SpaceX Crew Dragon DM-2: US returns to crewed launches (mission)

By DocM
in Science News & Discussion

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Grand Master

Jim K Global Moderator

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10 minutes ago, FloatingFatMan said:

It's hard to get over how much like bike gear those suits look like.  Are they full vacuum rated or just launch/flight suits?

It will help you survive a depressurization event of the capsule.  "You can just jump in a vacuum chamber with it, and it's fine." - Elon

 

You can't go space walking with them as they do not offer protection from space radiation and the severe temperature ranges. 

Grand Master

FloatingFatMan

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Just now, Jim K said:

It will help you survive a depressurization event of the capsule.  "You can just jump in a vacuum chamber with it, and it's fine." - Elon

 

You can't go space walking with them as they do not offer protection from space radiation and the severe temperature ranges. 

Would they provide enough protection on say, Mars?

Grand Master

Jim K Global Moderator

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10 minutes ago, FloatingFatMan said:

Would they provide enough protection on say, Mars?

No.  Probably for the same reason .. lack of radiation protection and the temp (in this case extreme cold).  They are designed for intravehicular activities only.

Grand Master

+Matthew S. Subscriber²

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Thanks @DocMfor that, hopefully I have enough time to catch the launch today... going into work as of today...

Grand Master

Skiver Veteran

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Can anyone answer a few questions here.

 

Why was yesterdays launch classed as an instantaneous launch? I first assumed it was to do with the rendezvous of the IIS but it doesn't make a lot of sense to not even have 10 minutes of wiggle room.

 

Correct me if I'm wrong but backup Window is Saturday and then Sunday - why do we have to wait 3 days for the first but only another day for the third? Again I assumed it was to do with the positioning of the IIS but surely time of day would be more relevant in that decision than the day itself?

Grand Master

FloatingFatMan

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8 minutes ago, Skiver said:

Can anyone answer a few questions here.

 

Why was yesterdays launch classed as an instantaneous launch? I first assumed it was to do with the rendezvous of the IIS but it doesn't make a lot of sense to not even have 10 minutes of wiggle room.

 

Correct me if I'm wrong but backup Window is Saturday and then Sunday - why do we have to wait 3 days for the first but only another day for the third? Again I assumed it was to do with the positioning of the IIS but surely time of day would be more relevant in that decision than the day itself?

You answered your own question. It's ALL about the positioning of the ISS, but the position of the launch point is a large factor as well. Remember, they're trying to hit a very small target moving at 17,500mph from 1000's of miles away.  If you're off by a few feet, might as well not have bothered launching to start with.

Grand Master

Skiver Veteran

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Just now, FloatingFatMan said:

You answered your own question. It's ALL about the positioning of the ISS, but the position of the launch point is a large factor as well. Remember, they're trying to hit a very small target moving at 17,500mph from 1000's of miles away.  If you're off by a few feet, might as well not have bothered launching to start with.

I don't ever recall the cargo dragon missions having an instantaneous launch window ( I could be wrong on that) and as I said, it makes zero sense not to build in some contingency for this sort of thing. They are not going to fuel the second stage/dragon to ONLY be able to reach the IIS based on the time it's launching that precisely. 

 

Again, same with the day - you said it yourself, it's passing over head at over 17,000MPH, it passes overhead multiple times a day so I do not see how the DAY actually matters, I would think the time of the launch is much more critical. Especially when the 3rd backup window is 24 hours after the 2nd. 

Grand Master

DocM

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14 minutes ago, Skiver said:

I don't ever recall the cargo dragon missions having an instantaneous launch window ( I could be wrong on that) and as I said, it makes zero sense not to build in some contingency for this sort of thing. They are not going to fuel the second stage/dragon to ONLY be able to reach the IIS based on the time it's launching that precisely. 

 

Again, same with the day - you said it yourself, it's passing over head at over 17,000MPH, it passes overhead multiple times a day so I do not see how the DAY actually matters, I would think the time of the launch is much more critical. Especially when the 3rd backup window is 24 hours after the 2nd. 

 

For all practical purposes Dragon launches to ISS use an instantaneous window - it's 1 second long. It involves orbital phasing, ISS crew schedule, and other factors.

Grand Master

FloatingFatMan

Posted
Posted (edited)
5 hours ago, Skiver said:

I don't ever recall the cargo dragon missions having an instantaneous launch window ( I could be wrong on that) and as I said, it makes zero sense not to build in some contingency for this sort of thing. They are not going to fuel the second stage/dragon to ONLY be able to reach the IIS based on the time it's launching that precisely. 

 

Again, same with the day - you said it yourself, it's passing over head at over 17,000MPH, it passes overhead multiple times a day so I do not see how the DAY actually matters, I would think the time of the launch is much more critical. Especially when the 3rd backup window is 24 hours after the 2nd. 

An additional factor that cargo missions don't have to deal with is life support. It doesn't really matter if it takes 5-6 days for cargo to arrive when it doesn't have to worry about breathing...  Crewed missions require the most optimal flight path possible to minimize flight time, hence you can't just push the GO button whenever you feel like it.

 

Also, it doesn't pass DIRECTLY overhead every few hours... Next orbit along will be a degree or two off the previous orbital path...

 

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