... After Trans Mars injection, the Dragon would pull away from the cargo section and turn around, then return to mate its docking hatch with one in the inflatable. It would then pull the inflatable out of the cargo hold, much as the Apollo command module pulled out the LEM. ...
Friends;Here are further answers relating to concerns that have been advanced.1. Habitable volume. As noted, if the Dragon capsule alone is used, this provides 5 m3 living volume per crew member, which compares to 2 m3 per crew on an Apollo capsule, 9 m3 per crew member on the Space Shuttle, or 8 m3 per crew member on a German U-Boat (Type VII, the fleet workhorse) during WWII. This would be uncomfortable, but ultimately, workable by a truly dedicated crew. However these limits can be transcended. The Dragon has a 14m3 cargo area hold below the aeroshield. Into this we could pack an inflatable hab module, in deflated form, but which if inflated, could be as much as 8 m in diameter and perhaps 10 m long, thereby providing 3 decks, with added volume of 502 m3 and a total floor space equal to 1.5 times as much as that in the Mars Society's MDRS or FMARS stations, which have proved adequate in size for crews of 6. After Trans Mars injection, the Dragon would pull away from the cargo section and turn around, then return to mate its docking hatch with one in the inflatable. It would then pull the inflatable out of the cargo hold, much as the Apollo command module pulled out the LEM. The inflatable could then be inflated. The other end of the inflatable would be attached to the tether, which is connected to the TMI stage, for use in creating artificial gravity.Upon reaching Mars the inflatable could either be expended, along with the tether system and TMI stage, prior to aerocapture. Alternatively, and optimally, the tether and TMI stage alone would be expended, but the inflatable deflated and retained for redeployment as a ground hab after landing.2. EDLUsing just its aeroshield for deceleration, the Dragon would have a terminal velocity of around 340 m/s on Mars at low altitude (air density 16 gm/m3). So we could either give it a rocket delta-V capability of 600 m/s (a 20% mass hit assuming storable or RP/O2 propulsion, Isp~330 s) to land all propulsive, or we could use a drogue to slow it down (a 20 m diameter chute would slow it to ~70 m/s) and then employ a much smaller rocket delta-V for landing.Robert
Interesting plan, albeit pretty limited capability-wise.IMO adding a few more Falcon launches to add further redundancy/capability (for example by pre-positioning assets in Mars orbit and on the surface) or the addition of a high-energy upper stage to the Falcon Heavy to increase its trans-Mars throw mass will probably be necessary to make the plan "fly" politically (reducing risk), or if you want more than just a flags/footprints mission with two astronauts and a Dragon on Mars.
2. EDLUsing just its aeroshield for deceleration, the Dragon would have a terminal velocity of around 340 m/s on Mars at low altitude (air density 16 gm/m3). So we could either give it a rocket delta-V capability of 600 m/s (a 20% mass hit assuming storable or RP/O2 propulsion, Isp~330 s) to land all propulsive, or we could use a drogue to slow it down (a 20 m diameter chute would slow it to ~70 m/s) and then employ a much smaller rocket delta-V for landing.Robert
Quote from: majormajor42 on 05/15/2011 02:28 pm"Zubrin's" Falcon Heavy Mars Mission Musk risks his personal fortune and millions of NASA/taxpayer $$$We triumphantly land on Mars.Zubrin: "You're welcome"In comparison to the 11.1 Billion we wasted on Constellation or the 10 billion more we waste on the Senate Launch System, we are getting new capability and it is an acceptable risk. Even if Musk was 10 years late it would still be better than the poppycock we are getting from NASA and congress.VRTPISRE327
"Zubrin's" Falcon Heavy Mars Mission Musk risks his personal fortune and millions of NASA/taxpayer $$$We triumphantly land on Mars.Zubrin: "You're welcome"
my point is what is Zubrin adding to the FH Mars concept that wasn't already discussed in other threads or (more than likely) Musk and team have already run some numbers on and might be perusing.
Quote from: Zubrin on 05/15/2011 11:55 pm2. EDLUsing just its aeroshield for deceleration, the Dragon would have a terminal velocity of around 340 m/s on Mars at low altitude (air density 16 gm/m3). So we could either give it a rocket delta-V capability of 600 m/s (a 20% mass hit assuming storable or RP/O2 propulsion, Isp~330 s) to land all propulsive, or we could use a drogue to slow it down (a 20 m diameter chute would slow it to ~70 m/s) and then employ a much smaller rocket delta-V for landing.RobertMy understanding of Mars EDL is limited, but from what I've read Dragon would not reach terminal velocity before hitting the ground. It would seem to require 500-1000 m/s of rocket delta-V.
What timeclock are we racing against, that a mission has to be done within this decade? How about 2025?
Quote from: majormajor42 on 05/16/2011 02:21 pmmy point is what is Zubrin adding to the FH Mars concept that wasn't already discussed in other threads or (more than likely) Musk and team have already run some numbers on and might be perusing.Zubrin/Mars Society and "Musk and team" aren't as unrelated entities as you might think.
The existential question being asked every year...
Well, why can't Musk send Man back to the Moon first, during this decade? Then we can do Mars the next decade.
If F9H is as cheap as Musk says it's going to be, then going back to the Moon first won't really sap away funds from a Mars mission. If anything, it would revitalize the public interest and enthusiasm so that more funding would be unleashed for the Mars mission.
I'd like to ask Dr Zubrin why such a Mars mission would need to be done in such a minimalist fashion at such an absolutely shoestring cost? Isn't there such a thing as going too cheap?Given the momentous importance of a manned Mars mission, why wouldn't it be worth it to spend a few more billion$ to increase the safety margins, the redundancies, and to improve the knowledge returned from the mission?Or, alternatively, if the F9H business model is sustainable, why not let it succeed and evolve into even better cost/lb to allow even more mission for the buck? What timeclock are we racing against, that a mission has to be done within this decade? How about 2025?
Quote from: sanman on 05/17/2011 02:09 amWell, why can't Musk send Man back to the Moon first, during this decade? Then we can do Mars the next decade.Musk has no intention of sending people to Mars or the Moon.. and he won't until someone who wants to pay for it says they do. I really wish people would listen to what Elon says rather than what they want him to say. QuoteIf F9H is as cheap as Musk says it's going to be, then going back to the Moon first won't really sap away funds from a Mars mission. If anything, it would revitalize the public interest and enthusiasm so that more funding would be unleashed for the Mars mission. It's Falcon Heavy now, they dropped the 9.. I'll tolerate it from Zubrin but not you If you want to go to the Moon, convince someone to pay for a Moon mission. If that's NASA they'll want to do it with their own rockets because it supports what they care about. If you want to do it privately, go raise the money. You can't pin all your hopes and dreams to Elon Musk.. the guy has already done miracles (as has Mr Bigelow), it's time for someone else to step up.