Author Topic: Tesla to Mars.  (Read 3477 times)

Offline speedevil

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Tesla to Mars.
« on: 12/02/2017 04:22 AM »
On twitter, elon tweeted ( https://twitter.com/elonmusk/status/936782477502246912 )
Quote
Falcon Heavy to launch next month from Apollo 11 pad at the Cape. Will have double thrust of next largest rocket. Guaranteed to be exciting, one way or another.


Payload will be my midnight cherry Tesla Roadster playing Space Oddity. Destination is Mars orbit. Will be in deep space for a billion years or so if it doesn’t blow up on ascent.
Further confirmation from SpaceXs head of new product introduction at https://twitter.com/RocketJoy/status/936786839268032513

Assuming for the moment that this is legitimate, and that it is a mission with minimal development effort, what 'lego' is available?

A dragon or two might be kicking around, superdracos, various parts from recovered S1s, ...

What might the trajectory be?
Is a stable mars orbit plausible - setting aside the 'million years' comment for the moment.
Might ion engines (to bring in SolarCity) help at all for anything, or is this going to be purely chemical?

Can dragon 2, assuming for the moment propulsive works ideally, with larger tanks, get anywhere near the surface, if he might even be underselling?

I note the optimum trajectory is closer to May than January.
If it was ever possible to launch in November, or even before, this implies either flexibility in target, enormous payload capability, or maybe a very, very last minute payload.
« Last Edit: 12/02/2017 04:32 AM by speedevil »

Offline freddo411

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Re: Tesla to Mars.
« Reply #1 on: 12/02/2017 05:19 AM »
If we assume that the upper stage can sustain itself with minimal boil off, here's one idea on how to construct a tesla mission.   

Launch in Dec/Jan/Feb.   Linger in a elliptical parking orbit around the Earth until May.  Fire engines in May.   


Offline x15_fan

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Re: Tesla to Mars.
« Reply #2 on: 12/02/2017 05:46 AM »
If we assume that the upper stage can sustain itself with minimal boil off, here's one idea on how to construct a tesla mission.   

Launch in Dec/Jan/Feb.   Linger in a elliptical parking orbit around the Earth until May.  Fire engines in May.

No chance S2 lasts more than on the order of hours on batteries keeping RP from freezing and avionics up. I think they need stage to last for like max 8 hours for NS GSO missions.


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Offline coypu76

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Re: Tesla to Mars.
« Reply #3 on: 12/02/2017 06:04 AM »
Is S2 cannot be used for Mars Orbit injection, then what?
Hohmann transfer orbit window to Mars begins only in March and runs through June, 2018.  A January launch will not be an ideal trajectory, but it may be possible to send the Tesla on a different orbit, perhaps with a turn around another planet, that will arrive at Mars slowly enough for a gravity capture in a high, eccentric orbit. 

Offline mikelepage

Re: Tesla to Mars.
« Reply #4 on: 12/02/2017 06:10 AM »
Count me amused, but also in disbelief if this gets up.

Gen 1 Roadster is listed on wikipedia as 1305kg.  So well within the capability of Falcon Heavy to demonstrate GTO first, then do trans-Mars injection.  However, horrific space debris problem if S2 malfunctions during that re-ignition...  Space debris in GTO is pretty much the worst possible outcome.

Offline Kaputnik

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Re: Tesla to Mars.
« Reply #5 on: 12/02/2017 06:25 AM »
You could interpret the tweet as 'same orbit as Mars' which would be a lot more achievable. Or at least some sort of heliocentric orbit that crosses the orbits of both planets.

I don't see how the payload needs to pose a greater debris risk than a satellite. Trying to extend S2 coast could cause problems, IMHO they won't do that unless completely confident.
Waiting for joy and raptor

Offline x15_fan

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Re: Tesla to Mars.
« Reply #6 on: 12/02/2017 06:34 AM »
Is S2 cannot be used for Mars Orbit injection, then what?
Hohmann transfer orbit window to Mars begins only in March and runs through June, 2018.  A January launch will not be an ideal trajectory, but it may be possible to send the Tesla on a different orbit, perhaps with a turn around another planet, that will arrive at Mars slowly enough for a gravity capture in a high, eccentric orbit.

Read more carefully, talks about deep space.  Simply crossing Mars orbit path satisfies the requirement. No need to go in orbit around Mars.


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Offline docmordrid

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Re: Tesla to Mars.
« Reply #7 on: 12/02/2017 07:28 AM »
Is S2 cannot be used for Mars Orbit injection, then what?
>

First blush, a hypergolic kick module leveraging Draco or SuperDraco with a vacuum nozzle.

Second blush, the flight test of a BFS methalox thruster kick module and all that entails. Go big or go home.

What additional mass would these require, and does FH have the margin for injecting 1305kg plus the module mass to Mars?
« Last Edit: 12/02/2017 07:34 AM by docmordrid »
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Offline deruch

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Re: Tesla to Mars.
« Reply #8 on: 12/02/2017 08:41 AM »
I just posted this in the Payload Speculation thread, but maybe more appropriate here, with minor edits:

It's probably not going to actually capture into Mars orbit, y'all.  According to https://trajbrowser.arc.nasa.gov/traj_browser.php , there is a launch opportunity on December 17th, 2017.  It puts the payload on a two year transfer, where it arrives at Mars after completing a whole orbit first.  Needs C3=33.3!   With post injection delta-v of 2.32km/s.  According to http://silverbirdastronautics.com/LVperform.html, Falcon Heavy, using booster RTLS and core ASDS recovery, can launch 872 kg to such a C3.  That's probably a little bit under what it can do in reality because FH performance specs has increased quite a bit in the relatively recent past and i'm not sure when Silverbird last updated their FH performance.  Tesla Roadster Gen. 1 is listed by Wikipedia as having a curb weight of 1,305 kg.  So, between some stripping (don't need a battery sized for an EV, etc.) and uprated Merlins on the FH, it's probably within reach.  But I don't think that is so if the car has to come up with 2.3+km/s of delta-v plus PV systems and comms, etc.  And they're going to miss that date anyways, so the actual launching will need even more performance, if it is still possible a few weeks later.

Best estimate is that it will maybe get close to Mars.  I'm dubious it will really course correct along the way or actually capture, even if it is still alive when it gets there after 2 years (again, doubtful).  But it can get out to the general vicinity, without a doubt.  Best playful payload ever!!
« Last Edit: 12/02/2017 08:42 AM by deruch »
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Online xanmarus

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Re: Tesla to Mars.
« Reply #9 on: 12/02/2017 11:08 AM »
Could they attach tesla to their Starlink satellite bus?
« Last Edit: 12/02/2017 11:10 AM by xanmarus »

Offline Ludus

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Re: Tesla to Mars.
« Reply #10 on: 12/02/2017 10:36 PM »
The Mars Orbit, not in orbit around Mars version seems much more reasonable.

There would likely be an some effort to legally block any project like this that tried to place a “silly” payload in Mars orbit because of US policy obligations toward Planetary Protection. Something in Mars orbit would crash on the planet eventually. The Cassini spacecraft was recently deliberately ditched into Saturn to avoid the chance it might hit one of the Saturnian moons that could have life. This tiny chance of contamination influenced the mission plan of a very serious and expensive spacecraft.
« Last Edit: 12/02/2017 10:37 PM by Ludus »

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