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Added: The basic item here is SpaceX has only 6 months to setup the mass production production lines for the sats. They have a little more time for ground terminals but not much more than a year from today to start producing GTs in significant quantity.
I guess it depends on wheather the satellite design has been frozen and it's "just" a case of designing the production system, or wheather they are still refining it.

If it's cooked then 6 months sounds viable, given the size of the objects involved. If it's still in flux then it's a question of what bits still have question marks over them and what hooks are built into the design to cope with known issues.
For example space on a PCB pre wired for additional processing or RF power (in case the on orbit tests show the models were optimistic) is an easy fix.  Other obvious questions would be the 45 eclipse every orbit for any satellite below about 800Kms and it's effect on all the systems.

Where it gets more doubtful will be interactions between systems and between systems and the space environment. Again if the sims have been conservative (and accurate) it should all run without a hitch, but that's what on orbit testing is for.
Space Science Coverage / Re: General SETI Thread
« Last post by missinglink on Today at 09:34 PM »
by the time that we get a reply back, then the people (and governments, countries etc) who originally sent the message will be long gone.
The best way to eliminate the wait time for a reply to arrive is to send yourself with your first message. Encode your entire genome and phenome plus your memories up to today. Include instructions for building you from the data. Make persuasive case that you are harmless and could not hurt a fly.
How often do we see two large objects generating shock waves only a few hundred meters apart?

The military flies large supersonic jets fairly close to each other quite often.
I know that.  The Falcon is much larger.

The B1-B flies supersonic and is about 45m long. It's a bit larger than a Falcon 9 first stage. While I'm not going to say that flying a rocket backwards is no different from flying a plane, it's not such a rare thing.

The B-1A was designed to fly supersonically as a matter of course. The B-1B lost the variable geometry intakes that allowed for optimal supersonic cruise, which lowered its maximum speed at altitude quite a bit. Further, B model gained the dorsal ridge of ECM equipment and additional software/sensors for low level, high-subsonic penetration into hostile airspace. Supersonic flight is no longer the airframe's forte, and I daresay B-1Bs rarely break the sound barrier operationally at all, to the extent they ever did. More importantly for this discussion, B-1's of neither model were ever intended to fly supersonically within a few hundred yards of one another.

That said, B-1 generally is a typical supersonic aircraft design of the era - long, sleek and properly pointed at the end that creates the main shockwave, with swept wings and tail that also optimize their secondary shocks. By stark contrast, a falling F9 is a blunt body with vastly different aerodynamics. Presumable SpaceX has done plenty of CFD modeling of potential shock interactions and have no concerns. But we (as outside observers) should not handwave away the discussion by reference to conventional supersonic airframe design.
Do we have an approximate launch date for this mission?
Commercial Space Flight General / Re: Nanoracks
« Last post by gongora on Today at 09:08 PM »
Mods: not sure if this should have a better home, but:

I spent this morning at NanoRacks HQ in Houston, and their airlock is confirmed to be manifested on SpaceX CRS-19. Saw the FPIP graphic and all.
Space Science Coverage / Re: General SETI Thread
« Last post by Dao Angkan on Today at 09:07 PM »
Iíll bite - as I work around and with aquatic species for a living. We catch live crabs in Boston Harbor as feedstock for exhibit animals. However we arenít allowed to put these crabs in exhibit to feed to large puffers etc because our Animal Care and Use Committee forbids it. Instead we have to euthanize the crabs in a two phase process that is pain free and humane to the crab. And before people say crabs canít feel pain or have the brain capacity for complex emotions - wrong (summoning the inner Jim).

Recent studies show inverts such as crabs have opioid receptors which strongly suggests sensation of pain. This is as opposed to nociception. Crabs have also amazingly shown the ability to have emotions. (I can quote scientific papers on this subject if desired).

Point being? Even us lowly developed Homo sapien have evolved to learn right from wrong, even when it involves a completely alien species as compared to our own.

Just ask any scientist involved with planetary protection...

Catching wild animals in order to kill them and feed them to other captured animals which are then displayed as an exhibit for a more intelligent species to observe only shows that what crabs might consider right and wrong is quite a bit different than what people "who work around and with aquatic species for a living" consider right and wrong, especially when they consider their "feedstock" to have emotions.
Space Science Coverage / Re: General SETI Thread
« Last post by hop on Today at 09:00 PM »
I should reword that as "who might consider us as a threat".
Yeah, this has always been my objection to the paranoia about transmitting signals.

It's hard to imagine a civilization that has the technological capability and motivation to come wipe us out but not passively detect the fact that Earth harbors life.

We would have a good chance of detecting biosignatures around nearby stars with current technology if we put serious budget behind it. We are nowhere close to being able to reach other star systems, let alone sterilizing whole planets when we get there.

Any civilization that can send substantial payloads between star systems isn't going to have trouble building, say 100 meter space telescopes.
SpaceX Mars / Re: Elon The Boring Company
« Last post by RedLineTrain on Today at 08:54 PM »
The Hawthorne City Council approved the full 2-mile length on a vote of 3-1 without much debate.  The amount of the appraisal was not stated (and I can't readily find any documentation), but I assume that it was for a nominal value, given that the lone dissenting vote complained that he didn't like the appraisal amount and how the appraiser was chosen.
I hold Kuiper Belt sized doubts SpaceX was ever planning on completely self-funding its Mars system. SpaceX has never been shy about taking government money and they almost certainly lack the internal resources to fund a system of this scale alone. In fact, they would be literally insane not to seek public funding as it would automatically put them at competitive disadvantage with every other aerospace company willing to do so.
Shotwell has been very clear that if you're a serious LV player you have to be bidding for a piece of the NSS launch market, and that's all USG in the US.

Quote from: Darkseraph
Winning an Airforce EELV contract may be a fantastic route for them to obtain substantial government funding for a BFR without running into direct competition with SLS. SLS doesn't seem to be going away any time soon and getting NASA to throw huge funds at a direct competitor to its own baby is aspirational at best. That doesn't mean they wouldn't use the capability if it already existed and was paid for by the airforce. NASA has made extensive use of Atlas V and Delta IV.   

I really expected their bid for EELV would have been to try get the government to pay for vertical integration capability on F9/FH and improvements to the second stage.
IOW stuff the USG really wants but for SX is more "nice to have, if we can afford it."

IRL NASA is a big contributor to SX funds both by direct funding of development projects and by buying launches. Longer term they can also all sorts of hardware and expertise that are not easily available (yes solar powered ISRU will probably work, barring any six month long dust storms, but having a 10Kw Kilopower nuclear generator on each ship would be pretty handy).
This puts SX in a slightly tricky position. You will notice Musk is always keen to emphasize how supportive NASA has been. You may also have noticed that SX don't really talk about SLS one way or another.

It's obvious that a rocket the size of SLS will need a budget the size of the SLS development budget to build the size of payloads it can carry and right now there seems to be no viable chance of getting that without killing off ISS unless "another player" can demonstrate it's no longer necessary (and given the politics it's doubtful even then), allowing ISS to continue, and allow NASA to send astronauts to Mars.

So a NASA/SX partnership is in everybody's interests, given Musk has said he wants SX to provide the transport element and it's everybody else's choice as to what is sent, beyond the ISRU system, which have to be developed and sent to make the return journey possible. 
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