Author Topic: Dragon Mars Flyby  (Read 9852 times)

Offline Airlock

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Dragon Mars Flyby
« on: 05/27/2012 04:42 pm »
There's been a lot of talk on this forum about the Red Dragon concept being developed to allow a dragon to land on the surface of Mars. I was thinking about it, and thought up something a bit more "simple" but nonetheless inspiring.

1) My current understanding is that spacex will maintain ownership of the CRS capsules after they return to Earth, and can do whatever they please with them as long as they are not re-flown on another CRS flight.

2) There is talk that they are already considering modifying these vehicles for DragonLab flights.

3) Within the next 5 years, they will have a rocket capable of launching dragon on an earth escape trajectory.

With those elements in place, I think that spacex should fly a dragon past Mars (not enter orbit) and then return the capsule to Earth. This would allow them to demonstrate the following:

1) GNC systems required to navigate in interplanetary space (GPS and LIDAR just won't cut it out here!)

2) dragon avionics can survive such a trip through the space environment outside the magnetosphere.

3) Scientists would get data about radiation exposure inside of a pressurized and (almost) man rated craft.

4) re-entry into the Earth's atmosphere from interplanetary speeds.

5) bragging rights of course...

In order to fund this, spacex could sell payload space similar to a dragon lab flight.  How may universities and space agencies would be more than happy to pay some money to get their instruments within a few thousand kilometers of Mars?

So, thoughts?

Offline baddux

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Re: Dragon Mars Flyby
« Reply #1 on: 05/27/2012 06:58 pm »
I suggested the same thing while ago, here's the thread: http://forum.nasaspaceflight.com/index.php?topic=26691.0

Offline Jim

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Re: Dragon Mars Flyby
« Reply #2 on: 05/27/2012 07:31 pm »
So, thoughts?

No need for another thread like this. 

And no, it isn't a good idea.  There is little added science to be had by a flyby

Online meekGee

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Re: Dragon Mars Flyby
« Reply #3 on: 05/27/2012 09:25 pm »
1) My current understanding is that spacex will maintain ownership of the CRS capsules after they return to Earth
So, thoughts?

For sure.  Exactly as you state - A wet run, demo of fast aerobraking on Earth - it will be too tempting to ignore.

I agree the science value is limited, but if you're going to debug such an increase in capabilities, you might as well debug it with a used Dragon and without an irreplaceable payload.  You just gain 2 years on your schedule.

And when you're confident, you're ready to start debugging your Mars EDL knowing that you can have a solid stating point.

And - let me throw out another idea - wouldn't they benefit greatly from small secondaries that can function as com relays and GPS, so their landings can be more precise?

What would be the minimum size of a GPS satellite if it is to be used for EDL?
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Offline Kaputnik

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Re: Dragon Mars Flyby
« Reply #4 on: 05/27/2012 10:29 pm »
Does a Dragon, without modification, have sufficient delta-v for the course-correction burns that will be required? Nobody has flown a free-return trajectory around Mars before, I'm not sure what the delta-v looks like.
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Offline aero

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Re: Dragon Mars Flyby
« Reply #5 on: 05/27/2012 10:47 pm »
Does a Dragon, without modification, have sufficient delta-v for the course-correction burns that will be required? Nobody has flown a free-return trajectory around Mars before, I'm not sure what the delta-v looks like.

Google the "Aldrin Cycler."
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Offline go4mars

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Re: Dragon Mars Flyby
« Reply #6 on: 05/29/2012 01:36 am »
There is little added science to be had by a flyby
4 main things get verified.  Not sure the expense justifies it but:

1) heatshield test.
2) communications/control test.
3) proves (or disproves) enough fuel for course corrections.
4) extended test of all dragon sub-systems in deep space.

Plus I guess SpaceX could have another famous wheel of space cheese.

Seems a shame to go all that way and not touch down.  If the Red Dragon mission in total is less than $500 million, I'm not sure you'd save a pile by bringing it back to earth instead. 
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Offline douglas100

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Re: Dragon Mars Flyby
« Reply #7 on: 05/29/2012 08:12 am »
4 main things get verified.  Not sure the expense justifies it but:

1) heatshield test.
2) communications/control test.
3) proves (or disproves) enough fuel for course corrections.
4) extended test of all dragon sub-systems in deep space.

A Mars flyby isn't needed to test any of these things. You're right: the expense doesn't justify it.
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Offline Ben the Space Brit

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Re: Dragon Mars Flyby
« Reply #8 on: 05/29/2012 09:43 am »
So, thoughts?

No need for another thread like this. 

And no, it isn't a good idea.  There is little added science to be had by a flyby

I think that it would be more an engineering than science mission, Jim.  Basically a technology evaluation mission with a little science thrown in as a bonus.

Basically, the questions to answer would be:

1. Can Dragon operate in deep space (thermal, radiation and other issues)?

2. Can SpaceX maintain communications at long ranges (such as building a high-gain tracking antenna)?

3. How long with the Dragon's electronics, thrusters and sensors remain reliable in the deep space environment?

Most of these could be answered by sticking a Dragon in the EML-1 halo orbit.  However, Elon Musk is a businessman.  There is both money and positive PM potentially to be made taking a few international sensors out on a 'grand tour' in to Venus, then out to Mars and finally back to Earth (maybe put an aerogel micrometeorite capture can behind the CBM door?).

The advantages deep spafce has over EML is that it is a more extreme communications test and, if the spacecraft becomes uncontrollable due to nav/RCS failure, it isn't a potential hazard in a patch of space likely to be used by human spaceflight in the near future.

However, most important is to get the megabytes of data on how Dragon's systems handle the BEO environment.
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Offline douglas100

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Re: Dragon Mars Flyby
« Reply #9 on: 05/29/2012 10:45 am »

Basically, the questions to answer would be:

1. Can Dragon operate in deep space (thermal, radiation and other issues)?

2. Can SpaceX maintain communications at long ranges (such as building a high-gain tracking antenna)?

3. How long with the Dragon's electronics, thrusters and sensors remain reliable in the deep space environment?

And the answer to all these questions is of course, yes, if the spacecraft is designed for the mission. It's not as if thrusters decide to stop working once they're in interplanetary space. Electronics can be shielded. Spacecraft have been already been built with high gain antennae which can transmit over interplanetary distances. Thermal management is in some ways easier in interplanetary space than in LEO. The DSN is there to receive the signals. We have known how to do these things for decades. It is completely unnecessary to do a Mars flyby to test them.

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Offline Ben the Space Brit

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Re: Dragon Mars Flyby
« Reply #10 on: 05/29/2012 10:54 am »
It is completely unnecessary to do a Mars flyby to test them.

It is if you don't know if you can do them/do it right.

Just look at the problems SpaceX had getting Dragon C2+ ready for flight.  There were no real mysteries there, no new technology.  However, translating what I suppose you could call 'book learning' into actual working technology and integrating it in a way that it all works properly together proved to be quite an endeavour in its own right.  I'm pretty sure that the SpaceX schedule slip is mostly due to their greatly underestimating exactly how hard it is to bridge the gap between what it says in the text books and working technology.

Consider it as mostly an ultra-long-duration 'stress test' to see how well what they've read in the text books matches with reality.

I'm not necessarily in favour or against this idea; I just wanted to point out that a justification is possible.
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Offline baldusi

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Re: Dragon Mars Flyby
« Reply #11 on: 05/29/2012 12:39 pm »
You don't need to do that. The environment is very well characterized. You just have to specify, test, test, test, test, and test again and certify.

Online meekGee

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Re: Dragon Mars Flyby
« Reply #12 on: 05/29/2012 02:12 pm »
It's good to see how SpaceX is now given such credit that they don't NEED to do a Mars fly-around just to prove themselves.

I think the original poster is arguing that they'd WANT to do it.  Sure, you can test the individual pieces w/o going to Mars, but as long as you've got a technology demonstration mission for all those pieces, the benefit of doing it "for real" outweighs the extra cost.  It's not like doing it near Earth is going to be cheap.
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Offline Airlock

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Re: Dragon Mars Flyby
« Reply #13 on: 05/29/2012 02:33 pm »
It's good to see how SpaceX is now given such credit that they don't NEED to do a Mars fly-around just to prove themselves.

I think the original poster is arguing that they'd WANT to do it.  Sure, you can test the individual pieces w/o going to Mars, but as long as you've got a technology demonstration mission for all those pieces, the benefit of doing it "for real" outweighs the extra cost.  It's not like doing it near Earth is going to be cheap.

Yes, the idea of selling payload slots on board was to help finance the mission, but the main purpose is to demonstrate their technology can survive the trip and to inspire the general public. I think that SpaceX wants to do this, especially since Mars is their well-established long term goal. Plus, if they pull off such a stunt, the marketing writes itself.

Offline douglas100

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Re: Dragon Mars Flyby
« Reply #14 on: 05/29/2012 03:57 pm »

 Plus, if they pull off such a stunt, the marketing writes itself.

Your description, not mine. As for marketing, I wonder. Remember such a flight will take over 2 years. It's not the sort of thing you can keep continuously in the headlines for PR purposes.
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Offline rklaehn

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Re: Dragon Mars Flyby
« Reply #15 on: 05/29/2012 04:00 pm »
I guess dragon really is the official successor to the space shuttle now. You used to get all kinds of threads about flying the space shuttle to the moon/mars/alpha centauri. Now you get the same with dragon.

Offline Mader Levap

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Re: Dragon Mars Flyby
« Reply #16 on: 05/29/2012 04:07 pm »
I guess dragon really is the official successor to the space shuttle now. You used to get all kinds of threads about flying the space shuttle to the moon/mars/alpha centauri. Now you get the same with dragon.
At least it is zilion times more plausible than Shuttle to Mars...  ::)
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Offline catiare

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Re: Dragon Mars Flyby
« Reply #17 on: 05/29/2012 06:29 pm »

[/quote]4 main things get verified.  Not sure the expense justifies it but:

1) heatshield test.
2) communications/control test.
3) proves (or disproves) enough fuel for course corrections.
4) extended test of all dragon sub-systems in deep space.

Plus I guess SpaceX could have another famous wheel of space cheese.
[/quote]

Would a Flyby to the Moon accomplish some of the same goals? (Except for item 3). I guess with a dozen spare used Dragons, both Flybys could be done. The moon would be operationally cheaper due to its duration. So why not do that one first?

Offline go4mars

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Re: Dragon Mars Flyby
« Reply #18 on: 05/29/2012 07:07 pm »
Some of it yes. 

But actually doing the Red Dragon mission would have a similar price tag to just flying by.  Even if it incrementally costs $50 million more or so for the landing version versus the fly-by version, that's well worth it. 

Red Dragon mission essentially gets you everything this does, plus science, plus proof of concept landing system on Mars, plus every ninny in the public looks at crew dragon, and thinks about it analogously with the Mars delivery version (even though there would be some differences "under the hood").     

 Landing on Mars is a far superior bang per buck. 
« Last Edit: 05/29/2012 07:08 pm by go4mars »
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Offline douglas100

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Re: Dragon Mars Flyby
« Reply #19 on: 05/29/2012 07:54 pm »

 Landing on Mars is a far superior bang per buck. 

Sure. That would be a proper objective rather than a stunt. Though how much more expensive a landing mission would be is guesswork.
Douglas Clark

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