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I have been watching Starman’s current location through the tracking that is being provided Falcon Heavy/Tesla 2018-017A.

The current orbit shows Starman’s current apogee 6,957 km and with a perigee of 187.7 km. I have watched tracking since this morning and do not see any change. Starman’s orbit seems to be constant on a 164.5 minute interval between apogee and perigee.

Initially I assumed that when it was stated that Starman’s third burn would send it into permanent orbit heading out into space past Mars that it meant the earth would get smaller and smaller from that point on.

It was than announced that the 3rd burn had taken place and that the permanent orbit had been established that would take Starman even further out into space than was planned.

I watched the tracking thinking at first that I would be able to watch Starman head out into space… yet I was surprised to discover that it wasn’t happening the way I thought.

So my question is what will cause Starman’s current orbit to change from the apogee of 6,957 km and a perigee of 187.7 km to one that eventually takes Starman out to an Apohellion of 2.62 AU.

What will be the influencing factor that causes Starman to break away from its current orbit around earth and form the much larger orbital pattern shown in the chart that has been posted?enter image description here

Will there be another burn maneuver performed that will change Starman’s current orbit?

My other assumption is that I am missing something on the tracking page and the current orbit is changing in a subtle way but becoming greater after each iteration of apogee and perigee.

Or maybe it is the influence of Mars gravity as Earth's orbit gets closer to Mars orbit as it seems to appear that it eventually will on the chart above... but that seems like a far stretch to think that Mars gravity could influence a spacecraft still in orbit within 6,947 km of Earth at it's apogee...

Any help in understanding what I am observing and what is actually taking place would be appreciated!

Steve

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    $\begingroup$ What you see at n2yo is most probably NOT the current orbit (imho should still be Earth-centered escape orbit at this time, but soon to be for sure a heliocentric one), but some intermediate orbit picked by radars between the burns (or maybe during the last burn? no idea if that is possible to happen. $\endgroup$
    – jkavalik
    Feb 7, 2018 at 20:59

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The orbital data provided by the website you mentioned is no longer valid and has not been updated. When the Falcon 9 second stage fired for the final time, it pushed the Roadster and Starman out of the Earth orbit listed on the website and into the solar orbit shown on the diagram.

In my opinion, the SpaceX interplanetary burn went badly wrong. If you are running a space mission and say your goal is to get into a Mars Hohmann transfer orbit and instead you find yourself headed out to the Asteroid Belt, you screwed up. Your test flight did not demonstrate the control required for future missions.

At first I thought they had just let the rocket fire for too long and did not cut it off when it reached the proper speed. The rocket had just spent six hours in the radiation belts of Earth, so maybe there was a computer glitch - maybe a bit got scrambled in the memory holding the computer code controlling the burn. All rockets have a little extra fuel ("margin") to handle unexpected launch issues like headwinds, hot / cold air densities, etc. If the computer did not shut the rocket off at the moment the speed was correct for reaching the solar orbit of Mars, then it could keep burning until all the extra fuel was gone. At that burnout, it could easily have the extra speed to pass the solar Mars orbit line and keep going into the Asteroid Belt.

Eventually SpaceX will announce the "orbital elements" for the Tesla, a set of six numbers that will completely define the orbit they reached. Once those are available, armchair astronomers everywhere will figure out just what happened.

A REMARKABLE ACCOMPLISHMENT FOR A TEST FLIGHT, NO MATTER WHAT. CONGRATS, SPACEX!

EDITED TO ADD: Orbital elements have been submitted by SpaceX:

https://www.projectpluto.com/temp/spacex.htm

http://orbitsimulator.com/gravitySimulatorCloud/yr/gsim2018.html?sv,1,2018-017A,2458157.50,-111461866041.424438,96754805789.259842,-75805769.378294,-22641.102635,-25244.753377,-706.797587,0,0,00FF00,90,65,,16000,0,12,1,0,

Earth is the blue circle, Mars is orange; Starman and the Tesla Roadster are on the green path.

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    $\begingroup$ I think it was clear from the beginning that the car would not get close to Mars anytime soon: "billion year orbit around the sun". Everything from the second paragraph is opinion-based and probably doesn't belong here. I thought that the third burn lasted until depletion of fuel, which demonstrates the higher lifting capability of Falcon Heavy and thus was a successful burn. $\endgroup$
    – Thomas W.
    Feb 7, 2018 at 22:33
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    $\begingroup$ They burnt to completion deliberately I hear [citation needed]. $\endgroup$
    – Uzer
    Feb 7, 2018 at 22:35
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    $\begingroup$ Can you provide reference to where you read that "orbit is ALSO inclined to 29 degrees" I would like to read the source. $\endgroup$
    – Steve
    Feb 7, 2018 at 22:38
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    $\begingroup$ " If you are running a space mission and say your goal is to get into a Mars Hohmann transfer orbit and instead you find yourself headed out to the Asteroid Belt, you screwed up" They never said it would be a Hohmann transfer, and they never said they would hit mars. it was always about the orbital hieght of Mars - granted, they worded it so that it could be read as if they wanted to fly to mars, but that was never the goal. $\endgroup$
    – Polygnome
    Feb 8, 2018 at 18:43
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    $\begingroup$ @JonathanKelsey I, too, am under the impression that the maneuver was burn-to-depletion, instead of targeting a specific orbit. $\endgroup$
    – Tristan
    Feb 8, 2018 at 20:13
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And here they are!

Keplerian orbital elements

Elon's Roadster

Epoch: 6 April 2018

a = 1.326427 AU

e = 0.256580

i = 1.052577°

Ω = 317.118857°

ω = 177.454188°

T = 2458153.505755 JD

I note with some satisfaction that my earlier guestimates about the longitude of the ascending node (Ω=317.9°) and the argument of the perihelion (ω=180°) were close to the truth.

The orbit diagram that Elon Musk tweeted on 7 February 2018 was incorrect. He might have done a conservation of energy calculation wrong and arrived at an overly high value for the Tesla Roadster's hyperbolic excess speed, relative to Earth.

https://ssd.jpl.nasa.gov/horizons.cgi

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Latest data show semi major axis of 1.34 AU, eccentricity of 0.2648 and inclination of 1.09°.

See https://www.projectpluto.com/temp/j95.htm#elements

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  • $\begingroup$ Wow...thanks for the info! I have found so many different resources to help me learn how all of this works over the last two days. $\endgroup$
    – Steve
    Feb 8, 2018 at 13:52
  • $\begingroup$ With that being said, I now have questions about what I am looking at when I look at this data. I am not sure what the correct etiquette is do I ask here in the comments or start a new question? $\endgroup$
    – Steve
    Feb 8, 2018 at 14:00
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    $\begingroup$ @Steve I would not mind if this thread is improved by edits of question and answers so that the information in question and answers is still meaningful in a few weeks. Otherwise, following up questions should be posted as a new question. $\endgroup$
    – Thomas W.
    Feb 8, 2018 at 14:28
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    $\begingroup$ Also compare the discussion of the updated orbit in Starman/Roadster in a=1.795 AU orbit, now what's the method to this madness? and Current speed of Tesla Roadster Which is moving to Asteriod Belt? $\endgroup$
    – Thomas W.
    Feb 8, 2018 at 14:32
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The orbit in question was published in a tweet by Elon Musk at 3:46 UTC:

Third burn successful. Exceeded Mars orbit and kept going to the Asteroid Belt.

This third burn happened after a coast phase of several hours. Before that, a restart of the upper stage engine at mission time T+28:22 for 30 seconds resulted in the the parking orbit with a apogee of about 7000 km. Tweet at 9:28 UTC:

Upper stage restart nominal, apogee raised to 7000 km. Will spend 5 hours getting zapped in Van Allen belts & then attempt final burn for Mars.

Since the TLE was reported shortly before midnight (UT), the third burn which sent the Starman on his trip to mars and beyond was not yet included.

Edit: The TLE previously visualized on n2yo.com was:

1 43205U 18017A   18037.94189123  .00000283 -50857-6  00000+0 0  9991
2 43205  29.0185 287.3580 3404246 180.0270 180.5840  8.75540848    00
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  • $\begingroup$ After I received the first comment from Jkavalik above I realized that I was dealing with a faulty assumption based on faulty data so I googled Two Line Element Sets and learned how to read them, etc and how they are used. In my original question I assumed that the tracking I was viewing was live data. $\endgroup$
    – Steve
    Feb 7, 2018 at 22:20
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Steve: There is nothing wrong with your assumption, only that you are a little impatient. That green orbit as shown in the diagram, that's taking it past Mars, so that more than a 3 year orbit. So after 2 days, on that diagram that's not even one pixel from Earth. Another Steve.

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  • $\begingroup$ I understand that... but the data I was watching was not "live" and was just looped and so was not showing any progression, and was just showing the earth locked orbit... the answers that have been,posted as well as references to very good links with addional useful info has been enough to answer my questions, or at least answered my questions in regard to this issue! What it has also has done is show me how little I actually understood about gravity, orbital mechanics, etc., etc. And that I have a lot of reading to do before asking more complex questions! $\endgroup$
    – Steve
    Feb 10, 2018 at 3:43

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