SPACE

[pogo]

It’s only one study, one interpretation. And the evidence for dark matter is not just rotation curves of galaxies.

My own view is Dark Matter is just that, dark matter. I.e. it’s ordinary baryonic matter: dust clouds, asteroids, stars that have exhausted their fuel, black holes. The evidence against this is that they’ve looked at the sky and not seen it, as even dark matter should be visible when it occludes other matter or due to gravitational lensing. But this seems very dubious: space is incredibly vast, and we can only see things that are bright like our sun. I.e. really really bright. Indirectly we can detect things close to a star, such as planets. But anything not part of a stars system would be undetectable, unless we happened to spot it passing in front of another star.

So maybe “dark matter” is out there and we simply haven’t seen it yet. Maybe the surveys that looked for it misestimated how much they would find, or maybe it’s just not very dense in our immediate neighbourhood, but is clumped more densely elsewhere.

[Absolute_Zero]

I'll rephrase one line just for you.

The advantage of the study above is that it (seemingly) obliterates the entire raison d'etre for EXOTIC dark matter.

[pogo]

This is how blue-sky thinking works: give us a lot of money and in 15 years we will have a working skyhook/moonbase/interstellar drive.

Or Mars shuttle:
Musk’s Mars moment: Audacity, madness, brilliance—or maybe all three
Musk thinks there can be human flights to Mars in 2024, which is ridiculous

And not just small flights: a hundred people to colonise Mars, a million by the end of the century. Simply impossible in all sorts of ways.

[tufty]

Rosetta touchdown / end of mission real soon now.

http://rosetta.esa.int/

[Absolute_Zero]

As it happens, Nature has a serendipitous article on the search for 'exotic' DM.

sub: The leading theory of dark matter is running out of room to hide.

[Deckard]

What a lovely idea

http://www.theverge.com/2016/10/1/13120 ... ct-funding

Now, a Kickstarter campaign wants to bring the NASA Golden Record back to our Earthlings’ hands, and it’s already passed its $198,000 goal by more than half a million dollars

[pogo]

America will take the giant leap to Mars

By Barack Obama, who probably has more say in it than anyone. But it’s all fantasy. E.g.

We have set a clear goal vital to the next chapter of America's story in space: sending humans to Mars by the 2030s and returning them safely to Earth, with the ultimate ambition to one day remain there for an extended time. Getting to Mars will require continued cooperation between government and private innovators, and we're already well on our way. Within the next two years, private companies will for the first time send astronauts to the International Space Station.

That’s the same space station that was launched when exactly? Getting private companies to deliver astronauts is a big advance, politically (if it happens) but it’s a step back technically from the Space Shuttle. Manned space exploration has stood still, not gone beyond a handful of people in low-earth orbit for twenty years. If anything it’s gone backwards, with the Space Shuttle being cancelled and nothing replacing it. And now he thinks they can get to Mars in the next twenty?

Or to put it this way. Yes, in theory they could go to Mars, by restarting the many programmes that were investigating it and spending whatever it takes to do it. And that is going to be passed by a Republican congress how? Even if the Democrats regain control of both houses the politics of spending untold sums on space is a pretty hard sell nowadays.

[Absolute_Zero]

Bring on the dark energy. My $0.02: standard candle fail.

et voilà

The ‘standard’ model of cosmology is founded on the basis that the expansion rate of the universe is accelerating at present — as was inferred originally from the Hubble diagram of Type Ia supernovae. There exists now a much bigger database of supernovae so we can perform rigorous statistical tests to check whether these ‘standardisable candles’ indeed indicate cosmic acceleration. Taking account of the empirical procedure by which corrections are made to their absolute magnitudes to allow for the varying shape of the light curve and extinction by dust, we find, rather surprisingly, that the data are still quite consistent with a constant rate of expansion.

http://www.nature.com/articles/srep35596

[Absolute_Zero]

NASA Eagleworks' peer-reviewed EmDrive paper has been accepted for publication.

http://arc.aiaa.org/doi/full/10.2514/1.B36120

1.2 mN per kW... which if it holds up as real [not an as-yet undiscovered experimental error], is currently ~300 x the next-best propellantless thrust per kilowatt, the solar sail.

[zip accident]

NASA Eagleworks' peer-reviewed EmDrive paper has been accepted for publication.

http://arc.aiaa.org/doi/full/10.2514/1.B36120

1.2 mN per kW... which if it holds up as real [not an as-yet undiscovered experimental error], is currently ~300 x the next-best propellantless thrust per kilowatt, the solar sail.

Eh? Which kilowatts does a solar sail use?

[Absolute_Zero]

If it helps... electricity -> laser -> sail

one watt == one joule per second

Here at our orbit, the total solar irradiance is around 1.361 kW/m^2

[zip accident]

If it helps... electricity -> laser -> sail

one watt == one joule per second

Here at our orbit, the total solar irradiance is around 1.361 kW/m^2

About this much then:

http://www.bbc.co.uk/news/business-11483542

They're springing up all along the motorways around here.

I was under the impression that solar sails gathered all their power directly from sunlight, not via photo-voltaics.

[KlaxonCow]

I was also under the impression that the way solar sails worked was by the pressure of the solar wind against their surface. Basically, the same principle as a sail on an ocean-going ship, except it's light pushing it along.

Yes, Wikipedia appears to confirm this notion: https://en.wikipedia.org/wiki/Solar_sail

[Darkflame]

The names been used for both ideas I think.

but it’s a step back technically from the Space Shuttle

Wasnt there a big discussion earlier in the thread how the shuttle, though seemingly more elegant, wasnt that good?

Also presumably we are talking about Musks now reasonably proven boaster recovery system here, so its not like nothing is recovered each delivery. (of which SpaceX has done a few to the ISS unmanned and more on the way).

With hope even that might be eventually replaced by the Syklon project though, but thats much further way.
https://en.wikipedia.org/wiki/Skylon_(spacecraft)

not gone beyond a handful of people in low-earth orbit for twenty years.

Yes, but though lack of trying/budget and different priorities. Presidents can promise about going to the moon or mars all they want, but it doesn't mean anything without needed support - and stability of vision.
This isn't some evidence of massive technical handles what have got humans stuck, the hurdles are relatively minor compared to the lack of willpower to do anything beyond rhetoric.

And that is going to be passed by a Republican congress how?

Saying loudly near, but not too, Trump how its a shame that america isnt leading the world in space travel anymore and wouldn't it look great to have some big prestige project with a lot of money going too it that would show the world how great the US is again.

[Absolute_Zero]

I was under the impression that solar sails gathered all their power directly from sunlight, not via photo-voltaics.

I didn't suggest otherwise... merely compared thrust to power for both.