Green Baron

Sounds fishy to me. How can it transfer a momentum several times ? Every time a tiny part ? And how does that help accelerating a craft away from a planet, as the beam opens up with distance ? Papers please :-) But it does. See the math above. In the case of an ion drive by 470 magnitudes, 10⁴⁷⁰. That is current tech and it is actually not my idea, i took it from an astronomical almanac. So how do you produce energy between the stars, for 100s of years ? Don't say nuclear. It is the toothbrush for the desert that lasts half an hour (the toothbrush, the desert laughs). How do you accelerate a manned interstellar ship's mass of lets say 10,000 tons (if that is enough) with 1g/ton ? Or 350MW/ton ? The shiny laser (if it works as envisioned) has no power, if the manages to reach the outer solar system after decades of near 0 acceleration. It is not a computer game. At home, the current comes out of the plug, but not in space. A few photons, a hydrogen atom every now and then, neutrinos incognito, that's it. There is nothing there we can develop because there are no sources to use. Nothing comes from nothing. Either you take billions of tons with you, or you make them on the way. There is no other way. Current tech projected into the future is by far not enough nothing is available in space. Current tech are ion drives and solar power, nuclear batteries for a few decades and a handful of Watts, and chemical engines. Btw.: Laser propulsion often refers to using a laser to heat something and the ablation drives a vehicle. Or use a laser to shine into a tube and the expanding air accelerates something. But that plays no role here. Apart from that, current serious proposals for laser thrusters are for station keeping and precise maneuvers in the inner solar system where there is energy available for conversion, not for interstellar travel.

Maybe one should check the numbers and refer to a proper publication and the actual state of the technology ? Just proposing, not criticizing the poster. In the end it might come out that it is not as ready as it seems ... Anyway, a micro- or millinewton here, an antiproton there, but wih today's tech we need energies and masses magnitudes beyond of what is in the obs. universe. It is easier to dust the Sahara alone over a weekend with a toothbrush :-) E=mc². One either schlepps billions of tons, once someone has figured out how to accelerate them to 1000km/s, and/or one opens up a new energy source for use underway between the stars. And, of course, the travelers should somehow survive.

Oh, have i shifted a decimal ? I hope to my advantage :-) Anyway, even a magnitude doesn't change things principally. @StrandedonEarth, yep, the LHC can produce tiny amounts (100s of atoms) of e.g. Antihydrogen and store them for minutes. But a handful of particles aren't suitable for propulsion. This machine has the size of a proper landscape, weighs thousands or even tenthousands of tons, rests deep under the earth, draws a medium range power plant and need a lot of attention. And its the cutting edge right now. Until further notice :-)

Very theoretical/fantastical and impractical for a heavy spaceship; laughably low thrust. Yeah, i got the math. I proposed it upthread ;-) The start mass to accelerate 1ton with an exhaust-v of 0.2c to 0,2c is 2,7 tons, the fuel mass 1.7 tons. I didn't make that clear, but we totally agree here :-) But there is no energy source to accelerate any mass to 0.2c, not fusion nor antimatter, not even theoretically. So we must live, even under the assumption of the best imaginable fusion drive (which we can imagine to have around 1.000km/s according to the link above and wikipedia), with around a billion tons of reaction mass per ton to accelerate to 0.2c. And the same to slow down. Sometime in a future. Is that correct ? Which brings us back to the initial point i proposed: imo, without shortcuts and a yet to discover energy source there is no imaginable way for humans to travel to other planets bs stars.

Yes. Because 1ton * e¹ ;-) Antimatter is fantastic. Impossible to generate in quantities with our available energy sources and near impassible to keep stable. Even in a high vacuum there are always a handful of molecules around to spoil the day. Can you give a sauce for the 0.1c ? I get 100-1000km/s from wikipedia ? What are "pre accelerated fuel pellets" ? They come pretty fast ? Forget lasers. We (not me) want to travel to another star. Even for the starshot gram size leafs they need 100 Gigawatts of laser. These are 100 millions of 1kW lasers ! Edit: anyway, in 50 or so years we may know more about fusion stuff. And if it can be scaled to something movable.

I get 2.72 ? But which energy source delivers the energy to accelerate stuff to 60,000km/s ? We are between the stars. Lots of nothing all around ... Edit: Even the sparse info i get on fantastic fusion rockets from wikipedia is 2 magnitudes off. Which leaves us with more mass than the universe contains ...

A mass could be orbiting our galaxy's central black hole Sagittarius A* with 30% light speed. This is assumed to be the lowest possible stable orbit, at an orbital height of around 6-10 times the diameter of a 4 million solar masses black hole. Article The mass (probably a compact gas cloud) orbits prograde, almost face on and changes polarization together with its from centroid(*) calculation inferred orbit. Orbital period is around 45 min. (*) a technique to calculate sub pixel resolution from small changes of exposure in neighboring pixels.

I think we are all just playing in our minds. Nobody seriously believes that anybody can put the mass of a continent into space and run a biosphere on it. Or an atmosphere worth of gases and an ocean worth of water on Mars. Or build a 50.000km long cable with a terrace and McDonalds and attach an asteroid on the the other end. Or not ?

Theoretically, you can have satellites in GSO where the elevator's platform is fantasized to be, but not above where the counter weight is or below, or they must be in resonance with the rotating elevator. So, either elevator or satellites. Both contraptions, elevator and ring, are unstable and subject to high mechanical forces, mainly tear from the own weight and the counterweight and coriolis. Neither regards earth's axis precession or tidal forces from moon, sun and other planets. Neither is stable and needs correction. Both are exposed to all sorts of pebble that buzz around and cross between GSO and earth surface every now and then. And i am not sure if we have enough obtainable metal in the earth's crust to build a ring. But, its scifi so everything is possible :-) And btw., is the material, even if it could be produced industrially, really strong enough to support its own + counterweight ? So, all in all, where are the news :-) ?

I doubt that the question can be answered quickly. Evolution, metabolism, complexity of cells, organs, functions of an organism play a role, mutation rates, environment, nutrient intake, .... As well as the overall organism and the environment. And, by the way, some trees don't grow much older than some humans. But i am no biologist and have no overview over the work on aging, be it at molecular, cellular, of an organ, whole organism, evolutionary and species level. And in the end maybe one sees that the molecular rates aren't that different in living organisms, it is the higher complexity or exposure to adverse conditions that makes some things fail earlier than others. But i do not know, just a random shower thought of mine ! Fact is: we are no plants, our lives cannot be prolonged over what the material and circumstances allow (physics !) and the same is true for a plant. Otoh, plants don't write scifi stories or play computer games :-) And we are no frogs, we have no antifreeze stuff in our cells and putting some in will wound or even kill us unless we figure out how to do it, which i cannot see. And even if we figure it out, it will not necessarily make a journey of hundreds or more years more survivable. For interstellar travel we need a combination of wormholes / warp drives / vacuum energy use and or a very long time, in the range of what all the history and early history since the first farmers until today took.

Poland is part of the European Union and as such we can assume the same or similar standards as in the other countries. Not sure if we have enough overview of the complete situation here to actually give hints.

Yes. The range is wide, from no effect to lethal consequences. Depending on wavelength and intensity it can be used as a therapy. Intense radio frequencies, UV, Microwaves and gamma rays will damage or kill. As will a simple electric discharge.

First: I am not a physicist and my understanding is probably not much better than yours. What i think is that you see earth (or one of the frames) as an absolute reference frame. But that is not the case. To transform one frame to another you must apply the Lorentz transformation to time dilation, relativistic mass, relativistic length and relativistic speed. The closer you get to c as a relative speed when transforming between two frames, the faster the term grows until it produces a division by 0 when c is reached. So, if you observe the dinghi that starts from a ship moving at 0.99c relative to earth (which makes the ship almost stand still when seen from earth due to time dilation) and the dinghi accelerates away from the ship to 0.9c relative to the mothership, it only accelerates 0.999c (or so) relative to earth. Hope that wasn't totally nonsensical. Maybe one of our physicists shows up and clarifies :-)

These are simply the gaps in our knowledge and understanding that may seem like physics couldn't fully explain nature. I would even say that, in the case of biology, our understanding of how organisms function and play together and evolve is pretty good, has made quite a few leaps forward in the past decades.

If i am not mistaken the ESA pictures of the cloud are real photos, no digital elevation modelling. I don't think they are retouched for height exaggeration (how so ?) except for colouring and contrast. The cloud may well stand several times the height of the obstacle above it, if we take similar phenomena on earth as a comparison. But i am sure future will tell us more about it.

View over the Caldera de Taburiente rim: A few telescopes are visible, but most of them hide behind the crest. Weathered phonolithic pile in the foreground. At the far left sheets of the former Taburiente shield volcano and at the far center, through the clouds, what seems like dikes and vents of Taburiente's predecessor Volcan de Garafia. Literally a section through a volcanic edifice (continuing below the cloud cover).

Skilled operators can indeed tell so, i have read the same and i can imagine it. There is nothing between the stars to convert into usable energy.

I don't think so. A detail photo, apparently in an early phase of the development (21. Sept): http://www.esa.int/spaceinimages/Images/2018/10/Mars_elongated_cloud_21_September

Thanks :-) Yeah, the article is on the fantastic side in some parts. Stasis for humans does not exist. All info i ever found or asked, as well as the articles we browsed upthread, are about temporary cooling of body parts by a few degrees and for hours, under intensive observation and attention by medics, to prevent deterioration for a transport into hospital for example. For now, lowering body core temperature below 30 degrees celsius is life threatening. Maybe in the future, who knows :-) I have absolutely no problem using hibernation in a scifi works. I only objected that it is no hard scifi because nobody knows how to do it yet (how to prevent a body from dying) and it is not as clear that it will work as is for example fusion energy, where we know that it works, have the first small experimental results, "just" look for an industrial realization. Edit: btw., in another thread, we came to the conclusion that accelerating a mass of 1 ton to 0.2c requires many magnitudes more than the mass of the whole observable universe as reaction mass, even with electric superpower ion drives. You We actually need a drive that accelerates reaction mass to relativistic speeds and even then millions or billions of tons for every 1 ton. So, anyway, you we probably need wormholes or warp drives or some magic to tap vacuum energy to reach other stars with humans on board. Valid until the contrary has been proven :-)

These lenticularis clouds can even stand several storeys tall over the mountain range and if the wind is excited into waves they reach in echelons far behind it, up to a few hundreds of km out into the forelands and frequently connected to a strong foehn in the Alps and surely to the great American north/south mountain ranges as well. Extreme example over the Andes. Besides the vortices pictured up in the thread, banner clouds are another variation of lee clouds, excited by local orography. Example http://www-das.uwyo.edu/~geerts/cwx/notes/chap08/banner.html What exactly it needs for the Marsian atmosphere in terms of humidity, wind speed, pressure difference and if it is water ice indeed, i am sure one day soon(tm) somebody will find out :-)

It isnt really, it is the view from orbit. The origin is the lee side of the mountain top. If you were under it it might reach over most of the sky.

"The chances of anything coming from Mars, are a million to one he said, the chances of anything coming from Mars, are a million to one .... but still, they come." In Jeff Wayne's The War of the Worlds, after the cited novel from H. G. Wells :-)

True. Programming wise it is trivial (using xcb which is the only basic event handling api i know). One would have to parametrize the durations and the beginner has to type in a disciplined manner (not KSP style, eh ?). Or let him type something and deduct the timing from medians of his strokes. Including variations for time of day, relative humidity, sleepiness of eyes and spectroscopic analysis of the gases in the user's exhaled air. A field for playing, for sure :-)

If i understand it right, it adds "malnutrition" to the possible causes of an early death on Mars.

Several with two different keys for dit and dah, when searching "convert morse code key press". Example https://github.com/willwade/MorseWriter But it would be a nice little exercise to read the timing of a single key press and release and translate it to dit and dah. Depends on OS of course ....