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Dear Dr. Filipe Wiltgen , Thank you for this brilliant scientific & technical question.
I think there is one impediment. It is about radiation.
Also, I believe the technology is already there, and some countries have made enough progress on incorporating this technology in their war machinery (as pointed out by Dr. Pedro L. Contreras E. )
Apart from this, I dream, one day I would be driving my bike or car that runs on nuclear fuel.
Best wishes and regards
Yoganandan
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Russian project to explore the moons of Jupiter after 2030 will be based on the nuclear propulsion spacecraft "Nuklon" with an electrical energy power of 0.5 MW. Such energy power gives the opportunity to significantly increase a data transfer performance to Earth. In my opinion, the speed of data transfer can be increase to 100 Mbit/sec. This value will be enough to use 4K Video for the investigation of dynamic processes in the atmosphere of Jupiter and moons. What is your opinion about this?
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I did confuse confuse bandwidth with delay a bit, but not in recent comments, I think, because I realised I was doing it.
Unless the entangled pairs are prepared on earth and then half are sent to Jupiter on the satellite, which would require coherence lifetimes of years (many orders of magnitude above present lifetimes), a signal has to be sent from Jupiter at lightspeed (for instance a photon entangled with the state on Jupiter) to convey the entanglement information between the two sites before the quantum measurement, so that the half of the entangled state can be set up on earth. This means that the actual data rate is still limited by the bandwidth of the lightspeed signals, even if data can be sent with no delay,
I guess if zero delay was possible, it would still be useful, for things like steering a remote vehicle, or conversation.
I expect that each entangled state will carry 1 bit, one Q-bit.
I am not sure instantaneous communication will ever happen. It may. I don't understand it enough to be sure it can't work. I hope it may be possible. It would also raise lots of interesting problems with relativity. I wouldn't invest my pension on it, but I might invest fun money.
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Which ozone sensor is perfect for
Balloon-borne Space Exploration project at a altitude of 40 kilometers? Please specify the model no also.
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Mmm.
At that altitude the concentration is ~10^11 molecules per cc.
I doubt that a COTS ozone sensor designed for use in 1 bar would be useful.
(at rtp there being 10^20 molecules per cc, give or take)
So a sensor would need to have 1ppb as its upper range, and have a resolution ten times better than that at least.
A spectral absorption method appears to be the best bet:
And you may need to 'fold' the optical path a few times to reduce the upper detection limit to the desired value. A Heriott or White cell may help.
The absorption of interest is in the 250nm range:
...and LEDs are available nowadays that can provide significant flux at those wavelengths - so no need to look at D2 or Xe lamps!
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A number of earth like planets have been discovered, but they are thousands of light years away. What are our chances of living on these planets?
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To do the same for what they did to Earth? Wherever we go; death will follow us . It is wiser to work for the other life; the Eternal one.
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I am trying to study the dusty hypersonic flow over a sphere to find out the effect of particles in increasing stagnation heat flux using DSMC. I am using particle-wall collision model proposed Tabakoff et al.[1] as there is no model proposed at hypersonic speed to the best of my knowledge.
Is there any other model available for particle-wall collisions at very high speed flows? Should I calculate the heat flux due to particles in the same way as gas-wall collision, i.e., change in energy before and after the collision?
[1] Tabakoff et al. "Effect of Target Materials on the Particle Restitution Characteristics for Turbomachinery Application." JOURNAL OF PROPULSION AND POWER Vol. 12, No. 2, March-April 1996
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Interesting question
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I want to start a philosophical discussion and ethical debate on the reasoning behind why humanity should and must become a multi-planet species.
  • What do you think is the most profound and captivating reason(s) that you have to justify SpaceX and Elon Musk's goal of making humanity a multi-planetary species?
Elon said during the 68th Annual ISC on September 29th 2017:
"I think fundamentally the future is vastly more exciting and interesting if we're a spacefaring civilization and a multi-planet species than if we are not. You want to be inspired by things. You want to wake up in the morning and think the future is going to be great."
I agree with him here, but I think there is something more profound and captivating that must be addressed with regards to becoming a species that lives on more than just one planetary body. Other questions we may want to consider to help us reach this answer include:
  • What are the ethical considerations we must address before colonizing other worlds?
  • Do humans really deserve another planet to potentially ruin, or even sustainably terraform, if we cannot even figure out how to sustainably balance our own home world?
  • One might ask why doesn't Elon use his genius to create new technologies that will advance the human race by solving some of the Earth's worst problems?
  • Has he simply given up on this planet and does he therefore want a clean slate to build up from?
  • Does Elon think that technological advancements resulting from the drive to become a spacefaring civilization (i.e. propellant production via. CO2 sequestration powered by 100% solar energy systems) will eventually rebound to help the Earth?
  • Must we start colonizing Mars now (i.e. beginning in the year 2022) like Elon's timeline suggests? Potentially, if we wait too long, technologies to reverse climate change on Earth may not have advanced enough without the excitement of being spacefaring...
Lets see what everyone thinks about this, and let's keep it civilized in here. Try and get real profound!
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If i may add my 5 cents to this:
  • What do you think is the most profound and captivating reason(s) that you have to justify SpaceX and Elon Musk's goal of making humanity a multi-planetary species?
--> Depends how you want to see Elon Musk: as the visionary who wants humanity to thrive and improve? Or just as the one who seeks fame and fortune for being the first in doing things?
In my humble opinion, humanity has yet to reach a level of mindset to overcome cultural and religious differences. We might have satellites and smart phones, but in our thinking we still behave like cave-men.
For example, the Americans, when setting foot on the Moon, put an American flag there. Not one showing Earth. How would it be on Mars, when Chinese, Indians, Europeans and Americans set foot there? Whom will it belong to? For sure not the entire humanity, so we would just bring all of our archaic thinking into a new world. All our problems and issues, and soon the new planet will suffer all the same problems as we have on Earth.
As long as we do not manage to live as one humanity on one planet (i.e. having a global government), there is no point in making humanity multi-planetary.
  • What are the ethical considerations we must address before colonizing other worlds?
--> As mentioned above: if you want to colonise something, who does it belong to? Is there indigenous life (whether intelligent or not)? Or is it a barren rock?
Now given the barren rock case: Who does it belong to? Imagine it has a huge amount of rare minerals on it. Is it "whoever finds it can keep it"? In the outer space treaty from the 1960s, they addressed this topic, saying that space belongs to all humanity, yet not all nations have signed this and yet when it comes to mining/farming/inhabiting these space environments, how is that regulated? And if violated, who prosecutes the violators?
There is a huge legal issue in regards to occupying space environments.
Now given the planet is not a barren rock, but an obviously inhabited planet: Now we can either develop yourselves as species and not touch the ecosystems of these planets, leaving them pristine for the indigenous life. Or we can act in the human way and do the same mistakes as we did in the past over and over again and just go there, exploit and trash the planet until its depletion.
The most difficult and realistic case is actually the case of Mars:
Why is Mars so interesting? Because in its past it was very similar to Earth, it had a denser atmosphere, a magnetic field, volcanism, starting plate tectonics, liquid water and all chemical ingredients for forming life. Mars might have gone through a similar evolution as Earth, forming microbial life, or maybe even be the origin of terrestrial life, as interplanetary transportation of rocks after impact events is proven to occur. Now, Mars is the perfect (and maybe only) place to actually study how life on Earth could develop and if life could develop on other planets as well, if life is unique or if it appears quite common throughout the universe.
But, if we send now a bunch of colonists there, who will bring lots and lots of organic material from Earth, we might spoil Mars to a degree where we cannot study this anymore, loosing a very unique opportunity.
Given the case there is still life around, wouldn't it be best to first study it, before building houses, schools and hospitals next to it?
And then there is another ethical consideration that needs to be taken into account:
Sending colonists to space with current technologists would use up significant amounts of terrestrial resources. Sending just 30000 colonists to Mars would already use up all the remaining mineral oil reserves on Earth, not to mention the metals, materials, supplies, etc shipped with the settlers. In order to send these few privileged people to Mars, the rest of humanity will have to sacrifice their lifestyle, their future and their environment. Is that ethical?
  • Do humans really deserve another planet to potentially ruin, or even sustainably terraform, if we cannot even figure out how to sustainably balance our own home world?
--> If we could terraform Mars, why not first terraform Earth? Reverse the effects of climate change, stop and reverse desertification. Earth is better studied than Mars, but as long as here high-ranked people make money with pollution and deny scientific facts, nothing will happen for the better. The money that Musk wants to spend on the colonisation could as well be spent to cover parts of the Earth's desert areas with solar power plants, providing humanity with CO2-free energy. That would benefit more people.
Also, terraforming Mars will not be sustainable. Mars is loosing its atmosphere, because of the lack of a global magnetic field. it might become a home for a while, but thinking into the far future, Mars will be back to where it is now.
Plus, how do we know we can potentially manage to create stable living conditions on Mars, when we are all about destabilising every environment we enter?
  • One might ask why doesn't Elon use his genius to create new technologies that will advance the human race by solving some of the Earth's worst problems?
  • Has he simply given up on this planet and does he therefore want a clean slate to build up from?
--> Maybe because it is easier messing up something new, rather than fixing something old?
  • Does Elon think that technological advancements resulting from the drive to become a spacefaring civilization (i.e. propellant production via. CO2 sequestration powered by 100% solar energy systems) will eventually rebound to help the Earth?
--> Musk's rockets use RP1 (refined kerosine) like all other rockets, and as long as this remains the cheapest fuel, nothing will change. Rockets are basically 95% fuel that is burnt. Using synthetical fuels is a huge cost factor. And especially since the CO2-concentrations (despite being high enough to significantly influence the climate) in the atmosphere are too low for economical use, I do not see any of this happening any time soon.
  • Must we start colonizing Mars now (i.e. beginning in the year 2022) like Elon's timeline suggests? Potentially, if we wait too long, technologies to reverse climate change on Earth may not have advanced enough without the excitement of being spacefaring...
--> No. We need to politically, economically and ecologically get our shit together first. We need to all reduce our negative imprint on the environment on Earth, foster international collaboration not wars, fear or hate, we need to change our thinking not towards maximising the monetary output, but in maximising our own happiness and humanity towards others.
Also, we should (must) explore Mars first. The right step is to first send a small groups of astronauts to carefully study Mars (and come back) over an extended period of time (~20 years) to really answer all our open scientific questions, before we can even think of inevitably spoiling the pristinity of the planet.
==> this would be the right way, and would avoid many of the mistakes that human explorers on Earth have done in the past (i.e. settling at their first arrival to a new place)
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Note in particular are you interested in the case where the rover may at times operate autonmously and at other times as a teleoperator while storing data for an astronaut user in a remote location, ie one of Mar's moons?
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This project is an engineer's dream. It has elements that require the project team members to creatively blend established (even old) techniques with new ones, in "outside the box" ways. Teleoperation in real-time is not possible, so giving detailed directions to the onsite exploration vehicle won't work. So, develop primitive routines that can be strung together like beads using higher-level commands. The rover should understand general commands from mission control, like "explore quadrant G31 and report", leaving details of how to accomplish that task to itself. An expert system would be an excellent starting point, with the "experts" being the development engineers and scientists. The rover sensors would allow monitoring planning and execution. Any exceptions to a routine, such as bumping into a rock, or approaching a precipice, would be reflected to control on Earth, to facilitate improvement to existing routines and addition of new ones. Then, creating a "curiosity" attribute to blend a variety of exploration methods would be helpful. How would a robot look for interesting planetary features and objects, or avoid weather? Imitating human behavior is a great place to start: nature has provided the plan. I gave a 3-hour presentation at MIT on this approach 7 years ago: “Tutorial: Biologically-Inspired Object-Oriented Design & Object-Oriented Programming for Robotics and Artificial Intelligence”, 15th IASTED Intl Conf on Robotics & Applic, MIT, Cambridge MA, Nov 1-3, 2010. I've given 26 presentations at NASA Houston since 2006, most involving artificial intelligence and robotics for space applications.
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There are already plans about the possibly terraforming Mars. I am wondering which factors are most important in creating a place that is habitable by humans. Also, if there are alternatives to Mars that are currently being considered. 
Here is the research that I found about terraforming Mars:
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The most fundamental environmental factors while terraforming a planet are temperature and pressure (which drive climate and weather), global energy balance, cryospheric-hydrological content and cycles, biogeochemical cycles and atmospheric composition. The ecology of a planet is then derived from these environmental conditions, as each species works together to adapt and evolve in their environment. We have only scratched the surface of potential planetary pathways. 
Apart from Mars, the most viable planet (or moon) for terraforming would be 1) the Earth's moon, 2) Titan, 3) Venus, 4) Ganymede, and many other potential possibilities, depending all on assumed technological abilities (see my project link below). 
I have also attached great publications in helping you answer your question. You may also refer to the 73 references listed on my project page: 
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Perhaps Human base space exploration is going to enter into next generation. A good time to get commercial benefit from available & approachable "Wealth" in Space. NASA, SPACEX, European Space Agency and other organizations are trying to explore the potential benefits in space. In this regard, there are few questions;
1) What commodities can be consider as "wealth" in space ?
2) What natural phenomenon in space can come under "space wealth" ?
3) How human can get benefit from space wealth ?
4) What are different trades other than space-tourism, communication & weather-satellites can be possible ?
5) Any other aspects plz ?
Thanks 
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Solar atmosphere causes difficulties in communication during opposition (when Mars is almost behind the sun w.r.t. Earth).
The question is: is it possible to define an extended radius for the sun, which the Earth-Mars line of sight should never pass through it? if there is, how much is it, in terms of angular separation?
I've read in some mainstream and NASA news that there is a two week blackout period during each synodic period of Earth-Mars. But I want to know the exact numbers. I'd appreciate any answer with technical references.
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The sun extends far beyond the visible diameter, and the outer layers are plasma in continual fluctuation of irregular shape, not a definable diameter. If you get an exact answer it will probably be wrong part of the time, and only approximately correct on average.
Laser communication should give better reliability near opposition. If Mars is visible the lasers should pass through with data streams.
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As part of the development of ISAAC, it would be beneficial to use COTS electronics for cost-reduction. However, ISAAC will be flying in Lunar orbit where the radiation environment exceeds that of LEO. I did some research in 2009/2010 for a star tracker that would have used COTS electronics and aluminum shielding. My question is this: Would it be possible to use aluminum to shield COTS electronics (namely radio transceivers and computer components) from the Lunar radiation environment? Again, this is just as a cost-saving measure (ISAAC would be sponsored by NASA to fly on a Korean Lunar mission), so it is possible to use rad-hardened components if really necessary. I also found some research on ResearchGate about plastics, but that indicated that PEMs are not a good fit for space travel.
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Hi Paul,
Just a quick point in the past if we have been concerned about the radiation susceptibility of certain parts we have used spot shielding using Tantalum, I think we did this over an ADC at one point for the Cluster mission. This combined with the aluminium chassis helped reduce the risk to an acceptable level.
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Martian dust flux density near the surface
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We used Mariner 1972 dust instrument data to calc column density for UVS data. Look for it in PDS Atmospheres data bases.
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I am wondering if it wouldn't be better to start using the term 'crew ground disconnect'. This seems a more objective and better description of tensions between astronauts and ground control.
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Jorge, please only post information that is relevant to the question. 
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can please provide some reference
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For space agency missions they tend to be custom-made, making nailing down the cost a little difficult. However, Busek has CubeSat to SmallSat-scale engines, which can give you a good idea.
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What is Creatures and Creators Matrix?
Behind all the activities there are mindsets………And apparently mindset have mind at backend.........Seemingly Artificial Intelligence is not so well developed yet to produce mindsets without original biological alive brain present inside the body......wondering what will happen when Artificial Intelligence will produce mindset by own.............!! 
Creatures and creators will learn definitely from each other...............about that scenario here are few questions
What do you think which directions the future AI based mindset can adopt and why?
What can be the basics and further developmental requirements of such mindsets?
And up till what extent such mind set can go to fulfill the desires?
What will be the factors which can have effects on it?
How good and bad will exist for AI based mind sets and what will be expected frame of reference (s)?
It can be foreseen that if space exploration don’t give them (AI based mindsets) the way out then a tough match will get play at Earth and In case of way out among cosmos then Nature will get a very strange events waves might be beyond space-time-relativity, if so then will natural laws get evolution, if again yes then in which direction and what will be the future matrix of Creatures and Creators?
Thanks
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 In a sense it has already happened. Think of large scale "Big Science" research projects involving hundreds of specialized collaborators from a variety of disciplines. No individual researcher can have an in-depth knowledge of the whole, yet conceivably all the detailed knowledge can be integrated within an expert system that can be used to answer questions beyond the intellectual capacity (intelligence) of any of the individual researchers. 
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This refers to the recent incident of presumably meteorite impact near Vellore in Tamil Nadu State, India, and supposedly first ever human causality due to meteorite(?) fall.
Knowing the quantum of space junk and their uncontrollable nature, nobody could write-off the plausibility of reentry of such materials into the atmosphere. If so, as they are nobody's child and also no country would own up their mess (as it may fix the anus of clearing the mess squarely on them and may also expose their mischief/incapability in space craft prowess) that in turn may warrant moral-monetary compensation. Nobody will own up their mistake, should the space junk was the source of the impacting materials. Should space junk was the source of the impacting material, Who is to be blamed? Who has to monitor? Who will fix the responsibility?
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Remember the Skylab fallout in the 70's? how much stress and terror it has created in the minds of people, even during the Print-Age media. What could have been the fear instilled in this digital media era, should such threat emerge ?
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I am looking for a formulation between the _vector_ of the hyperbolic excess velocity and the corresponding hyperbolic orbit, especially the turning angle and the pericenter distance vector.
I would like to model a gravity assist maneuver but how do I derive the turning of the spacecraft vecolicty vector correctly without knowing the pericenter distance. The incoming hyperbolic excess velocity vector is given, but without a corresponding position vector I cannot derive an orbit. But per definition the position is at infinity. I would appreciate any help!
I am aware that there are a number of equations to derive the scalar relations of this parameters, but is not the vector, i.e. the direction of the incoming excess velocity already setting these parameters as well? I do not assume that the pericenter of such a trajectory is independent of the direction, right?
Thanks in advance!
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The usual definition of "hyperbolic excess velocity" is a scalar speed so I'm unclear what extra information you have that lets you call it a vector. If you only have a direction, you get a family of asymptotes like the blue dashed lines on the diagram to the right in the link. If you are approaching say from the bottom left then you need some positional information to work out the eccentricity from which you get the turning angle. Just a direction on its own is not enough, obviously the closer you approach the planet, the greater the change of direction. If you can work out how close the asymptote passes to the planet, working out the eccentricity is just solving the trigonometry.
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What relevant science missions, that can be designed in cis-lunar space to get relevant science data not available but needed by the space science community?
Especially, taking nature of orbits around liberation points in consideration.
If possible, a narrowed down list of science instruments that can be deployed aboard a spacecraft would be great.
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Kuldeep,
Currently satellite communications and infrastructures at Earth, power grids, commercial aircraft routes, etc...are affected by the constant solar activity, such as solar flares and coronal mass ejections (CMEs). To this date, we can obtain early solar warnings about 55 minutes from the Sun-Earth L1 Lagrange (or Libration) point located at about 1,500,000 km from Earth (eg. the Advanced Composition Explorer (ACE) spacecraft).
An ideal mission would be to send a spacecraft to an orbit around the equilateral point L5 in the Sun-Earth system (SEL5) because from this Libration orbit around L5 (Trojan orbit), we will be able to anticipate space weather about 3-6 days (much better than 55 minutes!). Also, a mission to SEL5 would help characterize different CMEs among other things.
Similarly, a mission to the equilateral points of the Earth-Moon system (eg. EML5) will help alleviate some of the issues above mentioned but to a lesser extent since EML5 is about 4 times closer (distance Earth-Moon is 384,400 km) to the Earth than SEL1.
You can find more information about this in some papers, here is one:
1) L5 MISSION DESIGN TARGETING STRATEGY
Also, solar observations are not the only venue to anticipate space weather from the Lagrange points. Quasi-satellite orbits could be quite attractive for space weather too, see reference below:
2)HETEROCLINIC AND HOMOCLINIC CONNECTIONS BETWEEN THE SUN-EARTH TRIANGULAR POINTS AND QUASI-SATELLITE ORBITS FOR SOLAR OBSERVATIONS
Angelos Vourlidas wrote a very nice paper from the instrumentation point of view required for a spacecraft to obtain space weather observations from SEL5. See reference below:
3) Mission to the Sun-Earth L5 Lagrangian Point: An Optimal Platform for Space Weather Research: Mission to the Sun-Earth L5 Point
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The research of granular flow under reduced gravity environment is a hot topic all over the world. Most research results are sevices for space exploration. Whether there is a chance to applly these results to terrestrial disasters? Thanks a lot
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I am not quite clear about your question. Anyway, in planetology, comparing the environment (such as mountains stability) for example on Pluto, one simply compares the Pluto's gravity (0.067 of the Earth's gravity) which is 15-times smaller than the Earth's gravity. Comparing flowing media, such as wind on Venus, it is useful to calculate the settling rate of typical sand particles under the high gas viscosity and density at surface to see that that atmosphere's thickness, similar to honey, has incredible carrying capacity. For calculation of the settling rate use my Universal Sedimentation Equation (Brezina, 1979 http://www.granometry.com/index.php/en/variables/settling-velocity/sedimentation-equation ). For simple handling, I am using the table of my program SedVarNC - single number conversion.  My PARTEC 1979 paper is downloadable  here, if you wish, I could gladly send you a paper reprint if you email me (to jb@grano.de) your airmail address- 
Best wishes, 
Jiri
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I have just completed my paper on flyby anomalies and now need to make a prediction of the Juno Oct. 9, 2013 flyby anomaly.
Does anyone here on RG have any knowledge of the following:
V_infty: that is, the incoming Juno speed at infty.
V_prg: that is, the speed of the Juno spacecraft at the perigee.
Theta: that is, the inclination of Juno's orbit relative to the spin axis of the Earth.
_____________________________
I am surprised that NASA has up to now not published the data of this anomaly. Does anyone have any idea how far NASA has gone in their analysis?
Will be grateful for you responce.
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Probably not.
I wrote my code to calculate the "inclination" using the traditional definition: the angle of the Juno orbit plane relative to Earth's equatorial plane.
So that 28.006deg is the angle of the velocity vector at the time of perigee relative to the equatorial plane of earth. The velocity vector at perigee should be a vector in the plane of the orbit and at the maximum angle from the equatorial plane.
So the smallest angle from the orbit plane to Earth's spin axis should be 61.994deg.
The angle between Earth's spin axis and the normal to the orbit plane is again 28.006deg.
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We have experienced the bulk crystal growth of InSb / GaSb and its doped crystal by the novel technique such as vertical directional solidification (VDS) has shown detached bulk crystal growth in our laboratory. However, detached bulk crystal had observed in NASA Space Mission III-V microgravity experiments in 1994. Present study has been carried in International Space Station (ISS).
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I can add to above conciderations the following factors.1 In microgravity Marangoni convection might control crystal microstructure in the case of detached growth. The effect of this type of convection depends on the extention of free surface and temperature gradient along this surface. 2. vibrational convection might play essential role in solidification pattern formation dependently on geometry of the sample and parameters of low-friquecy vibration (g-gitter) Both effects might be more significant then gravitational convection in ground conditions.
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Multiple suppliers of off-the-shelf CubeSat hardware sell side panels for 0.5U CubeSats, but I have not encountered anyone actually building and flying one.  Has anyone else?
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I only know of CubeSat projects which use some combination of whole and half unit structures. For example, a FIREBIRD is a 1.5U CubeSat. This is generally how 0.5 U structures are used.I am aware of a design project to dock two identical 0.5U CubeSats with one another:
I think a 0.5U CubeSat may be difficult to use unless it is being designed as an engineering exercise. A structure that small will most likely eliminate the possibility of certaing subsystems like attitude determination and control, which may result in a poor communications link. 
Will there be a payload or is there any room after power, on-board computer, thermal control (heaters)?  If a CubeSat does not have a payload, then what is it's purpose?
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Are the chemical reactions that take place on earth really influenced by gravity or are they affected by another planet or satellite around the earth?
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I would say that the gravity-dependence of chemical reactions can be neglected for two reasons:
1) the enthalpy has to be used with a little bit carefullnes in this context. The enthalpy is defined as the energ content of thermodynamical systems. However, this holds for every system, regardless of the occurence of a chemical reaction. If you want to study chemical reactions, you have to use the change of enthalpy dH. This is defined by: dH = TdS + V dp (T being the absolute temperature, dS the change of entropy and V the volume). If you work at constant pressure dp = 0. This is mostly the case, as you have no pressure variation for solids and nearly no variation in liquids or gases (as long as you are not dealing with very large volumes (i.e. some km³ or so).
and, even more important
2) all chemical reactions are driven by the electrons, or, more generally, by electric forces between charged particles. As the electric force between, say, an electron and a proton, is around forty! orders of magnitude stronger than their gravitational force, one can immediately see that gravitation is neglible compared to electrical forces.
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To describe how bright a star seems.
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Oh this was a fantastic answer Paul. I was trying to understand
this redshift for last few months but never had enough time to
dig into the literature.
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I would like to gather a group of scientists to establish a consortium for Horizon 2020 calls focusing bioregenerative life support systems based on halophyte-mediated wastewater treatment for space exploration proposes.
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Hi Bernardo you can count on us. You know our potentiallity in a possible collaboration. We can stay in touch and have a meeting if you feel necessary.
All the best Miguel
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What is the technology level ratio?
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Could you put your question in clearer terms?
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Cooperation with big space-fare countries seems to be difficult for small countries.
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The usual role of small countries in space exploration comes in various forms:
a) Cube-Sat and Nano-Sat projects (creating small satellite payloads and launch them piggyback with larger missions)
b) creating a single instrument for a larger research mission
c) deliver key hardware elements (e.g. thermal insulation, thrusters) for larger missions
d) create added value products (especially in the fields of remote sensing, disaster monitoring or navigation)
e) very occasionally they may have had an astronaut in orbit (usually through international programmes like INTERCOSMOS or ISS and usually its not repeated for decades)
f) are often international experts in defined, specialized fields of space exploration (having to concentrate on certain aspects for budget and manpower reasons)
Small Countries are basically never
a) prime contractors for anything but the smallest space missions
b) having a permanent manned space programme
c) supporting ALL aspects of space exploration equally
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How much fuel can be saved for moon-earth missions and vice-versa? If we have a space station on moon similar to what we have what are the gains?
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Sundaresan,
If you posit an orbiting station around the Earth then you automatically save about a tonne per person of entry capsule.
But.
And it's a big but, you still need to brake into a LEO - and without using aerocapture, that means fuel. So it's not at all clear that a 'returning to a space station' model has a smaller launch mass than a ballistic aerocapture return.
The only way to be sure is to grind through the numbers, using the rocket equation and some plausible stored fuel combinations.
If you have a station orbiting the moon, then trips back and forth to the surface are a simpler exercise to calculate. You've got the rocket equation, a choice of Isp, and go from there with some plausible vehicle dry masses.
I suspect all of the above has been done to death at least 40 years ago. The NASA technical report server is online at:
Or find an old hand to chat to at the LPI in Houston each spring.
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Recently Hubble discovered a spiral in Antilia constellations claiming to be millions of light years away. Besides it is a thing of distant past as the nearest star is four and half light years away?
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Typical differential star velocities are of the order of 20Km/sec. Typical distances to the stars of constellations are about 1000 parsecs. At such distances, the projected separations in the plane of the sky for the individual stars that make up the constellation are about 150 parsecs. Now at 20 Km/sec, a star moves 20 parsecs
in a million years, or about 1/7 of the separation of constellation stars.
As a result, constellations will appear to show subtle changes over periods of about 100,000 years, and when a constellation star is nearby, it will be seen to move
substantially over periods as short as 1000-2000 years. This is how Halley noticed that Sirius and Arcturus had moved from their positions recorded in Ptolemy's catalog.
made some 1500 years earlier