 - No Cached
  • The discovery of 13 new families, made by physicists Milovan Šuvakov and Veljko Dmitrašinović at the University of Belgrade, brings the new total to 16.
  • All the solutions can be viewed online
  • Dario Izzo on 10 Mar 13
     
    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 :)
  • Francesco Biscani on 11 Mar 13
     
    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?
Isabelle Dicaire

ESO - eso1241 - Planet Found in Nearest Star System to Earth - 0 views

www.eso.org/eso1241

shared by Isabelle Dicaire on 19 Oct 12 - No Cached
LeopoldS liked it
  • Isabelle Dicaire on 19 Oct 12
     
    An Earth-sized planet is found orbiting Alpha Centauri B in the closest star system from us!
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