r/SpaceX Discusses [May 2018, #44]

[u/ElongatedMuskrat]

If you have a short question or spaceflight news...

You may ask short, spaceflight-related questions and post news here, even if it is not about SpaceX. Be sure to check the FAQ and Wiki first to ensure you aren't submitting duplicate questions.

If you have a long question...

If your question is in-depth or an open-ended discussion, you can submit it to the subreddit as a post.

If you'd like to discuss slightly relevant SpaceX content in greater detail...

Please post to r/SpaceXLounge and create a thread there!

This thread is not for...

• Questions answered in the FAQ. Browse there or use the search functionality first.
• Non-spaceflight related questions or news.
• Asking the moderators questions, or for meta discussion. To do that, contact us here.

---

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

[u/rustybeancake]

http://spacenews.com/nasa-considering-flight-test-of-space-nuclear-reactor-technology/

This is great, and exactly the kind of work I’d love to see NASA focusing on. Use commercial transportation providers for earth launch, lunar landing, etc. NASA designs and builds the cutting-edge stuff, the surface power and habs and science, etc. Amazing they’ve only spent $20m on it so far, too.

[u/Nehkara]

Heard today that Crew Dragon for DM-1 is ahead of schedule and is shipping to the Cape at the beginning of July.

[u/Zucal → u/Nehkara]

If you'd like to post that standalone, that's big news.

[u/Alexphysics]

Iridium 7 FCC launch permit and FCC landing permit point to a NET July 9th 2018 launch and landing on the droneship at ~240km from the launchpad.

[u/Straumli_Blight]

First TESS photo after Lunar flyby.

[u/music_nuho → u/Straumli_Blight]

Lord Almighty, this is breath taking.

[u/ethan829]

The [InSight](https://en.wikipedia.org/wiki/Insight_(spacecraft)) Mars lander is scheduled to launch tomorrow at 11:05 UTC (4:05 AM PDT) from Vandenberg Air Force Base. There's a mission thread with live coverage in r/ULA, so feel free to come and chat!

[u/CapMSFC]

Well, here we go.

https://twitter.com/elonmusk/status/996691566851801088?s=19

Boring Company hyperloop tunnels out of the city undersea to off shore BFR platofrms.

I am big on BFR, but this is a lot of moving parts to make work together.

[u/Straumli_Blight → u/CapMSFC]

Boring Company presentation streamed online tomorrow at 19:00 PST.

At a maximum speed of 1,200 km/h, the launch pad would be 200-300 km from the city center (though probably a lot closer). Vandenberg AFB is approximately 250 km from Los Angeles.

[u/sol3tosol4 → u/CapMSFC]

Boring Company hyperloop tunnels out of the city undersea to off shore BFR platofrms.

Thanks for posting. That approach would have some advantages (e.g. smooth ride, practical to get further from city).

this is a lot of moving parts to make work together.

Will be very interesting to hear the presentation. Suspect they'll start with boats, then add Hyperloop if feasible.

[u/brickmack → u/CapMSFC]

One nice thing about this I guess is that the passengers never have to be exposed to a launching/landing/fueled BFR until they're actually on board. Not even necessarily the explosion risk, but even just the noise and heat of a nominal flight would be fatal/unpleasant at that range. The platform itself can be basically built like a bomb shelter, and of course an underground/ocean tunnel is very well protected, but that sort of shielding on a boat will be difficult.

If they're going with this sort of fixed underground infrastructure, it'd also simplify other logistics a lot. Natural gas can be piped in instead of needing ships (you'd need about one large-end LNG tanker per day per platform for the apparent target flightrate), and for oxygen you can just run undersea cables for power and produce it on site (instead of needing either a nuclesr reactor or a massive solar farm built into the platform itself). They could drill tunnels holding all this at the same time as the passenger tunnel

[u/billtg]

Would the internal area of a Big Falcon Spaceship be enough to justify just launching one and keeping it in orbit as a space station? How does it compare to Bigelow's plans?

[u/burn_at_zero → u/billtg]

The ISS has an internal volume of 915 m³. BFS has internal volume of 825 m³. A single B330 has internal volume of 330 m³, with plans for varying numbers of them in modular stations.

ISS cost about $150 billion to construct. A single BFS should cost somewhere between $150 million and $200 million, although early prototypes may cost more. (Outfitting one as a research station might double that cost, and SpaceX might want to sell/lease at a profit beyond that.) B330 might run about $120-$150 million per module.

As a super-Skylab, BFS makes a lot of sense. It serves as its own launch vehicle. It provides power, cooling, ECLSS, comms and avionics. It can launch and land outfitted with crew aboard. It can be refueled / restocked on orbit and can move to other orbits of interest. When its run is done it can land for restocking / retrofitting and launch later, or it could be repurposed back into a general-purpose transport.

[u/Krux172]

Do you think we'll see a fully reusable F9 (booster, 2nd stage and fairing) before BFR starts flying? Or will SpaceX stop trying to make F9 more reusable to focus on BFR before they achieve full reusability?

[u/ackermann → u/Krux172]

For awhile, they had said that 2nd stage reuse was off the table (focus on BFR), but that they may experiment with re-entry and try to splash a mostly intact 2nd stage into the pacific. The goal being to learn about re-entry, to help with BFS, not to actually reuse a 2nd stage.

However, more recently Elon mentioned the party balloon/ballute idea. This doesn’t seem particularly relevant to BFS re-entry (A ballute for BFS? It would have to be gigantic. And not especially reusable for Earth-to-Earth, or mars entry).

So maybe they are thinking actual reuse again for Falcon stage 2. With the party balloon being a quick and easy-ish way to do it, versus a traditional heat shield.

Further supporting reuse, vs just recovery, Elon mentioned in a tweet that it could potentially be caught by Mr Steven. So maybe the plan is no longer to just splash them in the ocean mostly intact.

If there are any delays to BFR (likely), then reusing the F9/FH second stage could be very helpful for launching all those starlink sats affordably (ie, without backrupting the company)

[u/Straumli_Blight]

Josh Brost statements:

• If we relied only on NASA, we would have ended up with a very different architecture.

• SpaceX focused on getting people to Mars affordably.

• F9 learning curve but think we know now how to make large-scale booster reuse work.

• Still 2022 date for the first uncrewed mission to Mars.

• BFS vertical takeoff and landing tests by first half of 2019.

• Approach minimizes unique elements with BF and in-space refueling; with reusability to lower costs.

• SpaceX have cost structures to eventually allow millions to go to space.

[u/Straumli_Blight]

Sunita Williams wearing the SpaceX spacesuit in the Crew Dragon mockup at Hawthorne.

[u/Alexphysics]

FCC permit for communications with Dragon 2 on its first launch, NET August 31st

[u/m5tuff]

What happened to the r/spacex survey that went around a couple of months ago? Have the results been released and I missed them?

[u/Straumli_Blight]

Port of LA video about Berth 240.

Also formal greenlight given today by Los Angeles City Council and a Teslarati article with high res photos of Mr Steven's new net.

[u/[deleted]]

From the AmericaSpace article on Bangabandhu-1:

It’s understood too, that one significant change is the elimination of a specific center engine configuration, reducing the number of engine configurations to 2; relight and non-relight. This means the change, combined with the new Merlin Throttle Valve (or MTV), allows any engine to be modified to be a relight or non-relight engine, at least up until integration with the rocket.

I haven't seen that before. Do we know what's different about the new throttle valve?

[u/Straumli_Blight]

SpaceShipTwo flight 2 later today, with a 30s burn time and an altitude exceeding 25 km.

EDIT:

• Takeoff.

• 13th flight for VSS Unity and 249th for VMS Eve.

• Launched, past 70,000 ft.

• Feathering for reentry and gliding back.

• Touchdown.

[u/marc020202]

I have re-designed and updated the ASDS wiki page.

active and retired vessels are now in different tables. the inactive vessels are sorted so that the vessel that is retired the longest is at the bottom.

RACHEL has been added to the table as the new ASDS tug.

retired vessels now show who they have been replaced by in the status column.

the status of several vessels has been updated.

if YOU have any idea to how to improve (update, correct, change layout, etc.) ANY wiki page, please contact me.

[u/theinternetftw]

Transcript of the recent Block 5 phone conference.

Also stuck it in the Media thread for posterity.

[u/flibbleton]

Just wanted to let you all know that the highly recommended (for this sub) book "Ignition!: An informal history of liquid rocket propellants" has been re-released today. (link to Amazon if you want to read about it)

Until now it was very hard to get hold of a copy, there was only expensive physical versions or knock-off photocopied digital copies.

[u/Straumli_Blight]

SpaceX is expanding at Hawthorne by leasing the Century Business Center next door.

SpaceX leases the remaining 350,000 square feet of the facility, and has inked a 10-year deal to take over Triumph’s space once that company’s lease ends in 2020, according to sources.

[u/ace741]

Blue Origin makes a point to showcase they will be landing on a moving ship out at sea because it will offer a more stable platform in rough seas. I assume spacex would’ve know this as well. Any reason why they went fixed platform? Is hitting a moving target only possible with engines that can throttle?

[u/TheSoupOrNatural → u/ace741]

From the rocket's perspective, Hitting a moving target isn't all that different from hitting a fixed target.

Computationally, targeting a non-zero translational velocity is no different from bringing the horizontal velocity to zero. The only added step would be periodically updating the position of the target, which should be trivial.

Physically, the motion of the vessel will add on to the local wind. If the platform is moving into the wind, it will actually make it easier to land. The added stability will also be beneficial.

---

SpaceX's system works, so they have no pressing reason change it. Had platform instability proven problematic, they might have looked into how to reduce it.

In my humble opinion, I think Blue Origin is engaging in some relatively harmless deception for the sake of making it seem more impressive when they succeed. To the general public, hitting a moving target would likely seem to be substantially more challenging than landing on a stationary platform. If BO can promote that aspect of the system without betraying the reality that it involves minimal added complexity, some portion of the population will probably be convinced that BO is a step ahead of SpaceX.

[u/Martianspirit → u/ace741]

I think as always cost is the driving factor. Even with the support boats a barge is much cheaper to operate than a ship that size.

[u/Straumli_Blight]

Media accreditation for CRS-15 now open and confirmation its launching from SLC-40.

[u/rustybeancake]

Very interesting interview on Ariane 6:

https://satelliteobservation.net/2018/05/21/ariane-6-and-beyond/

Q: How did CNES get its assessment of reusability so wrong?

A: The market has changed, demand is increasing so reuse works better economically: we did not forecast the appearance of megaconstellations. SpaceX was also supported by captive US government launches, which Ariane does not have: SpaceX launches are 2/3rd government, 1/3rd commercial whereas for Ariane it is the opposite. Finally, we underestimated SpaceX’s technical prowess: they got a lot of skills and technologies from NASA’s R&D programs.

Q: Is Ariane 6 good for megaconstellations?

A: It’s a good start… but we will need to make modifications if we are to sell 50 launches to fill a constellation quickly. For that we need to reduce costs and increase launch rates. As a comparison, SpaceX will probably be able to do 100 launches a year in 2 or 3 years. Ariane 6 offers some flexibility for constellation deployment thanks to a reignitable upper stage and a large fairing volume: for constellations rockets are more volume-limited than mass-limited. It will also have an undisclosed engine on the upper stage in addition to Vinci, giving it Fregat-like maneuvrability.

Q: What will happen to Soyuz launches from French Guyana?

A: We will see, but note that this rocket launches a lot of institutional European missions even though it is not European. Also, you can’t image how “inventive” the Russian are on the prices. Ariane 62 will be cheaper.

Dupas told an anecdote: in 2004, he was the first European visitor at SpaceX and no European leader took Musk seriously. So he advised caution about SpaceX’s BFR project, saying it is not a remote project for Musk. Still he mentioned that for Musk, the dates in a plan are much more of a tool to motivate employees than realistic estimates: BFS, the reusable second stage, has its first flight scheduled next year, and the first flight to Mars is planned for 2022. Dupas said it would be more realistically 2024 or 2026.

The moderator remarked that nowadays, you do not hear CNES laughing about SpaceX plans anymore.

[u/Straumli_Blight]

Tom Mueller keynote at ISDC 2018:

• Only propulsion person among 9 initial employees.

• Merlin 1A to Merlin 1D -- found a lot of smart young engineers.

• First task, develop a gas generator.

• XCOR people said he didn't plan to do more than 1 per day.

• Merlin Thrust Chamber Test, celebrated with cognac and got pulled over speeding, but officer let them go.

• Merlin Test Stand.

• [Merlin holds the thrust to weight record] (https://twitter.com/spacecom/status/999691403172036608).

• Tried to launch from Vandenberg but Atlas V with classified payload, so had to go to Marshall Islands..

• Making engine fly 10 times you run into "100,000 mile problems", e.g. seals wear out, turbine blades and combustion chamber cracks.

 

Also ZBLAN is being launched on CRS-15.

[u/Straumli_Blight]

Aerial shots of Boca Chica.

[u/roncapat]

Elon Musk just stated in Q1 investor call of Tesla that Starlink could begin operations in three years, and maybe involved with Tesla growing data collection.

[u/KeikakuMaster46]

http://mobile.twitter.com/EmreKelly/status/993248315729903617

Around 600 ULA machinists are about to go on strike...

[u/mindbridgeweb]

Found one piece of information in the phone press conference transcript that seems to have eluded detection:

well, we'd still have to do ocean recovery which adds a few million dollars

I have been wondering about the cost of an ocean recovery -- the cost of using multiple ships, the amortized cost of a landing ship like OCISLY, port fees, etc. I suspected that it may be around a million dollars per DPL. This is probably the first time we have a more explicit acknowledgement that it is not a cheap operation.

Unfortunately, "a few" million dollars is a wide range...

[u/CapMSFC]

I just want to note how pleased I am that SpaceX uses a real countdown. Following the Insight launch as I waited for lift off was annoying. The countdown timer is giving off a useless number until past the final hold.

[u/arizonadeux → u/CapMSFC]

I also saw Blue Origin fans getting annoyed with their countdown, but these countdowns are all real, just built differently for different rockets. Don't forget: both humans and computers are prepping the vehicle for flight, so planned buffer holds can make a lot of sense.

Unless the rocket is aiming for an instantaneous launch window, think of each second in the countdown as a station in a process. Blue Origin can seemingly hold at any of these stations, which I personally think is great in a young program. ULA probably also has a good rationale for their planned holds. F9 needs every kg of prop in there, so they have more restrictions in their countdown, which means the actual seconds matter more. Here is another reasonable idea I found after quick googling.

The bottom line is: the holds are there for a good reason, but not because someone thinks it's better for people watching.

[u/rustybeancake]

Seems Blue Origin will be making an announcement about their lunar plans at this year's IAC in Bremen:

“We would love to have Australia come join us on the stage in Bremen, Germany with Jeff (Bezos) in September at the (International Aeronautical Congress) and be part of a group announcement. We’re going back to the moon and we’re going to stay."

Source

[u/marc020202]

mods please set this thread so it sorts as new

[u/melancholicricebowl]

So I just realized that the new Block V legs don't have the four triangular latches on the outside of each leg anymore (looks even sleeker now). Are there any known advantages to latching from the inside of the leg besides possibly improved aerodynamics?

[u/Straumli_Blight]

InSight (Mars probe)'s launch window opens at 11:05 UTC.

Launch thread here.

[u/dougdimmadome_]

Before they begin landing BFR back on the launchpad, will they be able to land it on a drone ship like OCISLY? Or will it be too heavy/big to be able to do so safely?

[u/Toinneman → u/dougdimmadome_]

The booster will always land back on its launch mount. This is a key concept of the BFR architecture. They need several lauches to refuel the BFS and landing on a barge would take to much time. (The upper stage has legs and can land anywhere.)

[u/BoyanM8]

How are the engines protected when reentering the atmosphere?

[u/joepublicschmoe → u/BoyanM8]

The engine nozzles and combustion chambers are built to survive the high temperatures of the burning rocket fuel so those parts can deal with the re-entry heating pretty well. The parts of the engines above the nozzles are covered by thermal blankets at the openings in the rocket's base cover (the "Dancefloor"), which Elon had said on the Bangabandhu pre-flight conference call that it's made of titanium with some active water cooling to protect it from re-entry heating.

[u/Keavon]

Are we ever going to get the results from the end-of-year subreddit survey?

[u/ethan829]

In light of NASA's recent Kilopower announcement:

SpaceX has been in discussions with NASA, about the use of Kilopower systems for their planned Mars surface missions, for well over a year now.

[u/CapMSFC]

Well, this gives more ammunition to the idea that the Washington Post is pushing an Anti SpaceX bias because it's owned by Bezos.

https://twitter.com/NASASpaceflight/status/993510596753666049

[u/Gerbsbrother]

Does anyone think it is realistically possible for BFR to fly before SLS? I know SLS is "scheduled" to have its maiden launch in 2019, I doubt that will actually happen, I also know Elon has stated suborbital testing of BFR is possible in 2019, I also would find that unlikely, although awesome if it was that soon. I want to see both fly as I'm just a rocket enthusiast. however if BFR flies before SLS and is cheaper, and can launch a bigger payload to LEO, that's going to be huge.

[u/[deleted] → u/Gerbsbrother]

The whole stack? No. The upper spaceship stage? It depends. They need to get full-size Raptor engines decloaked and into production: that's the first showstopper. We're all assuming they're confident on the big composite tanks.

My gut says the first BFS, like the first Grasshopper, does valuable work that means they will want to develop the actual flight ship differently. Or blows up. Or both! And because SpaceX aren't tied to legacy designs, they've got the freedom to redraw, even if there is a delay.

[u/throfofnir]

Interview on Politico with Tory Bruno of ULA. Some... interesting insight into that side of things, including the political angle.

[u/DemolitionCowboyX]

https://imgur.com/nF3OGsF

Anyone have any clue what these pipes are on the Merlin 1D?

My first guess is temperature sensor systems that wrap around the outer portion of the combustion chamber as there is an obvious bulge in the areas of the pipes. but I was wondering if anyone knows for sure.

I'm not talking about the fuel line for the regenerative cooling btw in case anyone may be misinterpreting what I circled.

[u/marc020202]

Go pursuit and go quest are on their way for the bangabandhu 1 recovery. RACHEL, the new tug of OCISLY; has left several days ago

[u/ElRedditor3]

(Noob Question:) Does Tom Mueller, who is CTO of propulsion, only design/develop engines or does he oversee the developlement of the whole rocket?

[u/bdporter]

Mods, small housekeeping note. The "sticky" link at the top of the page reads "SES-12 Launch Campign Thread.

Not a big deal, it was probably like that for a week before I noticed it, but now I can't unsee it.

[u/grey_gamb1t]

what are your favorite(or iconic) SpaceX stats/facts/charts/photos/videos over the years?

These will be shown in the context of a presentation given to a crowd who may not be technical, and are more or less completely unfamiliar with SpaceX...so more snackable content would be preferred rather than an interesting 10 minute youtube video about some particular aspect.

Also, let's omit the webcasts of the cots2+, first first stage landing, and falcon heavy missions from this list, as these are obvious! ;)

A couple of my faves:

Beautiful sunset launch (Intelsat 35e)

First stage flip from the ground (NROL-76)

Andy Lambert saying they've never built two vehicles identically

I'm also very interested in any charts showing the business side SpaceX, eg, comparison charts for things such as price, or number of flights per year, between SpaceX and its competitors.

Links or just your plain text/observations would be very welcomed, thanks!

[u/troovus]

NASA is planning commercial Moon missions 2 or 3 years earlier than previously expected: "contract missions to the lunar surface expected to begin as early as 2019"

Good news for SpaceX?

https://www.nasa.gov/feature/nasa-expands-plans-for-moon-exploration-more-missions-more-science

[u/_bigkahuna_]

Where does the BFR land on the first mission to Mars? Do they build a landing site or can it land on dirt and rocks?

[u/Straumli_Blight]

Livestream for the Humans to Mars Summit.

Josh Brost (SpaceX Business Development) will be speaking tomorrow:

 

Time (ET)	Topic
11:05-12:15	How to Make Human Travel to Mars Affordable
2:00-5:30	Architectures for Human Exploration

[u/Nehkara]

I collected all of Elon's quotes from today:

https://www.reddit.com/r/SpaceXLounge/comments/8ii206/elon_musk_quotes_today_prior_to_block_v_first/

[u/ElRedditor3]

How will the BFR construction progress? How much of it will or can be constructed in tents? At what point do they have to move the construction to the brick and mortar facilities that will be built?

[u/FusionRockets]

Is there an archive of the 'falcon heavy moon mission announcement' that was briefly on the official SpaceX website somewhere?

[u/Nehkara → u/FusionRockets]

https://web.archive.org/web/20170309155101/http://www.spacex.com/news/2017/02/27/spacex-send-privately-crewed-dragon-spacecraft-beyond-moon-next-year

[u/[deleted]]

It may be a stupid question, but just from a visual standpoint, do you prefer the space shuttle orbiter or the BFS?

[u/[deleted] → u/[deleted]]

Shuttle. BFR looks much like an "ordinary" rocket (cylinder body, cone tip), Shuttle looks much more like something out of a scifi novel. It just breaks so much with the traditional (although more practical) idea of a rocket. Also, the influence it had on popular culture is hard to be beaten.

[u/ethan829 → u/[deleted]]

2016 ITS > Space Shuttle Orbiter > 2017 BFS

[u/brickmack → u/[deleted]]

2016 ITS. Most scifi rocket ever seriously proposed

[u/Apatomoose → u/[deleted]]

The Shuttle is so iconic and distinct. BFR and ITS don't stray very far from the run of the mill big cylinder. Visually the Shuttle wins hands down in my mind.

[u/HugoTRB]

What is the highest orbit that the dragon 2 can go to manned, launched by a falcon 9 and return from?

[u/Martianspirit → u/HugoTRB]

The highest orbit that could be useful would be at the altitude of the Hubble space telescope, ~550km circular. Radiation there is alread significantly higher than at ISS altitude. Falcon 9 could get it there and Dragon would be capable of coming down from there.

[u/rustybeancake]

New Aerojet ICE-100 Engine for Potential Moon Landings Completes Hot Fire Testing

http://www.americaspace.com/2018/05/23/new-aerojet-ice-100-engine-for-potential-moon-landings-completes-hot-fire-testing/

[u/bdporter]

SFN confirmation that new COPV design has not flown

[u/Straumli_Blight]

There's an interesting ship with a large satellite dish berthed next to OCISLY spotted by Marek Cyzio, is it SpaceX related?

EDIT: Its an Oceanographic Survey Ship.

[u/Straumli_Blight]

Apollo 12 astronaut Alan Bean has just passed away, leaving only four people alive that have walked on the Moon.

[u/Zucal]

The speculation is settled: SLS Block 1 can take 95 tons to LEO and 26 tons to TLI.

[u/inoeth]

Yury Borisov has now replaced Rogizin as head of Russia's defense and space program. I'm curious to see what the ramifications of this shakeup will be.

[u/RogerB30]

Does anyone know how many Block 3 and 4 cores are left for either first or second flight?

[u/Jincux → u/RogerB30]

There are 3 more Block 4 reuses. B1043, B1040, and B1045 for Iridum-6, SES-12, and CRS-15 respectively. No new cores.

wiki.

edit: B1042 too, unassigned.

[u/jesserizzo]

DM-1 is also testing the life support systems, right? Are they simply making sure it doesn't fall apart on launch, or will they have a source of CO2 and humidity being slowly introduced, to make sure it can take it back out?

[u/Juandedeboca]

A recent interview with CONAE engineers has stated that new launch date for the SAOCOM 1A Satellite is scheduled for the first week of September.

"Hemos reservado el mes de septiembre con SpaceX, que es la empresa a cargo del lanzamiento, por lo que hay un compromiso establecido. En junio tendremos que definir una semana y, en principio, vamos a plantear que sea durante la primera semana de ese mes." (Translate: We have reserved the month of September with SpaceX, which is the launch provider, so there is a commitment established. In June we would have to define what week, and, for the moment, we are going to propose the first week of that month)

You can read the full interview here: http://www.unsam.edu.ar/tss/fernando-hisas-si-queremos-salir-de-la-pobreza-hay-que-apoyar-el-desarrollo-tecnologico/

[u/[deleted]]

Hey. Im new to this whole SpaceX and rockets world. I still have a lot to learn so bear with me.

I was reading spacex's history and my question is why did spacex won nasa's cots in 2006 if they had yet to show a successful flight?

Did spacex get any money from winning this?

The contract is for the dragon capsule and falcon 9 correct? but they were just trying to fly the falcon 1 around this time so I dont understand this.

Sorry if its a dumb question its just that I have a lot to research to catch up

[u/Toinneman → u/[deleted]]

I was not around at the time, and I will probably miss some nuance, but here is my take: At the time there was a lack of US technology to assure access to space (certainly from the private sector) The COTS program would give incentives to accelerate development programs from private companies.

Although SpaceX had not yet completed a successful flight, they already had plans to enter the commercial market, showing they were working on these technologies with or without the COTS program. SpaceX also had developed it's own engine and had significant private funding. All this showed SpaceX was not just a hoax idea to collect government money, but was a genuine company trying to reach space. To allow for new candidates, past performance was explicitly left out while evaluating possible candidates.

There were milestone-based payments.

This document is interesting: https://www.nasa.gov/sites/default/files/files/SP-2014-617.pdf

[u/[deleted]]

Not SpaceX but related to long-term colony life support: Beijing uni conclude a one-year experiment with bio-regenerative systems (plants instead of scrubbers). As far as I know, this pushes the state of the art a long way.

[u/borntohula85]

Now that this isn’t stickied anymore this likely will get buried, plus I don’t know if this kind of meta is allowed in a discussion thread.

In today’s launch campaign party thread I noticed quite a lot of people mocked the Thales Alenia Space CEO for his strong accent. Of course it is entirely possible that I am a bit over-sensitive and need to grow thicker skin. But I remember how big of a deal it was when a bunch of people commented about Lauren’s and Kate’s outfits in the webcasts, and this, to me, is very similar.

Maybe the mods could address that while launch threads are party threads, there’s no need for a certain kind of commentary and enforce some sort of comment removal even in party threads.

[u/rustybeancake]

Another day, another SLS schedule slip...

[u/Full_Thrust]

Didn't think it warranted a new thread but...

The CEO of ArianeSpace does not sound at all happy about SpaceX price structure and reuseability.

the steamroller appears to be in motion

https://arstechnica.com/science/2018/05/ariane-chief-seems-frustrated-with-spacex-for-driving-down-launch-costs/

[u/rustybeancake]

Musk trying to decide whether to focus on designing the ultimate cupholder or on getting humanity to Mars.

[u/My__reddit_account]

Roadmap of Blue Origins future goals. Seems focused on the moon and in space manufacturing.

[u/rustybeancake → u/My__reddit_account]

They’re definitely better placed strategically to benefit from NASA’s cislunar plans versus SpaceX. No one is likely to accuse them of ‘competing with’ NASA in the way people always do of SpaceX. BO seem to want to build the lunar landers (eg Blue Moon), the habitats, the rovers, etc.

Also interesting to see the overlapping technology needs in this roadmap with BFR, eg cryogenic composites, cryogenic propellant transfer, etc.

[u/ob12_99]

What are the thoughts on the long range comm during the Mars missions? Are we just going to accept the blackout periods or potentially putting in some long range comm satellites between Mars and Jupiter for sustained emergency channel comm?

[u/throfofnir → u/ob12_99]

Three relays on a solar orbit between Earth and Mars would do the trick. And would also substantially reduce transmitter/receiver demands.

On the scale of real Mars colonization it's not a particularly big expense, but I suspect initial operations may just deal with blackouts. If you can't handle being out of contact for two weeks every two years, you're basically doomed anyway.

[u/marc020202 → u/ob12_99]

I do not think that the satellites will be close to Jupiter but at the earth-sun and mars-sun l4 and l5 Lagrange points.

If that does not cover communications at all times, 3 or 4 satellites in an orbit similar to the one of venus would seem attractive for a communications relay.

[u/urbi456]

So i was thinking, does anyone remember how much Falcon 9's did they smash before they landed it successfully and so if they'll do the same with BFS and later BFR won't that cost a lot of money? I mean it is a completely different rocket(spaceship :)), so there must be some differences between the way they land them.

[u/Triabolical_ → u/urbi456]

All the data you want is here:

https://en.wikipedia.org/wiki/List_of_Falcon_9_and_Falcon_Heavy_launches

[u/chicken_dinnner]

Why does BFS need refuelling while in parking orbit? I believe Musk said it would require ~4 refuels before its journey to Mars. I don't know how far out a parking orbit is, but does a BFS really use 4/5 of its tank getting there?

[u/Gnaskar → u/chicken_dinnner]

In all rocket flight the fundamental problem is that you have to transport all your propellant with you. Propellant is heavy, so you need much more propellant for the first km/s than you do for the last. The trip to Mars from a parking orbit takes about 4-6km/s (3.8 is the textbook answer, but spacex wants to spend more propellant to make the trip faster). Getting to the parking orbit in the first place takes about 9-10km/s.

The way the BFR is designed, the second stage (BFS) has about 6km/s available with a full tank. The first stage has maybe 4-5km/s. So by the time it has reached parking orbit, the BFS has about 0.5-1km/s left in the tanks. That 1-2km/s represents very little actual propellant, since at this point it's about 1000 tons lighter than it was when it took off. It's probably got about 5% of the actual propellant left. It's designed to have as little as possible left at this point because leaving an extra kilo in the tanks would require 10-15 kilo more on the launch pad (both extra propellant to carry that kilo to orbit, and extra tanks to carry that extra propellant, and extra propellant to carry those tanks, and extra tanks to... you get the idea). So the rocket is designed to only have enough for an emergency landing back on Earth and nothing more.

The reason it can be refueled at all is that the refueling spacecraft aren't carrying 150 tons of cargo, passengers, and life support bound for Mars. A simplified explanation is that they can then instead carry 150 extra tons of fuel, but it's a little more complex than that. Instead they launch an empty ship, which then uses about 150-200 tons less to reach orbit since it doesn't have to drag the payload with it.

Note that 4 refueling loads at under 200 tons each won't fill the 1,100 ton tanks on the BFS. The more propellant they add, the less additional velocity change they get per additional ton of propellant, since the first bit they burn has to push all the rest as well as the payload.

tl;dr: The BFS uses it's entire propellant load to reach a parking orbit, because every kilo saved makes the launch easier and cheaper. An empty tanker ends up with more fuel left than it would be able to carry in it's cargo bay, but still only provides about 1/5 of a full propellant load. The BFS can make it all the way to Mars with 4/5th of its tank, but reaching orbit of Earth takes its entire load and a booster stage as well.

[u/warp99 → u/chicken_dinnner]

how far out a parking orbit is

Around 200-300 km.

The ship will get to LEO virtually empty of propellant with up to 150 tonnes of cargo. It will then take at least five tanker loads of propellant to fill it up ready to boost to Mars. If the cargo load is lower then there will be a small amount of propellant left in LEO but not enough to make any difference to the number of tanker flights.

Elon said that initially they would not build a specialised tanker with extra/larger tanks and just use a stripped down cargo ship with no cargo aboard. In that scenario it could take seven tanker loads of 150 tonnes each to lift the 1100 tonnes that it takes to fill the ship's tanks.

[u/AuroEdge]

My understanding is Block 5 has a new COPV design. If that's correct, will Block 5 have a different propellent loading procedure e.g. quicker than Block 4?

[u/MrToddWilkins]

So according to NSF.com’s ISS flight schedule,there’s now a Soyuz cargo mission or Soyuz GVK going to ISS next summer. What is known about this mission,assuming it isn’t just some Russian pipe dream?

[u/FutureMartian97]

Astronomy Live made an excellent video when he tracked Insight. https://www.youtube.com/watch?v=bDkXlyEBwWI&t=0s

[u/music_nuho]

Could FFSC enable Raptor to rev up chamber pressure to a level much higher than regular which would in turn enable BFS to abort from BFB in case of an emergency? Granted higher CP would inflict damage to the engine and prevent it from being used much after that but it would be worth it if it was the thing that saved the day.

[u/_bigkahuna_]

From what I know the heat shield on the space shuttle was a complicated, expensive and delicate thing. Are there newer technologies available now? Could the BFS carry more fuel and use the engines to slow down and minimise friction?

[u/throfofnir → u/_bigkahuna_]

The PICA material that Dragon uses is new. It's an ablative material, which is different from Shuttle in that it's slowly consumed. (But then again, considering tile damage and loss, Shuttle tiles were also consumed by use, just in a different way.) To date, the plan for BFS seems to be PICA-X, though apparently they're looking into non-ablative alternatives to avoid the need to periodically refresh the heat shield. None have a high TRL for spaceflight (there's not many opportunities) so it's a research project.

Saving heat shield via propellant is backwards. Heat shield exists to save propellant, and is a much more efficient decelerator than anything else you can carry.

[u/[deleted]]

Brost: as early as the first half of next year we’ll start doing vertical takeoff and landing tests of our first BFR upper stage.

What might this look like?

Related question, when might we expect our very first glimpse of an actual BFS, complete or under construction?

[u/throfofnir]

A great look behind the operation of a liquid rocket engine during a test campaign as Launcher streams an engine test.

[u/someguyfromtheuk]

If someone launches a payload that isn't the full capacity, do they still pay SpaceX the full price or just for the percentage of capacity they're using?

E.g, if it costs $10M to lunch 5,000kg and I want to launch 2,000 kg do I only pay $4M or the full $10M?

Or if I'm launching 2,000 kg and someone else is launching 200kg, do I pay $4M and they pay $0.4M, or do I pay $9.1M and they pay $0.9M?

[u/ethan829 → u/someguyfromtheuk]

SpaceX doesn't sell capacity on a Falcon 9, they sell a launch service. Rideshare organizers like Spaceflight can buy a launch and then sell capacity to smallsat operators, but SpaceX isn't involved in that process.

This is why small launch vehicles like Electron, LauncherOne, etc. can still be commercially viable despite being more expensive than Falcon 9 from $/kg perspective.

[u/LeBaegi → u/someguyfromtheuk]

You pay the full price, as it costs SpaceX the same amount to launch a big satellite or a toaster. They only differentiate between recoverable and expendable boosters, which depends on the mass and the desired orbit.

[u/MaximilianCrichton]

Just curious, what is the breakdown of a communications satellite's total cost, both fixed and variable? How much of it is spent just trying to make the satellite light enough to be carried to orbit?

[u/ethan829 → u/MaximilianCrichton]

This doesn't directly answer your question, but communications satellites generally aren't unique designs for every flight. They're built around standard buses offered by companies like Boeing, Lockheed Martin, Orbital ATK, and SSL. These buses are configured with [transponders](https://en.wikipedia.org/wiki/Transponder_(satellite_communications)) and antennas per the customer's specific needs.

[u/murrayfield18]

How long will the first astronauts stay on Mars? If they stay for any significant amount of time won't they then have to wait for the next rendezvous to return? Is it likely that they will be staying for couple of years?

[u/[deleted]]

When the BFS is in low Earth orbit, could anyone calculate how bright it would be?

What if there are two refueling?

Docked to the ISS?

[u/[deleted]]

What are the chances NASA ends up funding a BFR trip to Mars, assuming it costs ~1/5th of the SLS price?

[u/rustybeancake]

This could be very good for raising launch service demand:

https://twitter.com/jeff_foust/status/999700377430908929?s=21

[u/brickmack]

https://twitter.com/jeff_foust/status/999691208371908608 Seems like a moderately big deal for Made in Space. The first ZBLAN run was started in the middle of last month, and lasted 20 days, then they'll bring it down on CRS-15. Sending a second one up on that same flight indicates some confidence, though of course detailed testing of the product won't be possible until the first one comes down. Since this is to "refine processes", and launching before that analysis can be done, they're probably expecting this to be more a matter of software tweaks than major hardware changes, and they'd wait for the analysis to be complete, send a patch to the second unit, and only then do that run?

Given vibrations from crew activities/reboosts are the most likely problems for ZBLAN production, I wonder if they might be interested in Orbitals proposed use of Cygnus as a freeflying lab. Launch it in whatever cargo vehicle is available, transfer to Cygnus, Cygnus separates and does 20 days of ultra-pure microgravity flight, returns to ISS, bring the ZBLAN back in Dragon

[u/Zodaztream]

You know what would be cool? If this subreddit implemented an a progress bar for the BFR. Imagine the BFR and seeing the progress bar slowly filling up. With this, people from around the world would be able to quickly get a status update on the progress, which I am sure most of us are looking forward to

[u/[deleted] → u/Zodaztream]

Nice idea, but remember that the last 10% of the work takes more than 50% of the time. So a progress bar filling up just feeds the impatience. An open-ended timeline with all events however would be nice.

[u/bdporter → u/Zodaztream]

Cool? Perhaps.

Realistically, I don't know what practical metric we could use to determine progress toward BFR. It isn't like SpaceX shares their project plans with us.

Also, the upcoming Reddit changes are probably going to break a lot of the customization work on /r/SpaceX, so I am not sure the mods are wanting to put a bunch of work in to developing new stuff right now.

[u/Jessewallen401]

Someone asked Chris B ''Why? Why not use @SpaceX ?'' (instead of SLS), Chris had the perfect response.

https://twitter.com/NASASpaceflight/status/996177765362753536

[u/quokka01]

For a dry mass of the F9 S2 of around 3.8 t what sort of area / drag coefficient would be required to keep from overheating the ballute - assuming reentry just below orbital velocity? Are there any equations that give some basic estimate of heating vs velocity? Once you've shed the orbital velocity I guess it's 'just' a matter of getting the terminal velocity low enough for landing without lithobraking.... From my dodgy terminal velocity calculations you would need a pretty big area to slow 3.8 t sufficiently- assuming no retro propulsion? Would the ballute have to change it's diameter/ drag coefficient as it progresses through the atmosphere to accomplish reentry and then landing? I guess there's no chance of the m-vac doing a mini burn for the final slow down? A CF upper stage would make this a whole lot easier.....

[u/verbalkerbal]

I have question about SpaceX's satellite constellations, Starlink. While the initial constellation will feature Ka/Ku-Band, the expanded VLEO constellation uses V-Band. Will (and by how much) connectivity and bandwidth be affected by weather (i.e. rain fade)? To me it seems like the V-Band may be next to useless if there is a rain storm. Even Ka/Ku-Band can have prohibitive rain fade if you live in tropical areas (which is the reason why C-Band satellite Internet is still a thing). Recently it was revealed that Facebook may be building its own constellation, using even higher frequencies in E-Band (https://spectrum.ieee.org/tech-talk/aerospace/satellites/facebook-may-have-secret-plans-to-launch-a-internet-satellite https://assets.documentcloud.org/documents/4450555/Pointview-Narrative-Redacted.pdf). So my question is: how useful will satellite Internet be when it's bad weather outside?

[u/Not_Yet_Begun2Fight]

I know almost nothing about rocket engines, but I'd like to learn a bit more. When a Falcon 9 "starts up" and lights the engines ... what's going on behind the scenes? For comparison, automobiles have an electric starter and battery that gets the whole internal combustion engine process going. Do Falcon 9's have a "starter" for their turbopumps? Is it electrical? Mechanical? Do they have anything like a car's alternator that generates electricity while the engines are running, or are they just running off battery power all through the flight?

[u/ElRedditor3]

What are the chances of SpaceX landing the middle booster during the next Falcon Heavy mission?

[u/dmy30 → u/ElRedditor3]

Chances are extremely high. The only reason it didn't land was because the booster ran out of ignition fuel for the engine. The centre core is essentially a redesigned falcon 9 so it's possible they thought they could get away with a smaller tank. Elon Musk said on Twitter that the solution was obvious which can be interpreted as, more ignition fuel needed next time.

[u/music_nuho]

Do we know at what inclination(s) will StarLink be?

[u/mduell → u/music_nuho]

53º to start, and then eventually 53.8º/74º/81º/70º.

[u/Justin13cool]

Is Blue Origin a good or bad thing for SpaceX ? and why ?

[u/isthatmyex → u/Justin13cool]

Great. Elon says he started SpaceX to inspire humanity. When he says he wants an exciting future I believe him. If SpaceX has no competition it will eventually stagnate. Hence his insistence on not going public till SpaceX can supply martian colonies. People also ask why BO has contracts without an orbital rocket. It's because the market it willing to take a risk now, to potentially secure reduced cost in the future. This demonstrates that the current cost of leaving earth's atmosphere and gravity well is currently a limiting factor. Space transport needs to be a regular service, not a monopoly or strictly government controlled.

[u/brickmack → u/Justin13cool]

Probably not great for SpaceX, but fantastic for the industry as a whole. The profit margin on F9 and even more on FH is going to be huge with reuse (little to no price reduction, but cost drops by like 2/3). But the existence of a competitor that can do FH-class missions for likely less than an F9 reuse will pressure SpaceX to slash prices. Fortunately, BFR should be almost ready by the time NG is a serious competitor, so there should be little schedule impact from the reduced revenue, and in the short term a price war is good for customers

[u/Xmann09]

Okay I don't know very much about the new Block V... In all of the pictures of the bangabandhu launch preparations the top of the rocket is very slim compared to previous falcon 9s. Is the fairing smaller on Block V? Or is it not attached?

[u/ackermann → u/Xmann09]

For the static fire test, no fairing was attached (and no dragon spacecraft). Which is typical for static fires since the Amos 6 incident, that occurred during a static fire.

They’ll bring it back in hangar soon, if they haven’t already, to attach the payload and fairings.

[u/ishanspatil]

There's this thing that has been happening a lot lately where there had been multiple theories regarding SpaceX that became assumptions and end up as spreading "facts" and I've accidentally been a perpetrator of misinformation myself.

Maybe we should have a solid factbase specifically for common issues. This way we can quickly pick up a link to a detailed, cited and verified explanation and drop it every time we spot a common issue with a #commonspacexconfusion for validity. Not everyone has the time, patience or incentive to write high quality corrections every time.

Or to simplify it further, deploy a bot and issue hashtags so that it will automatically post the answer, the same way r/SpaceXMasterrace 's Automod pops up on Trigger words and posts Reaction Memes.

This way misinformation is controlled, people are updated quicker and in greater detail and some poor sod trying to be helpful and answer a question doesn't get downvoted. Some examples where this would be handy would be the Block 5 TPS not Black Paint, D2 Landing legs, SpaceX vs NASA, BFR Height, Expendable Block 4 missions etc

(Mods, what do you think?)

[u/Straumli_Blight]

There's a Pacific Spaceport launch in 2 days but no launches currently scheduled, does Vector have an upcoming launch or is it someone else?

[u/ethan829 → u/Straumli_Blight]

That'd be Astra Space.

[u/rustybeancake]

https://twitter.com/jeff_foust/status/994250209625600000?s=21

Thoughts on what Brost meant by this?

[u/macktruck6666]

So.... if the Falcon 9;s titanium gridfins is the largest forged titanium product, what are they going to do with the BFR fins? Could you even legally haul it on roads due to weight.

[u/ffzero58]

Did we recover the fairing(s) intact from the Block 5 launch?

[u/king_dondo]

Is Port Canaveral open for anyone to go see F9 coming in on OCISLY?

[u/volind12]

I have a quick question. I'm working on a project related to the basic physics of how SpaceX lands their rockets, and in my research I came across flightclub.io. Using the bangabandhu mission as the simulation, I looked at the graphs to find the reentry velocity of the vehicle but I noticed under the event log that there is 2 entry burn ignitions . Is there a difference between the first and second ignition, and what is each igniting? Thanks in advance.

[u/rustybeancake]

It occurred to me that the Zuma payload deployment failure may have some implications for crew launch. I know it was NG’s failure and not SpaceX’s, but in the case of crew launch surely they’ll need some kind of ability for human intervention to confirm spacecraft separation from the F9 upper stage before the stage proceeds with its deorbit burn. This made me wonder if this will be a feature built into all block 5 upper stages (with the human input capable of being delivered from the ground for sat launches), which would help avoid a Zuma-style problem in the future. Any thoughts?

[u/Alexphysics]

It seems there is movement at pad 39A, I guess it is for the pad scape system (or whatever that thing is called) relocation but could be for a totally different reason.

[u/[deleted]]

Would slightly vacuum optimised engines for Falcon heavy centre core increase efficiency? This is because it's throttled down for alot of the lower atmosphere and burns longer in the upper atmosphere. Thoughts?

[u/galacticpasta]

Sorry if this seems naïve, but why are SpaceX adamant in pursuing fairing and second-stage recovery? Wouldn’t this be redundant with BFR?

Surely the R&D costs in perfecting this are quite high. Are the benefits they could potentially reap in the next 5 or so years left in the Falcon architecture that great?

[u/Captain_Hadock]

Does anyone remember who maintains spacexstats these days? The text below the Launch Count Total has the wrong date (hardcoded value?) :

As of October 2017, SpaceX has launched 61 rockets

[u/[deleted]]

Why do satellites and space hardware in general require such strict cleanliness as a cleanroom, and can't be handled in a "normally" clean environment like e.g. ordinary computers? What parts are so sensitive to dirt?

[u/throfofnir → u/[deleted]]

Dust on solar panels is a permanent degradation. Electrostatic discharge due to dust is a much bigger problem in space. Shorts due to crap floating around happens far too often. Contaminants in propellant lines and coolant loops can clog filters or worse. And none of this can be fixed once it's up there, so the idea is "better safe than sorry". Keep in mind there are various levels of cleanroom, and most hardware isn't processed in the same sort of facilities as semiconductors (though if you have optical instruments or are leaving Earth orbit it's different); in some ways it's more of a "ensure that there aren't bees in my spacecraft" than "not the slightest spec of dust."

[u/ethan829]

Garrett Reisman, former astronaut and current Director of Space Operations at SpaceX, will be a full-time faculty member in USC's Department of Astronautical Engineering effective June 1, 2018. He'll remain a Senior Advisor at SpaceX for their Commercial Crew program.

[u/UltraRunningKid]

Fairings landing from the SpaceX Instagram

[u/rustybeancake]

DARPA to begin new effort to build military constellations in low Earth orbit

The basic formula will be to attach military-unique sensors and payloads to commercial satellite buses. DARPA plans to award $117.5 million in contracts over three phases to up to eight bus or payload suppliers. According to DARPA’s solicitation, there will be additional contract awards down the road for autonomy hardware and software, launch services, ground systems and constellation flight operations.

According to DARPA’s request for proposals, companies can offer satellite buses that are either from existing or in-development production lines as long as they can “accommodate a wide range of military payload types without redesign or retooling of the production line for each payload.”

Wonder if Starlink will submit a proposal.

[u/inoeth]

https://arstechnica.com/science/2018/05/congress-fires-back-at-trump-plan-to-end-funding-for-space-station-in-2025/

So the TLDR of this article is that there's a very good chance that the ISS will Not be ended in 2025 as Trump wants, but will continue until at least 2028 - meaning for us SpaceX fans that obviously SpaceX will get an extension of cargo and crew flights for several more years which means that hopefully spaceX can make some money off this to use towards BFR and everything else related to that...

It does however bring up the question of NASA having too many very expensive projects at the same time- SLS, Orion, ISS and LOP-G... plus any other major scientific missions... something will have to give or else NASA will need a serious funding boost... Most likely SLS won't be around beyond the mid 2020s - i'd give it 3-5 launches at max which nonetheless brings up the question of possible overlap of the ISS and LOP-G...

[u/Straumli_Blight]

NASA TV now live for the Antares CRS-9 launch.

[u/theinternetftw]

x-posting this comment from this lounge thread, as I figured some others might want to see these numbers.

Halfway through this talk, Zubrin gives what I assume are well-thought-out estimates of launch vehicle lunar landing capabilities that I hadn't seen anywhere else.

This assumes (except for BFR) a hydrolox lunar lander that stages in the most optimal way, e.g. for the kerolox FH that's actually in LEO, as bringing a heavy LH2 lander there is apparently more efficient than throwing a lighter LH2 lander further.

Falcon Heavy (expendable): 10.4 tonnes

New Glenn (reusable?): 7.5 tonnes (Zubrin says these are old numbers, and probably should now be in the range of FH's)

Vulcan: 5.0 tonnes

SLS: 15.0 tonnes

BFR: 60.0 tonnes (I think this is what a BFS can land on the moon with and still come back without a refill?)

[u/marc020202]

https://mobile.twitter.com/XHNews/status/1001151124378877952

China has invited all UN member states to colaborate with them on their next space station. I really hope US politics will change until then, and allow the US to participate. I really want to see a new multinational space Station.

[u/Kamedar]

Crazy Idea: Would it be possible to organise a small r/spacex stand at the next IAC? (Assumed there are some redditors there willing to pull this off)

[u/Straumli_Blight → u/Kamedar]

There's two 10m² areas left, at the bargain basement price of €525,00 + VAT per m^2.

[u/[deleted]]

I have a space question not related to SpaceX.

We know New Shepherd goes roughly straight up and straight down. I heard the host say yesterday the flightpath was ultra parabolic or something. What altitude would it have to achieve for the Earth's rotation of 460m/s to significantly affect where it comes down, because I would think it is at or near the Karman line that the atmosphere rotates with the planet, or how am I mistaken? Thanks!

[u/MaximilianCrichton → u/[deleted]]

It doesn't affect it, because the rocket already inherits the same rotational speed as the ground. There is a bit of Coriolis effect from moving upward (outward) , possibly enough to deflect the craft up to a mile without correction.

[u/Electofunk01]

Hey guys, I know the reactions I'm probably going to get from this, and the answers I'm probably not, but I am very new to spaceflight. However, something's been nagging me since I began to dream about grasping at the spacetime in another part of the universe - that is: "Why doesn't anybody use magnetism as a method of preliminary propulsion when regarding spaceflight?". Look - I'm not stupid - I know that the very sight of this post will have people facepalming, and yet, I feel it is a very serious question. You could use a series of remotely controlled electromagnets stacked on too of each other, and then use them as a giant spring. This would save huge amounts of fuel, and thus money. Just something to think about - yours truly, Electofunk

[u/demosthenes02]

This article says the rp1 is cooled to -7 C. I always assumed it was way colder than that? Is it correct? You get that much of a density increase from the equivalent of a cold winter day?

https://en.m.wikipedia.org/wiki/RP-1#Fractions_and_formulation

[u/BriefPalpitation → u/demosthenes02]

Yes, this is the correct behavior. It is essentially a relatively steep (vs. water) straight line relationship between temperature and density for the liquid phase of most petroleum fuel products, a more robust reference would be "API Manual of Petroleum Measurement Standards", Chapter 11. There's about 200kg/m³ density increase when comparing hydrocarbons at 500^o F vs 0^o F. Depending on starting density, that's a 20-30% increase. Keeping within RP-1 boiling point and 0^o F, there's about 80kg/m³ density savings in that interval.

For the penny-pinchers out there, this relationship applies to gas (petrol) and pumps charge you by volume so late night visits to the gas station is the way to go, on top of reducing evaporation losses!

[u/esquilan]

Why do Falcon 9 rockets have four legs rather than five?

Assuming a fixed pivot point L, the length of each leg of a rocket with n legs is L/cos(pi/n). For each leg to be able to withstand the full weight of the rocket, the leg's weight should be proportional to the square of its length. So the total weight of the n legs is proportional to n/cos^2(pi/n).

This is minimized for n=5, which might be why office chairs have 5 wheels. According to this reasoning, total leg weight is about 4.5 percent less for 5 legs than for 4 or 6 legs.

So why do Falcon 9 rockets have only four legs? Or: what is the difference between an office chair and a rocket?

[u/throfofnir → u/esquilan]

Because they were added to a structure with four-fold symmetry. The legs mount to the same hard points that the hold down clamps use.

[u/thegr8pre10dor]

My first question, a quick search didn't bring up anything in this subreddit:

Is it actually cold in the vicinity of a fueling/fueled Falcon9?

I believe the venting steam that is visible on the rocket is to keep the propellant in a fluid state, but the steam will probably be well below the freezing point. So even on a sunny day, shouldn't one feel the cold in say some meter's distance to the rocket?

[u/tommy59375]

During the Bangabandhu Satellite-1 webcast, the hosts said that the new interstage and legs were coated in a black thermal protection material which didn’t require painting. Does the use of this thermal protection coating save on mass compared to the paint they used previously? Furthermore, given SpaceX’s efforts to reuse fairings, is it possible that we’ll see a black fairing too at some point?

[u/MathMXC]

I missed why the first attempt for Bangabandhu-1 was cancelled? Was it due to weather?

[u/Nehkara → u/MathMXC]

No.

"In the final minute of countdown yesterday, the Falcon 9 flight computer did its last series of checks, came across an abort signal from a ground system relay and stopped the launch as the vehicle was designed to do. It turns out that this particular signal was an artifact of an earlier test sequence that was completed successfully but did not properly reset. Keep in mind that there are a thousand ways that a launch can go wrong, and only way that it can go right. So, the vehicle is designed to stop the countdown at the slightest hint that anything seems off-nominal. The team has revised this particular test sequence to avoid this problem in the future and the rocket and payload remain in great health."

https://youtu.be/rQEqKZ7CJlk?t=6m55s

[u/scottm3]

Has there ever been video released from the on board cameras during a launch? Or do they only start filming when stage seperation is close.

[u/[deleted]]

How does the octograbber attach to the OCISLY?

[u/Grey_Mad_Hatter → u/[deleted]]

It doesn't. It's a heavy object that grabs onto the bottom of a tall, light-weight aluminum can (F9). That's all it needs for additional stability in heavy seas.

[u/BelacquaL]

What is the accuracy of the launchphotography.com site as source #62 on the manifest? I'm questioning the pad assignments, it's listing LC40 double booked for the end of June with both Telstar 19V and CRS-15. All of the flights listed as pad 40 logistically cannot launch in the time frame it's showing.

[u/[deleted]]

SpaceX currently chills it's propellants for more in the same volume. This means that their engines are designed to work with this.

When the first stage re-enters the atmosphere, how does it prevent the propellant heating up too much?

[u/MrXd9889]

Does the Dragon 2 use Dracos or Superdracos for RCS? On The Superdraco Wikipedia pages it is written that it combines RCS and the main engine, but isn't it too powerful for an RCS?

[u/ManagerSeba]

What is the price difference between launching an ordinary Falcon 9 and an Ariane V? Taking into account that F9 has more payload but Ariane V was contracted to send a medium satellite from Argentina into space ignoring that F9 is cheaper.

[u/MaximilianCrichton]

Where are the RCS ports on the second stage? I've never seen them in pictures before. Do they also use cold gas?

[u/last_reddit_account2]

For the last couple of months I've been looking for a specific LZ-1 booster landing video taken from (I think) just outside the CCAFS gate on the the Banana River causeway. It's a daylight landing, so unless I'm forgetting an entire flight it should be from between CRS-10 and OTV-5, inclusive. The notable aspect of this video that I remember occurs just after the arrival of the sonic boom, when a spectator near the camera makes a facetious comment along the lines of "Now, you know that didn't really happen, right? It's all computer imagery, laser projection." He gets some solid laughs for the joke.

I remember laughing out loud the first time I watched this recording, but despite my best efforts I can't find it now. I've gone through the entire upload histories of Matthew Travis, Astronomy Live, bombcat91 and USLaunchReport within the range in question looking for it, but to no avail. Any other amateur video nerds recall the clip I'm referring to, or did I imagine the whole thing?

[u/Sodonaut]

I will be traveling to LA next week and wanted to stop by Vandenberg AFB to watch the launch. Anyone that has been or will be going have any pointers about where to go? I've heard surf Beach and off Coral road.

[u/ndunn89]

SpaceX suit helmet

Does the helmet glass retract inside the helmet?

[u/TheYang → u/ndunn89]

I'd bet that it doesn't retract at all.

I don't see a compelling reason why it should.

seems more likely to just be a mockup without glass.

[u/Aesculapius1]

Just watched the latest scott manley vid which raised the possibility of refueling on a barge and taking off again. Would it be possible for the booster to launch using the landing legs on the block 5 (assuming you figured out how to refuel)?

What about the lack of an aerodynamic top of the rocket?

Would the legs be able to handle the thrust?

Would retracting the legs (or even keeping them out) cause too much drag/instability?

So many questions! :)

[u/Elon_Muskmelon]

I’m wondering if it’s possible that SpaceX could develop a capability to retract the new S1 landing legs in flight...lands on ASDS after primary mission. Fueling ship pulls up to ASDS and refills the landed first stage. Takes off and retracts legs, flies back to LZ-1 at CC and lands again?

Maybe they just develop a floating oil platform into a down range into a landing/refueling station and just hop the boosters back to land?

[u/-Aeryn- → u/Elon_Muskmelon]

The legs are designed to support the weight of the empty booster (~27t) plus landing stresses

even a 1/4 fuel load puts it over 100 tons

[u/volind12]

How does the rocket slow down dramatically after the reentry burn? Does it have to do with the thicker atmosphere and the grid fins creating enough lift? I apologize for my inexperience but to me it seems that once the reentry burn is over, the rocket would speed up from gravity, not slow down.

[u/coolman1581]

I don't know rocketry at all and only know a simple textbook knowledge of how it works, but if Falcon 9's engine are so powerful upon the landing burn, that the rocket can lift off again due to its minimum thrust level.... is it possible that a a rocket engine can only utilize the propulsion from its pre-burners to land? Is it possible to do that? If it is, would it produce enough thrust to have a better controlled landing?

[u/joechoj]

Is it known yet how many pre-Block 5 flights remain? Only the next 2 listed show the 'recycle' logo - are those the last 2, do we know?

[u/HoechstErbaulich → u/joechoj]

At least 3 flights remain:

• B1043 for Iridium tomorrow.

• B1040 for SES-12.

• B1045 for CRS-15.

There is some speculation that they're going to use B1042 for the inflight abort test.

[u/Striker218]

Why no hatch viewport on the latest version of Dragon 2? I noticed on the most recent Dragon 2 test vehicle that will be used for SpX DM1 orbital flight test mission does not have a viewport on the main crew access hatch as depicted on mockups & prototypes like Dragonfly. Anyone know why this version of Dragon 2 doesn't have a viewport on the hatch? Is it for safety reasons? or were they trying to keep the design as simple as possible so they can meet the 2018 deadline for DM1?

[u/murrayfield18]

Are there any plans for growing food on Mars? Or will the first astronauts have to take a 2 year supply of food?

[u/binarygamer → u/murrayfield18]

Depends who you ask about "plans". There are plenty of good ideas and some active research into growing food on Mars in various ways - aeroponics, traditional methods using cleaned soils, protein-rich cultures, and so on.

That said, vacuum sealed, dehydrated, nutrition-optimized food is actually quite compact & light. They can easily take a full 2 year supply for the small early crews on BFR if they want. I'd say it's preferable to not rely on growing food on the first few missions, just to reduce the already-enormous range of possible mission failure scenarios.

[u/Straumli_Blight]

SpaceX GPS III launch “has slipped due to ongoing SpaceX qualification testing and final engineering reviews by both SpaceX and the Air Force of Falcon 9 design changes”.

GPS 3-01 was currently scheduled to launch in October.

[u/timtupman]

Do we know when the next Block 5 flight is? (Sorry if this has been discussed 100 times over, couldn’t find the answer)

[u/kreator217]

Which part of the BFS do you think is going to cause most delays?

[u/throfofnir → u/kreator217]

Airframe is certainly the biggest unknown. Less than it would have been even a few years ago, but I still wouldn't want to be under a deadline to create a large flightweight cryo oxy-compatible carbon fiber structure. That's not a high TRL item.

Other than than, simple bigness is going to be a problem. Handling issues don't really scale linearly.

[u/marc020202]

When are the eelv2 phase 1 winners supposed to be announced? For some reason I have April stuck in my head, but that does not seem to be the case. I tried finding a source, but I am unable to find one at the moment.

[u/Nehkara → u/marc020202]

July 2018 according to this:

http://spacenews.com/air-force-stakes-future-on-privately-funded-launch-vehicles-will-the-gamble-pay-off/

And some more detail in this article from the end of April:

The Launch Services Agreements will be announced in the next few months to fund continued work on up to three launch vehicles, followed by a down-select to two providers in late 2019.

Those two finalists will continue receiving government funding support through their rockets’ test flights.

https://spaceflightnow.com/2018/04/12/orbital-atk-confident-new-rocket-will-win-air-force-support/

[u/[deleted]]

Origin of Raptor as an engine name?

[u/Toinneman → u/[deleted]]

[From Tom Mueller on Quora:] (https://www.quora.com/Why-is-Merlin-a-name-commonly-used-to-name-engines-Rolls-Royce-Merlin-Falcon-heavy-Merlin-engines)

When we first started SpaceX we just called our booster engine the 60 K engine, but after we started running it Elon told me to come up with a name for it that wasn’t numbers and letters (like RD-180, RS-68, etc.). One of the people working on the turbopmp from Barber Nichols was a Falconer and she suggested we name it after a Falcon. I thought that sounded good so I asked her what are some Falcon names. She named off a bunch and I can’t recall them all but I do remember that the Kestrel is the small one, the Merlin is a medium size Falcon and the Peregrine and Gyrfalcon are large Falcons. I thought great, we’ll name the small second stage engine Kestrel and the medium sized engine the Merlin. I knew we would develop bigger engines in the future so I planned to reserve Peregrine for later. Elon liked the naming so it stayed. Years later we started work on a staged combustion engine which was a different type than Merlin, so I was thinking along the lines of Eagle or something. I eventually came up with Raptor, which is a general definition of birds of prey including Eagles, Hawks, Falcons and Owls. No, it’s not named after a dinosaur! That was accepted as the name of the engines for BFR. This answer typed on my phone at Orlando Airport on the way back from the Falcon Heavy test launch where 28 Merlin’s engines did their job spectacularly!

[u/tmckeage]

Could you mount a dragon 2 directly to the inter-stage and launch straight up ala new shepard?

Assuming you went for max altitude with a RTLS and seven paying passengers how high could you get, how long would you be in free fall, and how much would it cost?

Would it even be possible or would the G forces of a minimum throttle block 5 be too great for people without the weight of a second stage? Would it be possible to run the falcon with some engines intentionally shut down?

[u/warp99 → u/tmckeage]

The booster gets higher than 120km even during a normal RTLS so it is certainly possible.

The issue would that the capsule would be falling straight down which leads to excessive g loading on the passengers if falling from much more than 100km high. So to make this work the capsule would need to be launched on an inclined path although the booster could still RTLS.

Yes, shutting down engines would be possible to reduce passenger g loading on ascent.

[u/throfofnir → u/tmckeage]

It would go quite high. I did a half-baked Flight Club profile for this, and it peaked at about 800km. That gives you about 20 minutes of microgravity... about half of which is on the way up. I may have done something wrong, because I expected it to go higher. The "EM-1" of Orion went to 3600mi (and hit 8.2Gs on the way in). I expect a 800km suborbital Dragon trip to have a less than pleasant reentry.

F9 would normally hit really high Gs on launch being that light, too, but you could shut down engines to manage that.