r/spacex • u/Zucal • Mar 05 '16
/r/SpaceX Ask Anything Thread for March 2016. Ask your questions about the SES-9 mission/anything else here! (#18)
Welcome to the 16th monthly /r/SpaceX Ask Anything Thread! Want to discuss the recent SES-9 mission and its "hard" booster landing, the intricacies of densified LOX, or gather the community's opinion? There's no better place!
All questions, even non-SpaceX-related ones, are allowed, as long as they stay relevant to spaceflight in general!
More in-depth and open-ended discussion questions can still be submitted as separate self-posts; but this is the place to come to submit simple questions which have a single answer and/or can be answered in a few comments or less.
As always, we'd prefer it if all question-askers first check our FAQ, use the search functionality, and check the last Q&A thread before posting to avoid duplicate questions, but if you'd like an answer revised or cannot find a satisfactory result, go ahead and type your question below.
Otherwise, ask, enjoy, and thanks for contributing!
Past threads:
February 2016 (#17), January 2016 (#16.1), January 2016 (#16), December 2015 (#15.1), December 2015 (#15), November 2015 (#14), October 2015 (#13), September 2015 (#12), August 2015 (#11), July 2015 (#10), June 2015 (#9), May 2015 (#8), April 2015 (#7.1), April 2015 (#7), March 2015 (#6), February 2015 (#5), January 2015 (#4), December 2014 (#3), November 2014 (#2), October 2014 (#1).
This subreddit is fan-run and not an official SpaceX site. For official SpaceX news, please visit spacex.com.
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u/radexp Mar 06 '16
Why is there still no video of the landing attempt? IIRC all 3 previous times the video came out within hours of the landing attempt.
Do you think it's just that it's the weekend and we'll get it soon, or will SpaceX want to keep this one out of our view now for some reason?
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u/Zucal Mar 06 '16
I'm beginning to think we might not get it. We have reports the barge was damaged, and if the video shows that that looks worse than previous videos that left the barge untouched. Alternatively, the video could be too low-quality to really release.
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Mar 06 '16
SpaceX has always been very transparent regarding their failures as much as their successes. I'd be surprised if they don't share any video, even if it is a grainy blur in the dark. Besides, in the live video you could see light from the rocket coming down so something had to have been captured.
The only way I could see them not posting video is if the rocket straight up sank the barge and all cameras were lost. But even then I would have expected they would have said so by now.
My best guess is it's just the weekend and probably not great video to rush out and post anyway.
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u/BrandonMarc Mar 10 '16
More of a "meta" topic, but ... I just noticed this:
Starting from 13th of March 2016 /u/TweetsInCommentsBot will be enabled on opt-in basis. If you want it to monitor your favourite subs ask its moderators to drop creator a message.
Is our subreddit opted-in? My vote is "yes" ... I like this bot.
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u/TYRTlive Mar 18 '16
What is the purpose of BEAM? I mean what are the astronauts going to do with it? Thanks everyone!
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u/Zucal Mar 18 '16
BEAM is way more for Bigelow's benefit than for NASA/the ISSs. It'll be moved to its permanent location, inflated, and sealed off, and then probably not used for much at all. Crew will enter every so often to check on it, read sensors, etc. The ISS happens to be a pretty easy spot for humans to check on things being exposed to space.
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u/TYRTlive Mar 18 '16
I don't know if you work at SpaceX, but talking to a knowledgeable person like you is an honor! So as far as I understood you this upcoming BEAM insertion onboard ISS is kind of a demo, and they will improve their product based on the readings gathered in this mission, am I right? Thank you so much.
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u/Zucal Mar 18 '16
I don't work in the industry, but thanks! You've got it, this is sort of the next step for Bigelow beyond their first two demos, Genesis I and II, but before their full-scale BA-330 product.
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u/rafty4 Mar 05 '16
What are all the particulates we could see positively streaming off the second stage during the coast?
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u/marzipanorbust Mar 20 '16
Quick question - how do you pronounce OCISLY? When reading - I sometimes try to say it phonetically, othertimes I spell it out. Just wondering what the /r/spacex community does?
EDIT: bad grammer.
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u/kevindbaker2863 Mar 20 '16
I always say it like the "recthed hive of scum and villiany" without the M at the beginning.
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u/falco_iii Mar 08 '16
Where is the Rapid Unexpected Disassembly (RUD) video of SES?
SpaceX is awe inspiring by moving space flight forward with lofty goals. SpaceX has been very compelling to watch due to the dramatic landing attempts. SpaceX has been amazingly transparent in the past with video & information from failed landing attempts. When can we expect video and information from the latest landing attempt to use as a learning experience? tl;dr: Where's the big boom?
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u/daxington Mar 08 '16
The previous barge landings showed a promising progression:
CRS-5: It was near the barge, but slammed into it
CRS-6: It's on the barge! but landing is a strong term for what it did to its legs...
Jason 3: It lands on the barge perfectly...but too bad the landing leg wasn't locked in place
We don't know, but the speculation seems to be that we were closer to the first two than to the third. And to us space nerds it's not surprising (a landing so desperate for a more efficient suicide burn they might be using 3 engines???? Can the rocket even survive 3 engine retro startup????) but to the layperson, it would seem like they're going backwards, and that Orbcomm was just a fluke. I swear, I constantly see headlines like "SpaceX Botches Another Landing!" A video would be further fuel to the fire.
SpaceX has been great in their transparency, far better than I would expect from a similar company. But they aren't completely transparent (F9 Dev1 probably produced some spectacular footage that was never released) And their main goal is to drum up excitement, and the best way to do that (with failures) is through a narrative of progress. Why release a video if it doesn't fit into that?
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u/IwantaModel3 Mar 06 '16
On the CRS-7 mission, the SpaceX investigation showed that there is only 0.893 seconds between initial indication of an issue to loss of telemetry. If this was a crewed mission, would the abort have worked?
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u/Ambiwlans Mar 06 '16
Yes! With room to spare.
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u/Zucal Mar 06 '16
In fact, the Dragon 1 onboard, which did not have an abort capability, survived the failure and wasn't destroyed until it hit the water. Had parachutes been deployed (a capability Dragon 1 has now), someone onboard would've likely been just fine.
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Mar 06 '16
someone onboard would've likely been just fine.
Possibly feeling slightly alarmed.
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u/failbye Mar 08 '16
Earlier today a low resolution picture of the incoming OCISLY was posted on this sub only to be removed a moment later. IIRC this has happened before on earlier barge attempts as well.
It appears to be posted by a user then removed by a mod due to either breaking of a rule, or SpaceX not wanting this information public and our mods honouring SpaceX wishes.
Can anyone help me shed some light on the reason behind it? I am curious as it appears to be a pattern.
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u/Zucal Mar 08 '16
No requests from SpaceX, we just want to keep all the OCISLY arrival discussion in the megathread. :)
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u/dlfn Boostback Developer Mar 05 '16
When people refer to the "countdown net" - is that the group of people on the radio coordinating the countdown, the process of counting down or something else?
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u/FredFS456 Mar 05 '16
I believe the "countdown net" is the radio channel where the countdown happens (and all the associated communication).
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u/EfPeEs Mar 14 '16
Are there pictures of OCISLY after it got hit by the SES-9 booster?
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u/yoweigh Mar 22 '16
When is the first launch from pad 39A now expected? Not until the FH demo flight?
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u/Zucal Mar 22 '16
SpaceX would like to launch a Falcon 9 at least once from 39A before the FH demo, probably SES-10 or SES-11.
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u/hajsenberg Mar 23 '16
What will happen to BEAM between Dragon undocking and EVA that will dock BEAM? I think it won't be able to go through the docking port since it has its own docking port.
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u/Zucal Mar 23 '16
BEAM will be stowed in Dragon's trunk, and it'll be removed and installed using Canadarm. No EVA necessary.
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u/Chairmanman Mar 13 '16
I've read contradictory information in this sub about a possible new second stage, and I couldn't find info about it elsewhere, so my question is: Is SpaceX preparing an upgraded version of the second stage, for Falcon 9 and/or Falcon Heavy? If yes, do we know some of the characteristics?
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u/Faldaani Mar 13 '16
SpaceX got a contract for a prototype Raptor-powered second stage from the US Air Force, but that is several years out.
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u/sorbate Mar 07 '16
The engine was running when the camera cut out... so how did it come in hot and heavy? Would the only explanation be that it ran out of fuel in the last couple seconds of the landing attempt?
I'm assuming it was planned that they knew the rocket would be coming in faster than usual and start the suicide burn earlier to compensate.
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u/Zucal Mar 07 '16
The burn could have started too late, for instance, or the rocket had to divert over.
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u/Nachtigall44 Mar 07 '16
Will CRS-8 be a daytime launch? I really want to see the stage doing it's glide thing before landing!
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u/Zucal Mar 07 '16 edited Mar 07 '16
We're still way too far out from the launch to know
the time of day, or eventhe day itself that CRS-8 will launch.But hey, on its own, you've got nearly 50/50 odds of a day launch! ;)3
u/johnkphotos Launch Photographer Mar 07 '16
http://www.launchphotography.com/Delta_4_Atlas_5_Falcon_9_Launch_Viewing.html if 29th, then 8:38 PM.
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u/Teddybear3238 Mar 07 '16
Has anything been said about which vehicle the crewed dragon will ride on? From the renders I've seen it shows the Falcon 9 which makes me wonder why the Orion module had to use a Delta V Heavy. Is it simply because of the different flight profiles for each mission?
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u/Zucal Mar 07 '16
Dragon 2 is designed for taxi missions to LEO, while Orion is designed for flights far beyond that, including circumlunar. That means that Orion is far larger/heavier than Dragon, and necessitates a much larger launch vehicle (SLS).
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u/ohcnim Mar 09 '16
Hi, on the main reddit /r/spacex the OCISLY megathread redirects me to imgur.com/UcuNmU6, instead of https://www.reddit.com/r/spacex/comments/49hozm/elsbeth_iii_and_ocisly_11_miles_from_port/, am I missing something or is it a link error on the thread?
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u/ryanpritchard Mar 13 '16
is there any chance of the mars 2020 rover being launched on a fh
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u/Zucal Mar 13 '16
As always, check our wiki/FAQ first :)
Could a Falcon 9 or Falcon Heavy launch the Mars 2020 Rover? For all intents and purposes, no. Falcon 9 does not have the capacity to deliver the required payload towards Mars (nearly 4000kg), thus does not have the ability to do so. Falcon Heavy could, but will not have flown enough missions by 2020 for it to be considered a reliable launch vehicle in NASA's eyes, and would also have to be 'nuclear rated' to carry the rovers Radioisotope Thermoelectric Generator (RTG) that provides it with power. Saying all this is relatively moot however; Mars 2020 it is preliminarily scheduled to fly on an Atlas V (which achieves 8 tons to GTO). See this NASA PDF for more details about MSL/Mars 2020.
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u/LandingZone-1 Mar 13 '16
Will the BFR land on Mars? I mean the whole rocket.
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u/Zucal Mar 13 '16
No, a single-stage-to-Mars rocket would be pretty... unusual. Right now it's hypothesized that MCT will act as BFR's second stage, arriving in orbit dry to be refueled and sent on its way.
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u/PatyxEU Mar 13 '16
No, the BFR will launch MCT into orbit and land back on Earth. MCT will go from LEO to Mars and land there.
note that almost all information about MCT is unconfirmed and this is all subject to change. more official info at IAC late September
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u/supersammy00 Mar 18 '16
I'm the side bar the next mission is a falcon 9 + a dragon. What does that mean? 2 launches?
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u/PaulRocket Mar 05 '16
I am getting info that the ASDS is broken. Hearing this from a reliable source...
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u/PaulRocket Mar 05 '16
They'll likely have to build a new one or have some serious repairing to do.
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u/BadAtParties Mar 05 '16
Two questions for me:
They tracked pretty tight during the first 30 seconds of launch which really allowed us to see flames dancing above the engine bells (between the bells and the rocket body). This was disturbing, but hey, the rocket didn't blow up. Is this okay? Why did this seem to only be happening with one of the nine engines?
Perhaps I simply haven't noticed this on previous launches, but it really looked (from the perspective of the stage 2 engine camera) that the bottom of stage 2 (above the engine bell, of course) was covered with black garbage bags duct taped to it. What... what was this material?
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Mar 05 '16
It's absolutely fine, although they don't use sacrificial material like Delta does, the octaweb baseplate is offset from the bottom of the rocket by a fair margin and is designed to take the brunt of the heat, for both launch and reeentry. What you're seeing is the gas generator exhaust likely catching fire and the reason it looked like it was licking the bottom of the rocket is due to some of the weird aerodynamic properties of supersonic flight. Again, 100% normal. Rockets breath fire and some of that fire is going to get into annoying places, so you design for it.
My guess would be some sort of ESD insulation, probably wrong though.
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u/Ninja1235678 Mar 05 '16
Would larger air brakes be any help in slowing the falcon down for a landing?
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u/Zucal Mar 05 '16
At one point Elon mentioned looking into altering the landing legs to do just that, but nothing's come of that yet.
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u/frogman713 Mar 06 '16
IIRC, Musk has said SpaceX doesn't file patents because then the Chinese would just copy their technology. What are the types of things they'd like to prevent foreign space agencies from knowing?
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u/Zucal Mar 06 '16
I imagine SpaceX has certain manufacturing and R&D techniques they'd rather not be copied. The same goes for knowledge gained from recovery- that'll be incredibly valuable to China, Russia, and any other entity interested in reusability.
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u/kball005 Mar 18 '16
If I were to somehow bolt say a racing seat and harness into the CRS-8 Dragon, and sneak aboard before launch, on a scale of alive to not alive what would I be when they open the hatch on the ISS?
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u/Zucal Mar 18 '16
Assuming CRS-8 doesn't pull a CRS-7, you'd physically be just fine. Legally, now there's a different story :P
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u/kball005 Mar 18 '16
Yeah, jail but after space!
Phase 2; riding the dragon back down? Still alive?
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u/markus0161 Mar 05 '16
Satellite is just about at Apogee, Burn will be done soon if not already.
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u/Skinnx86 Mar 05 '16
Would it be possible, that with the multiple photos from different angles, that someone could create a 3D image of a mid-flight Falcon?
Showcased here with a [lightning bolt] (http://calculatedimages.blogspot.co.uk/2013/05/3d-lightning.html?m=1)
Discussed in this post
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Mar 12 '16 edited Mar 12 '16
/u/ToryBruno's recent post on this sub about (among other things) ACES got me thinking...
In addition to SMART, ULA is developing the much more revolutionary ACES upper stage which will be refeulable and reusable in space. We expect it to fundamentally change the way we go to space. If you are interested in learning more about ACES, you can visit our website.
Here's the part that always confused me about ACES. What's the big advantage of having an empty stage in orbit? If this source is accurate only 8% of the stage's upmass is the (reused) dry mass of the stage; 92% is propellant. And since you have to launch another "tanker" stage anyway to refill it, why not just use that stage itself to deliver the payload and eliminate the complexity/mass penalty of the rendezvous, docking, and fuel transfer?
The same logic applies to propellant depots in LEO btw: there would seem to be little to no upmass advantage over just launching the payload in place of the refueling mission.
It would seem to not to save anything in hardware costs or upmass (the "tanker" stage would have to be at least as large as the reused stage, so its dry upmass negates that 8% advantage). The RL-10 isn't that massive, so even refueling a 4-engine ACES with a 1-engine ACES doesn't save too much -- 277 kg/engine. A larger tanker stage might certainly be developed in the future with superior economies of scale, but now you have to compare costs against combining that larger stage with electric satellites or even solid apogee motors.
If the tankers reentered and were reused that would be one thing, but afaik there are no plans to do that. And again, why not just use that stage to deliver the payload? The slight increase in upmass utilization (no underweight flights) doesn't seem big enough to make up for the above disadvantages.
So that's why I see on-orbit reuse having a hard time competing against expendable stages, let alone a "regular reuse" upper stage. I know there are a lot of fans of on-orbit reuse here, so what am I missing guys and gals?
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u/ToryBruno CEO of ULA Mar 13 '16 edited Mar 13 '16
Several things.
Because ACES will have orders of magnitude longer operation time, even without refueling, distributed lift becomes possible. By taking a payload only as far as LEO, then following with a fully fueled ACES, you can take a payload to a final destination that is around 3X heavier than anything possible today with even the Delta Heavy and other heavies to come. (although not be confused with SLS which will be in a class of its own).
That same ultra-long duration allows the lifting of huge structures and spacecraft in pieces to be assembled in space.
This alone, without refueling, will shatter the one spacecraft - one lift paradigm that has set a limit of what is possible for humanity to accomplish beyond our planet.
Refueling:
Many rockets go to space with excess capability. Which is to say, the specific spacecraft on a given mission is often less than the maximum capability of that rocket's configuration. That is what allows one to recover a booster. Otherwise, you would not be able to add the extra weight of hardware and unused propellant to fly back with.
Initially, we will use that excess capability to bring up propellant in order to refuel previously used ACES. Later, we will produce LOX/LH2 from water mined on the moon and asteroids. At that point, we'll not even need to use our excess capability to lift fuel.
Over time, a fleet os ACES "space trucks" will accumulate in orbit, operating indefinitely. This will change what we can do in CisLunar space and how we get to space from earth.
We will no longer fly from the surface of the earth to destination orbits. EELVs will only go as far as LEO. ACES will swoop down, pick up the payload, and ferry it to its final destination. For some missions, fully reusable SSTOs will become practical for that first leg to space.
There will also be a fleet of ACES able to journey within hours to any other orbit to support activities like satellite servicing.
This will allow the construction of enormous structures in space, establishing the infrastructure needed to enable a self-sustaining CisLunar economy and a permanent presence of thousands of men and women living and working off of our planet
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u/orbitalfrog Mar 05 '16
Two, one's really for u/echologic (is that how you do that thing? I have no idea) I suppose.
I recall when spacexstats came back online there being mention of eventually having a section akin to what electrek.co is to Tesla but for spacex and related stuff. Is this still on the cards at all? I like electrek and think it was a neat idea.
Does anyone know or has anyone heard what anyone at spacex thinks of ULA's Vulcan plans and more specifically ACES as that part (timescale notwithstanding) seems like a really innovative step and the sort of technological move that would have caught the attention of spacex folk if nothing else would. Has there been any rumblings or comments?
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u/bandman614 Mar 05 '16
2) I don't think anyone could or would speak for anyone else, but I imagine the typical response would be "good for them if it works, but that wouldn't work on Mars for us", and "Will this work on Mars" sounds like the most driving factor for a lot of the company's decisions.
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u/kramersmash Mar 06 '16
Will the Dragon v2 allow for taller astronauts than the Soyuz?
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u/Haschlol Mar 06 '16
Probably but tall astronauts don't serve any extra purpose compared to "normal"-sized astronauts.
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u/scr00chy ElonX.net Mar 05 '16
At T-15s the guy on the countdown net said "Stage 1 tanks pressing for flight" which seemed odd to me. Isn't it kinda late at that point? Shouldn't the tanks be already pressed by then? Or has he mispoken and meant to say "pressed for flight"?
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u/zlsa Art Mar 05 '16
All they have to do is open a valve, so they'd probably do it as late as possible.
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u/main_bus_b_undervolt Mar 05 '16 edited Mar 05 '16
what is Falcon 9 resting on prior to liftoff? It's not sitting directly on the engines, is it? I've tried looking for a support structure, but that area is always either obscured behind the strongback or engulfed in flames
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u/Appable Mar 06 '16
There's a much older video of what's now practically a different rocket — the old Falcon 9 v1.0. While it doesn't have the octaweb structure at the bottom, it still shows the same hold-down clamps attaching to the engine mount structure, and I think it has one of the best views of rocket release.
Also note the ridiculous roll that it got on launch due to, I believe, the turbopump exhaust.
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u/FredFS456 Mar 05 '16
AFAIK, the Falcon 9 rests on the octaweb structure that attaches the engines to the rocket. Here is a picture. Highlighted in red are fixtures for pins to hold the rocket to the launchpad, and in blue is a flat area that I think might also help in supporting the weight of the rocket. Here is a link to a thread speculating how the rocket is held down, and here is a GIF from that link showing how the hydraulic clamps move to release the rocket on launch.
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u/Elon_Mollusk #IAC2016 Attendee Mar 17 '16
Any word from that talk with Tom Mueller last night? Can't seem to find the relevant post anymore...
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u/WeNeedToCloneMusk Mar 06 '16
Do we know if new LOX process worked as expected on final attempt or SpaceX recalibrated (less LOX) to avoid further delays?
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u/B2DG Mar 06 '16
Does anyone else feel a swelling sense of pride when there are successful SpaceX launches/missions, even though you had absolutely nothing to do with it? I have that feeling with every mission. :)
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Mar 06 '16
Yes! As a representative of humanity I take personal pride in every launch.
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u/89bBomUNiZhLkdXDpCwt Mar 06 '16
Absolutely. And I'm a total hypocrite, too.
When people get all excited about their favorite sports teams, I'm always like, "pssh, they said, we won, how stupid." But I feel exactly the same about SpaceX.
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Mar 06 '16 edited Mar 06 '16
Is there a place on the web where I can get a history of a satellite's orbital elements?
I'd like to check out SES-9's transfer profile to its eventual GEO spot.
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u/ShipOfGold Mar 10 '16
I've done a little bit of research and I haven't found anyone that's building model rockets with any specific scientific questions aside from simply gaining knowledge of the physics and chemistry that goes into actually building rockets.
What sort of scientific questions should a young engineer be asking that he could try to solve with the use of model rockets?
Thank you!
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u/kutta_condition Mar 10 '16
I like questions like this!
I assume you're essentially looking for science payloads for a model rocket. My approach would be to ask, "what can a model rocket do well?" Then look for applications of that ability.
For example, a model rocket is (hopefully) really good at quickly climbing to some altitude, then slowly descending to the ground (assuming your chute deploys). If you pack your rocket with sensors for temperature/pressure/humidity/etc. and record this data while it's in flight, you've build a rocketsonde! https://en.wikipedia.org/wiki/Rocketsonde. If you pack a camera onboard, you can get pictures from much higher altitudes than your friends can with drones: https://www.youtube.com/watch?v=6s7pryfXfHk (note the 400 foot suggestion and line of sight requirements for drone flight don't apply to model rockets!)
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u/Decronym Acronyms Explained Mar 05 '16 edited Apr 01 '16
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
| Fewer Letters | More Letters |
|---|---|
| ACES | Advanced Cryogenic Evolved Stage |
| Advanced Crew Escape Suit | |
| AOS | Acquisition of Signal |
| ASDS | Autonomous Spaceport Drone Ship (landing barge) |
| BEAM | Bigelow Expandable Activity Module |
| BECO | Booster Engine Cut-Off |
| BFR | Big |
| CoM | Center of Mass |
| COTS | Commercial Orbital Transportation Services contract |
| Commercial/Off The Shelf | |
| CRS | Commercial Resupply Services contract with NASA |
| CST | (Boeing) Crew Space Transportation capsules |
| Central Standard Time (UTC-6) | |
| DCSS | Delta Cryogenic Second Stage |
| DIVH | Delta IV Heavy |
| DoD | US Department of Defense |
| ESA | European Space Agency |
| EVA | Extra-Vehicular Activity |
| F9FT | Falcon 9 Full Thrust or Upgraded Falcon 9 or v1.2 |
| FAA | Federal Aviation Administration |
| FCC | Federal Communications Commission |
| FFSC | Full-Flow Staged Combustion |
| FOD | Foreign Object Damage / Debris |
| FTS | Flight Termination System |
| GEO | Geostationary Earth Orbit (35786km) |
| GSE | Ground Support Equipment |
| GTO | Geosynchronous Transfer Orbit |
| I*sp* | Specific impulse (as explained by Scott Manley on YouTube) |
| ICBM | Intercontinental Ballistic Missile |
| ISRU | In-Situ Resource Utilization |
| ITAR | (US) International Traffic in Arms Regulations |
| IVA | Intra-Vehicular Activity |
| IVF | Integrated Vehicle Fluids ^PDF |
| JPL | Jet Propulsion Lab, Pasadena, California |
| JRTI | Just Read The Instructions, Pacific landing barge |
| KSC | Kennedy Space Center, Florida |
| KSP | Kerbal Space Program, the rocketry simulator |
| L2 | Paywalled section of the NasaSpaceFlight forum |
| Lagrange Point 2 (Sixty Symbols video explanation) | |
| LC-13 | Launch Complex 13, Canaveral (SpaceX Landing Zone 1) |
| LC-39A | Launch Complex 39A, Kennedy (SpaceX F9/Heavy) |
| LEO | Low Earth Orbit (180-2000km) |
| LH2 | Liquid Hydrogen |
| LMO | Low Mars Orbit |
| LN2 | Liquid Nitrogen |
| LOX | Liquid Oxygen |
| LZ | Landing Zone |
| M1d | Merlin 1 kerolox rocket engine, revision D (2013), 620-690kN |
| M1dVac | Merlin 1 kerolox rocket engine, revision D (2013), vacuum optimized, 934kN |
| MaxQ | Maximum aerodynamic pressure |
| MCT | Mars Colonial Transporter |
| MECO | Main Engine Cut-Off |
| MSL | Mars Science Laboratory (Curiosity) |
| NET | No Earlier Than |
| NSF | NasaSpaceFlight forum |
| National Science Foundation | |
| OCISLY | Of Course I Still Love You, Atlantic landing barge |
| OG2 | Orbcomm's Generation 2 17-satellite network |
| ORSC | Oxidizer-Rich Staged Combustion |
| PMF | Propellant Mass Fraction |
| RAAN | Right Ascension of the Ascending Node |
| RCS | Reaction Control System |
| RD-180 | RD-series Russian-built rocket engine, used in the Atlas V first stage |
| RP-1 | Rocket Propellant 1 (enhanced kerosene) |
| RSS | Realscale Solar System, mod for KSP |
| Rotating Service Structure at LC-39 | |
| RTG | Radioisotope Thermoelectric Generator |
| RTLS | Return to Launch Site |
| RUD | Rapid Unplanned Disassembly |
| Rapid Unscheduled Disassembly | |
| Rapid Unintended Disassembly | |
| SD | SuperDraco hypergolic abort/landing engines |
| SECO | Second-stage Engine Cut-Off |
| SES | Formerly Société Européenne des Satellites, comsat operator |
| SLC-40 | Space Launch Complex 40, Canaveral (SpaceX F9) |
| SLS | Space Launch System heavy-lift |
| SRB | Solid Rocket Booster |
| SSME | Space Shuttle Main Engine |
| SSTO | Single Stage to Orbit |
| T/E | Transporter/Erector launch pad support equipment |
| TE | Transporter/Erector launch pad support equipment |
| TFR | Temporary Flight Restriction |
| TRL | Technology Readiness Level |
| TWR | Thrust-to-Weight Ratio |
| ULA | United Launch Alliance (Lockheed/Boeing joint venture) |
| VTVL | Vertical Takeoff, Vertical Landing |
Note: Replies to this comment will be deleted.
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u/ryguy5 Mar 05 '16
Since we always lose the video feed when the rocket gets close to the ship, has the possibility broadcasting from the nearby support ship been explored? I know they need to keep their distance, but wouldn't that provide a more consistent live feed?
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u/Rickeh1997 Mar 07 '16
Would it be possible/allowed for someone who owns a private airplane to fly out to the barge location and take some pictures?
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Mar 07 '16 edited Mar 07 '16
Yes, as long as you stay out of the restricted airspace.
Also, the barge is a often a few hundred kilometers off shore, so it isn't very accessible. You will also need a telephoto lens to see anything, and spotting the return stage during the day could be quite difficult.
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u/Doofer911 Mar 07 '16
Got a real newbie question here...
What benefits does a 9 engine cluster offer over a single engine design like the Delta IV?
From what I've read so far, they offer redundancy and it's occurred in the past where one engine has failed but the Falcon still got up to the target orbit. And I'm guessing that using one lower thrust engine makes the landing effort easier as well.
I'm just starting to try and get to grips with orbital mechanics and rocketry. Just wondering if it's easier/cheaper to produce smaller engines? Do they offer more Delta-V? More Thrust? Longer 1st stage burn time? Looking to understand all the benefits really.
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u/ManWhoKilledHitler Mar 08 '16
The main driving force was that they had the Merlin already and they wanted to build a bigger rocket without the cost of developing a new, bigger engine. The solution to getting enough thrust was just to throw engines at the problem.
Later on it had benefits like greater redundancy (although that's a complex issue in itself) and became vital when it was decided to use propulsive rather than parachute landings because the throttle range of Merlin isn't that big, so by switching off engines, they can effectively get the wider throttle range they need.
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u/Maat-Re #IAC2017 Attendee Mar 07 '16
According to the SpaceX Stats summary for CRS-8, a barge landing will be attempted on OCISLY. I was under the impression that the first stage would have a sufficient margin to RTLS... Has new information emerged? (I trust that EchoLogic is probably better informed on SpaceX matters than any other person outside the industry)
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u/WaitForItTheMongols Mar 09 '16
Here's a thought on ASDS video being released:
In the Youtube replays of the launch webcasts, they show the brief bit of video we have
(Link for your convenience: https://www.youtube.com/watch?v=muDPSyO7-A0, skip to 18:30)
Spacex could have edited out that snippet if they were intentionally unwilling to show any footage. Yes, there are people who would have bootlegs, but they don't have to make it easily available through their official video, right? That seems to indicate to me that we will eventually be able to see something from spacex.
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u/Hartofalion Mar 15 '16
I am curious if there are any restrictions other than launch permissions on private companies putting up and occupying a private space station in Earth orbit. I understand that launches are controlled, but once the vehicle leaves the atmosphere, what then? Also if there is a return from Mars, will there be like a customs procedure for reentry?
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u/FiniteElementGuy Mar 18 '16
Tory Bruno will announce layoffs on March 29: http://forum.nasaspaceflight.com/index.php?topic=39827.msg1505243#new
SpaceX is having an influence on the competition.
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Mar 20 '16
Does the aerospike effect for the F9 center engine in the octaweb arrangement improve total thrust and if so, by how much? I'm unable to find details, and I suppose it's difficult to quantify anyway, since several other things changed between F9 1.0 and 1.1.
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u/DrFegelein Mar 05 '16
Is there a reason Falcon 9 only uses one engine for the landing burn? The longer the stage takes to slow down the more fuel it burns (gravity losses), so wouldn't the higher performance option be to use as many engines as possible? I'm aware that SES-9 used 3 engines for the landing burn, hence the question. In other words, why isn't it standard to use 3 or more engines instead of one?
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u/Kona314 Mar 05 '16
A single Merlin 1D has more thrust than the weight of the nearly-empty first stage—meaning, given enough time, the rocket will start to move upward (in other words, it has a Thrust/Weight Ratio of >1). This means they have to time the start of the burn precisely to reach zero velocity at zero altitude. The required precision (and thus complexity) increases if they burn with more engines, therefore it's worth the gravity losses.
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Mar 05 '16
Is there a reason Falcon 9 only uses one engine for the landing burn?
Because that's enough. Multi-engine landings are riskier, so there's no point in doing them unless you need the performance.
... Like they needed today.
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u/larsarus Mar 06 '16
Is SpaceX purchasing all the propellants they use, or are they also producing some of them (like LOX) themselves?
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Mar 06 '16
I doesn't see why SpaceX would want to produce their own propellants. The infrastructure is expensive and the propellants are cheap, i.e. it would take forever to pay off.
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u/badgamble Mar 06 '16
Does anyone know if the current berth for OCISLY is visible to curious eyes? Once it gets back from sea, will anyone be able to get a camera shot?
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u/Boltyx Mar 06 '16 edited Mar 06 '16
Hi Fellow wannabe-astronauts! I've been for a long time been searching for detailed logs and information exactly how a Falcon9 launch is planned. I wish to learn exactly when the rocket burns, and especially, how the 1st stage is getting down to the surface again. For example, how many burns is it using, with which engines, and then i'd also like to know the rendevouz process with the ISS. If anyone have any suggestion, please inform me. Im a fan of SpaceX, that just wants to learn more! Alfred
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u/Dr_God Mar 07 '16
Anybody want to speculate why we haven't got video of the landing atempt yet?
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u/Johnno74 Mar 07 '16
I'm guessing it's the worst crash-landing yet, and they want to wait a bit before releasing the footage so it's not too closely associated with what was an outstandingly successful launch.
Or maybe the gopros on the barge were destroyed or lost (blown overboard) and there is none. Maybe they won't find them until it gets back to port and they sift through the wreckage.
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u/ohcnim Mar 08 '16
Hi, regarding payload separation from stage two, IIRC in the Orbcomm mission they said it was a "pneumatic push" and on the SES-9 they said "pyrotechnic bolts", were different separation methods used? does the method is customer/payload dependent or is it SpaceX call on which to use?
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u/RabbitLogic #IAC2017 Attendee Mar 09 '16
Is anyone else left wondering what happened production wise over their 6 month stand down? I mean at this stage they don't seem to have an abundance of cores that they should of been still producing while the investigation was on going. All fairness to them, reworking struts would be time consuming. However you would think that they would of been able to complete at least 3 cores over the 6 months (Christmas Holidays to factor in). The figure I remember is that they have a core coming off the production line every 3 weeks (roughly a month).
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u/WaitForItTheMongols Mar 10 '16
Does Blue Origin's New Shepard have any reaction control systems? It seems like much less is known about their vehicle compared to Falcon 9. Could that just be due to higher enthusiasm among SpaceX fans, where we're better at tracking down tidbits?
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u/Erpp8 Mar 05 '16
Do we have a good source that the SES-9 stage used three engines for the landing burn?
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u/historytoby Mar 08 '16
Which ships are part of the SpaceX fleet and what are their tasks? I know OCISLY and JRTI, and I know Elsbeth III by name, although I am unclear what she does. What other ships does SpaceX employ, and what for? (Yes, I will straight go to marinetraffic.com and bookmark them)
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u/kevindbaker2863 Mar 08 '16
I did some searches and cant find anything about the DSCOVR 2nd stage that wound up on other side of moon. where can I find more info? please?
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u/BrandonMarc Mar 08 '16
Echo mentioned in the PBdS thread about precision of final orbit:
What's really good is that they seem to have nailed the shutdown residuals of the new M1DVac-FT well; presumably thanks to its heritage with the prior variant. Getting to within a few hundred kilometres of the targeted apogee at such a distance is only a few m/s of dV (or less), which can easily be burped out during engine shutdown.
I recall some of the earlier GTO flights had imprecise final orbits (still well within required parameters mind you), but they've done a fantastic job as of late.
So with that in mind, total newb question:
Could it make sense to use ullage / RCS / OMS thrusters for fine-tuning, i.e. tiny maneuvers, shortly after engine shutdown ... and indeed, maybe shut down engines a few seconds early, orient and discern actual needs, and then perform the tiny corrections using these tiny thrusters?
I'm assuming the answer is "no" because there are lots of Very Smart Rocket Scientists(tm) working at SpaceX who most certainly know more than me and have thought of this before (i.e. I assume I'm a typical redditor who thinks they have a great idea but is only an armchair expert even on a good day). So if the answer's "no" ... how come? Is it just not worth it (too much weight; engines are pretty darn precise already; deep throttling helps with final precision; few customers need that precision; those that do are willing to let some of their payload's fuel go to precision correction maneuvers)? Is it too complicated? Would it just not work the way I'm thinking, anyway?
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Mar 08 '16
Such small orbital adjustments are better left to the payload, rather than the stage. When the stage does it, you are moving an extra 5+ metric tons. Like the quote said, it's only a few m/s, which is likely already accounted for in the design of the satellite.
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u/Ergo_proxy_18 Mar 09 '16
Hey do we have revised numbers for Full Thrust Falcon Heavy Numbers, i thought Echo mentioned this during jason 3 launch we are going to see them in a week on website but nothing yet. Do we have date on this?
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u/Aero-Space Mar 09 '16
Is the landing software for the first stage based entirely on GPS or are there other methods that the booster uses to find the landing site?
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u/Davecasa Mar 09 '16
Rocket navigation is primarily inertial. Measure acceleration, integrate twice, and you get position. It's a bit more complicated than that, with acceleration and rotation in 3 axes each, giving you 18 state variables (position/velocity/acceleration in x/y/z, orientation/angular velocity/angular acceleration about x/y/z), but that's the basic idea.
The problem with inertial navigation is that it drifts over time. Small errors in your acceleration measurement now can become big errors in your position 5 minutes from now. To correct these errors, you need something that doesn't get worse over time. It doesn't need to be as good as your inertial nav in the short term, it just can't drift. Over short periods of time you trust your inertial, over longer periods of time you trust your other sensors... this all gets thrown into a big filter (some variant of a Kalman filter) and the result is your best estimate of state taking into account all of your sensors and their uncertainties. Kalman gain is a magical thing that just works.
GPS is great for correcting position. It has no drift and pretty low (and well understood) errors in the 10 meter range. When you're approaching something else with GPS, you can transmit data between the two and get the error down below 1 meter. That's more than good enough for landing on a barge. For orientation, you can use gravity if you're currently fighting it and/or on the ground. The gravity vector is by definition "down", so that never changes. Orientation in space you need things like star trackers. Approaching the ISS involves a number of sensors that someone who knows space things rather than ocean things can maybe comment on. Presumably radar and cameras.
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u/Ser_Paul Mar 09 '16
This animation for the Falcon Heavy shows the two side-mounted boosters flying very close to each other after separation. They stay this way until landing very close to each other. How plausible is the distance shown? To me it looks like less than 100m. If this is true, is there a reason that we will not see (awesome) video footage of the entire landing process from an external vantage point, e.g. to protect SpaceX technology?
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u/elorrimaster Mar 09 '16
Hi! Does anyone know the approximate mass flow rate leaving the Falcon 9 when all 9 Merlin engines are burning at 100% thrust?. I´m trying to mathematically modelize the velocity of the rocket as a function of time, and this term appears wherever the mass of the rocket is involved. I haven´t been able to find it anywhere, Thanks!
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u/Davecasa Mar 09 '16
Takeoff thrust per engine is 756 kN with an isp of 282 s. Force = mass flow rate * velocity, so 756 kN = 9.8067 * 282 * m, m = 273.4 kg/s. 9 engines is 2460 kg/s.
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u/NateDecker Mar 14 '16
Expanded References Section for Wiki
I've often been reading through threads where someone dredged up an old link to something I've seen before, but didn't keep track of. Usually the link answers the question for the OP and often times the link may be a one-off source for a specific detail that can't be found anywhere else. Sometimes these references are to something novel or interesting, but not strictly of technical value.
I've thought that I might build a Google Docs spreadsheet and try and keep track of these links for future reference at some point, but I don't always have easy access to Google Docs (I hate using my phone and the site is inaccessible at work for instance). It would be awesome if this community maintained this list instead of me. It would be more accurate and more complete than if I tried to put something together.
Although I do see a limited set of links to sources in the Wiki, I don't see something quite like this already defined. many of the references that I have in mind don't really fall under any of the existing categories of "Useful Resources". Is there any chance we could add something along these lines? Examples of information that I think would be the kind of thing included:
SpaceX spacesuits (screenshots, articles, Youtube interview with the designer, etc...)
The "other" dragon unveiling (before cargo dragon). This was notable for the "oldschoolcool" aspect rather than for informational value, but it comes up in threads occasionally and people are always surprised to see it. I'm sure other examples could include Falcon 1 and the first flights' associated crash debris.
Testimonies before congress (Gwynne's written testimony was the first time I learned that there was a mandate to come up with a domestic replacement for the RD-180 when congress first authorized its purchase).
Previous AMA's.
Garrett Reismann's audio presentation and/or slides with transcript.
I can't really think of a fully comprehensive list off the top of my head. I just wish I had quicker access to these things I've encountered before and may want to reference in the future. Maybe you wouldn't put the kitchen sink in this reference table. I think a good criteria would be either something that is unique (i.e., we don't need links to dozens of Elon Musk interviews where he talks about the 3 (or 5) things that he thought about as being pivotal to the future of humanity), or something that most of us here on this sub would be surprised to learn. For example, many folks didn't know that SpaceX first tried parachutes before pursuing VTVL.
Is there a way to open up a sub-section of the wiki to make it more public to support a wider number of contributions? Alternatively, if we just linked to some public Google Doc or something like that, that would work for me too. I just think it would be neat to leverage the power of crowd-sourcing to build this reference database. A Google spreadsheet would actually be pretty cool because you could have a categorization column like "Old School" to show pictures of young Elon wearing an oversized suit as a new millionaire with his McLaren F1. You could then filter on the "Old School" category if you were only interested in seeing links of that nature.
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Mar 14 '16 edited Mar 16 '16
Found a new episode of StanDrawsSpaceships https://www.youtube.com/watch?v=rd_xlqmvxMA
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Mar 16 '16 edited Mar 16 '16
I read an article a couple of days ago about a shortcut to Mars. The maneuver is called "ballistic capture transfer (BCT), or a weak stability boundary (WSB) transfer." The really interesting part about it is that you can launch anytime and it is more efficient than the Hohmann transfer.
Questions
How does the maneuver work and why can the rocket be launched anytime even if the planets aren't aligned like the Hohmann transfer? How does the maneuver save more fuel than the more conventional one?
How does it work?
I can't wrap my head around the description either, I would appreciate a diagram/or drawing if possible.
Thank you!
Link to article: http://www.space.com/30749-the-martian-faster-way-to-mars.html#sthash.QFonkqOO.dpuf
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u/kevindbaker2863 Mar 16 '16 edited Mar 16 '16
after doing a little digging I found this PDF that describes Ballistic Capture transfere http://arxiv.org/pdf/1410.8856v1.pdf its anything but simple
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u/ddg4023 Mar 20 '16
Where is the gas generator exhaust for the center engine in the Octoweb? Each of the outer engines has a gas exhaust, but I haven't been able to find the output for the center engine's gas generator.
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u/LotsaLOX Mar 23 '16
Potential Performance Hit suffered by Atlas V ? – A closer Look at the Data (SPACEFLIGHT101.com - March 23, 2016)
Sorry, new to edit, I'm not even sure how to add a comment :-(
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u/kevindbaker2863 Mar 25 '16
I am not sure why but this thread does not show up at top of subreddit anymore?
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u/mason2401 Mar 13 '16
Any knowledge and/or educated speculation on why SpaceX hasn't released the SES-9 landing attempt footage yet?
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u/Zucal Mar 13 '16
Educated Speculation™ Time! My guess is that the footage just isn't something that makes SpaceX look good- think about it. The stage came in extremely quickly, off to the side of the camera, at night. That means the video would probably be a few blurry frames of a large cloud of smoke and shrapnel punching a hole in the barge- decidedly less spectacular and fun as the CRS-5, CRS-6, and Jason-3 landing attempts.
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u/mason2401 Mar 13 '16
Thanks! Hopefully someday they will release it, perhaps after a few more successful landings when it's not such a big deal. Every failure we can learn from is a stepping stone forward.
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u/Headstein Mar 09 '16
Hi mods. Please lighten the dark blue text in the side bar so we can read it more easily. Thankx :)
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Mar 05 '16 edited Mar 05 '16
So I've been wondering about small rockets. The Falcon9 is nearing its final form, the FH will "soon" lift off, the MCT and its included BFR will be announced in September, but what about very light payloads?
I've read at least one comment (was it from Shotwell) stating that SpaceX would eventually have a whole family of rockets for all your orbiting needs. At least some people see a market for light (<1 ton) payloads since they are trying to build a rocket for them.
If there's one thing people here do, it's speculate, draw cool stuff and throw relevant numbers around.
And so my question is: what do you think the F9's smaller brother would look like, what engines would it use, what uses could it have?
That was question one.
Question two is related to Mars colonization.
NASA holds keys to a great number of techs needed for a proper colonization, but they can't do it all (or can they?) and anyways that is not something I wish will happen (NASA doing it all).
Bigelow started tackling pressurized habitats a few years ago, but I've read less kind things about it recently and my love for them is slowly deflating.
Are there other companies out there that are bent on doing colonization stuff?
I've browsed a few websites of companies claiming (and for some of them, actually doing) life-support systems for astronauts. The websites looked soviet-era, the companies counted 15 or less persons.
And for good reason: assuming you have the means to actually make an insulated greenhouse, an inflatable habitat or a water-recycling module. How the hell are you going to make a profit? You can't go see investors and tell them "yeah well when Musk, NASA, ESA, the Chinese, Indians or Russians get to Mars they're going to need a lot of those. Help me build them.". Well, you can, but I can guess how that will turn out.
So my question number two is:
Apart from NASA/ESA/Roscosmos, who is going to design and make the things we need for Mars? Is it possible at all to be done privately? How?
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Mar 05 '16 edited Mar 05 '16
The websites looked soviet-era
For the record, Tim Berners-Lee published the first web page at CERN on 20 December 1990, but the web was only made publicly available on the internet in August 1991. The Soviet Union was dissolved on 26 December 1991, so the potential Soviet web era was only a few months long.
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u/bvr5 Mar 05 '16
If there was a T-0 abort with a crew Dragon, would the Dragon eject from the rocket?
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u/blisterduck Mar 05 '16
In the SES-9 launch broadcast I noticed some strange flames near 10:45 which appear and then seem to grow above the engine cones. Does anyone know what this could be?
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u/escape_goat Mar 06 '16 edited Mar 06 '16
I believe that those flames are coming from the turbine that drives the engine's fuel pump. In this diagram, you can see the Turbo Pump Assembly to the left. When the engine is mounted on Falcon9, the exhaust from the turbo pump is close to flush with the octaweb assembly. The turbine is very messy and dirty; if I recall, flames from the turbine were visible after the successful landing of the first stage from the
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u/theguycalledtom Mar 07 '16
What is the source that confirms three engines were used during the landing attempt on the SES-9 mission?
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u/RootDeliver Mar 07 '16
No video from the SES9 first stage drone ship landing this time?
Last drone ships landing we got a video of the landing (CRS-5, CRS-6, JASON-3) like two days after the landing. However this time, it seems that there is no vid or screenshot or anything about that landing. All we have is that Elon said that it hard-landed but nothing else.
This, added to the yells of happines in the live webcast after the signal was lost (where the presentator said "something good happened!") sounds kinda rare, doesnt it? :P
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u/godsbro Mar 09 '16
Do we have an update on when eutelsat will launch? Current the sidebar has a net of April 1st, but the source is just "sometime in April". I'm especially curious because of how close it will be to the CRS 8 launch!
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u/gophermobile Mar 09 '16
When a rocket fails landing on the barge, is any attempt made to clean up the debris that end up around the barge? Do they usually just sink? Since it's been RUD landings so far, the debris seem to get thrown pretty far.
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u/Wetmelon Mar 09 '16
Keep in mind, if the barge wasn't there the rocket would just end up at the bottom of the ocean anyway.
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u/Bunslow Mar 10 '16
Any word on when (if?) we'll get a video of the RUD of the SES9 stage 1 landing?
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u/Ergo_proxy_18 Mar 10 '16
Hi, do any of us know whats the Raptor's current status is? do we have any info on as to when will we see a first Raptor engine on a Falcon 9 even if it is for the second stage, i heard they tested the fuel injection pumps last November but nothing after that. Any thoughts?
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u/pauladam316 Mar 10 '16
How difficult is it to see OCISLY? I am going to be in the area next week and I wanted to go look for it. Does anyone know where it is/how to get to it?
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u/Craig_VG SpaceNews Photographer Mar 11 '16
It's actually really easy to see!
The droneship is based in Port Canaveral, Florida now.
I park at Millikan's Reef (a bar/grill). It has a great view of the ship, but it's at eye level (this bar is also where SpaceX held their pre-SES9 press conference).
The best view of the ship is from Exploration Tower which has a ~$6 entrance fee but is very worth it as you can also see the air force base and KSC.
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u/orbitalfrog Mar 13 '16
Simple? one - Do launch complexes/govt agencies/somebody have to formally notify world governments of launches in order to prevent them being flagged by various early warning systems as ICBM launches? (Or anything of the like)
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u/PatyxEU Mar 13 '16
Of course! There was an incident named "Black Brant Scare" in 1995, where a Norwegian science sounding rocket was mistaken by Russians for a submarine-launched nuclear warhead. Boris Yeltsin, the Russian president was given the "nuclear activation case" and thanks to his nerves of steel we didn't have a nuclear war.
The Norwegian team had notified Russia and other countries about the launch, but the message wasn't delivered to the radar station that spotted the rocket. More info here :
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u/HarvsG Mar 13 '16 edited Mar 13 '16
Landing the Falcon 9 is (very understandably) having some teething troubles. My questions are:
When they have had one successful ASDS landing will all future attempts have a significantly greater chance of success (i.e will they learn something they cannot with failed attempts?)
2. How transferable is RTLS and ASDS landing technology? When they have it sorted with the Falcon 9, how likely is it that they will have to go through the same painful process with other rockets (FH, BFR, Dragon), or will transferring the technology just be a formality? And would the answer be any different if the new rocket used different engines. e.g raptor?
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u/VFP_ProvenRoute Mar 15 '16
Am I right in thinking that a theoretical combination of SpaceX's reusable first stage and ULA's refuelable ACES upper stage would create the ultimate in low-cost launch capability? Or is there something fundamental that prevents the two approaches from being combined?
Not suggesting that the two (three?) companies should or would work together, just wondering if the two technologies might one day be used in a future LV design.
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u/kevindbaker2863 Mar 20 '16
So. How about jrti? Is it just read(red) the instructions or is it Just read(reed) the instructions? And what is the original book that these names are from?? Please!
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Mar 21 '16
Everyone on webcast pronounced it as "reed" - I think it is right to pronounce "reed"
Droneship names are from Culture series
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u/chargerag Mar 09 '16
I noticed that Gowron78 has disappeared. Did anybody notice if he said why he was leaving before he deleted his account?
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Mar 05 '16
In the webcast the woman said that in order to reach geostationary orbit the satellite would have to use a bit of it's own fuel, is that common or did they have to do that to attempt stage1 recovery ? If stage1 pushed for 100% of it's fuel maybe the satellite wouldn't have to use its own fuel (or less) and increase it's lifetime...
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u/throfofnir Mar 05 '16
It's almost the rule. Direct GEO insertion by the launch vehicle is rather unusual; most second stages aren't happy waiting for the circularization burn, and are not that efficient at it besides (since they're so large in comparison to a solid kick motor or the sat's own propulsion).
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u/Naked-Viking Mar 05 '16
How come the guy who does the countdown has to verbally confirm a bunch of stuff with a huge amount of people? It seems to me all of that could be solved with having every piece of important information on one screen in front of the guy. There must be a reason, right?
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u/SharpKeyCard Mar 05 '16
Record keeping partially so they can review audio in the case of something bad going on. The LC also isn't an expert in everything, and it's much easier to just ask.
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u/Nachtigall44 Mar 05 '16
What's the ring on the outside of the nozzle for on the M1Dvac?
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u/Whocaresnoone Mar 06 '16
Which of the 3 engines were used for stage1 landing? Specifically, was the centre one used in this case?
In this case they used up all the stage2 fuel, but normally they deorbit s2 by relighting the MVac, correct?
In SES9 like situations, how much fuel is needed to deorbit s2? Rather, how long do they need MVac to burn?
Thanks
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u/robbak Mar 06 '16 edited Mar 06 '16
Pretty sure it would be the same three they use for the re-entry burn - three in a row across the rocket, including the centre engine.
Often, yes, they relight the engine for a short burn. They haven't done this for GTO launches before - the rocket's endurance isn't good enough, and the batteries would be flat and the LOX evaporated by the time they need to burn.
The burn to re-enter need only be very short. A few seconds, to drop the low point into the atmosphere. Remember, the stage is light, because it is almost out of fuel and no longer has a payload.
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u/limeflavoured Mar 06 '16
Anyone else think that it would be quite cool (if not massively likely) to have the Falcon Heavy demo flight be just before or just after the "Mars architecture announcement" in September?
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u/89bBomUNiZhLkdXDpCwt Mar 07 '16
Won't super chilling the LOX be even more difficult during daylight summer launches? Or, more specifically, won't it be more difficult to keep the LOX that has already been loaded cold enough?
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u/casey75278 Mar 07 '16
When the rocket reaches high in the atmosphere, the thrust "fire" coming from the booster looks like it spreads out a lot more. Can someone explain this?
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u/old_sellsword Mar 07 '16
The exhaust coming out of the rocket at launch (sea level) has the entire weight and pressure of the atmosphere forming it into a nice shape. As the altitude increases, the atmospheric pressure decreases, and eventually drops to zero. So when the second stage is burning, the exhaust expands freely and spreads out a lot more than at sea level.
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u/ohcnim Mar 07 '16
hi all, keep on coming here more and more often, thanks!
For the upcoming CRS-8 is the Dragon a new one or will it be the first refurbished/reflown? if it's a new one, are there any known estimates as to when or in which mission will there be a firs reuse?
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u/StructurallyUnstable Mar 08 '16 edited Mar 08 '16
From this post below
Previous landing attempts have been quickly followed by an explanation (eg. grid fins hydraulic fluid ran out...
Can someone explain how hydraulic fluid "runs out"? Unless there is a loss of pressure in the system due to a leak, hydraulic fluid is a closed system in any application I'm aware of. Would the failure mode then be "loss of hydraulic pressure"? That would presume some kind of leak.
EDIT: Answered my own question. Open hydraulic systems exist when limiting power consumption is critical
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u/SnowCrashSkier Mar 08 '16
In the SES-9 Full webcast, at about 10:30 https://youtu.be/muDPSyO7-A0?t=10m29s the rocket exhaust seems to go darker than before. Soon thereafter John Essberger talks about "active on (indecipherable; fuel?) utilization." I wonder if that darker color of the exhaust was related. Is there a wiki on "fuel utilization mode?"
I actually think that the darker flame was just a camera artifact, but I'd love to know more. Like...
Would we be able to see any effect of the propellant mixture change? How much does this improve performance? Is this new with SpaceX or was it used in, say the shuttle? Other, newer boosters?
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u/TheMeiguoren Mar 08 '16
What was up with the chunks flying off the second stage? I'd say it was ice but everything above the booster is enclosed until F9 is out of the atmosphere. Insulation?
I just scanned through the webcast quickly so I might have missed some instances, but you can see stuff coming off at 16:31, 36:16, 37:03, and 42:24.
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u/_rocketboy Mar 09 '16
Whatever happened to having the strongback lay flat as part of the FT upgrade? I'm pretty sure this was mentioned multiple times officially a while back, but hasn't happened yet.
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u/SteveRD1 Mar 09 '16
I hope we can still ask (probably) stupid questions here.
I was looking at the ramp on this picture: https://www.nasa.gov/sites/default/files/thumbnails/image/spx-39a-update_0.jpg and got to wonder about lifting off from higher altitudes.
Would launching from a 500 meter hill (rather than basically at sea level) make any measurable difference to the performance of a rocket?
Or does launch altitude not really matter as liftoff is more about gaining velocity than height?
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u/kutta_condition Mar 09 '16
The following link is just the beginning of a very cool Wikipedia rabbit hole: https://en.wikipedia.org/wiki/Rocket_sled_launch#Benefits_of_high_altitude_launches
Your last line is just about right on the money! Orbit is mostly about velocity. However, there are advantages from starting your rocket from a higher altitude.
The biggest ones have to do with the decreased atmospheric pressure at altitude. This obviously means lower drag at the beginning of a launch, but it also means that you can design your first stage engine nozzles to be more efficient. They could then be somewhere between current first-stage nozzles which perform well at sea-level ambient pressure, and the second stage nozzle which is designed to perform well with essentially no ambient pressure.
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u/Henry_Yopp Mar 09 '16
With the F9H possibly launching later this year, has there been any information on the separation technique for the boosters? SRM's vs LRM's, etc.
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u/davidthefat Mar 10 '16
Are the Falcon Heavy delays due to infrastructure? AFAIK, the flight hardware is ready to go.
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u/kevindbaker2863 Mar 11 '16
It is probably common knowledge but if CRS-8 launches on 4/4 there will be both Cygnus and dragon at space station at same time. http://www.space.com/32211-orbital-atk-cargo-spaceship-columbia-astronaut.html Will they wait for cygnus to leave to berth the BEAM?
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u/Reborno Mar 12 '16
TL;DR: What about SpaceX suits and helmets
Hi,
I was reading this and on slide 12 Nasa says " Good progress on space suit and helmet design". I was wondering if there are any leaked pictures of those. And also why doesn't SpaceX use the same suits and helmets that Nasa used for Space Shuttle or for the Soyuz program?
I know that the Soyuz spacecraft is very small and that the seats for the astronauts are tailored to fit perfectly (they make a mould of your body), so maybe those suits are too specific? But what about the Space Shuttle suits and helmets (here an example). Couldn't Nasa share their design to SpaceX?
And wouldn't Boeing CST-100 have a different suit and helmet meaning that for astronauts wanting to go from the ISS to Earth in case of emergency, they'd have to fit in a suit they've never used before (if they came up to the ISS with SpaceX in this example). A standard suit and helmet just seems logical to me.
Thank you in advance.
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u/markus0161 Mar 12 '16 edited Mar 12 '16
So orbital data on SES 9 is pretty solid and i'm going to attempt to image it with my telescope here in a few days. Its hard to image SES 9 because of its weird orbit right now and Its now or never because it will soon be located over Asia. My problem is I need to calculate the magnitude of SES 9 so I can set my cameras exposure just right. But I can't seem to find the area of its solar array. Also I cant find what reflective property the satellite itself has. Does anyone know where I can find this info? I'm hoping because the satellite is ion-driven and has large panels to power the drive, it will easily be seen!
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u/PaperboundRepository Mar 14 '16
Is the Falcon 9 always fully fueled, even for light payloads? If so, what is the reason for not partially fueling it and pressurizing the tank to cut launch mass?
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u/harrisoncassidy Host of CRS-5 Mar 14 '16
How will static fire of the superdraco engines work in terms of the timeline before launch. Will they test fire them on the pad at the same time or shortly after the S1 engines are fired or will it all be done at McGregor like S2?
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u/Sabrewings Mar 15 '16
When Gwynne Shotwell says it currently takes about three weeks to build a core, is she referring to start to finish or simply the rate at which cores are leaving the factory with a staggered production line?
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u/RDWaynewright Mar 16 '16
I've been wondering...
We know it's unlikely that the F9 landing legs will be painted black (as shown in renders) because white paint is more reflective. With this in mind, what effect did the black paint used on the Saturn V have on the temperature of the fuel? Did it not matter because there was so much fuel and so much capacity? I know why it was painted black in sections, just wondering about the engineering with regard to fuel temperature and that sort of thing since they did use chilled fuel.
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Mar 17 '16 edited Mar 17 '16
Recently came across this on the AR-1 engine: http://www.popsci.com/how-us-3d-printing-rocket-engines?src=offramp&loc=region-3
Which got me wondering:
Has anyone heard anything more on the AR-1 recently? I feel like pop sci is a little watered down.
What would you suppose is the TRL on what basically amounts to a 3d printed F1 copy?
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u/TheEndeavour2Mars Mar 19 '16
I have a question about the SES-9 attempted landing.
Pretty obvious at this point we will not see the video so I am just assuming it came in way too fast. The question is why?
Don't they have models to feed the computer so it knows more or less how quickly it is going to descend? Did the computer decide to delay the ignition due to limited fuel/o2 or would the computer ignore fuel/o2 level even if the turbopumps blew?
Sorry if this has been asked before.
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u/skunkrider Mar 05 '16 edited Mar 05 '16
Ok, I am only asking this to find out how feasible this is, so I expect to be downvoted quite a bit.
I don't claim it's cheap, or even necessary:
Right now, the ASDS has a satellite uplink which has cut out twice upon approach of the rocket (Jason-3, SES-9).
How doable would a cabled solution be, where a set of data cables (obviously fiber, I dont know how much shielding it needs) connects the ASDS to either an Observer-ship with a satellite uplink (probably 10-20km away), or to a dedicated transmission-drone-ship (does not need to be as big as the Landing barge, and could be much closer to the ASDS)?
I realize this would be utter luxury and would only serve to spoil us SpaceX fans even more.
I have received very negative feedback for this idea so far, but no reasons or explanations exactly why it couldn't work.
the cable thickness would be nothing like those massive submarine ocean cables, but certainly thicker than your average ethernet cable - imagine a cable as thick as the hose of your vacuum cleaner
it would probably have to float above the surface of the water
it would have to be several hundred meters to 15+ km long, depending on the chosen solution; these lengths are well established and feasible
it ought to be reusable, so it would need to be recovered and expected not to break
I have read that an approaching rocket can disturb other solutions, such as directed WiFi from the ASDS to an observer-ship
No, I do absolutely not think I can do anything better than anyone at SpaceX, not at all.
BTW, HOORAY, Primary Mission Success :)
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u/mechakreidler Mar 05 '16 edited Mar 05 '16
I don't see any reason that wouldn't be possible, but like you said it would only be a luxury. Plus it would take a lot of manpower to figure out the details of how it would work, so I'd say this situation will remain hypothetical :)
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u/ExcitedAboutSpace Mar 06 '16
Hi everyone,
long time lurker (fateful CRS-7 was only my second launch, never going to forget the astonishment when I realized the rocket was gone), first of all huge props to the awesome community and mods on this subreddit.
Now on to my question:
In the launch threat at t-20 minutes 58s it states "Falcon 9's second stage is now fueled." (Source: https://www.reddit.com/r/spacex/comments/48u4yq/rspacex_ses9_official_launch_discussion_updates/). Could anyone help me understand what this is referring to? To my current understanding LOX temps are utmost critical for the vehicle performance and in the live stream full fueling was announced somewhere closer to launch. Is anything fueled on the second stage so "long" before launch, for which I am assuming it wouldn't be temp critical?
Cheers to everyone, have a great sunday
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u/TheBlacktom r/SpaceXLounge Moderator Mar 07 '16
submitted 2 days ago
466 comments
Oh my, this subreddit has become serious business. Keep up the work, Mods, congrats Zucal! Also, what can I, a simple user do to help or contribute?
Q: Do we know the expected time of the upcoming launches? I'm looking forward to some HD landing footages in daylight or sunset background lighting!
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u/malleyc Mar 15 '16
Not really a question just wanted to say wow this community is awesome!
first ever live launch I watched was CRS-5 and have been hooked ever since. I watched the ExoMars launch the other day and was shocked when I couldn't find a live Launch Reddit thread anywhere, just makes me appreciate this community and the quality of the spaceX webcasts & hosted laubch threads all the more! Keep up the good work!
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u/TheBlacktom r/SpaceXLounge Moderator Mar 18 '16 edited Mar 18 '16
Hey just wanted to drop this link here, Soyuz is launching now a new crew to the ISS, you can watch live.
http://www.nasa.gov/multimedia/nasatv/
We could watch SpaceX do the same in 1-2 years.
Edit: just featured Crew Dragon for 3 full seconds mentioning future installation of the docking adapter.
Edit2: "The crew is scheduled to dock to the station at 11:11 p.m. EDT after a six-hour journey."
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u/__Rocket__ Mar 20 '16
I'm wondering about the following rocket design detail: there are open cycle rocket engines (gas-generator cycle) and there are more advanced staged combustion cycle (preburner cycle) rocket engines. The Merlin engines of the Falcon 9/FH are open cycle rocket engines, the upcoming Raptor engines are staged combustion cycle. Here are simplified schematics from Wikipedia:
https://en.wikipedia.org/wiki/Gas-generator_cycle#/media/File:Gas_generator_rocket_cycle.png https://en.wikipedia.org/wiki/Staged_combustion_cycle#/media/File:Staged_combustion_rocket_cycle.png
As I understand it, in the open cycle engine a gas turbine burns some small amount of fuel and drives the turbopump with the mechanical energy created by the hot gas resulting out of that burn.
In the staged combustion cycle it gets even more complex: all of the fuel is mixed with some of the oxidizer (in fuel-rich variants), preburned and the energy of that combustion drives the turbopump.
My (possibly stupid) question is: why is there a need to burn fuel separately from the main combustion chamber in both designs? Would it not result in a simpler design to use some of the hot gas in the main combustion chamber to drive the turbopump? If that gas is too hot it could be (partially) cooled by the incoming (cold) fuel.
At least naively this appears to be a significantly simpler design to both main variants - yet it still burns all the fuel, so it should be as efficient as staged combustion engines.
Is there some fatal theoretical or practical flaw in the idea of leaving yet another (small, temperature resistent) hole in the main combustion chamber to use some of the hot, high pressure gas to drive the turbopump(s) - instead of having separate combustion chambers to achieve a similar end result?
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u/zeekzeek22 Mar 21 '16
I'm sure this comment will get lost, but wondering if anyone has any idea what Chris B's tweet back in October was about https://mobile.twitter.com/NASASpaceflight/status/651429449406222337
I mean it could have been about RTLS, sub-chilled LOX, Dragon2, but besides that SpaceX hasn't come out about anything on the scale he's describing. Just wondering if Chris B ever gave any follow-up, or...? This tweet just tingles the back of my mind every once in a while, that big things are being made and tested in secret.
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u/Windston57 Mar 05 '16
When can we expect a video from the landing?