Astronauts Begin Final Spacewalk To Repair Hubble

An anonymous reader writes "Astronauts John Grunsfield and Andrew Feustel began the fifth and final spacewalk of their Hubble Space Telescope repair mission this morning at 8:20AM. During their spacewalk the two will install the second battery group replacement in an equipment bay above the Wide Field Camera 2 and next to the compartment where the first battery set was installed on the second spacewalk. Each of the battery module weighs 460 pounds and contains three batteries. The batteries provide electrical power to support Hubble's operations during the night when there's no sun to power the solar arrays."

The batteries weigh what?

[Sockatume]

I'm willing to bet that the batteries don't weigh anything right now. ;) Of course using "mass" as a verb is just taking the piss, so I won't do that. I'm sure someone will.

Re:

[barzok]

Or you could say "the batteries have a mass of <whatever> kilograms"

Because no one would have a clue WTF the Imperial unit of mass is.

Re:

[pete-classic]

Um, it's the pound [wikipedia.org]. Doesn't everyone know that? 2.2 lbs to the kilo.

While weight certainly means the force created between two masses due to gravity, it is almost always used interchangeably with mass in practice.

-Peter

Re:The batteries weigh what?

[vlm]

Um, it's the pound. Doesn't everyone know that? 2.2 lbs to the kilo.

While weight certainly means the force created between two masses due to gravity, it is almost always used interchangeably with mass in practice.

Still messed up. Trying to compare a metric unit of mass to a imperial unit of weight using a conversion factor that only works at roughly sea level on earth.

Metric unit of weight - Newton N
Metric unit of mass - Gram g

Imperial unit of weight - Pound lb (you know, like Pound Sterling being a pound of silver?)
Imperial unit of mass - Slugs

Re:

[pete-classic]

Did you click the link? No one uses slugs. Pounds are commonly used to express mass as well as force (weight).

Since there is a mass version of the pound, and it is defined in terms of kilos the conversions actually work perfectly in any (or no) gravitational field. (Though the conversion factor is exactly 2.20462262, not 2.2.)

Seriously, click the link.

Don't get me wrong in all of this. I advocate the metric system. But I don't understand the seemingly willful misunderstanding of the modern imperial sys

Re:

[vlm]

modern imperial system

That, sir, is an oxymoron. Like "Military Intelligence" or "Deafening silence" or "clean coal"

The "mass pound" and "weight pound" may be equal at sea level in a certain location or whatever, but probably not equal at any other gravitational potential, which must make for some confusing equations and explanations. Therefore, Why the willful misunderstanding? Because its icky to have the same name for inertial mass and gravitational weight/force.

Thank you Peter for the info. Always a pleasure to converse

Re:

[pete-classic]

There's no question that it's a kludge.

The "mass pound" and "weight pound" may be equal at sea level in a certain location or whatever, but probably not equal at any other gravitational potential

There's no "may" about it. For the Math to work they can only be equal at exactly 1G. The thing is, we never really use the "weight pound" in practice. I mean, if someone asks you what you weigh do you ask for a reference altitude (or gravitational force)? Absurd.

Put it this weigh (yuk-yuk), if you want to buy a

The U.S. Customary system of units must die!

[Z-MaxX]

modern imperial system

That, sir, is an oxymoron.

I put forth a compelling argument for the United States to join the world with the International System of Units [gibibit.com]. Forward this to your friends who still think that ounces (fluid ounce or international avoirdupois ounce? British or U.S. fluid ounce? Apothecary ounce?), pints, and inches are the way to go.

Re:

[AshtangiMan]

I always used slugs as an engineering student. The lb-m and lb-f system seemed wrong to me, and most of the people who used it ended up losing points because of the missing 32.2. When not working with the metric system, I would still opt to use slugs when needing to have a mass unit.

Re:

[jo42]

How many stones [wolframalpha.com] is that?

Re:

[pete-classic]

Stone is the plural of the unit of weight, stone.

Fourteen. But you knew that.

-Peter

Re:The batteries weigh what?

[blueg3]

Pound-mass or slug, your choice.

Re:The batteries weigh what?

[Jamamala]

According to my back-of-an-envelope calculations, I get their true weight to be 1729N.

F=GMmr^-2
=G * Mass of earth * mass of box * (Earth's radius + Hubble orbit height)^-2
=(6.67x10^-11 * 5.9742x10^24 * 208.7) * ((6378 + 559)x10^3)^-2
=1729.20 N

Re:The batteries weigh what?

[Maddog Batty]

Only true if the HST + shuttle were stationary and balanced on a very tall table rather than being in orbit. As they are actually in free fall, effective gravity is zero and hence the weight is zero too.

(Yes I do understand that gravity is acting on the HST + shuttle to keep it in orbit but there is no force required to support them which is the definition of weight)

Re:

[mangu]

As they are actually in free fall, effective gravity is zero and hence the weight is zero too

Then what keeps it in orbit? If effective gravity were zero it would fly away in a straight line.

I do understand that gravity is acting on the HST + shuttle to keep it in orbit but there is no force required to support them which is the definition of weight

If someone drops a 760 kg machine on your head that machine would weigh absolutely nothing, until it hits your head?

Every time these weight vs. mass discussions a

Re:

[Nyeerrmm]

They're weightless in an orbiting reference frame, they have weight in an inertial, Earth-fixed reference frame. You don't claim that a person in free-fall off of a building in weightless. In the Vomit Comet-type aircraft, you experience 'weightlessness' because the lack of windows effectively puts you in a free-falling reference frame. However, its all really the same thing and I think most of us here are able to recognize what is meant.

Re:

[frieko]

You're wrong, GP is right. Weight is the amount of force needed to hold an object stationary, or equivalently, the amount of gravity acting on the object. Regardless of the actual amount of opposing force. You don't look up at a falling anvil and think, "whew, good thing it's weightless!"

Re:

[dustrider]

You missed the centripetal force of the orbit they're in :)

Re:The batteries weigh what?

[Xzisted]

What is the equivalent of that in unladen swallows?

Re:The batteries weigh what?

[jmn2519]

African or European?

Re:

[Hazelfield]

African or European?

I don't know that! (AAAAARRGGHHHHHH!!!)

Re:

[geekmux]

According to my back-of-an-envelope calculations, I get their true weight to be 1729N.

F=GMmr^-2
=G * Mass of earth * mass of box * (Earth's radius + Hubble orbit height)^-2
=(6.67x10^-11 * 5.9742x10^24 * 208.7) * ((6378 + 559)x10^3)^-2
=1729.20 N

Ah, but I see you failed to calculate the mass of your envelope...

Re:

[systroi]

hmm... interesting calculations

Re:

[Faux_Pseudo]

And in space the weight of the batteries isn't 460 pounds either.

reminds me of ...

[jsnipy]

Doing my final upgrade on my system with AGP. You just know this is it :(

Re:

[Anonymous Coward]

Seems like it would have been a perfectly valid statement if they added ".... on Earth." to the end of the sentence.

Would you prefer they only talk about the mass of objects in space? (something that wouldn't make sense to the majority of their readers)

Whereas, "460 pounds" makes sense to everyone (well, everyone using the imperial system) even if it's technically incorrect.

Re:

[multisync]

Whereas, "460 pounds" makes sense to everyone (well, everyone using the imperial system) even if it's technically incorrect

Well, technically the batteries weigh the same while on Earth as they do while orbiting it, they're just falling at the same rate as the shuttle, astronauts and Hubble, so they appear weightless. Are you "weightless" while skydiving?

Re:Proof...

[Maddog Batty]

Technically the batteries have the same mass while on Earth as they do while orbiting it. The weight in orbit is zero. (which is the point the above are making)

See here: http://en.wikipedia.org/wiki/Mass_versus_weight [wikipedia.org]

Re:

[multisync]

Technically the batteries have the same mass while on Earth as they do while orbiting it. The weight in orbit is zero.

Okay, but you're talking about the lack of the sensation of weight [wikipedia.org].

If there is no contact with any surface to provide such an opposing force then there is no sensation of weight (no apparent weight). This happens in free-fall, as experienced by sky-divers (until they approach terminal velocity) and astronauts in orbit, who feel "weightlessness" even though their bodies are still subject to

Re:

[Sockatume]

Weight is the force resisting gravity. If you're in orbit, you're no longer resisting it, so you don't have any weight.

Re:

[multisync]

You're resisting gravity by moving tangentially at the same rate as you are falling toward the center of the body you're orbiting. So your weight would be the amount of force necessary to maintain your tangential velocity.

Re:

[Chris Burke]

So, in orbit your weight depends on the density of matter around you, and would be zero in a perfect vacuum?

That doesn't sound right.

Also, defining a force perpendicular to gravity as resisting gravity makes little sense.

Re:

[liquiddark]

I think you need to read this [xkcd.com].

Re:

[Sockatume]

To elaborate on that, the ship stays in orbit by virtue of not resisting gravity! The pseudo-force (numerically equal to the ship's weight, but not the same force) from the gravitational attraction is what curves the ship's orbit. Without that force pulling the ship inwards (like the force on the string when you whirl a yo-yo above your head), it'd be a straight line.

Re:

[notarockstar1979]

Well, technically the batteries weigh the same while on Earth as they do while orbiting it, they're just falling at the same rate as the shuttle, astronauts and Hubble, so they appear weightless. Are you "weightless" while skydiving?

Not exactly. Weight=Mass*Gravity, therefore as gravity decreases weight decreases (assuming the mass of the batteries didn't change).

Re:

[Anonymous Coward]

Are you "weightless" while skydiving?

Only briefly. Once you hit terminal velocity, there is no longer any sensation of falling (no acceleration). For the vast majority of your dive, you "weigh" the same as you do on the ground. Instead of being held up by the floor or a piece of furniture, you are held up by a (relative to you) fast-moving updraft.

Re:

[Sockatume]

I had fun thinking about that example, it's not obvious. To understand it, realise that the skydiver reaches constant (terminal) velocity eventually, and therefore is no longer experiencing acceleration due to gravity. The force that stops him accelerating is the air resistance, which has become exactly equal (and actually physically equivalent) to his weight. A skydiver at terminal velocity is no more weightless than a man lying on his face a lift which is descending at constant speed. Another good example

Re:

[crispin_bollocks]

> Seems like it would have been a perfectly valid statement if they added ".... in bed." to the end of the sentence.
Fixed that.....

Re:Proof...

[fuzzyfuzzyfungus]

There are two possibilities:

1. "Science" Journalist studied journalism in journalism school. He writes ok; but his only science credentials involve being able to "rewrite in his own words" NASA press releases.

2. Science Journalist is a perfectly decent dude, and submitted a story with a mass in kilograms value. He was then smacked down by an editor for violating "standards" that require using imperial measures in the US. Since, as everybody knows, a kilogram is 2.2lbs universally, a simple multiplication brought the copy into compliance with correct standards.

Re:

[Daniel Dvorkin]

3. Science Journalist knows that any reasonably intelligent person will understand the implied "... on the surface of the Earth" appended to the phrase "weighs X pounds," and really doesn't care about that tiny minority of readers whose chief joy in life is showing off how clever they are by telling everyone, in a breathless OMG-I'm-the-first-person-to-notice-this-EVAR tone, that mass and weight are not the same thing.

Re:

[Chris Burke]

Option 4: They know that pounds are a unit of mass, in addition to weight [wikipedia.org], and are thus actually smarter than the pedants on slashdot.

HA HA JUST KIDDING HOW COULD THAT BE?!

Watch it live

[Audiophyle]

Check it out on NASA TV [nasa.gov] if you haven't had the chance yet. Viewing Hubble the way the astronauts see it is a neat experience.

Re:

[erbbysam]

I've spent most of this week studying for finals, and this has been great just to leave up in the background instead of music. It's unfortunate from an entertainment stance that this is the final spacewalk, however I do realize just how dangerous that it is to be out there.

Re:Watch it live (on Linux too)

[achurch]

If it redirects you to the "no player found" page (as it did for me), try:

mplayer -playlist 'http://playlist.yahoo.com/makeplaylist.dll?id=1369080&segment=149773'

(The original link is http://www.nasa.gov/55644main_NASATV_Windows.asx [nasa.gov], but MPlayer doesn't seem to be able to handle multiple levels of playlists.)

As one who (perhaps from Kubrick's 2001) had a sense of EVA actions being slow, deliberate things, it's neat to see that the work's going practically as smoothly as if it was being done in a lab.

Re:

[e9th]

Thanks much.

Re:

[trayrace]

There's also a 1200k stream available: http://playlist.yahoo.com/makeplaylist.dll?id=1368163 [yahoo.com]

Re:

[certsoft]

Nasa TV is also available unscrambled on Echostar 7 (119.0 West) if you have a FTA (Free to Air) receiver and a circular LNB.

Not above the WFC2

[Zpin]

It's actually Wide Field Camera 3 now. It has been exchanged in the first spacewalk.

Re:

[Bemopolis]

Awww, you made me cry, you bitch.

Oh WFPC2, I will miss your tell-tale chevron superimposed over the sky like a Batsignal. Also, I will miss your useful filter set, so unlike that on WFC3 which treats nebular astronomy as if it were a mere curiosity. Galactic astronomers are such telescope hogs.

If I were still in the biz I would curse thee, WFC3! But, given all of the bad luck HST has had over its lifetime that would just be piling on.

Astronaut helmet cams

[192939495969798999]

Let me just say, thanks NASA for the astronaut helmet cams! That footage lets me live out my astronaut fantasies without all the space-induced nausea and military training.

Re:Astronaut helmet cams

[Paperweight]

That's the only thing holding you back?

First tweets from space

[alen]

http://twitter.com/Astro_Mike [twitter.com]

one of the astronauts is live blogging on twitter from the shuttle

Re:

[CopaceticOpus]

Hmm, apparently being an astronaut is hard work, but it's also a great experience, and the views can't be beat!

Why even bother writing from space when he could have simply written those generic updates ahead of time? (Perhaps because that approach didn't work out so well [astroengine.com] for the Chinese.)

batting .900 for the mission so far

[peter303]

They fixed everything they supposed to during the first four space walks except for part of an instrument that was to far gone. They fixed some things that werent even deisgned to be serviced.

Comment removed

[account_deleted]

Comment removed based on user account deletion

Re:

[account_deleted]

Comment removed based on user account deletion

Re:

[WindBourne]

Hmmm. Was duracell used on that electric wrench?

Re:

[DNS-and-BIND]

Good job shilling for your viral advertising job! As an American who has been away since 2002, these sorts of obvious shilling probably look like innocouous comments, but to me, viral shilling is as obvious as a dick on a pumpkin. I've never heard of this weak-ass slogan before, and I can't conceive of any reason to repeat it, other than you are a paid shill or a creature of such zero life as you can be enhanced by repeating someone's slogan.

I love NASA TV

[peter303]

I've been listening to and occasionally watching all the space walks streaming live on NASA TV while at work. Thats one video site they havent banned yet. I'm listening to the fifth space-walk now. The view is straight down at earth behind the shuttle.

Every once in a while I hear them count off. I think they are counting seconds they apply a tool, but I haven't been paying close attention.

Re:

[bruce_the_loon]

They're counting turns on bolts or number of guide-lines still visible as they slot something in.

Or sometimes the amount of O2 they have in their tanks.

Re:

[RpiMatty]

How do I watch NASA TV????
Using firfox on winxp here at work and it keeps redirecting me to a help page.
http://www.nasa.gov/help/multimedia/odplayer.html [nasa.gov]

Apparently it thinks I need to install more plug ins... but I never even get a chance to see the webpage with the video.

Have a stream address I can plug into VLC?

Re:I love NASA TV

[LordKaT]

mms://209.73.189.79/bcpenc252181?StreamID=81684353&pl_auth=56e0ca2df8a3b81fa447c77c49dbf0f1&ht=120&pl_b=00CEBE2C2D18A488577820B4444A1179CB&CG_ID=1369080&Segment=149773

Re:

[Auraiken]

Thanks.

Orbit?

[the_Bionic_lemming]

Considering the Hubble's orbit is 96-97 minutes, When exactly would it be night for the hubble? Or do the batteries click on and off every other 45 minutes? That's one heck of a recharge/discharge cycle.

Re:

[Nyeerrmm]

Yes, when sizing out the power system for a spacecraft you figure out the eclipse period, as well as total power requirements. From there, you can size the solar cells to collect the power needed for a whole orbital period (probably double the power requirements, assuming a 50% eclipse period, which is likely in LEO), and then the battery size, based on the power required and expected eclipse time.

All LEO satellites, except those in sun-synchronous orbits that keep them situated above dusk/dawn all the tim

Re:

[Chris Burke]

Astronaut floating in shuttle "Ahhh they are pretty light up here."

"... but they are massive."

Which is actually pretty close to a real quote from an astronaut from ages back.

Those batteries are not going to be easy to move around, just because they are in freefall.

Really live?

[PPH]

Is the audio feed delayed? What happens if an astronaut lets loose an f-bomb when a tool goes drifting off?

Re:

[icebike]

Fbomb is not prohibited on the Internet.

The Hubble has replaceable batteries

[aaandre]

but the ipod and iphone can not?

Re:

[jo42]

Welcome to modern capitalism in accordance to The Cult Of The Pod People (c)(tm).

Re:

[K. S. Kyosuke]

Astronomers calling NASA hotline to have the Hubble batts replaced == iPodders calling Apple hotline to have their iPod batts replaced. I haven't noticed astronomers changing the Hubble batteries on their own.

Space Walk

[hackus]

The last space walk is suppose to last 6 hours.

That is incredibly dangerous to be outside for that length of time in such primitive suits.

I wish them good luck however, and pray they return safely.

God speed!!

-Hackus

Re:

[icebike]

I submit all space walks are dangerous, but given the history or death and injury during space walks (ZERO) I don't think you have any valid basis for attacking the suits.

Re:

[moosesocks]

Wouldn't radiation be a concern?

Re:

[WuphonsReach]

That is incredibly dangerous to be outside for that length of time in such primitive suits.

I would not call today's suits primitive. Especially compared to the suits used during the Mercury/Apollo era.

Is there still room for improvement? Always. Massive improvements? Maybe not. Barring improvements in fabrics / construction technology.

Why not go the source??

[icebike]

Why would the OP link is story to some obscure third party blurb site when a direct link to WWW.NASA.GOV would make far more sense.

You could even watch live at the Nasa site:
http://www.nasa.gov/multimedia/nasatv/index.html?param=public [nasa.gov]

Great Job!

[viyh]

I've been glued to NASA TV since this began and I just have to say, the Atlantis crew kicked some serious ass! They hit some hurdles but overcame everything and went beyond everyone's expectations. Here's a summary of what got added/repaired:

• Wide Field Camera 3
• New gyros
• New batterys
• Repaired the Advanced Camera for Surveys (this is the camera responsible for the pretty photos), they got the wide-field channel working, but not the high-res channel. This was expected. Now, they have redundant commu

Insignificant figures

[S-100]

460 pounds. That makes it 208.656755845 kilograms, right?

Re:

[Dollyknot]

The really clever thing about this was, they never went to the moon six times, they tried not to go to the moon actually seven times, 'coz one time they failed in their attempt not to go the moon, but luckily the three astronauts survived their attempt at not going to the moon.