Green Baron

Jupiter is full featured planet. It could be a proposed, but not yet accepted object called a Fusor, but it is around 13 times too light to start an own fusion (overcome the Coulomb barrier). But the boundary, though being several times above Jupiter's mass, isn't exactly a sharp one. A quick search: http://ukads.nottingham.ac.uk/abs/2011ApJ...727...57S Jupiter's internal excess heat is mainly attributed to gravitational energy release ("sedimentation" in the following link), maybe some D-D fusion may contribute http://iopscience.iop.org/article/10.1086/305797/fulltext/ but that is less than clear.

To generate 60MW on Mars with upper range consumer grade solar panels near the equator you'd need around 300,000 m² of them (divide by area/panel), less with the better ones mentioned up in the thread. They only need dusting and an exchange no earlier than in 20 years. Or 6,000 of the 10KW nuclear reactors. Edit: Solar power generation near the Marsian poles isn't possible/practical.

More than double that. https://en.wikipedia.org/wiki/Multi-junction_solar_cell Theoretic maximum ~70%. Which other technology can reach that ?

While this is all true, solar sails and aerodynamic sails are not comparable. There is one special case where an aerodramatic sail works only by the pressure of the wind on a downwind course, but this is rarely the case and even avoided when sailing because it is the most inefficient course and demands full attention when doing so with the usual fore and aft sails. Edit: ignoring the low Marsian pressure, a wind sail needs to be adjusted to the wind conditions and the course, which would be counterproductive to solar power generation in which case it needs to be adjusted towards the sun. Also flexible solar panels are less effective than rigid, subtracting more from the already low efficiency on Mars.

Aw, thanks. Didn't mean to step on anyone's booted foot ... :-)

Well, at least the military men are honest. I am a complete idiot, but isn't there a wide span between Lieutenant and General ? Wesa make you bombad general !

Did they say which Wednesday ?

I get averages of 2.37m/s² to 0.5c, 2.14 to 0.9c and 1.57 to 0.99c simply by dividing the speed in m/s with the time in seconds. Is that wrong ?

Yep, i fear that is not the correct way. The Lorentz factor describes the change of relativistic mass, contraction and time dilation at speeds. Speed is a variable, not the outcome. I'd rather think the other way round: acceleration at 0.9c requires double reaction mass or exhaust velocity compared to 0c, from the reference frame of start. As the ship leaves the acceleration in reference to the start goes down as time dilation kicks in at high speeds (1s on board is 7s at the start, ship's mass is 7 times its rest mass Edit: @0.99c). If you want the exact acceleration on board at a certain time you need the rest masses and thrust or exhaust v to do the math. Once you have that you can then calculate the effect of relativity as you did via the Lorentz factor and apply the result to the masses and times to obtain the acceleration in reference to the start. Hope that was correct ....

None that i knew. Earth's atmosphere doesn't exist alone and is in constant exchange with bio-, cryo-, hydro- and lithosphere (yes !). Up in the thread I have linked a study that suggests that - besides being lost to space - an ocean worth of water could have been drawn into the martian mantle shortly after the time the crust solidified. That water would be mostly locked in minerals in depths between 0 and 90km, or might be present as pore water. Problem is that minerals from Mars that arrived on earth are dry. But these minerals are from a greater depth (100km, @PB666), ejecta from the Marsian boreal plains. Yes, but these processes ceased on Mars at the same time as they ceased on earth. Dust from space or impacts play no role any more these days. We (or whoever feels entitled) would rather have to find a way to use the water that is there. But before that happens somebody should actually have a look, get a bunch of samples, have the samples scrutinised in laboritories. Remote sensing is nice but does not protect from misinterpretations or especially the "see what i want to see"-effect ;-)

Second thought: assuming linear acceleration from 0 to 297,000,000m/s in 1,892,216,000s that is a moderate ~1.57m/s² acceleration. Hope i didn't forget or add a 0 on the way. 0s are important sometimes :-)

I was a youngster when i first saw that movie, but i already liked Beethoven. In relation to my age, it was the most impressive and disturbing movie a have ever seen ...

Nope. The process is much too slow ... But it is (if the interpretation is correct and things are as they seem) in the wrong latitudes for an astronaut with a shovel and a bucket. Don't buy a ticket yet ;-)

No problem, just pointing out that these two are the same. tl,dr: in several locations with steep scarps and blueish reflections the MROs imaging spectrometer detected an absorption that points to H2O-ice. "Several lines of evidence" indicate that this is only an outcrop of much deeper ice deposits rather than just frost. The scarpes likely form and retreat by sublimation of the ice.

Already linked by @tomf and me farther up :-) http://science.sciencemag.org/content/359/6372/199

1.) we need wet and dry mass and thrust or exhaust velocity to do an estimation. Also relativity comes into play at higher speeds, meaning you can throw out as much as you want and as fast as you want, if there is dry mass left it will not accelerate much more Edit: Lorentz term results to ~7 at 0.99c. Frankly: the video is is just color and sound, no specific information (or i scrolled over it because i wanted the time back :-)), and a little bit blabla. And, oh, it makes a sound in space. What does that tell us ? :-) 2.) [mechanic voice] "too many variables, cannot calculate" :-) If you can specify a few cornerstones like hypothetical handwavial propulsion system and type of fuel we could play with some numbers ...

"I think I can safely say that nobody understands quantum mechanics." Richard Feynman

To sum up: entering a new ice age stadial would not be visible during a human lifetime. Ice shield dynamics in the Pleistocene in principle follow a timeline of long buildup (10.000s of years) and quick retreat (thousands of years). There are short term fluctuations of course, especially during OIS-3 (oxygen isotope stage) but these did not disrupt a trend. Otoh these days greenhouse gases are accumulating so fast since the onset of industrialization and especially in the last decades that the retreat is about to break all past records. It hasn't yet done so, there is one example of ice retreat after the last stadial that was around 1.5 times faster than the observed actual retreat. But that started from a point of maximum spread. Current weather: The ocean and especially the northern Atlantic is not a homogeneous soup. Currents at different levels transport salinity and temperature. A main motor of the global conveyor belt lies there as part of the thermohaline circulation (deep water formation), where warm saline water flows down in a giant elevator off the coast of northern America and Greenland. That can switch states in front of ocean floor thresholds (ridges), thus transporting the warmth and moisture farther north or not, depending on where that elevator resides. Atmospheric polar fronts and subtropical air can meet, and if the differences in energy are huge then a lot of energy can be released. The polar front and the circumpolar jet stream can form "bights", causing pressure differences and fast formation of cyclones. Depending on the pressure differences these can develop into proper storms. Oceanic and atmospheric circulation function together with mutual influence. I didn't want to write a sermon so i stop, but i hope i could transport the insight that a lot of energy in the system means higher contrasts and so more impressive events :-). All not that easy, but not impossible to grasp ....

@Diche Bach, i haven't watched the video because it smells like pseudo science and i have limited bandwidth. There is no new ice age coming because we actually live in an ice age. Yet. No, it is not "rash", in contrary, it is conclusive and a direct observation, perfectly collimated with anthropogenic climate change. I was on the same side until just a few years ago (have studied geoscience as a side subject but do not practice). We are getting better at distinguishing between natural and the anthropogenic signals. It is too simple to say "wasn't climate always changing ?". Yes, it was and will be, we want to know how much of the change is natural and how much is human induced and we are getting better with the analyses. Ignoring or denying the published results isn't helpful any more. I linked one report for 2016 farther up in the thread, so you can read things up, the 2016 report can be read without fear of political influence and is not behind a paywall. Let me add since that in the past 2 years a lot of advancements have been made and newer publications draw a picture of accelerated ocean warming and ice retreat in the Northern sea, Greenland and Antarctica (shelf ice and glaciers). If you want to know more i suggest you let go of the so called social networks and get to the sources, in condensed form but behind paywalls Nature Geoscience, Science Magazine (AAAS), or the AGU, publications by your countries Geological Survey, ... And, yes, @p1t1o, got a point: weather is not climate ! But more energy in the atmosphere and higher contrasts in temperature and atmospheric water may express themselves in local phenomena, like the snowstorms and cold in northern America. But this in no way contradicts oceanic and atmospheric temperature rise, and again, it a local phenomenon.

Isn't that Fritz Perls "Gestalttherapie" ? Now who was first ? Or the same thought came upon different people. Probably many have had this before :-)

Oxygen production on earth 2.97Gy ago: https://www.nature.com/articles/s41561-017-0036-x That does not mean that the atmosphere was not reduced any more (still ate up oxygen if provided), but that at least in oases in shallow oceans oxygen production was running. And it means that the hypothetical Great Oxygenation Event was preceded by more gradual steps of oxygen rise.

In contrary, the regulations for safety for all kind of vehicles are very strict and becoming ever stricter. That includes all stages of the life cycle from design (call me if you need examples :-)), construction, traffic regulations, equipment of the vehicles, the infrastructure, regular checks and part exchange, licensing and renewing etc. Valid for cars, trains, ships, aircraft, cable cars, pick other ... I remember that people were wondering that the shuttle was designed without a crew abort system, i also remember that such designs were discussed but not implemented, i assume because of weight. @GoSlash27 has a valid point, i think.

I'm interested, could you point me to something to read about that (not Wikipedia) ? Did it affect human population as well ? Afaik origin, spread and cause of the plague (black death in 14th century) is at least principally understood, last i read was a study that compared historic DNA samples from different sites between Asia and Europe that showed and confirmed that indeed Y.p. was responsible. America wasn't part of the known world by then (sorry, guys :-)).

Greece is bronze age and younger, Egypt starts in neolithic. They had these things. Well, the faucet was a wooden slider because no iron. But you could be a local hero if you showed the wheel and cart to the pre-Bronze age Egyptians (it comes up in early bronze age), so they could make their pyramids just a little higher and shinier and beat a little heftier and faster on their neighbours. But be aware that is was incredibly easy to do something inappropriate for one of the deities, or hit the wrong time when worshiping one deity was out of style and another one came en vogue, as dictated by the current leaders.

When would it make any sense to haul up a factory, energy production, raw materials, maintenance crews and parts, spare parts, tools and stuff like lubricants, arrange for deposit of waste, used tools, ad so on instead of directly hauling stuff up ? Let alone raw materials which always have smaller or greater part of waste, it would always and on any scale be cheaper to just prepare everything on planet and then shoot it up.