Author Topic: SpaceX FH : Falcon Heavy Demo : Feb 6, 2018 : Discussion Thread 2  (Read 585169 times)

Offline Nomadd

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Any particular reason to think the engines were all from one core?

Same chain of custody, so to speak. Work with an individual recovered engine would likely be more relevant for the refurbishment of others if all engines experienced (roughly) the same conditions during their first flight.

I'm very open to being wrong, though. Just seems intuitive to me that you would want to use engines from the same flight if you were planning on reusing a whole bunch.
I was thinking that certain engines on returning boosters might tend to come through in better shape than others.
Those who danced were thought to be quite insane by those who couldn't hear the music.

Offline speedevil

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I was thinking that certain engines on returning boosters might tend to come through in better shape than others.
I don't think we've ever heard anything about reuse other than the stage number, and comments about the severity of the landing from SpaceX.
Not that that means it hasn't happened of course.
Engines being swapped seems like an obvious thing to mention as one of their routine briefings, with no particular reason they shouldn't.

Online FutureSpaceTourist

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Hey @ticklestuffyo these are arriving to the employees at SpaceX this week. The red thread was flown in the nosecones of the side boosters ❤ Note employee number also embroidered into patch. What a sweet keepsake for them!

https://twitter.com/julia_bergeron/status/1017282170933731328

Offline woods170

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Hey @ticklestuffyo these are arriving to the employees at SpaceX this week. The red thread was flown in the nosecones of the side boosters ❤ Note employee number also embroidered into patch. What a sweet keepsake for them!

https://twitter.com/julia_bergeron/status/1017282170933731328

Another "Wheel of Cheese" moment. I'm glad SpaceX is sticking to that tradition.

Online matthewkantar

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7239?

Offline cscott

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Offline Lar

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7239?
Employee number.
If I recall correctly this number does not shift downward with attrition, once you get it, it's yours forever. But it means you were the 7238th hire or whatever...
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline soltasto

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7239?
Employee number.
If I recall correctly this number does not shift downward with attrition, once you get it, it's yours forever. But it means you were the 7238th hire or whatever...

Actually I think it is quite the opposite. It shifts downwards for each employee who leaves the company. I saw some employee collection pictures and the number gets down with each mission.

Offline MechE31

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7239?
Employee number.
If I recall correctly this number does not shift downward with attrition, once you get it, it's yours forever. But it means you were the 7238th hire or whatever...

Actually I think it is quite the opposite. It shifts downwards for each employee who leaves the company. I saw some employee collection pictures and the number gets down with each mission.

It does shift down as people leave. If you leave and later return, you regain your original spot. 

Offline Lar

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I stand corrected.
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline mgeagon

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At my company, you get an employee number on DOH. It is used for everything from badging and company website access to payroll and insurance. It would be nearly impossible to change this number every time someone leaves the company. We also get a seniority (sometimes called longevity) number that does go down every time someone leaves the company. If someone gets rehired, he or she would get the same employee number, but would go to the bottom of the seniority list or as appropriate considering total years of service. Perhaps the term “employee number” has different meanings among employers. It is hard to imagine a number being placed on a commemorative patch that does not identify a specific individual’s permanent association with SpaceX.

Offline tyrred

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Indeed, at a certain point the employee number becomes nearly nebulous depending on the turnover rate.  It's a hardscrabble time for big business these days.

Take a little time to let that sink in, if you will.  That little startup rocket company has come so far, aw.

I can't wait for the next FH launch, though it certainly won't have quite the same optics as maiden launch...

Offline MechE31

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At my company, you get an employee number on DOH. It is used for everything from badging and company website access to payroll and insurance. It would be nearly impossible to change this number every time someone leaves the company. We also get a seniority (sometimes called longevity) number that does go down every time someone leaves the company. If someone gets rehired, he or she would get the same employee number, but would go to the bottom of the seniority list or as appropriate considering total years of service. Perhaps the term “employee number” has different meanings among employers. It is hard to imagine a number being placed on a commemorative patch that does not identify a specific individual’s permanent association with SpaceX.

The employee number on the patches aren't for record keeping, they have separate numbers for that, they're really only used for the patches.

Offline crandles57

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Do we know whether Mars flyby helps circularise orbit to keep perigree above Earth apogee? Or maybe changes the inclination of the orbit?

Offline Rondaz

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Starman’s current location. Next stop, the restaurant at the end of the universe.

https://twitter.com/SpaceX/status/1058518183064219648

Offline envy887

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Do we know whether Mars flyby helps circularise orbit to keep perigree above Earth apogee? Or maybe changes the inclination of the orbit?

No and No. It won't fly close enough to Mars to significantly alter its orbit in the near future.

Offline ugordan

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Do we know whether Mars flyby helps circularise orbit to keep perigree above Earth apogee? Or maybe changes the inclination of the orbit?

No and No. It won't fly close enough to Mars to significantly alter its orbit in the near future.

Even if it did, by now it likely diverged from the last known tracking solution after launch sufficiently enough that the impact of such a flyby would be indeterminate.

Offline speedevil

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Even if it did, by now it likely diverged from the last known tracking solution after launch sufficiently enough that the impact of such a flyby would be indeterminate.
It was nailed down pretty well for the near future.

https://ssd.jpl.nasa.gov/horizons.cgi

Searching 'tesla' brought up:
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Encounter predictions for s10 (w/radial 1/r^2 non-gravitational acceleration)
     Date    = Nominal encounter time (Barycentric Dynamical Time)
     CA_Dist = Highest probability close approach distance to body, au
     MinDist = 3-sigma minimum encounter distance, au
     MaxDist = 3-sigma maximum encounter distance, au
     Vrel    = Relative velocity at nominal encounter time, km/s
     TCA3Sg  = 3-sigma uncertainty in close encounter time, minutes
     Nsigs   = Number of sigmas to encounter body at nominal encounter time
     P_i/p   = Linearized probability of impact

 Date (TDB)       Body  CA Dist  MinDist  MaxDist  Vrel  TCA3Sg  Nsigs P_i/p
  ----------------- ----- -------  -------  ------- ------ ------ ------ ------
  2018 Feb 08.09690 Moon  .000936  .000936  .000936  3.961   0.41 47509. 0.000
  2020 Oct 07.26768 Mars  .049530  .048923  .050242  8.150  27.40 6.63E5 0.000
  2035 Apr 22.35934 Mars  .015504  .004378  .027978  8.219 170.47 31247. 0.000
  2047 Jan 11.89023 Earth .031919  .031716  .032123  4.493 249.70 78398. 0.000
  2050 Mar 19.52949 Earth .119113  .113778  .124369  7.397 538.54 2.61E5 0.000
  2052 Sep 05.15606 Mars  .176363  .172469  .180319  5.738 2185.5 8.68E5 0.000
  2067 Apr 15.90202 Mars  .043270  .025712  .061471  7.192 1115.0 42565. 0.000
  2084 Sep 17.92284 Mars  .116962  .093449  .141170  9.753 787.45 6.55E5 0.000
  2085 Jan 01.96490 Earth .083063  .049368  .112186  6.224 5208.9 1.00E5 0.000
  2088 Mar 09.95754 Earth .049146  .033491  .063322  5.106 4505.2 1.17E5 0.000


In short - out to 2088, it does not get meaningfully inside the hill sphere of any large body.
The encounter in 2035 with Mars is very distant, and does not meaningfully change the dispersion of distances - the positional uncertainty up till 2088 is 75 hours, or about 0.006AU along the track.

Observations may help, but in the near term, these are _hard_. For example, next summer, you would need of the order of twenty hours of time on the Keck.
(Only an hour in Oct 20!)
It sort-of-becomes an amateur capable object in Jan 2047, at mag 19.6.

Offline ugordan

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Even if it did, by now it likely diverged from the last known tracking solution after launch sufficiently enough that the impact of such a flyby would be indeterminate.
It was nailed down pretty well for the near future.

You are missing my point. Like I said, *even if it did* have an encounter with Mars in the near future, the uncertainties in the last available tracking would likely have grown too large to predict the result of such a flyby by the time it happened. Outgassing from the stack, solar radiation pressure perturbations, etc propagated many months into the future accumulate and deviations from the JPL elements increase. They may publish the "final" orbital elements to a high degree of precision, but that doesn't mean that the combined 2nd stage / Roadster stack actually *is* on that orbit anymore and flybys are very sensitive to the actual impact parameter.

Offline Comga

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Caught this during Gwynne Shotwell's TED presentation, FH being lifted up before being placed on the TEL.

The most powerful active rocket in the world AND a recovered first stage in one photo?
How can that not be a favorite?
Thanks for snagging it!
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

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