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The logic of prop-loading the F9 after crew boarding is absolutely unassailable. How could working near a fueled, pressurized rocket, and boarding crew on a fueled, pressurized rocket, be safer than evacuating the pad and securing the crew in a LES-equipped capsule before any prop begins to flow? How???

The Titan II killed or injured several pad workers in this exact scenario--while they were working on or near a fully fueled, pressurized rocket.

No rocket is pressurized for flight until the final seconds of countdown, as far as I know. So crew weren't working on a pressurized, fueled rocket with either Shuttle or Titan II. There is only head pressure at the bottom of the tanks from the weight of the propellant higher up, but no flight pressurants.

AMOS-6 is a pretty good example of why exposure time and risk are not correlated. The LOX tank and the COPVs were being filled, with pressures, fill levels, and temperatures constantly changing until they reached an unstable point that hadn't been reached before, resulting in the explosion.

Once filled, everything on a non-sub-cooled rocket is basically in steady state and can sit with occasional topping for boiloff for as long as you want with nothing really changing. This doesn't really work for a subcooled rocket.

SpaceX wants to make the process inherently safe and controlled. Every other type of vehicle is fueled with passengers and crew aboard. But they have a lot of work to do to prove that Falcon 9 is just as safe as other vehicles, since the fuels are inherently more dangerous.

The Titan II fatalities occurred in operational silos where the Titans were fully fueled and capable of being brought to flight pressures within minutes.

http://www.themilitarystandard.com/missile/titan2/accident_374-7_1976.php
http://www.themilitarystandard.com/missile/titan2/littlerockaccident.php
http://www.themilitarystandard.com/missile/titan2/accident_533-7_1978.php

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Space Science Coverage / Re: General SETI Thread
« Last post by CuddlyRocket on Today at 07:14 PM »
Next, our Sun, based on some cursory Googling, appears to be of a type (G-type main sequence), that only represents 5% or so of all observable stars in the Universe.

'In the Universe' over-estimates the strength of our knowledge of star population distributions. Basically, we can only do surveys within range of our telescopes - which is longer for brighter stars - which we can call our 'solar neighbourhood'. And then we have to add the caveat that our neighbourhood may not be typical - but we can pray in aid the principle of mediocrity there!

So, in the solar neighbourhood, 7.5% of stars are Class G main sequence. Class K are 12% and Class M, 76%. (For completeness, Class F 3%, Class A 0.63%, Class B 0.13% and Class O 0.00003%.) Though Gaia will be doing a more complete survey, so it will be interesting to see if these figures shift significantly.
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This interesting article explains why it's been tricky getting Falcon Heavy in position to fire her engines:

https://www.teslarati.com/whats-causing-spacex-falcon-heavy-delays/

That was interesting. .......The shrinkage issue ......

A couple of people in L2 were actually able to do the math and estimate the potential contraction in centimeters and inches. Can't share the details here of course, but another plug for L2, and the posts are still on the next to last page in Discussion Thread 13. If not, w/o saying too much the easiest way to find them is by doing an advanced search for posts by Lar with keyword 'banana' (don't laugh too hard yet, that search brings up 2 posts)
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Difficult to see how pad crew that have evacuated the pad, can be injured by a prop-loading mishap, when the prop-loading begins only after they have evacuated the pad.

So right there, the number of personnel exposed to danger has been halved or more than halved.

The remaining personnel still in danger--the flight crew--are sitting in a fully armed launch escape system that necessarily features, as part of its fundamental design, successful operation upon detection of a sudden, unanticipated booster explosion on the pad. Of course the LES doesn't eliminate the risk of LOC but without it, the LOC probability is 1.

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A F9 S2 would need much more than a bigger battery to survive longer & have on the fly change capability while on orbit.   You’d basically need to design it with ACES like capability.  You need power generation, comms, & thermal control that includes an RCS system.   

How long would CRS-2 have lasted if they didn’t override & deploy the solar panels?  Look at how quickly Skylab nearly reached loss of mission when thermal & power went out of whack.   LEO is not friendly to electronics.
17

Does SpaceX have the capability of leaving the S2 in orbit and deciding at some future time to deorbit it?


no, as stated many times before, there is no commanding capability and the batteries only last for a matter of hours.
Everybody keeps repeating that, but it really doesn't make any sense from a technology and engineering standpoint.

Yes, it makes great sense.  There aren't tracking sites in the right places to be able to send the commands.  There isn't enough time to diagnose and correct problems in time.
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ISS Section / Re: Schedule of ISS flight events (part 2)
« Last post by Olaf on Today at 06:47 PM »
https://twitter.com/SpcPlcyOnline/status/953671679800217601
Quote
Gerst: once cmrcl crew available, will still fly US astronauts on Soyuz and Russian cosmonauts on our vehicles bc always need at least one Russian and one American on ISS to operate it.  But won't be buying any addl Soyuz seats.

https://twitter.com/SpcPlcyOnline/status/953673434055180288
Quote
Gerst -- Russian cosmonauts on cmrcl crew vehicles, and US astronauts on Soyuz at that time, will be on no exchange of funds basis. Will be an American on every Soyuz, and a Russian on every [operational] cmrcl crew flight.  As I said before, need one of each on ISS at all times.
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SpaceX Mars / Re: BFS quarantine ?
« Last post by CuddlyRocket on Today at 06:47 PM »
But initially until it can be proved, SpaceX most likely have to decontaminate both ways.
You won't be able to prove there's no life on Mars for millennia, even with a thriving human colony there (which would probably make decontamination pointless anyway). There are places on Earth we haven't managed to prove lifeless yet! And Mars is a big, virtually unexplored place.

Quote
There is no law forcing them to do so, but the least SpaceX wants to is to piss off NASA. And this is important for NASA.
It's important to some people in NASA, principally scientists, and they've been allowed free-reign because it wasn't impinging on other people's aspirations etc. If and when it starts doing so, there will be push-back.
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The logic of prop-loading the F9 after crew boarding is absolutely unassailable. How could working near a fueled, pressurized rocket, and boarding crew on a fueled, pressurized rocket, be safer than evacuating the pad and securing the crew in a LES-equipped capsule before any prop begins to flow? How???

The Titan II killed or injured several pad workers in this exact scenario--while they were working on or near a fully fueled, pressurized rocket.

No rocket is pressurized for flight until the final seconds of countdown, as far as I know. So crew weren't working on a pressurized, fueled rocket with either Shuttle or Titan II. There is only head pressure at the bottom of the tanks from the weight of the propellant higher up, but no flight pressurants.

AMOS-6 is a pretty good example of why exposure time and risk are not correlated. The LOX tank and the COPVs were being filled, with pressures, fill levels, and temperatures constantly changing until they reached an unstable point that hadn't been reached before, resulting in the explosion.

Once filled, everything on a non-sub-cooled rocket is basically in steady state and can sit with occasional topping for boiloff for as long as you want with nothing really changing. This doesn't really work for a subcooled rocket.

SpaceX wants to make the process inherently safe and controlled. Every other type of vehicle is fueled with passengers and crew aboard. But they have a lot of work to do to prove that Falcon 9 is just as safe as other vehicles, since the fuels are inherently more dangerous.
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