Is it just me, or is this basically the coolest SpaceX launch yet? Sending a craft outside the gravity well of earth and very likely recovering the first stage.
Man. That's cool.
If it works out as-planned, Elon will have lots of bragging rights and I wouldn't be surprised if NASA makes a point of emphasising the degree of funding and old NASA ideas behind SpaceX's technology. It's always good to have major successes going into Presidential Election year for the the politicians to want to look good by being associated with!
Is it just me, or is this basically the coolest SpaceX launch yet? Sending a craft outside the gravity well of earth and very likely recovering the first stage.
Man. That's cool.
As long as we don't end up with a hanging pad, yes!
What is the expected opporational lifetime of the second stage?
There's an XKCD for that ;-)
https://what-if.xkcd.com/26/
........ although I think it's incorrect. The Earth's getting 0.8 milliseconds out of step every day at a near constant rate, which is a different thing entirely to slowing down by 0.8 milliseconds every day?
No, the XKCD is correct. The Earth's day is 86400.008 seconds long, which means that the cumulative difference from exactly 86400 seconds adds up to a single (leap) second every 125 days on average. XKCD says:
This difference fluctuates over time based on weather and other effects (it’s actually shortened a bit since the early 1990s), although in the long run, it will definitely get larger as the Earth slows.
which is the truth, it IS gradually getting larger, but on a much longer time scale (thousands or millions of years).
Yes, it is ~86400.0008 seconds long every day. However, Earth's rotation period isn't slowing by 0.8 milliseconds every day. The rotation period itself is fairly constant at 86400.0008 seconds, it is the cumulative effect of all those 0.0008 seconds that means a leap second is required every 1,250 days or so. Speeding Earth's rotation by the equivalent to 0.0008 seconds per rotation (with 4 billion Petit Princes) drops the rotation time to 86400 seconds, removing the need for leap seconds in one day.
If you massacre the same number of Petit Princes the next day, Earth's rotation period is then 86399.9992 seconds and we need to start using negative leap seconds. The next day, 86399.9984 s, the next 86399.9976 s, we need negative leap seconds at a faster rate the longer the Prince-icide continues?
Is it just me, or is this basically the coolest SpaceX launch yet?
It seems that every SpaceX flight is their coolest flight. This one will also be very cool from the photograpty standpoint - it will happen only 35 minutes after sunset = rocket will get into the sun on ascent.
Re.: Earth's Rotation - Didn't the Boxing Day Tsunami measurably affect Earth's rotational speed, at least for a whle? It's actually a lot more flexible than many people would be comfortable to imagine!
Yes, it is ~86400.0008 seconds long every day. However, Earth's rotation period isn't slowing by 0.8 milliseconds every day. The rotation period itself is fairly constant at 86400.0008 seconds, it is the cumulative effect of all those 0.0008 seconds that means a leap second is required every 1,250 days or so. Speeding Earth's rotation by the equivalent to 0.0008 seconds per rotation (with 4 billion Petit Princes) drops the rotation time to 86400 seconds, removing the need for leap seconds in one day.
Yes. And that is exactly what the XKCD article says. I'm not sure why you are reading it differently.
Yes, it is ~86400.0008 seconds long every day. However, Earth's rotation period isn't slowing by 0.8 milliseconds every day. The rotation period itself is fairly constant at 86400.0008 seconds, it is the cumulative effect of all those 0.0008 seconds that means a leap second is required every 1,250 days or so. Speeding Earth's rotation by the equivalent to 0.0008 seconds per rotation (with 4 billion Petit Princes) drops the rotation time to 86400 seconds, removing the need for leap seconds in one day.
Yes. And that is exactly what the XKCD article says. I'm not sure why you are reading it differently.
"If we wanted to get rid of leap seconds, we’d need to keep the Earth spinning at a more constant rate. This means speeding up the Earth and shortening each day by about 0.8 milliseconds."
And:
"Here’s the bad news: To get enough spin, we have to hit the Earth with on the order of a billion liters of rock per second (several times the volumetric discharge rate of the Amazon). This adds up to about
one six-mile dinosaur-killing asteroid every couple days. Humanity—and life—wouldn’t survive the bombardment long."
And:
"Unfortunately, the steady high-altitude meteor shower would deliver just as much energy to the atmosphere that
daily giant impacts would, and the eventual death toll would be the same: Seven billion humans, plus four billion Little Princes per day."
The XKCD thinking is clearly a continual acceleration of 0.0008 seconds per day forever more (or at least until Earth splits apart a la YORP), not a one-off reduction to a rotation period to 86,400 seconds
The XKCD thinking is clearly a continual acceleration of 0.0008 seconds per day forever more (or at least until Earth splits apart a la YORP), not a one-off reduction to a rotation period to 86,400 seconds
If we wanted to get rid of leap seconds, we’d need to keep the Earth spinning at a more constant rate. This means speeding up the Earth and shortening each day by about 0.8 milliseconds.
It takes about a decade for the core to sync up with the crust, so we’d have to plan the impact schedule carefully to avoid overshooting.
In other words, the impacts would need to happen at the given rate for a total period of one decade before the Earth's rotation had sped up by 0.8 milliseconds.
The XKCD thinking is clearly a continual acceleration of 0.0008 seconds per day forever more (or at least until Earth splits apart a la YORP), not a one-off reduction to a rotation period to 86,400 seconds
If we wanted to get rid of leap seconds, we’d need to keep the Earth spinning at a more constant rate. This means speeding up the Earth and shortening each day by about 0.8 milliseconds.
It takes about a decade for the core to sync up with the crust, so we’d have to plan the impact schedule carefully to avoid overshooting.
In other words, the impacts would need to happen at the given rate for a total period of one decade before the Earth's rotation had sped up by 0.8 milliseconds.
Aha! Now it makes sense. I'd read that section as merely a bit of geologic interest, rather than that setting the duration for the Prince-storm. I'd read it as the time to get back to steady state after the comet impact, totally independent of what followed. The sync time should be independent anyway - it'd still take 10 years to sync up following the demise of the final prince.
Yes, it is ~86400.0008 seconds long every day. However, Earth's rotation period isn't slowing by 0.8 milliseconds every day. The rotation period itself is fairly constant at 86400.0008 seconds, it is the cumulative effect of all those 0.0008 seconds that means a leap second is required every 1,250 days or so. Speeding Earth's rotation by the equivalent to 0.0008 seconds per rotation (with 4 billion Petit Princes) drops the rotation time to 86400 seconds, removing the need for leap seconds in one day.
Yes. And that is exactly what the XKCD article says. I'm not sure why you are reading it differently.
"If we wanted to get rid of leap seconds, we’d need to keep the Earth spinning at a more constant rate. This means speeding up the Earth and shortening each day by about 0.8 milliseconds."
And:
"Here’s the bad news: To get enough spin, we have to hit the Earth with on the order of a billion liters of rock per second (several times the volumetric discharge rate of the Amazon). This adds up to about one six-mile dinosaur-killing asteroid every couple days. Humanity—and life—wouldn’t survive the bombardment long."
And:
"Unfortunately, the steady high-altitude meteor shower would deliver just as much energy to the atmosphere that daily giant impacts would, and the eventual death toll would be the same: Seven billion humans, plus four billion Little Princes per day."
The XKCD thinking is clearly a continual acceleration of 0.0008 seconds per day forever more (or at least until Earth splits apart a la YORP), not a one-off reduction to a rotation period to 86,400 seconds
I get the Silicon Valley- Mean Jerk Time video in my head reading this conversation. Love it
I'm fairly certain they meant disposed of into solar orbit (i.e. Earth escape), not into the Sun. Without gravity assists and such, you'd need like 30km/s of delta-v or so (I think), which a lot, even for an empty upper stage.
Since DSCOVR is going to SEL-1, the upper stage will essentially already be at Earth-escape, so it really doesn't need much of any propellant for the disposable burn.
After SC sep, CCAM, depletion burn and stage pressure blowdown of tanks is scheduled for 2nd stage.
Is it just me, or is this basically the coolest SpaceX launch yet?
It seems that every SpaceX flight is their coolest flight. This one will also be very cool from the photograpty standpoint - it will happen only 35 minutes after sunset = rocket will get into the sun on ascent.
Another of their earlier 1.1 flights was like this, and had some spectacular shots. One guy even tracked the rocket on camera for quite some time.
Is it just me, or is this basically the coolest SpaceX launch yet?
It seems that every SpaceX flight is their coolest flight. This one will also be very cool from the photograpty standpoint - it will happen only 35 minutes after sunset = rocket will get into the sun on ascent.
Another of their earlier 1.1 flights was like this, and had some spectacular shots. One guy even tracked the rocket on camera for quite some time.
I believe the SES-8 (second v1.1 launch) was the one that rose up into the sunset with some very exceptional footage resulting from that. Or did you mean the Orbcomm launch that flew a very lofted trajectory?
Another of their earlier 1.1 flights was like this, and had some spectacular shots.
Yep, SES-8 - my photos attached (I know they are not very good).
Is it just me, or is this basically the coolest SpaceX launch yet?
It seems that every SpaceX flight is their coolest flight. This one will also be very cool from the photograpty standpoint - it will happen only 35 minutes after sunset = rocket will get into the sun on ascent.
I thought everyone realized we were just joking about the second stage being disposed of in the sun. That's not going to happen, even if the FCC thinks it should. This launch will look pretty cool though. Because it's going up so soon after sunset, at some point in its ascent the rocket will be high enough to
get into the sunlight.
I thought everyone realized we were just joking about the second stage being disposed of in the sun. That's not going to happen, even if the FCC thinks it should. This launch will look pretty cool though. Because it's going up so soon after sunset, at some point in its ascent the rocket will be high enough to get into the sunlight.
I don't see why all the naysayers are naysaying regarding the second stage disposal in the sun issue. Sure, sure, delta/v and all that, but if the FAA wants it, it must be done! NASA faced a very similar issue (delta/v and time) regarding a manned visit to a NEO, but they solved it with the ARM mission plan; bring the asteroid to lunar orbit and do the mission there.
Therefore, the delta/v issue of getting the F9 stage to the sun is a false one, for it overlooks the obvious solution; use the ARM mission plan as a guideline, and instead of sending the 2nd stage to it, bring it to the second stage at L2.
There, problem solved! Y'all are just too conventional in your thinking....
I thought everyone realized we were just joking about the second stage being disposed of in the sun. That's not going to happen, even if the FCC thinks it should. This launch will look pretty cool though. Because it's going up so soon after sunset, at some point in its ascent the rocket will be high enough to get into the sunlight.
I don't see why all the naysayers are naysaying regarding the second stage disposal in the sun issue. Sure, sure, delta/v and all that, but if the FAA wants it, it must be done! NASA faced a very similar issue (delta/v and time) regarding a manned visit to a NEO, but they solved it with the ARM mission plan; bring the asteroid to lunar orbit and do the mission there.
Therefore, the delta/v issue of getting the F9 stage to the sun is a false one, for it overlooks the obvious solution; use the ARM mission plan as a guideline, and instead of sending the 2nd stage to it, bring it to the second stage at L2.
There, problem solved! Y'all are just too conventional in your thinking....
Hmm... that might be good for the SolarCity stocks. We could be onto something.
I thought everyone realized we were just joking about the second stage being disposed of in the sun. That's not going to happen, even if the FCC thinks it should. This launch will look pretty cool though. Because it's going up so soon after sunset, at some point in its ascent the rocket will be high enough to get into the sunlight.
I don't see why all the naysayers are naysaying regarding the second stage disposal in the sun issue. Sure, sure, delta/v and all that, but if the FAA wants it, it must be done! NASA faced a very similar issue (delta/v and time) regarding a manned visit to a NEO, but they solved it with the ARM mission plan; bring the asteroid to lunar orbit and do the mission there.
Therefore, the delta/v issue of getting the F9 stage to the sun is a false one, for it overlooks the obvious solution; use the ARM mission plan as a guideline, and instead of sending the 2nd stage to it, bring it to the second stage at L2.
There, problem solved! Y'all are just too conventional in your thinking....
I think I prefer the sun to stay just where it is, thank you very much. Besides, if it didn't work for Mohammed, I doubt something way bigger than a mountain is going to go to the second stage anyways.
Re.: Earth's Rotation - Didn't the Boxing Day Tsunami measurably affect Earth's rotational speed, at least for a whle? It's actually a lot more flexible than many people would be comfortable to imagine!
Dunno about that one, but the Great Tohoku earthquake of 3/11/11 did speed up the day by 1.8 microseconds.
