Jump to content

For Questions That Don't Merit Their Own Thread


Recommended Posts

9 minutes ago, kerbiloid said:

Confused the "Oberth effect" and the "Oberth maneuver".

[copy ... Wikipedia ... paste]
Oh, that's a thing? Well, the "Oberth maneuver" is one special application of the "Oberth effect".

Link to post
Share on other sites
4 hours ago, AHHans said:

Wasn't there a probe recently that was something like two thirds heat-shield and burned away most of that while entering Jupiter's atmosphere?

I wouldn't exactly call Galileo recent.

Edited by DDE
Link to post
Share on other sites

Moderator's note:  @ARS asked an interesting question about calculating interatomic distances in metals, and the ensuing discussion became quite lengthy, so it has been split off into a separate thread (including the original question).

The new thread is located here:

We now return you to your original thread, already in progress.  :)

Link to post
Share on other sites

This isn't a question, but here's a picture I took today of the Jupiter/Saturn conjunction. The picture of the Moon is taken today at the same scale. Taken through 127mm Maksutov-Cassegrain telescope, 17mm eyepiece, iPhone 11 focal setup.

ConjunctionAndMoonSameScale.jpg

*afocal setup

Link to post
Share on other sites

@BrotoroFantastic!  

 

...Takes me back to when I was in college looking through the University telescope (albeit at each, individually)

.

Great pic!

Okay - So --- I'm still hoping for links to images from the Saturn / Jupiter conjugation; but I can't resist posting this:

Japan space agency reveals what's inside capsule brought back from asteroid - CBS News

You can see the regolith that Hayabusa2 brought back -- but the crazy thing: why is the guy carrying the sample container in (effectively) a bomb-hazmat suit?

Edited by JoeSchmuckatelli
Link to post
Share on other sites
14 hours ago, Brotoro said:

This isn't a question, but here's a picture I took today of the Jupiter/Saturn conjunction. The picture of the Moon is taken today at the same scale. Taken through 127mm Maksutov-Cassegrain telescope, 17mm eyepiece, iPhone 11 focal setup.

Amazing photo.  I went out with my Maksutov-Cassegrain (convergent evolution, :D) last night but clouds rolled in right as I was getting set up.

Edited by Entropian
Link to post
Share on other sites
12 hours ago, JoeSchmuckatelli said:

@BrotoroFantastic!  

...Takes me back to when I was in college looking through the University telescope (albeit at each, individually)

Great pic!

Okay - So --- I'm still hoping for links to images from the Saturn / Jupiter conjugation; but I can't resist posting this:

Japan space agency reveals what's inside capsule brought back from asteroid - CBS News

You can see the regolith that Hayabusa2 brought back -- but the crazy thing: why is the guy carrying the sample container in (effectively) a bomb-hazmat suit?

Yes, its looks like an bomb protection suit, who make little sense, the reason for that suits is giving you protection if something explodes. 
Now I assume nothing on the return capsule can explode.

Perhaps it was to protect from the wildlife :) 

Link to post
Share on other sites
1 hour ago, magnemoe said:

Yes, its looks like an bomb protection suit, who make little sense, the reason for that suits is giving you protection if something explodes. 
Now I assume nothing on the return capsule can explode.

Perhaps it was to protect from the wildlife :) 

Well, it’s possible that there were unfired (redundant) pyrotechnics on the craft 

Link to post
Share on other sites
2 hours ago, magnemoe said:

Yes, its looks like an bomb protection suit, who make little sense, the reason for that suits is giving you protection if something explodes. 
Now I assume nothing on the return capsule can explode.

Perhaps it was to protect from the wildlife :) 

Drop bears?

Link to post
Share on other sites

Random musing I think probably doesn't deserve its own thread:

Space Shuttle would have been better with Kerolox Main Engines. My reasoning: 

1. No insulation foam.

2. RP1 up top would prevent falling ice.

3. Extreme reusability of Kerolox engines have been demonstrated.

4. It doesn't need to go BLEO so low ISP isn't a handicap.

5. Smaller External Tank.

Yes it would be about 700t heavier on the pad, but it'd still be lighter than Saturn.

Link to post
Share on other sites
11 hours ago, RCgothic said:

Extreme reusability of Kerolox engines have been demonstrated.

Was it, though? I believe the coking is the reason for the rush to methalox.

Link to post
Share on other sites
2 hours ago, DDE said:

Was it, though? I believe the coking is the reason for the rush to methalox.

Whilst I'm not sure if individual Merlins have flown/fired more times than SSMEs, I believe the SSMEs were completely overhauled between flights whereas Merlins apparently needs little more than cleaning fluid.

Link to post
Share on other sites

Does this situation possible considering how light reflects off a reflective surface?

2 Snipers are hunting each other. They are elite soldiers expert in camouflage. At one point, while both are under camouflage, and facing each other (they're not aware they are staring at each other), the sun is positioned in such a way that the sunlight glints from the scope's lens of both of them (basically they see the scope glint of each other, not just only one of them)

Also, since lasers can reflect off reflective surface, is it possible for sufficiently powerful laser to not reflect off reflective surface at all simply by burning through it from the sheer amount of heat at the moment of contact? Basically a laser that melts through the mirror it's supposed to reflect off

Link to post
Share on other sites
1 hour ago, ARS said:

2 Snipers are hunting each other. They are elite soldiers expert in camouflage. At one point, while both are under camouflage, and facing each other (they're not aware they are staring at each other), the sun is positioned in such a way that the sunlight glints from the scope's lens of both of them (basically they see the scope glint of each other, not just only one of them)

That would only work when the front element (the glass) of the scope extends beyond the hood of the scope and the sun is perpendicular to both snipers. Or when the sunlight bounces of something else into the scope. However I don't think scopes have extending front elements, because a lens hood prevents flaring and other visual artefacts.
 

1 hour ago, ARS said:

Also, since lasers can reflect off reflective surface, is it possible for sufficiently powerful laser to not reflect off reflective surface at all simply by burning through it from the sheer amount of heat at the moment of contact? Basically a laser that melts through the mirror it's supposed to reflect off

A mirror will still reflect some of the light. So if there is a insanely powerful laser there is a reflection of that laser. However if the laser is powerful enough to instantly melt/vapourize the mirror the reflection might last too short to notice.
Assuming a mirror reflects 99% of the laser something else is going to receive 99% of that laser too and that something is going to get burned too.

Edited by lrd.Helmet
more stuff
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...