NASA Finds, Fixes Small Glitch in LADEE Moon Probe

Friday's moon-bound NASA launch from Wallops Island went well, but, says NBC News, "[H]ours after the 11:27 p.m. EDT (0327 GMT) liftoff, NASA officials reported that the spacecraft's reaction wheels — which spin to position and stabilize LADEE in space without using precious thruster fuel — unexpectedly shut down. By Saturday afternoon, the glitch had been traced to safety limits programmed into LADEE before launch to protect the reaction wheel system, NASA officials said. Those fault protection limits caused LADEE to switch off its reaction wheels shortly after powering them up, according to a mission status update. Engineers have since disabled the safety limits causing the glitch and taking extra care in restoring the fault-protection protocols."

wheels...

[Longjmp]

Maybe NASA are rocket scientists, but it seems they still have trouble getting wheels going [wikipedia.org]
;-)

Re:wheels...

[confused one]

ok, here's a challenge for you... design a flywheel based guidance system. make it redundant. make it work in the most inhospitable environment known to man -- space. hard vacuum. reactive ions (free ionic oxygen). radiation. operating temperature range -200 degF to 200 degF. The only cooling option for your motors and electronics is via a liquid loop and a large radiator. power is limited to a few tens of watts from a solar panel. You have to design it so it works for a decade without maintenance or repairs. good luck.

Hear that "WHOOOOSHING" sound?

[Anonymous Coward]

Hear that "WHOOOOSHING" sound? It's a joke flying right over your head.

In space ...

[PPH]

... no one can hear your jokes WHOOOOSH.

Re:

[jonfr]

We use kelvin in space. Not old and outdated Fahrenheit.

About Kelvin, http://en.wikipedia.org/wiki/Kelvin [wikipedia.org]

Based on the moon, the space temperature is around 120K (-153C) in our solar system this close to the sun on the dark side.

Temperature on the moon, http://www.space.com/18175-moon-temperature.html [space.com]

Re:wheels...

[confused one]

I work for a sensor company. If you want Kelvin, then I'll use Kelvin. I don't really care if it's Celsius, Rankine, or frequency of cricket chirps. Our environmental chambers happen to be set up in Fahrenheit, because our production staff is comfortable with those units; and I used degF because it's what the U.S. centric audience would know. You might be surprised to know that in the real world, people might not use the scale you expect them to, even if it's a standard.

Re:

[Longjmp]

Our environmental chambers happen to be set up in Fahrenheit, because our production staff is comfortable with those units;

I assume some people involved in this [wikipedia.org] were also very comfortable with their units.

Re:

[confused one]

someone forgot to do the conversions before sending data to the customer.

Re:

[Anonymous Coward]

Good point. You do what you need to do to get the job done. Many people forget that we used Fortran to get Apollo 11 to the moon, rather than the government "standard" of Algol 60.

Re:

[confused one]

I don't have that conversion factor in my books; however, if you are willing to provide me with the information, then YES, I'd be happy to calibrate your sensors in units of "fires of a thousand suns".

Re:

[Nivag064]

Most of the world uses Celsius (for science, Kelvin is okay) - isn't it about time the USA caught up?

I learnt MKSA (metric) units primarily from an American Physics textbook almost 50 years ago when I was at high school. I was brought up using the Imperial system - being in the England until I arrived in NZ when I was 12.

The metric system is so much easier to use, why are Americans so backward???

Re:

[confused one]

We're stubborn. We (as a country) started out as groups of outcasts, explorers and adventurers. When the King got carried away with taxation, we made ourselves into a country full of outcasts, fighting to separate ourselves from the British Empire, and then separated the western parts of the country from the Spain and Mexico. We tend to do things our own way and ignore the suggestions of others. Sometimes we even fight among ourselves... It's just the way we are.

Re:

[Anonymous Coward]

The question of the temperature in space is sort of silly. Maybe someone can pin a number down and maybe not. But the real question is heat transfer and the equilibrium point. There is no conduction or convection, so only radiative heat transfer works. If you are facing the Sun you are going to get a shitload of incoming radiative heat transfer and if you aren't then you are going to emit like a black body (unless you also get reflected light).

This is why a comparison with the Moon isn't valid. Conduction w

Re:

[mcgrew]

We use kelvin in space. Not old and outdated Fahrenheit.

In space, Kelvin makes the most sense. Celsius logical, but a degree C is too broad a measurement and .1C is too fine for air temperature. Fahrenheit was obviously designed for air temperature measurement. Zero is damned cold, a hundred is damned hot, and a degree F is about the smallest temperature change skin can sense.

For cooking and chemistry Celsius makes the most sense. Different scales for different purposes.

Re:

[Tablizer]

"Dammit Jim! Imma rocket scientist, NOT a wheel scientist."

Directed Crash?

[wrackspurt]

LADEE [bbc.co.uk] will end its mission by crashing into the Moon.

Will the crash site be chosen in some hope of finding ice on the moon? Finding ice on the moon is crucial to a moon base isn't it? There's been no mention whether searching for signs of ice is part of LADEE's mission.

Re:

[Longjmp]

LADEEs main missions are to examine the moon's atmosphere (or rather if there is any), along with gathering information about particle impacts (for further moon missions) and generally moon's surface
The final crash is collateral damage (okok, they'll watch dust rising from that impact closely too)

Last words...

[Gothmolly]

You arrogant ass, you've killed us!

Re:

[sumdumass]

I thought it was "what does this button do?"

Re:

[tocs]

No no ... it is "Watch this..."

SEE

[Revek]

Aren't they useful.

Switched them off because of a silly safety limit?

[osu-neko]

Jeb would never do that. Jeb has no limits.

Re:

[DerekLyons]

Hah! Another kerbalnaut - we're everywhere!

sounds like torque-tach mismatch fault detector

[decsnake]

the ought to know better than to have that enabled at launch. You need to characterize the wheels on orbit and be sure that the limits are good before you turn that one on.

about the nice LADEE!

[Gravis Zero]

hello nice LADEE! http://www.space.com/22639-moon-dust-mystery-nasa-spacecraft.html [space.com]

The Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft is expected to investigate lunar dust and the moon's extremely thin atmosphere once the craft makes it into orbit around Earth's closest celestial neighbor about 30 days after launch.

that's right, the moon has an atmosphere [space.com] kinda. it's technically an exosphere. [wikipedia.org]

In the moon's atmosphere, there are only 100 molecules per cubic centimeter. In comparison, Earth's atmosphere at sea level has about 100 billion billion molecules per cubic centimeter. The total mass of these gases is about 55,000 pounds (25,000 kilograms), about the same weight as a loaded dump truck.

before you ask, neither LADEE nor the internet is a big truck.

what they aren't telling you is that the NSA is coercing NASA to ***CARRIER LOST***

Just like Star Trek...

[prisoner-of-enigma]

Every time they had an insurmountable engineering problem, the Chief Engineer just says "override the safeties" and everything is fine. Good to know NASA is finally catching up to The Final Frontier!

Re:

[Tablizer]

It really does:

http://ourstorybeginsdotcom.files.wordpress.com/2011/10/lady_in_moon.jpg [wordpress.com]

More crappy Ball Aerospace reactions wheels?

[brillow]

I hope these aren't from the same company that built the crappy wheels on Kepler. Ball should stick with the mason jars.