Author Topic: Red Dragon Discussion Thread (2)  (Read 181597 times)


Offline Roy_H

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Re: Red Dragon Discussion Thread (2)
« Reply #1 on: 12/25/2013 01:54 AM »

Elmar Moelzer
Re: Red Dragon
« Reply #1165 on: 12/11/2013 07:50 PM »
Quote from: Kaputnik on 12/11/2013 07:09 PM

    Well if my trig is correct, to get down to that sort of loss you need the thrusters to be firing at 20-25deg from vertical.
    If they are actually at 45deg, which the artists' impressions suggest, the losses are about 29%.

The display of the Dragon in the artwork is outdated. As has been stated by several sources before and can be seen in some mockups shown by SpaceX. The actual setup of the superdracos on the updated dragon will be slightly different. The superdracos will be in a kind of nose that protrudes from the capsule and because of that will be angled more downwards.
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I read somewhere that if the SDs are angled out (~45deg) and fired in upper atmosphere they will "trap" air that would otherwise slip by and effectively increase aero braking. It would make sense to me that the thrust angle of the SDs would be variable so it could be more vertical during landing stage. If the SDs were mounted with a hinge near the bottom of the capsule on the outside edge, they could swing out to near vertical position.
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Online AncientU

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Re: Red Dragon Discussion Thread (2)
« Reply #2 on: 03/08/2014 02:11 PM »
"If we shared everything [we are working on] people would think we are insane!"
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Online MikeAtkinson

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Re: Red Dragon Discussion Thread (2)
« Reply #3 on: 03/08/2014 08:49 PM »
New news.... Sample return!
http://www.space.com/24984-spacex-mars-mission-red-dragon.html

Interesting, this study says Red Dragon can deliver 2 tons to Mars, the previous study for the drill mission said 1 ton IIRC. I wonder what has changed?

Offline Dalhousie

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Re: Red Dragon Discussion Thread (2)
« Reply #4 on: 03/08/2014 09:07 PM »
New news.... Sample return!
http://www.space.com/24984-spacex-mars-mission-red-dragon.html

Interesting, this study says Red Dragon can deliver 2 tons to Mars, the previous study for the drill mission said 1 ton IIRC. I wonder what has changed?

More detailed modelling, the one tonne was also a conservative minimum.  I have seen a paper or at least a presentation on it but I can't find it either on my computer or the internet.
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Offline meekGee

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Re: Red Dragon Discussion Thread (2)
« Reply #5 on: 03/08/2014 09:26 PM »
The referenced story says:

Quote
... most scientists regard a sample-return trip as a "Holy Grail" mission ...

I guess different people have different sized holy grails...   The space community has gotten so used to thinking small it's depressing.
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Offline Norm38

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Re: Red Dragon Discussion Thread (2)
« Reply #6 on: 03/09/2014 03:37 AM »
I don't see Red Dragon having much role past the prototype phase, but that is a critical role to fill.  Once the EDL systems are proven out, the stage is set to scale up to the MCT. So sample return is a great project, excited to see it happen.  It will go a long way towards retiring risk.

Offline a_langwich

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Re: Red Dragon Discussion Thread (2)
« Reply #7 on: 03/09/2014 04:02 AM »
The referenced story says:

Quote
... most scientists regard a sample-return trip as a "Holy Grail" mission ...

I guess different people have different sized holy grails...   The space community has gotten so used to thinking small it's depressing.


It's a priority in the decadal study for planetary science...the space science community has very wisely gotten used to thinking about what is possible under the budget they've been given.

Offline Wigles

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Re: Red Dragon Discussion Thread (2)
« Reply #8 on: 03/09/2014 06:16 AM »

The referenced story says:

Quote
... most scientists regard a sample-return trip as a "Holy Grail" mission ...

I guess different people have different sized holy grails...   The space community has gotten so used to thinking small it's depressing.


It's a priority in the decadal study for planetary science...the space science community has very wisely gotten used to thinking about what is possible under the budget they've been given.

Yes, but unfortunately even with the current budget this isn't possible.

Offline Kaputnik

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Re: Red Dragon Discussion Thread (2)
« Reply #9 on: 03/09/2014 09:26 AM »
I'm surprised that a second FH is seen as more cost effective than designing a better sealed sample return container.
Does the incoming sample container aero capture into orbit in this proposal? All seems a bit wasteful, IMHO. Plus you have the risk of the 'contaminated' returning spacecraft hitting Earth by accident anyway.
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Offline rpapo

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Re: Red Dragon Discussion Thread (2)
« Reply #10 on: 03/09/2014 10:41 AM »
I'm surprised that a second FH is seen as more cost effective than designing a better sealed sample return container.
Does the incoming sample container aero capture into orbit in this proposal? All seems a bit wasteful, IMHO. Plus you have the risk of the 'contaminated' returning spacecraft hitting Earth by accident anyway.
I would hazard a guess that the bit about the second capsule going to a high Earth orbit was part of mitigating that risk. 
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Offline manboy

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Re: Red Dragon Discussion Thread (2)
« Reply #11 on: 03/09/2014 11:42 AM »
New news.... Sample return!
http://www.space.com/24984-spacex-mars-mission-red-dragon.html
This was the presentation description on the IEEE website

"Mars Sample Return Using Commercial Capabilities: Propulsive Entry, Descent, and Landing"

"Mars Sample Return (MSR) is the highest priority science mission for the next decade as recommended by the recent Decadal Survey of Planetary Science. We report on the Entry Descent and Landing technique used to support an MSR mission using a Red Dragon capsule. The Red Dragon Mars configuration uses bank angle control and supersonic retro-propulsion, with no required parachute system, to perform Entry, Descent, and Landing (EDL) maneuvers. The EDL landed mass performance envelope covers a range of entry masses, landing altitudes, and minimum and maximum atmosphere density."
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Offline Prober

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Re: Red Dragon Discussion Thread (2)
« Reply #12 on: 03/09/2014 05:46 PM »
New news.... Sample return!
http://www.space.com/24984-spacex-mars-mission-red-dragon.html

Interesting, this study says Red Dragon can deliver 2 tons to Mars, the previous study for the drill mission said 1 ton IIRC. I wonder what has changed?

All I see is an article written what study are you referring to?  Link please.
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Offline Aerospace Dilettante

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Re: Red Dragon Discussion Thread (2)
« Reply #13 on: 03/09/2014 06:00 PM »
New news.... Sample return!
http://www.space.com/24984-spacex-mars-mission-red-dragon.html

Interesting, this study says Red Dragon can deliver 2 tons to Mars, the previous study for the drill mission said 1 ton IIRC. I wonder what has changed?

All I see is an article written what study are you referring to?  Link please.


I think he was referring to this: http://solarsystem.nasa.gov/docs/7B.4_Karcz_Feasibility%20of%20a%20Dragon-derived%20Mars%20lander%20for%20scientific%20and%20human-precursor%20missions.pdf

Offline Arb

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Re: Red Dragon Discussion Thread (2)
« Reply #14 on: 03/09/2014 06:16 PM »
Wonder what this would cost, and how long it would take, if funded privately?

If using one (reusable?) Falcon Heavy it ought to easily be within the financial capability of many very-high-net-worth individuals...




Offline adrianwyard

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Re: Red Dragon Discussion Thread (2)
« Reply #15 on: 03/09/2014 07:56 PM »
I'm surprised that a second FH is seen as more cost effective than designing a better sealed sample return container.
Does the incoming sample container aero capture into orbit in this proposal? All seems a bit wasteful, IMHO. Plus you have the risk of the 'contaminated' returning spacecraft hitting Earth by accident anyway.
By 2022 we should know if reusability of FH is practical and brings the hoped for savings. if it does, then I could see this being a good tradeoff. It would change the ascent vehicle specs quite dramatically, principally allowing a much larger mass to be returned:
+ Because no Earth TPS is needed (perhaps not much of an aeroshell at all). Also no seal/protection hardware.
+ MAV is less complex because no precise Earth entry navigation is needed if it's being picked up by a Dragon later.
+ Perhaps less maneuvering fuel, and lower power requirements (mass) if it's passive after the Earthwards burn.

In terms of overall mission risks it seems a wash.

+ It's 2x the launches. If the return mission fails at some level, no samples are  returned.
+ The return Dragon mission will have the means to capture a sample from a range of trajectories, some off-nominal.
+ It can spend a lot of mass on the planetary protection hardware, adding more confidence.

But historically sample return missions have been said to be worthwhile with minuscule samples, so I'm not how great the benefit is in terms of scientific payoff.

Offline Kaputnik

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Re: Red Dragon Discussion Thread (2)
« Reply #16 on: 03/09/2014 10:49 PM »
I'm surprised that a second FH is seen as more cost effective than designing a better sealed sample return container.
Does the incoming sample container aero capture into orbit in this proposal? All seems a bit wasteful, IMHO. Plus you have the risk of the 'contaminated' returning spacecraft hitting Earth by accident anyway.
By 2022 we should know if reusability of FH is practical and brings the hoped for savings. if it does, then I could see this being a good tradeoff. It would change the ascent vehicle specs quite dramatically, principally allowing a much larger mass to be returned:
+ Because no Earth TPS is needed (perhaps not much of an aeroshell at all). Also no seal/protection hardware.
+ MAV is less complex because no precise Earth entry navigation is needed if it's being picked up by a Dragon later.
+ Perhaps less maneuvering fuel, and lower power requirements (mass) if it's passive after the Earthwards burn.

In terms of overall mission risks it seems a wash.

+ It's 2x the launches. If the return mission fails at some level, no samples are  returned.
+ The return Dragon mission will have the means to capture a sample from a range of trajectories, some off-nominal.
+ It can spend a lot of mass on the planetary protection hardware, adding more confidence.

But historically sample return missions have been said to be worthwhile with minuscule samples, so I'm not how great the benefit is in terms of scientific payoff.

There is no 'free' way to return the sample capsule to the vicinity of Earth. For one, it cannot be passive after TEI as there will probably be mid course corrections at least. Secondly, it has to either enter and land directly or enter orbit. Either way requires the ability to precisely target the spacecraft trajectory.
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Offline adrianwyard

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Re: Red Dragon Discussion Thread (2)
« Reply #17 on: 03/10/2014 02:42 PM »
My knowledge of celestial mechanics is quite limited so I may be missing something, but I was expecting the dV of a F9H+Dragon to be able to rendezvous with a sample container on a fairly wide range of trajectories. Is that not the case? To be clear, I'm assuming you know the precise trajectory of the container months in advance, and have the dV to choose to meet up in many places along the way (not just HEO/LEO). If necessary you could launch early, use slingshots, and if necessary use them again afterwards and take your time making it back to Earth.

In an extreme case, you could send the return Dragon on a free return trajectory all the way to Mars and meet up with the container as it begins its' journey toward Earth. The Dragon would perform the mid course corrections. In fact, that scenario may allow the max conceivable return mass.

On a related note: one possible use of a large-mass sample return capability would be a full intact core from a drill.
« Last Edit: 03/10/2014 02:47 PM by adrianwyard »

Offline Prober

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Re: Red Dragon Discussion Thread (2)
« Reply #18 on: 03/10/2014 08:49 PM »
From the first thread Jim posted this:

"That is to ambiguous.  A few astrobiologists proposing a mission is not "NASA". "

Is this still the case, or has NASA adopted this "idea"?
 
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Offline neilh

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Re: Red Dragon Discussion Thread (2)
« Reply #19 on: 03/10/2014 09:01 PM »
New news.... Sample return!
http://www.space.com/24984-spacex-mars-mission-red-dragon.html
This was the presentation description on the IEEE website

"Mars Sample Return Using Commercial Capabilities: Propulsive Entry, Descent, and Landing"

"Mars Sample Return (MSR) is the highest priority science mission for the next decade as recommended by the recent Decadal Survey of Planetary Science. We report on the Entry Descent and Landing technique used to support an MSR mission using a Red Dragon capsule. The Red Dragon Mars configuration uses bank angle control and supersonic retro-propulsion, with no required parachute system, to perform Entry, Descent, and Landing (EDL) maneuvers. The EDL landed mass performance envelope covers a range of entry masses, landing altitudes, and minimum and maximum atmosphere density."

There's an additional abstract on the IEEE page:

Quote
2.0612 Mars Sample Return Using Commercial Capabilities: Mission Architecture Overview
Paper Details :
SCHEDULED ON:
Wednesday Morning, March 05 @ 11:00, in Gallatin
AUTHOR(S):
Andrew Gonzales
SYNOPSIS:
Mars Sample Return (MSR) is the highest priority science mission for the next decade as recommended by the recent Decadal Survey of Planetary Science. We report the feasibility of a complete and closed MSR mission design using A Falcon Heavy, a Red Dragon capsule, a Mars Ascent Vehicle, an Earth Return Vehicle, and a retrieval mission. The mission can start in any one of three Earth to Mars launch opportunities, beginning in 2022:A direct to Earth strategy is enabled by the Red Dragon’s landing capability and is used as opposed to a rendezvous and sample transfer in Mars orbit. The objective of the approach was to use emerging commercial capabilities to reduce the number of mission systems, with the goal of reducing mission cost.

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