Quote from: Lar on 06/05/2016 07:21 pmThe point about driving AI is not driving per se, although that's a useful part of the overall problem... it's that they implemented something that learns. ...with two years of learning time the units might be better than when they arrived...The way that most successful AI learning works is that they use large amounts of data for training. For instance Tesla collections 1 million miles of driving data every 10 hours. This data is used to train the algorithms, but also used to evaluate how the AI does on real world data, it is also used to detect real world corner cases and allows humans to tweek the AI to handle these unusual situations better. Tesla also runs autopilot in shadow mode on customers cars, comparing what new algorithms do with what the human driver does.For rover driving on Mars we have none of that, no large data sets, no real world data around the landing site, no ability to look at corner cases and no ability to compare AI results with what a human would do. This applies not only to driving but also to many other tasks the mining system would have to perform.
The point about driving AI is not driving per se, although that's a useful part of the overall problem... it's that they implemented something that learns. ...with two years of learning time the units might be better than when they arrived...
Robotic deployment of thin-solar panels to power an atmospheric water adsorption system is the most practical means to refuel an initial landing vehicle, it requires the least knowledge about the martian subsurface and is the most reliable due to minimal moving parts and minimal contact with abrasive regolith.
Quote from: Paul451 on 06/06/2016 01:15 pmQuote from: Robotbeat on 06/06/2016 01:27 amIf they simply install a large (but very lightweight) crane A crane isn't mining equipment....on Earth.[...]I never said you'd use a bucket-line
Quote from: Robotbeat on 06/06/2016 01:27 amIf they simply install a large (but very lightweight) crane A crane isn't mining equipment.
If they simply install a large (but very lightweight) crane
Quote from: Robotbeat on 06/06/2016 03:32 pmQuote from: Paul451 on 06/06/2016 01:15 pmQuote from: Robotbeat on 06/06/2016 01:27 amIf they simply install a large (but very lightweight) crane A crane isn't mining equipment....on Earth.[...]I never said you'd use a bucket-lineOkay, in all seriousness, how did you envision using a crane to do mining, without a bucket or scoop?
Quote from: Impaler on 06/07/2016 01:29 amRobotic deployment of thin-solar panels to power an atmospheric water adsorption system is the most practical means to refuel an initial landing vehicle, it requires the least knowledge about the martian subsurface and is the most reliable due to minimal moving parts and minimal contact with abrasive regolith.Absolutely, given what we know now. But a Red Dragon or two could inform more efficient techniques, if conditions supported it.
Raptor with a 4 m nozzle loses about 1% of ISP compared to a 4.8 m nozzle: 376 s vs 380 s.This is based on sim in RPA lite using: Methane/LOX at:9.7 MPa chamber pressure (same as Merlin)2.8 O/F ratio (optimum for methalox at 9.7 MPa)165 expansion ratio for the 4.8 m nozzle (same as Merlin Vac)115 expansion ratio for the 4 m nozzle (assuming same throat diameter as the 4.8 m nozzle)
From the FH discussion speculating on Raptor upper stage for FHQuote from: envy887 on 06/08/2016 01:29 pmRaptor with a 4 m nozzle loses about 1% of ISP compared to a 4.8 m nozzle: 376 s vs 380 s.This is based on sim in RPA lite using: Methane/LOX at:9.7 MPa chamber pressure (same as Merlin)2.8 O/F ratio (optimum for methalox at 9.7 MPa)165 expansion ratio for the 4.8 m nozzle (same as Merlin Vac)115 expansion ratio for the 4 m nozzle (assuming same throat diameter as the 4.8 m nozzle)IF Rvac does have a 4.8m diameter, what does this say about max # of Rvac engines for the hypothetical 2nd stage BFS @ a given stage diameter? Makes the case for >10m with even 15m having issues with # of Rvacs.10m is out for > 3 engines12m only fits 4 engines15m seems OK for a ring of 6 engines, or 5 engines and a center engine. Maybe too little swivel clearance for CE.My guess is 15m BFS with slightly under 4.8m Rvac diameter bell, say ~4.5m such that a center engine is feasible.4.5m also allows a 12m BFS to hold 5 engines in a ring.
By more US DV I mean (1) less performance needed from 1st stage BFR making the big boy's re-use environ slightly more benign and lowering cost {My unsubstantiated assumption}, (2) when you re-fuel in LEO you still need the tankage structure mass for propellant for the BFS's DV needed for fast transfer to Mars, say 90-120 days whatever, possible or maybe not propulsive breaking, aerobraking and powered landing.Using today's F9 as a model, the Rvac would have ~ 110% the thrust of the assumed 230mT Elon referred to.
Quote from: Robotbeat on 06/07/2016 05:11 pmYou still haven't said how you can use a crane to do mining. (Let alone how this could be automated.)
...4 engines precludes a center engine landing...
Quote from: envy887 on 06/08/2016 04:02 pm...4 engines precludes a center engine landing...Not true. An axi-symmetrical "Y" shape with 4 engines would allow it.
The nozzle extensions of vac engines will need protection to survive reentry at least on earth. So they will probably be retractable for that reason. Can the remaining nozzle part formed like first stage engines and work as such in retracted state?
...Also of interest: in a vacuum it gets 92 to 96 % of the performance fully expanded vac nozzle. If the mission requires that last 4-8% of performance, then an extension failure would cause LoM.