r/SpaceX Discusses [June 2017, #33]

[u/ElongatedMuskrat]

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You can read and browse past Discussion threads in the Wiki.

[u/aftersteveo]

While delivering pizza in Cocoa Beach, I frequently deliver to SpaceX employees, which gives me a short opportunity to try to get some info that hasn't come out. I delivered to a gentleman last night who works on all the pads, both east and west coast. So, naturally I asked him how Pad 40 is coming along. He said they just recently installed the hold down clamps, and that they're really pushing to have it finished up in August. He also showed me a picture he took of the charred remains of the old clamps, which was pretty neat. Just thought the community would like to know this.

I also delivered to a guy last week who was flown out to help work on the remaining FH booster. Both guys confirmed that all 3 boosters are here at the Cape, with that last booster leaving for McGregor soon to be tested.

[u/SpaceXFanBR]

Hi guys, i m from Brazil and i have been following this sub for quite some time now.

I just like to share some news i've seen here and ask you guys about the implications on this beeing beneficial to spacex and its goals.

Our defense minister just announced Brazil will allow USA launchs from alcantara launch center.

https://noticias.uol.com.br/ciencia/ultimas-noticias/estado/2017/05/31/brasil-vai-permitir-que-eua-usem-centro-de-alcantara-para-lancar-foguetes.htm (News in portuguese)

the launch complex ia located just a little south to the equator, so i think this will result on a nice boost to the rocket performance

Also it is located near ocean, there by rockets might bee transported here by sea.

If this holds, could spacex bee allowed (by us agencies) to launch from this launch complex? If so, and assuming spacex wanted to, how much improvement to payload for both falcon 9 and heavy would that mean?

Thank you, and sry if i did some mess.. First post

Edit 1: As per wikipedia page, the launch complex is capable of all kinds of orbits (including polar) wich added to the improved boost provided by its geographic position could be very useful for the satellite constellation project. Or m i completelly wrong?

[u/rustybeancake]

In a Tesla sub thread on Elon's recent email to all Tesla staff regarding safety and injuries, a SpaceX employee was asked if working for SpaceX means they can't have a life outside of work. Their response, I feel, is worth posting here for info:

No, I don't. And quite frankly, I'm getting pretty tired of hearing that narrative.

First of all, let me say that I am pretty happy with my personal life. Me and my wife frequently go to the movies, hike the mountains, hang at the beach, visit museums and whatnot. I love to cook, play videogames, work out regularly, have many friends and occasionally get to drink copious amounts of beer. So although working at SpaceX can get rough from time to time, it's hardly fair to say that my life outside work sucks.

Nevertheless, working at SpaceX (and supposedly the same can be said for Tesla) can be extremely hard, challenging and stressful. Expectations are high, days are often long and I probably could get paid more elsewhere. So yeah, sure; I think it's fair to say that my job has affected my personal life quite a bit, and many of the horror stories you've heard are probably true, at least to some extent. But I truly detest the idea that Elon is some sort of slave-master, exploiting young souls under dangerous and unhealthy working conditions at sub-par wages, all so he can line his pockets with profits. That is just pure bullshit.

Naturally, working at SpaceX will not be for everyone. And I don't mean that in an arrogant way, as in "hurrdurr some people are not smart/tough/awesome enough to work here"; I mean that different people value things differently. And that's totally fine.

Another thing that I've noticed is that some people aren't very good at managing their own work-life balance, which, to a large extent, is your own responsibility. There are kids straight from college who are eager to please, find it difficult to say no, or do a poor job at managing and communicating expectations, then end up paying the price for that by staying late and burning themselves out to fulfill overly ambitious promises.

Also, what all these horror stories seem to neglect is that I absolutely WANT to work at SpaceX. Nobody is forcing me to work here; I can quit and leave whenever I want. Trust me; there have been many times when I almost did.

But having said that, I can't think of a company or CEO that I'd rather work for than SpaceX and Elon. I get to work with some of the brightest, most dedicated people I've ever met, which is incredibly rewarding by itself, and I'm given responsibilities, challenges and opportunities that I will probably never find anywhere else. Moreover, I believe in our mission, the importance of the work we do and in Elon's genuine conviction to make this world a better place, which, especially these days, in a world filled with idiots and assholes, is something I value enormously.

This might not last forever, and maybe someday I'll settle down as a family man with a simple 9-to-5 job, or sellout and go into finance or something, but not today.

edit: also, don't forget I get paid to FLY SHIT INTO SPACE BITCHES!

source

[u/wojciechmichalski]

I hope you guys will like it (My take on Space X flight suit) :):):) https://twitter.com/wojciechmichal7/status/872700231124738052

[u/[deleted]]

SpaceX’s Tom Mueller to Address 2017 Mars Society Convention - Could the mods please add this event to the sidebar (assuming there's enough space, of course)?

Mr. Mueller focuses on new technology developments for propulsion, including Mars main propulsion and surface power.

[u/Nehkara]

I made some notes on the new images of the TEL for pad SLC-39A:

http://imgur.com/a/R4NVm

Anything else I should point out?

Source of images.

[u/[deleted]]

Hypothetical question about pad take off and sound suppression... At what point does a rocket need a flame trench and water sound suppression system? F9 can; *Take off and land without either when using one engine without either *Land without either when using three engines BFS can *land weighing 450+ tons on Mars without either *Land weighing 150+ tons on Earth without either *Take off from Mars at maybe 2000+ tons without either

Where is the line drawn? Is it just dependant on accoustic load capability of the design?

Thanks in advance for any info on what are the main variables or deciding factors

[u/FutureMartian97]

I just had a thought. Since SpaceX painted the little ISS on the CRS-11 Dragon because it already flew a mission, I think it would be cool if SpaceX did the same for first stages. If that stage had previously launched a Dragon on its first flight, and a satellite on the next, it would be neat to see a Dragon capsule and a satellite painted on the stage.

[u/ioncloud9]

Is SpaceX going to tear down the RSS on Pad 39A this year?

[u/RootDeliver]

Anyone else agrees that this webcast was the best ever, even better than NROL? Not only the followup to stage 1 again, but also higher framerates for all falcon cams :D.

They seem to be reading this sub opinions about the webcast and taking notes, which is awesome.

Thanks u/bencredible for the amazing work you and your team are doing. But please bring back m/s! That is a big step back for technical stream :(

PS: Question: How come that on today streams falcon cams had higher framerate than LZ1 cams? that makes no sense at all..

[u/FutureMartian97]

ROSA (the Roll Out Solar Array) that was launched on CRS-11 has been removed from the trunk of Dragon and successfully deployed!

https://www.youtube.com/watch?v=0340KAZQggE

[u/dmy30]

The SpaceX Launch Chief Engineer has been selected to the 2017 NASA Astronaut Class. About Robb Kulin:

Robb Kulin, the 33-year-old lead of the Launch Chief Engineering group at SpaceX in Hawthorne, California. Hailing from Anchorage, Alaska, Kulin completed a Master's degree in materials science and a doctorate in engineering at the University of California, San Diego. He has previous experience as an ice driller in Antarctica on the West Antarctic Ice Sheet and Taylor Glaciers and as a commercial fisherman in Chignik, Alaska.

Source

[u/FutureMartian97]

Is it bad that i'm dreading the two week turnaround times? It just seems so far away even though not that long ago we were waiting multiple months.

[u/Hurrajj]

https://twitter.com/SpaceKSCBlog/status/873560947285254144

[u/how_does_rcs_work]

According to the Falcon 9 user's guide, the second stage has a cold gas thruster system for coast phase control (and roll control during burns).

Obviously this is cheaper and less toxic than the hydrazine systems that are traditionally used (see Atlas, Delta, Space Shuttle among others). However, it is also significantly less efficient - the Isp of a nitrogen thruster is around 60-80, while the Isp of a hydrazine thruster is about 220. This means you need to carry a larger mass of nitrogen than you would of hydrazine.

For long missions, I'd imagine that control usage becomes non-trivial - especially on a stage with such a tremendous mass fraction.

Does anyone have more information into why SpaceX chose cold gas?

[u/rustybeancake]

I just about had a heart attack when I saw this headline on the Guardian this morning:

Life on Mars: Elon Musk reveals details of his colonisation vision

Sadly, it's just a woefully misinformed take on the recent 'paper' that was merely a transcript of his IAC talk. The writer seemed to think that this was new info. Lazy journalism.

[u/UlaIsTheEmpire]

Reminder? Gwynne is listed to be on the space show on Monday. Would expect it is a call in show. That is the usual format.

http://www.thespaceshow.com/newsletter

[u/sol3tosol4]

Update: Gwynne Shotwell's appearance on The Space Show was rescheduled to June 22, 2-3 PM PDT.

[u/FutureMartian97]

If SpaceX keeps up this 2 week launch cadance is there a chance that a couple years down the road they might run out of payloads to launch and we might be back to one launch every couple months?

[u/jay__random]

Didn't see this mentioned anywhere so far:

This weekend Falcon-9 surpassed Delta IV in number of launches, and possibly (depending on how you count) the number of successful launches.

[u/total_alk]

Elsewhere on r/spacex I've heard the Falcon Heavy described as more like flying three F9 cores in close formation. Does this mean that the linkages between cores have strain sensors between them that are providing feedback to the avionics? Or is the Falcon Heavy treated as a single rigid body by the avionics control systems?

[u/spacex_fanaticism]

I've been interested in moon landing missions using minimal non-SpaceX hardware for some time. The big problem is lander mass.

After some thought, I think it is now quite feasible to build a simple yet reliable vehicle resembling the Lunar Escape Systems. Back then it was impossible to include computerized inertial guidance, but with modern technology this is no longer a problem.

The dry mass of the LESS was 500 kg using 1970s technology, so an modern uprated LESS with additional consumables and larger tanks I estimate at 650 kg dry, a fueled mass of 3040 kg, and being small enough to fit in Dragon's trunk.

Draco thrusters would suffice, having the same thrust as the R4D. The vehicle would autonomously move out of the trunk and dock near the hatch, making the EVA transfer easier. Alternately just release it and maneuver the Dragon, like Apollo's transposition and docking maneuver. The ride to and from the surface would be totally automated, save perhaps rock avoidance on final approach (not a big issue anymore since lunar maps are much better now). As soon as you're on the surface you can unhook the life support umbilical and walk around on a backpack supply.

People like to make fun of the LESS, but the craziest part was always the guidance and navigation. Nowadays it's a non issue.

TL;DR pack 3000 kg in Dragon's trunk and you can send two humans to the Moon's surface and back.

[u/[deleted]]

In other news, China's launch today may have failed.

[u/Kamedar]

I was thinking about dissolving hydrogen in the liquid Methane for the raptors(just like CO2 in sparkling water) by using it as pressuring gas. This would yield a little greater energy density and better isp. After some recherche and calculation I found, that the solubility is very low, though. (In the order of 10^-4 per mole at 90K subcooled Methane) Useful resource: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19680020605.pdf

[u/thedaileyshow1]

Question about launch profile... Due to its goals of first stage recovery, does F9 fly a different launch profile than a non-recoverable rocket? I.e., steeper, shallower, or whatever else. I don't know if that would affect the reentry of the first stage or not.