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Red Dragon
ugordan
post Aug 9 2011, 08:07 AM
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QUOTE (ZLD @ Aug 9 2011, 01:44 AM) *
Also, very large parachutes will be necessary to slow the craft; is there anything in the works for a booster module to help slow during decent?

The abort thrusters now being developed for uh... not-unmanned flights are envisioned to (at some point later) also serve for propulsive landing capability. See this video at about 1 minute mark. I'd think the parachutes would be pretty useless on Mars for such a big capsule (over 4 tons dry mass without propellant load) and propulsive landing would be the primary means of shedding the remaining velocity after entry. I'm not sure they'd deploy correctly in the first place, IIRC, they'd deploy at supersonic speeds on Mars and they deploy subsonically on Earth, after two drogues stabilize the capsule.


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pospa
post Aug 9 2011, 11:09 AM
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We are talking about Discovery category mission, right?
It should/must be cheap.
It's nice that many of you are suggesting minirovers and tumbleweeds rolling or jumping out of Red Dragon (RD), but why not just stick to that concept NASA Ames if thinking about.
RD will stay mostly in the standard shape or configuration as it will be that time for other unmanned missions in order to keep lander price low as much as possible.
Number of external moving tool(s)/instrument(s) would be very limited just to the sampling acquisition set -> 1 m drilling suite + camera(s) on the robotic arm sticking out of standard side hatch.
Then all other lab instruments (many and heavy) can do a lot of science by analysing samples inside of the RD capsule.
Of course meteo instruments and other cameras can be deployed through top hatch together with Ultraflex solar arrays and antena(s).
And perhaps some cheap seismometric penetrator(s) could be simply ejected during EDL phase as well.
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Drkskywxlt
post Aug 9 2011, 12:51 PM
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Although I think this proposed proposal (how's that for redundancy?) would certainly win high marks in the "cool and awesome" category that would make it great for EPO, it has to compete against the other Discovery proposals in two areas: science return and risk.

Mounting cameras on the outside to just take some panoramic pictures certainly won't scientifically wow the review panel. Adding some seismic sensors and weather sensors might make it more interesting, but then basically you've made Red Dragon into a very heavy version of GEMS. Which brings me to:

Risk. GEMS apparently won high marks for being low-risk. Although I'm sure Elon Musk and SpaceX would argue that Red Dragon would not be high risk, I think it would be very hard to convince a risk averse NASA review panel of that fact. Any new technology is always viewed as riskier than proven technology. I think the Red Dragon team would really have to wow the review panel with some amazing science to overcome their risk.

Chris McKay and Elon Musk are smart guys though, so I'm sure they could pull it off if anybody could. I'd be rooting for it smile.gif
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algorimancer
post Aug 9 2011, 12:57 PM
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QUOTE (pospa @ Aug 9 2011, 05:09 AM) *
...why not just stick to that concept NASA Ames if thinking about.

Possibly because, after experiencing Pathfinder and MER in comparison to Viking and Phoenix, we've learned to appreciate the dramatic returns a rover can deliver. It need not be a very large rover. I could easily envision a pneumatic "mortar" that rapidly pops several small rovers through the hatch which could explore the local region at least out to line-of-sight (hundreds of meters to kilometers, given a tall antenna), communicating with the dragon vehicle as with Pathfinder. Really not that difficult to do.
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Mongo
post Aug 9 2011, 05:01 PM
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For a Mars mission, there are two kinds of distance to be traversed. All the previous missions that moved beyond the immediate landing spot have been rovers that moved to various locations on the Martian surface. But a mission could also take samples vertically, by means of a drill.

So if a drill could be extended out of the main hatch, it might be able to extract cores at various depths to be analysed by the huge mass of lab instrumentation on board the Red Dragon. The mission would examine a smaller number of samples, but with far greater depth of analysis.

I am thinking along the lines of the NASA Ames proposal, which does seem to me to have the greatest scientific return using Red Dragon.
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djellison
post Aug 9 2011, 05:18 PM
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It's not out of the question that the vehicle could hold in reserve enough fuel to hop to a different site as well.

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Mongo
post Aug 9 2011, 05:37 PM
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I had a wild idea, does anybody know if it is technically feasible?

Instead of extending a drill mechanism out of the main hatch, would it be possible to simply drill straight down right through the heat shield? This drill would, after all, be built to drill through solid rock, and I believe that the material that heat shields are made of is designed for heat resistance/ablation, not rock-like strength, in fact they are quite fragile as I understand it. Or alternatively, perhaps the shield could incorporate a small 'cap' directly below the base of the internal drill mechanism, that can be removed upon landing. (It might be simpler and less problematic to simply drill right through the heat shield, though.)

If the drill is not required to be physically extended out the main hatch by some kind of robot arm, the mass and volume saved by not including the required arm mechanism could be used for additional instrumentation, not to mention that it would be a lot easier to extract the drill cores to the interior of the Red Dragon.
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ZLD
post Aug 9 2011, 05:53 PM
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Drilling through the bottom is a possibility, as its a low density carbon material but I'm not sure about placing a hatch on the underside of the craft. At that point, you are adding a lot more cost in redesigning and testing for the capsule.

Another idea they could do, is land multiple capsules at various locations around the planet that have large, steerable, parabolic antennas, similar to that on Galileo/TDRS, that would be deployed out of the top. Could be useful as a second relay station in space, or maybe radio telescope investigations with more distance from the Sun, or possibly with some magic, interferometric observations between here and there.

Including a mortar loaded with something similar to MetNet impactors could also be interesting though, shooting them out in different directions during descent.

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Fran Ontanaya
post Aug 9 2011, 07:05 PM
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It may be robust enough to survive a winter buried in CO2. Then a snow rover could just roll out the hatch. laugh.gif


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lyford
post Aug 9 2011, 11:30 PM
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Delurking in this thread just long enough to say HOORAY that other folks are fans of the Tumbleweed rovers! We may get rolling yet!


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MarsInMyLifetime
post Aug 10 2011, 06:08 AM
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I'm new to UMSF, but a long-time advocate of robotic missions. The premise of this thread is not unlike the problem handed down to American engineers and scientists right after WWII: "Folks, we have a bunch of V-2s here. What kind of science can you do with something made for an entirely different use?" First steps were crude, but the variety of science eventually done was outstanding--for a war missile.

I'd modify some things in the uncrewed version of Dragon to make it more Mars-mission worthy: replace the heat shield with a Viking-class conic shield (physics and success of the design dictate using what works); cut away the heat shield for landing--no need to soft land that mass; remove the Earth-style parachutes from the lower bays and instead have an MSL-class parachute system in a new nose bay filling the formerly empty nose cone volume; remove the vestigial forward hatch and ISS docking system and use the space to store and unfold 6 round solar arrays for power akin to those on Beagle (the central platform would hold antennae and instruments like mastcams and lidar); replace the pressure vessel sides with ribs to reduce some weight without compromising the aeroshell; use the landing leg tubes to guide sampling drills on telescoping shafts to the surface; with the heat shield gone, open a trap door hinged on one side as a ramp to the surface for mobile exploration tools (moles, Pathfinder-class bots, or even tumbleweeds if you must); utilize the deployed sensor bay as a weather station and lower-level camera platform. And the remaining space (of which there is still plenty in that huge hull) could be for what I think is the most valuable primary payload: testing the various IRSU technologies for water and fuel production out of the atmosphere.

I recall, though, that the V-2 was replaced by cheaper, more efficient sounding rockets for all the science roles that it pioneered, and I suspect this modified Dragon, even if gifted on the science community, might quickly go the same route!
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ugordan
post Aug 10 2011, 08:06 AM
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QUOTE (MarsInMyLifetime @ Aug 10 2011, 08:08 AM) *
I'm new to UMSF, but a long-time advocate of robotic missions. The premise of this thread is not unlike the problem handed down to American engineers and replace the heat shield with a Viking-class conic shield (physics and success of the design dictate using what works);

Why? What's to say that's the only design that works? Even circumlunar flight reentries were proven out by different capsule shapes, both Apollo and Zond (which Dragon is more similar to).

I don't think either replacing the hatch or modifying the pressurized hull structure would work. You're approaching a lander development program and not reusing the Dragon design so the whole point gets lost. That becomes a Dragon only by name, besides what's the point in reducing the mass if Falcon Heavy can launch more mass to Mars than any useful scientific payload you can put inside Red Dragon?


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MarsInMyLifetime
post Aug 10 2011, 04:08 PM
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QUOTE (ugordan @ Aug 10 2011, 02:06 AM) *
...You're approaching a lander development program and not reusing the Dragon design so the whole point gets lost. That becomes a Dragon only by name, besides what's the point in reducing the mass if Falcon Heavy can launch more mass to Mars than any useful scientific payload you can put inside Red Dragon?

Granted, but once that mass gets to the vicinity of Mars, the devil is in getting it to the surface successfully. These were just changes I needed to envision for the EDL preliminaries in order to make the game work for me. I'm on the surface now, somehow, and in the payload mode. I'll still stick with the IRSU demonstration packages for initial payloads--methane generation first, then water purification. I'd still put station-keeping science (mastcam, weather sensors, and comms) on the top in place of the docking adapter.


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Jim from NSF.com
post Aug 12 2011, 12:33 AM
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QUOTE (Astro0 @ Aug 9 2011, 02:39 AM) *
OfJust about anything is possible here, after all, most of this conversation is based on a capsule that hasn't been finally designed or built to do the job of going to and landing on Mars. All we have is an idea, a video (so I'm told), a graphic and thankfully a whole bunch of people here with some imagination and an interest in exploration. wink.gif

No, it has been designed and built. Red Dragon is the existing Dragon
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Jim from NSF.com
post Aug 12 2011, 12:41 AM
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QUOTE (djellison @ Aug 8 2011, 08:21 PM) *
And yet again, Jim, you argue against something I've not proposed. I didn't propose delivering PHX's instruments. I didn't propose driving a rover out of the door. Yet you decided to have an argument with me about such things.

I have made my point - and made it clearly. The issue is not how to deliver payloads previously sent to Mars with Dragon. It's what payloads could you send to Mars with Dragon. You continue to ignore that simple statement and start arguments over things I've not said or even inferred.



I am going to blow my wad on this. I am not talking about previous instruments but any type of one. Dragon is a bad platform. The ideas since your post demonstrate that it is. Most are non viable.

Ideas modifying the structure are non starters. It isn't a dragon the. Opening hatches, non starter again, the avionics are not designed for vacuum.

There is out of the box thinking and then there is off the reservation which most of the ideas are.
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