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Comment: Re:We may hear from Philae later (Score 1) 337

by SharpFang (#48434981) Attached to: Philae's Batteries Have Drained; Comet Lander Sleeps

Yes, the comet's perihelion is about 1.3AU so not much farther than Earth's orbit (and so Earth surface heat input), and yes, ice melting temperature drops significantly with pressure. As for what forms the emission takes, this is one of the huge questions Rosetta is suppoed to answer - we've never observed a comet from near enough to see how exactly the melting process works. In one hand, the chance that they will be explosive is quite low (though non-zero, under-rock ice pockets heating up and accumulated steam blasting its way out), on the other hand Philae weighs about 1 gram while on Chury, and its size is around 1 cubic meter. That's about the parameters of 1m^3 sized soap bubble when it comes to reacting to "wind". So the emission doesn't have to be anywhere near to explosive; even mild zephyr from under the surface can move the lander.

Since we still don't know about the character of the emissions from the comet, we can only guess whether the point when Philae heats up enough to starts charging its batteries happens before or after the comet produces enough steam to blow it away.

Of course, had the harpoons deployed, that would be moot. Currently the outlook isn't too good. Philae is in a hole, which can channel the steam into a stream. Plus its systems could have been damaged by extreme cold, plus even the intensified sun input may be insufficient, plus the 'seasonal shift' of shadows can (though is unlikely) to worsen the shadow conditions... Still - until the comet actually begins emitting steam and we see how it does it, we have really no clue what's going to happen.

Check this nice graph for water behavior in different pressures.

Comment: Re:Who cares about the lander? (Score 1) 337

by SharpFang (#48406451) Attached to: Philae's Batteries Have Drained; Comet Lander Sleeps

Spend some time on Tumblr, see some blogs of these. They are very much the same, echo chambers / mutual admiration societies, the word 'misandry' uttered with pride. Or look into how some men's rights organizations were snubbed.

Here, have a link to get you primed on a sample of what you're facing.

Comment: Re:Hey don't worry (Score 1) 337

by SharpFang (#48406303) Attached to: Philae's Batteries Have Drained; Comet Lander Sleeps

Yes. Cubesats are currently within most university space enthusiasts clubs budget now, and launched in such number thae ISS got a launcher/gun for them installed to streamline the process. I can easily see small probes going that way once cost per kg out of Earth gravity well gets on par with current cost per kg to LEO.

Comment: Re:Who cares about the lander? (Score 1) 337

by SharpFang (#48393261) Attached to: Philae's Batteries Have Drained; Comet Lander Sleeps

Actually, it's insult when used by people described as "cishet scum" by the SJW. "Cishet scum" means non-transgender heterosexuals. Anyone who isn't currently described as "discriminated" is scum. According to SJW if you're white male, with male identity and not homosexual, you are pretty much the worst blight of this earth.

The core of the SJW legion is female supremacists - the kind of extremist feminists who are absolutely not satisfied by the idea of equality of genders, claiming e.g. that all men are supporters of the rape culture (and about 10%-20%, (varies with different groups), are actual rapists.)

They also take a great offense in assuming one's gender basing on physical characteristics, and using plain pronouns like 'he, she' when referring to people, without first asking them which gender pronoun they want used (xe, shi etc...?). It's the kind of people who will protest when presented with a form that requires you to enter your gender and provides two checkboxes - [ ] male [ ] female - ability to check either, both or none is insufficient to describe their genders...

Comment: Re:Fair-weather power sources are lame... (Score 1) 337

by SharpFang (#48392489) Attached to: Philae's Batteries Have Drained; Comet Lander Sleeps

There was one more significant concern: the thermoelectric generators have actually pretty low efficiency, something of order of 10%. Lots of heat generated by the generator would affect the ground around, risking melting the ice and causing exactly the problems with "steam blast" mentioned a little above.

OTOH, Philae could definitely use a couple more thrusters, to be able to control its descent and move around.

Comment: Re:We may hear from Philae later (Score 1) 337

by SharpFang (#48392467) Attached to: Philae's Batteries Have Drained; Comet Lander Sleeps

You got the mass an order of magnitude too big. It's a little under 100kg. And while a *blast* is unlikely to do anything, a continuous push, even very weak, can move it. You need only around 1N of force to get Philae to move up against the gravity; even less in horizontal direction.

Comment: Re:We may hear from Philae later (Score 1) 337

by SharpFang (#48392411) Attached to: Philae's Batteries Have Drained; Comet Lander Sleeps

Nope.
A human could -push- it over escape velocity. With a good shove.
Philae is still 100kg of inert mass so kicking it will either injure your foot or break the panels. OTOH its weight is around 10g, and the escape speed is some 0.8m/s, so propelling it to escape speed really doesn't require much work.

Comment: Re:We may hear from Philae later (Score 1) 337

by SharpFang (#48392369) Attached to: Philae's Batteries Have Drained; Comet Lander Sleeps

Generally we see them whenever the comet is near the sun - as the "comet tail" - you know, the distinguishing feature of comets that sets them apart from asteroids?

And melting ice on Earth happens in ~1bar atmospheric pressure. Meaning water is liquified instead of vaporized, and presence of air limits the range of any steam blast to several meters at most, while in vacuum a "steam tail" may run for many kilometers with no atmosphere to disrupt it.

Comment: QA rejects. (Score 2) 178

by SharpFang (#48391873) Attached to: Ask Slashdot: Is Non-USB Flash Direct From China Safe?

Most likely QA rejects. Now why they were rejected by QA - this is your opportunity for getting decent media cheap. Sometimes the controller is broken and you'll end up with a fancy guitar pick. But sometimes the number of bad blocks on flash exceeds the standard. Run 'badblocks' on your card, and you'll get a card 95% the size of respective 'brand' at 20% the price. As a bottom line, this may cost some work and don't expect your profit is 4x the value of 'certified', but you may come out profitable.

Comment: Re:Hey don't worry (Score 1) 337

by SharpFang (#48391803) Attached to: Philae's Batteries Have Drained; Comet Lander Sleeps

Depends on the amounts of Delta-V you need. That's a bulk solution - high fixed cost, but can scale up almost indefinitely on the cheap. Not really what we're working with currently - lots of gravity assists, decades-long missions, budget cropped to the minimum. If you need a ton of stuff transported to the Moon, that's a very bad solution - plain chemical rocket will be better. If you want a regular route between the Asteroid Belt and Earth, transferring 500 tons in either direction, chemical, ion etc don't nearly scale up this nicely. Bringing the reactor to the orbit would be very costly, but once there it could operate at marginal cost for a long time producing a lot of delta-V on the cheap as long as you can just supply water.

Think of it as a truck engine. If you're going to a grocery store at the corner (orbit), you walk there, or take a bicycle, because using a truck would be ridiculously expensive. Now if you need to move a truckload of raw materials 100 miles (outer planets), walking or bicycle will be a poorer choice than renting a truck - and cost more summarily, in food and accomodations along the way. Currently if we want to travel that 100 miles, what we do is walking + hitchiking (gravity assists) which is cheap, takes time, doesn't let you to take a lot of cargo and gets you weathered from all the time you spent traveling (old equipment fails).

Pound for pound, the amoeba is the most vicious animal on earth.

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