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So the payload of the maiden Falcon Heavy flight will be... Elon Musks's Tesla enter image description here

This is one part publicity stunt (it's going to be playing David Bowie's Space Oddity, if for nothing more than the irony) as well as one part test flight. So, normally I'd expect this to just go up, get a few viral photos, and make a flashy re-entry. But Musk is aiming higher. Much higher

Destination is Mars orbit. Will be in deep space for a billion years or so if it doesn’t blow up on ascent.

Now, you can send anything you want into orbit or into space (no air resistance, corrosion, etc). However, I'm curious how he intends to do this. Normally you send a smaller rocket into orbit and it breaks orbit with said rocket and goes on its merry way thanks to inertia and gravity. Is the FH booster going to burn longer? Is there some second booster hidden somewhere? (seems unlikely for a mission with 50/50 odds of it blowing up) Or is it just going to aim as far out as possible to send it on it's merry way?

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I haven't been able to find any statements on the exact target orbit, but the general consensus is that the payload won't be in orbit around Mars, it will be in an eliptical orbit around the sun and 'touch' the area of space that Mars orbits within. Reaching an orbit around Mars requires much more fuel, the real goal of this launch is to test the rockets capabilities so it makes sense to be able to use some fuel to land the boosters rather than use that fuel to insert a rather useless payload into Mars orbit.

As suggested in the comments below, Musk may have been purposefully vague about the target orbit in an attempt to make us assume it will be in orbit around Mars, and therefore a grander achievement than it really is. The SpaceX website makes the same statement, claiming that Falcon Heavy can take a 16,800kg payload 'to Mars'. The weight of a Tesla is around 1,300kg.

From Musk's Instagram post:

Test flights of new rockets usually contain mass simulators in the form of concrete or steel blocks. That seemed extremely boring.

Of course, anything boring is terrible, especially companies, so we decided to send something unusual, something that made us feel.

The payload will be an original Tesla Roadster, playing Space Oddity, on a billion year elliptic Mars orbit.

The phrase "billion year elliptic Mars orbit" sounds like it could be an elliptical Mars orbit, (orbiting around Mars) in a technical context, but in a social media post, the interpretation could be a bit more loose.

enter image description here


To explain the expected orbit, the image below is a diagram of a Hohmann Transfer, the most fuel efficient method of transfering between two objects that orbit the same body. The grey circle is the Sun, the green ring is Earths orbit around the sun, and the red ring is Mars's orbit around the sun. The transfer is done with two burns, first you move from the green orbit to the red orbit, then once you reach the target orbit, you circularize your orbit.

enter image description here

SpaceX plans to make only the first burn, and orbit in the yellow ring, allowing them to reach the orbit of Mars around the Sun, but not stay there forever. The 'Half-Hohmann Transfer' allows them to do this as cheaply possible and still claim to reach Mars.

The tweet is a little misleading, rocket science is hard enough without the 140 character limit per tweet.

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    $\begingroup$ Thanks for your input, I may have misunderstood the question and the nature of this board before answering. I included the relevant references I could find, the answer I initially made may not be relevant at all so feel free to edit, delete, or give me some advice it if it isn't necessary :) $\endgroup$ – Bazul Jan 6 '18 at 2:10
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    $\begingroup$ How does that look? $\endgroup$ – uhoh Jan 6 '18 at 2:26
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It can't reach Mars Orbit. That would require some kind of a long stable rocket fuel on board, and the ability to separate from the second stage, none of which appear to be the case in the rocket. Not to mention that it would require approval from the US government to do so under the planetary protection act, it doesn't have any indicator of power to keep it going for that long, and that would add a huge expense overall to the mission. Lastly, it would require that the launch occurs in a Mars transfer window, which won't happen until March.

I think the desire not to orbit Mars, but reach the orbit of Mars around the Sun. Perhaps an elliptical orbit with one end at Earth's distance, and a second at Mars. A close flyby of Mars might be possible, but orbiting Mars isn't.

Edit- Just to add a bit more. The cost to send the Telsa in to space without any "smarts" is probably under a million. They would have to do a vacuum test, vibration test, manufacture the stand, and probably do a few modifications, but all in all not a huge amount of engineering would be required.

In order to orbit Mars, it would need the following:

  1. A long life time rocket fuel, of a variable amount. It would need to make some kind of course corrections mid-way. This would also need to be centered on the payload's mass, to allow for it to work. Note that would require some small mid-course adjustments, as well as a longer burn to orbit.
  2. Long term power- Most likely the batteries, while large, would not be sufficient.
  3. Attitude control- Would have to involve some nozzles for adjustment.
  4. Approval from NASA- In order to comply with Planetary Protection laws.
  5. Long range communication- Some kind of a dish.
  6. Some kind of a processor to connect everything together.
  7. Thermal control.
  8. Launching at the proper launch window.

Basically, they would need to convert the Roadster into a proper satellite. There is zero evidence that ANY of this has been done. The cost to do so would be in the $10+ million range, and would take considerable engineering work to accomplish.

Bottom line, it would be awesome, but it's far too much work and cost to do on a publicity stunt that has such a high chance of failure.

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  • $\begingroup$ So it's going to go in a straight line until it reaches/passes Mars orbit? $\endgroup$ – Machavity Jan 5 '18 at 20:01
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    $\begingroup$ @Machavity threre's pretty much no such thing as "a straight line" when dealing with orbital dynamics :) — it's going into an orbit around the sun that takes it out to Mars' orbit (not necessarily the planet), and as close to the sun as Earth's orbit (not necessarily the planet). $\endgroup$ – ReactingToAngularVues Jan 5 '18 at 20:24
  • $\begingroup$ What do you mean by "a long stable rocket engine"? $\endgroup$ – Organic Marble Jan 5 '18 at 22:05
  • $\begingroup$ Can we say the payload sent in heliocentric orbit is the car + second stage attached together? If yes, how much do these two parts weigh? $\endgroup$ – qq jkztd Jan 5 '18 at 22:06
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    $\begingroup$ @qqjkztd It's unclear at this time if the vehicle will be separated from the second stage. It's mounted on the standard payload adapter (as indicated by the photos provided by SpaceX), but whether a separation mechanism is included we do not know. This should be asked as its own question. $\endgroup$ – ReactingToAngularVues Jan 5 '18 at 22:08
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It will be in an elliptical Heliocentric orbit with a perihelion at the Earth's distance from the sun, and an aphelion at Mars' distance from the sun. But it shouldn't get close enough to either planet to be captured by their gravity and impact, or be flung outwards by a gravity assist.

The Falcon 9 second stage will put it onto this elliptical orbit.

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    $\begingroup$ Do you have any references to back up your assertions? $\endgroup$ – Organic Marble Jan 5 '18 at 22:04
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    $\begingroup$ Both answers should probably be converted to comments, pending citations. A rough approximation is that we know that Falcon's upper stage can't do a Mars Orbit Insertion, but there's very little public about the specific orbit of the vehicle. We shouldn't be relying on rumors and inside sources — it's okay to wait. $\endgroup$ – ReactingToAngularVues Jan 6 '18 at 0:55
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    $\begingroup$ @uhoh This one makes specific claims "It will be". Neither answer is very good. I also asked for clarification on the other one. $\endgroup$ – Organic Marble Jan 6 '18 at 1:08
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    $\begingroup$ Yes, I might have spent more time lurking rather than starting to answer things, to aborb the culture. That link about "certain practices" says: "This site is all about getting answers. It's not a discussion forum. There's no chit-chat." Hmmm, this seems like chit-chat, which we on FB call meta-discussion if we're discussing group management or poster reputations. But in any event, I just couldn't stand to see the post about the GG exhaust manifold being used for TEA-TEB ignition. Should not need a "reputation" to declare that to be an impossible engine design feature. $\endgroup$ – Bill Carton Jan 10 '18 at 19:37
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    $\begingroup$ I also hang out at Nasaspaceflight and their L2 forums, and have given multiple talks on SpaceX in SoCal. NASA invitations for multiple Social Media events at CRS6 and CRS9 launches. In this case, the FH doesn't have the delta-v at this launch window to arrive at Mars distance when Mars is present, I hear from insiders that there was no Planetary Protection-level sterilization process, so a landing is out of the question by treaty. The last issue about S2 putting the payload into the Mars transfer orbit is obvious from the fact that the only source of propulsion is the second stage. $\endgroup$ – Bill Carton Jan 10 '18 at 19:44

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