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NASA's Kepler Enters Emergency Mode 75 Million Miles From Earth (theverge.com)
Loren Grush, writing for The Verge: NASA engineers have declared a mission emergency for the agency's planet-hunting spacecraft Kepler, which has somehow switched into emergency mode. Now that a mission emergency has been declared, the Kepler team has priority access to NASA's deep space telecommunications system in order to try to get the spacecraft back to normal operations. Emergency mode is the lowest operational mode the spacecraft has. It also requires a lot more fuel than usual, which is why the Kepler mission team is working hard to get the spacecraft back to normal. But communication with Kepler isn't easy. The spacecraft is estimated to be 75 million miles away from Earth right now, according to NASA, so any communications signal traveling at the speed of light will take up to 13 minutes to travel to and from the spacecraft. Kepler has detected nearly 5,000 exoplanets over the years -- of which 1,000 have been confirmed.
To & from is 150 million miles, which works out to 13 minutes. How did they 'fail'?
Safe mode probably use thrusters instead of reaction wheel to control the attitude. Reaction wheel works with electricity (from solar array, so "unlimited"), thrusters use fuel.
Even if they don't get ti fixed, Kepler has had an absolutely amazing run. The initial planned mission lifetime was 3.5 years, and that was in 2009. So we've gotten almost twice as much out of it as it was planned.
One of my favorite computer games from the 1990s was Masters of Orion II, 4X space exploration/conquering game. One thing in that game and many similar games was the idea that you couldn't find out what planets were in a star system until you had actually sent a probe there. It is absolutely amazing that shortly after those games were made, we had the technology to detect planets in other star systems while remaining in comfort here.
Why the hell don't sigs show up on the mobile site?????
Because, sigs is short for signature, and signatures were originally on paper...aka STATIONARY. Therefore, they can't be mobile.
rewriting history since 2109
Have gnu, will travel.
A gyro to rotate you, not sense your rotation - here are the Kepler reaction wheels. (It has already had 2 reaction wheel failures.)
Note: Inertial sensing gyros are generally gimbaled, so they can stay rotating in the same direction. Reaction wheels are generally fix mounted, and are spun up and down as needed to get the desired attitude (or rate of rotation). If the spacecraft is being torqued by something (say, a small gas leak), the wheels will spin faster and faster to soak up the excess angular momentum until they reach their design limit, and have to be despun. This is called a momentum dump, and requires some other system (i.e., thrusters) to finally get rid of the excess angular momentum.