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Comment Why Emergency Mode uses more fuel (Score 5, Informative) 70

User Statistical at Ars Technica explained it nicely:

Normally Kepler (in K2 mode) uses the pressure from sunlight combined with the two remaining reaction wheels to maintain orientation. It still does need periodic thruster usage but the heavy lifting is done by solar pressure and reaction wheels which makes the propellent usage very efficient. However it is a complicated and precarious balancing act. It needs full instrumentation, computer operation, and periodic updates from Earth to work.

When it goes into emergency mode it falls back on 100% station keeping thrusters because that is simpler although far more expensive in terms of fuel. They don't know exactly why it went into emergency mode but for whatever reason Kepler believed it could not maintain orientation without it.

In emergency mode it has to expand propellent because without some station keeping it would begin to tumble uncontrollably. If you have a spacecraft millions of kms away from Earth, tumbling out of control with its communication array no longer pointed at Earth you will probably never regain control. So it is a last ditch effort to maintain proper orientation on the hope that command & control update can fix the problem. It begins "looking" for an command & control signal from Earth (using propellent to orient the spacecraft). If/when it finds it, it then tries to keep that orientation using 100% station keeping thrusters regardless of fuel consumption. It will continue to do so until standard operation is restored or it runs out of fuel.

About Kepler's K2 mode:

Kepler's Second Light: How K2 Will Work | NASA

Comment Re:Measure blood pressure with just an iPhone? (Score 3, Informative) 50

The Instant Blood Pressure app (IBP; AuraLife) estimates blood pressure (BP) using a technique in which the top edge of the smartphone is placed on the left side of the chest while the individual places his or her right index finger over the smartphone’s camera.

image
I guess it's more accurate than rolling fair dice or plucking daisies.

Submission + - Apple apologises for iPhone 'error 53' and issues fix, reimbursements (bbc.com)

arielCo writes: Apple has said sorry to iPhone customers whose phones were disabled after third-party replacement of the TouchID fingerprint sensor, and issued a fix for the problem.

In a statement, Apple said that "error 53" occurs when a device fails a standard security test designed to ensure that the Touch ID fingerprint scanner is working correctly.

However, the company added: "We apologise for any inconvenience, this was designed to be a factory test and was not intended to affect customers.

"Customers who paid for an out-of-warranty replacement of their device based on this issue should contact AppleCare about a reimbursement."

A software update has now been released so that iPhone customers with disabled phones may restore their device via iTunes on a PC or Mac.

Comment Re: Acceptable Ads (Score 1) 523

Hobbyists spent their own money or mooched their university maintaining (home)pages that got a *lot* less traffic than now, and the content was rather crappy.

And this isn't about corporate greed - suppose you start a webcomic, or writing jokes. People like it, and you want more free time to dedicate to it rather than work 9 to 5 or designing commercial posters (a very typical case). Not everyone is willing to fork over for a t-shirt or a book (I don't buy books often). Some can't/won't fork over on Patreon. So you put up a few well-behaved ads and catch a constant drip.

Comment Re: Acceptable Ads (Score 1) 523

Look at F2P games. They have a lot of free users and a small number that actually pay lots of money. Games compete for the user's time and disposable income with each other and bring new content all the time while still making a profit and actually growing.
Websites for some reason can't? Maybe it's because they hardly offer any interesting/new content?

If they don't offer compelling content, they don't get enough hits and the fixed costs drive them out of business. But what about sites that do get traffic but a lot of them doesn't deliver revenue? Those play a numbers game, much like free-to-play games, and the numbers may or may not add up.

And lets not start on those crap "news" these days. I'm not interested in a novella length article about the damaging effects some stupid diet or some political game in some far forgotten town nobody finds on purpose without Google.

If they offer REAL content, people will: donate, click on ads/disable adblocker, or buy a subscription. Until then, they're the parasites bloating the search engines pointlessly.

Oh, but I was replying to someone arguing that there are no acceptable ads. As in “I want my Web free of ads - you figure out how to run it”.

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