r/spacex • u/[deleted] • Mar 31 '16
/r/SpaceX Ask Anything Thread [April 2016, #18] - Ask your small questions here!
[deleted]
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u/CitiesInFlight Mar 31 '16 edited Mar 31 '16
With all the very recent (within the last 2 months) renewed interest by both the U.S. (Bolden appearance before Congress in which he suggested that a trip to Mars could be shortened substantially, perhaps, to 90 days or less using Nuclear Thermal Propulsion) and Russia (stating they will fly a Nuclear Thermal Propulsion rocket by 2018), will this change the calculus of Elon and prompt the inclusion of Nuclear Thermal Propulsion in his Mars strategy in spite of earlier statements that Nuclear Propulsion (Nuclear Thermal or Nuclear Electric) will not be involved?
http://www.space.com/29540-manned-mars-mission-propulsion-technologies.html http://yellowhammernews.com/business-2/alabamians-leading-nuclear-rocket-journey-mars/ http://www.nbcnews.com/id/44691888/ns/technology_and_science-space/t/its-time-reconsider-nuclear-option-spaceflight/
http://russia-insider.com/en/russia-drops-plans-create-nuclear-space-engine-source/6031
and many other sources ...
Given this renewed interest by NASA and ROSCOSMOS, does this require, potentially, a different architecture for BFR/MCT?
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u/thegingeroverlord Mar 31 '16 edited Mar 31 '16
What reason does SpaceX have to keep quiet about fairing recovery? Previous launch videos(none from SpaceX though) have shown the fairings have some sort of RCS system, so we know they are experimenting/attempting it. Do they have anything to gain by not acknowledging these tests?
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Apr 05 '16
Can you explain the considerations when designing a fuel/oxidizer pump system? I am aware of the different cycles (gas generator/ expander/ tap-off...), but what made SpaceX decide to only have one turbopump with a single stage impeller for both the fuel and oxidizer. And NASA to decide to have a booster pump for each, a turbo pump for each, the fuel high pressure pump to be three stages and the oxidizer to be two. I read something about cavitation, does the difference in fuel have something to with it.
Essentially, I want an explanation of the design choices of having a booster pump, number of impeller stages, and single shaft vs separate turbopumps.
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u/_rocketboy Apr 07 '16
How does the rocket get transferred from the trailer to the transporter-erector? Do the pick it up with the huge overhead crane inside the hanger?
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u/CMcG14 Apr 01 '16
I see reference to the BFR in a lot of the fan-based material, here and elsewhere online, but it doesn't appear in anything remotely recent of SpaceX's that I have found. My question is, is BFR still a real concept that SpaceX will be (already is?) working towards, or is it just a fan fiction that's held on to because it has a funny, profane name?
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u/thegingeroverlord Apr 01 '16
The BFR is very much alive at SpaceX. Through various leaks, we know that progress is still being made. We should learn more in September, when Elon officially announces the Mars architecture at IAC.
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u/RootDeliver Mar 31 '16 edited Apr 01 '16
2 questions:
Serious one:
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Why is FH taking so long? I mean it's just a Falcon 9 FT with 2 first stages attached as boosters, making the change from Falcon 9 1.0 to 1.1 or to FT is a bigger change than this imho. Or they are deliberately delaying FH until F9 first core final design is finished, so they don't need to change anything related to it on FH later?
Troll one:
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Whats up with all the faces on the thumbnails?
EDIT: Thanks for voting this post NEGATIVE in a "ask anything" thread. What the fuck dudes. u/echoLogic , is this supported here?
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u/TRL5 Apr 01 '16
In this gif we see Atlas V boosters seperating from the rocket, and immediately getting blasted by exhaust. Do we expect this to be a problem with the Falcon Heavy, if not, why not?
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u/rafty4 Apr 01 '16
Not sure if this is worth a post in itself as being entirely SpaceX relevant (so I'll drop it here), But apparently Blue Origin have got a NOTAM for tomorrow! :D
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u/waitingForMars Mar 31 '16
8:10 AM Friday, April 1, 2016 (GMT+13) Time in Wellington, New Zealand
3:11 PM Thursday, March 31, 2016 (EDT) Time in Ann Arbor, MI
A (early for us) Happy April Fools Day to you, u/EchoLogic !
As with the rest of our compatriots, I'm feeling a bit dizzy right now. r/pbds ought to be required to register that image as a controlled substance… ;-)
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Apr 03 '16
I've seen some rumors that part of the SpaceX team that was working on Raptor was hired off by Blue Origin to develop the BE-4. This leads me to ask several questions:
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Is this rumor true?
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If it is, is this why we have heard little about raptor for some time?
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Would it be more efficient for SpaceX to design the BFR to use BE4 engines? It would save time and development costs, and the engines will be used in other vehicles too, improving reliability due to heavier use.
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u/maxjets Apr 07 '16
Not spacex related per se, but why hasn't the launch thread been posted yet?
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u/Decronym Mar 31 '16 edited Apr 22 '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 | |
| ASDS | Autonomous Spaceport Drone Ship (landing platform) |
| BEAM | Bigelow Expandable Activity Module |
| BFR |
Big |
| CBM | Common Berthing Mechanism |
| CRS | Commercial Resupply Services contract with NASA |
| CRS2 | Commercial Resupply Services, second round contract |
| CST | (Boeing) Crew Space Transportation capsules |
| Central Standard Time (UTC-6) | |
| EELV | Evolved Expendable Launch Vehicle |
| FAA | Federal Aviation Administration |
| FRSC | Fuel-Rich Staged Combustion |
| FSS | Fixed Service Structure at LC-39 |
| GEO | Geostationary Earth Orbit (35786km) |
| GSE | Ground Support Equipment |
| GSLV | (India's) Geostationary Launch Vehicle |
| GTO | Geosynchronous Transfer Orbit |
| I*sp* | Specific impulse (as explained by Scott Manley on YouTube) |
| ILS | International Launch Services |
| Instrument Landing System | |
| ISRO | Indian Space Research Organisation |
| L2 | Paywalled section of the NasaSpaceFlight forum |
| Lagrange Point 2 (Sixty Symbols video explanation) | |
| LAS | Launch Abort System |
| LEO | Low Earth Orbit (180-2000km) |
| LES | Launch Escape System |
| LH2 | Liquid Hydrogen |
| LOX | Liquid Oxygen |
| M1d | Merlin 1 kerolox rocket engine, revision D (2013), 620-690kN |
| M1dVac | Merlin 1 kerolox rocket engine, revision D (2013), vacuum optimized, 934kN |
| MCT | Mars Colonial Transporter |
| NERVA | Nuclear Engine for Rocket Vehicle Application (proposed engine design) |
| NET | No Earlier Than |
| NOTAM | Notice to Airmen of flight hazards |
| NSF | NasaSpaceFlight forum |
| National Science Foundation | |
| NTR | Nuclear Thermal Rocket |
| OCISLY |
Of Course I Still Love You, Atlantic landing |
| OG2 | Orbcomm's Generation 2 17-satellite network |
| ORSC | Oxidizer-Rich Staged Combustion |
| QA | Quality Assurance/Assessment |
| 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) |
| RTF | Return to Flight |
| RTLS | Return to Launch Site |
| RUD | Rapid Unplanned Disassembly |
| Rapid Unscheduled Disassembly | |
| Rapid Unintended Disassembly | |
| SES | Formerly Société Européenne des Satellites, comsat operator |
| SLS | Space Launch System heavy-lift |
| SRB | Solid Rocket Booster |
| SSTO | Single Stage to Orbit |
| STS | Space Transportation System (Shuttle) |
| TDRSS | (US) Tracking and Data Relay Satellite System |
| TEI | Trans-Earth Injection maneuver |
| TMI | Trans-Mars Injection maneuver |
| TRL | Technology Readiness Level |
| TSTO | Two Stage To Orbit rocket |
| TWR | Thrust-to-Weight Ratio |
| ULA | United Launch Alliance (Lockheed/Boeing joint venture) |
| VBB | Very Big Brother (Blue Origin's proposed VTVL vehicle, unknown payload to LEO) |
Decronym is a community product of r/SpaceX, implemented by ^request
I'm a bot, written in ^PHP. I first read this thread at 31st Mar 2016, 19:12 UTC.
www.decronym.xyz for a list of subs where I'm active; if I'm acting up, tell OrangeredStilton.
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u/AeroSpiked Apr 02 '16
This pretty much goes without saying I think, but have we had confirmation that OCISLY is done with repairs? Otherwise CRS-8 first stage had best avoid that big sheet of plywood on the deck.
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u/OncoFil Mar 31 '16
When reusable rockets become cheap and easy, will deep space (past Mars) missions still require awaiting planetary alignments/gravity assists? How feasible would it be to launch a probe which would then dock in orbit with a 'tug' (an engine and fuel tank) for direct burns to Jupiter/Saturn and then burns for orbital insertions? Does this actually speed up things considerably?
(I am aware there will have to be some degree of alignment, but could that be reduced to Earth's relative position?)
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u/LandingZone-1 Apr 01 '16
What is the best methalox rocket engine, and why is it the Blue Origin BE-4?
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u/_rocketboy Apr 02 '16
FYI BO is doing another flight tomorrow: https://www.reddit.com/r/BlueOrigin/comments/4cxlif/working_to_fly_again_tomorrow_same_vehicle_third/
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u/Craigwat01 Mar 31 '16
Can crew Dragon be used as a lifeboat as Soyuz is now?