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uhoh
uhoh
00:06
@kimholder oic thanks!
 
3 hours later…
Sir Cumference
Sir Cumference
03:18
@Hohmannfan Yep. Never seen it in my life
I'm used to only seeing low magnitude stars :/
Needless to say, first time I saw a bright night sky, I freaked out
uhoh
uhoh
04:05
@kimholder if you want to remove my erroneously posted then deleted answer below here that would be fine.
@kimholder it makes me look even more SE-awkward than usual.
kim holder
kim holder
04:40
@uhoh you aren't SE-awkward. you have a style, which is developing. that post can't be deleted more than it already is. anyhow, it lead to the other question, which is good.
uhoh
uhoh
05:08
@kimholder ok that's a nice way to look at it :)
Hohmannfan
Hohmannfan
@SirCumference I hope you did not react like you was from planet Krikkit.
My Other Head
My Other Head
05:21
@Alessandro Cuttin, Another reference of possible relevance to your problem, esp if you are going to use the Deep Space Network:deepspace.jpl.nasa.gov/dsndocs/810-005/…
 
3 hours later…
XKCD
XKCD
08:04
Whenever I see a picture of the moon where the points go more than halfway around, I assume it's being eclipsed by one of those Independence Day ships and interpret the rest of the image in light of that.
 
1 hour later…
Antzi
Antzi
09:16
Shooting star aren't exactly an uncommon event...
You should take more trips to the country side ^^
 
4 hours later…
Juan
Juan
13:29
@PearsonArtPhoto @PearsonArtPhoto do you remember which software do they use?
 
1 hour later…
Stack Exchange
Stack Exchange
14:47
Podcast #88 - All About Documentation, Mostly
Kaitlin Pike on September 26, 2016
Welcome to The Stack Overflow Podcast, recorded September 20 at our headquarters in NYC. This week’s episode is brought to you by adorable otters, who hold hands at night so they don’t float away from each other. The episode is also brought to you by Compose, an IBM company. Compose is a production-ready, cloud hosted platform for building enterprise applications on open source database technologies.
geoffc
geoffc
15:05
Intriguingly a friend at a photo shop in NYC, famous one, told me right after the AMOS failure, a huge order came in from SpaceX. Thought that was interesting.
PearsonArtPhoto
PearsonArtPhoto
@Juan It was some L3 product, I think InControl was it's name, if I remember right...
@geoffc That could mean a lot of things. Damaged cameras, lack of cameras, or maybe even something else... Hmmm...
geoffc
geoffc
15:19
@PearsonArtPhoto Food for thought, eh? Did not get a detailed list of equipment, just that it was a large order.
PearsonArtPhoto
PearsonArtPhoto
Even that was more than you probably should have heard;-)
Hohmannfan
Hohmannfan
If a rocket explodes on the launchpad and no one is around to film it, does it still cost $60M?
geoffc
geoffc
@Hohmannfan Yes, and the trees file a class action lawsuit about all the noise.
Antzi
Antzi
15:45
@Hohmannfan We launched it I swear... Your satellite must be broken somehow. Maybe a Hitomi spin ?
Juan
Juan
16:03
@PearsonArtPhoto this one:www2.l-3com.com/trf/incontrol ?
PearsonArtPhoto
PearsonArtPhoto
That looks right.
Juan
Juan
16:28
thanks
 
1 hour later…
Hohmannfan
Hohmannfan
17:44
sed -i ...ouch. Lesson learned, I make a backup next time.
sed, saving labour and destroying data since 1974.
geoffc
geoffc
18:25
Musk is tweeting about Raptor in advance of the IAC.
twitter.com/elonmusk/status/780280440401764353?lang=en
Anyone doing a US presidential debate party? I am bring hot air popcorn! Those two could pop tons of it with their hot air! (BUt Trump is at least entertaining!)
Hohmannfan
Hohmannfan
Whatever the result of this election is, the proper response is "LOL".
Anybody around to talk about space exploration of whatever? I need a distraction from crying over my regular expressions.
geoffc
geoffc
18:42
@Hohmannfan This is the most entertaining election season EVAH!
Hohmannfan
Hohmannfan
Even for people outside the US.
geoffc
geoffc
They are expecting Superbowl style viewership for the debate tonight. Expecting to break MASH's record for TV.
I am Canadian, I bounce back and forth to the States, it is complicated, so I do not get to vote, but I get to follow along.
Hohmannfan
Hohmannfan
How long do you have to live in the US to vote?
Oh God, regexes to undo other regexes are complicated. Data partially recovered with sed -ri 's/^([1-9]{2})0([1-9]{2})0\2.\10\2_0_.*/\10\2\ \10__\2__/' ref.backstab
Yay! An hour of work saved!
geoffc
geoffc
18:57
@Hohmannfan Be a citizen. Not about living here, about immigrating legally. I am on a green card, not a citizen. I could have applied for citizenship years ago, but chose not to.
 
1 hour later…
Sir Cumference
Sir Cumference
20:09
Uh, anyone here able to answer another orbital mechanics question?
Hohmannfan
Hohmannfan
yup
You know there is a site for that, it is called "space exploration stack exchange" :P
Sir Cumference
Sir Cumference
In binary systems, under what conditions will $m_1a_1 = m_2a_2$?
Hohmannfan
Hohmannfan
Just when the masses are equal, I guess. It is always m_1a_2 = m_2a_1.
Sir Cumference
Sir Cumference
@Hohmannfan Not sure how I would word my question any more than I just did
Hohmannfan
Hohmannfan
^disregard above comment by me.
Think momentum. Both stars are in apoapsis/periapsis at the same time, so m_1a_1 is always equal to m_2a_2.
Sir Cumference
Sir Cumference
20:15
@Hohmannfan I heard it has something to do with the eccentricities being equal and each star being on opposite sides of the barycenter?
Hohmannfan
Hohmannfan
Was the momentum reasoning clear enough?
Sir Cumference
Sir Cumference
@Hohmannfan Doesn't really address the other things I brought up
Hohmannfan
Hohmannfan
Try the circular case first. Then it is trivially true, as the barycentre is always the centre of mass:
user image
Further more, as the eccentricity is the same for both stars, the apoapsis distance is the semi-major axis multiplied by some constant. They both are at the apoapsis at the same time, so m_1a_1 must still be equal to m_2a_2 in order for the centre of mass to be the barycentre.
So "under what conditions?"
Always
It is really this relationship in disguise:
user image
Just replace 'r' with 'a'
Sir Cumference
Sir Cumference
20:30
All right, I oughta clear this up. Does this only apply to binaries when both stars are on opposite sides of the barycenter?
Hohmannfan
Hohmannfan
In a binary system, the stars are ALWAYS on the opposite sides of the barycentre.
The centre of mass must be on the line between them.
Sir Cumference
Sir Cumference
@Hohmannfan So we can't have something like this?
user image
Ah, crap
Just realized the problem...
Hohmannfan
Hohmannfan
What do you mean? They are at opposite sides in that image
Sir Cumference
Sir Cumference
Sigh...hold on, does it matter whether one of the orbits encompasses the other?
Hohmannfan
Hohmannfan
No.
Sir Cumference
Sir Cumference
20:34
All right, that clears things up.
So in any binary, $m_1a_1 = m_2a_2$? And $e_1 = e_2$?
Hohmannfan
Hohmannfan
yes.
Sir Cumference
Sir Cumference
All right then
Thanks
Hohmannfan
Hohmannfan
A handy geometric fact you can use to derive some equations: The two ellipses in a binary system are of identical shape, one is just rotated 180 degress and scaled. The scaling factor is the same as the mass ratio.
@SirCumference I can not stress that fraction-equals-fraction-equals-fraction equation. It may not be written that way in a textbook or something, but by simple rearranging, you get all the required equations for binary systems.
Sir Cumference
Sir Cumference
@Hohmannfan Nah, we've gone over that in class a lot of times
There are, of course, equations that involve other stuff than just the ratio equation
Hohmannfan
Hohmannfan
But in this case, it was just a ratio equation:
user image
Sir Cumference
Sir Cumference
21:18
Welp, first year in college is rough. I probably should've learned more orbital mechanics beforehand
Hohmannfan
Hohmannfan
If I remember things right, the first year in college is the 13th year in school in the US. Is that correct?
wiki... yup, looks like that is correct.
Sir Cumference
Sir Cumference
@Hohmannfan Yep.
Also, we go from freshman > sophomore > junior > senior. They do the same in Norway?
Hohmannfan
Hohmannfan
1-4 barneskule, 5-7 mellomtrinn, 8-10 ungdomsskule, 11-13 vidaregåande. Then it is university.
I have started in the 12th grade.
Sir Cumference
Sir Cumference
21:34
@Hohmannfan Oh, I was listing the college grade levels
Well, they also apply to high school too
In high school, 9th grade is synonymous with freshman, 10th with sophomore, etc. In college, we just call them freshman, sophomore, etc.
Hohmannfan
Hohmannfan
So you are a 'freshman'.
Sir Cumference
Sir Cumference
Yep
Jeel Shah
Jeel Shah
21:56
Hello! I was wondering what the Elon Musk event is about?
geoffc
geoffc
@JeelShah Mars plans baby! Mars!
Jeel Shah
Jeel Shah
@geoffc Ohhhhhh nice! Where can I find the live event link?
geoffc
geoffc
He has been talking about manned missions to Mars from day 1. Now he plans on talking at some level fo detail (to be seen!) how he plans of doing that.
We know they plan to build a monster booster (BFR - Big F-ing Booster) to launch an MCT (Mars Colonial Transporter). This is predicted to have 100,000lbs payload to Mars, so MONSTER booster. People are expecting 25-30 Raptor engines at around 1 million lbs thrust. (Though if I do the math right, the Raptor he discussed in Twitter yesterday/today it is only 600 Klbs thrust).
How much he will show? Who knows! Looking forward.
@JeelShah Kim (mod here) scheduled it for this chat room.
Upper right corner of this screen.
chat.stackexchange.com/rooms/info/9682/the-pod-bay?tab=schedule
Ah, you found it.
Jeel Shah
Jeel Shah
22:20
@geoffc Awesome! Thanks for the insight. I'm looking forward to watching it :D
kim holder
kim holder
23:15
@JeelShah This is the link: livestream.com/accounts/4426843/events/6315496/…
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@uhoh congratulations on your shiny new Socratic gold badge :)
alternate address for speeches from the IAC: veloenvivo.com/iac/eng.html
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