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Thread: Tesla Roadster / Starman - orbital characteristics

  1. #1
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    Tesla Roadster / Starman - orbital characteristics

    Anybody have the orbital characteristics for the Tesla Roadster/Starman?

    I wanted to enter them into my Starry Night program. So I could ride along!

  2. #2
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    Well, see what Musk tweeted as a start:

    https://pbs.twimg.com/media/DVZ0h3YW4AIc-9w.jpg

    Apohelion: 2.61 AU
    Perihelion 0.98

    But I haven't seen any ephemeris data yet.

  3. #3
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    Quote Originally Posted by schlaugh View Post
    Well, see what Musk tweeted as a start:

    https://pbs.twimg.com/media/DVZ0h3YW4AIc-9w.jpg

    Apohelion: 2.61 AU
    Perihelion 0.98

    But I haven't seen any ephemeris data yet.
    Wow, they really gave it a bit more of a push than they proposed. Let's hope it doesn't end up smashing into something farther on down the road.
    I know that I know nothing, so I question everything. - Socrates/Descartes

  4. #4
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    Quote Originally Posted by DaCaptain View Post
    Wow, they really gave it a bit more of a push than they proposed. Let's hope it doesn't end up smashing into something farther on down the road.
    "But, officer, I had the right of way ..."

  5. #5
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    Quote Originally Posted by grapes View Post
    "But, officer, I had the right of way ..."
    LOL, It doesn't matter if the stone hits the pitcher or the pitcher hits the stone, it's going to be bad news for the pitcher.
    I know that I know nothing, so I question everything. - Socrates/Descartes

  6. #6
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    From Bill Gray of Project Pluto, tweaked with images during the escape burn, preliminary orbital elements were:

    Orbital elements: 2018-017X
    Perigee 2018 Feb 7.108542 +/- 0.000217 TT = 2:36:18 (JD 2458156.608542)
    Epoch 2018 Feb 8.0 TT = JDT 2458157.5 Gray
    q 7131.80034 +/- 1.97 (J2000 equator)
    Peri. 152.15202 +/- 0.024
    Node 285.31375 +/- 0.0012
    e 1.2024743 +/- 0.000383 Incl. 29.21177 +/- 0.0018

    Orbital elements: 2018-017X
    Perihelion 2018 Feb 6.490939 TT = 11:46:57 (JD 2458155.990939)
    Epoch 2018 Feb 10.0 TT = JDT 2458159.5 Earth MOID: 0.0002 Ma: 0.0114
    M 2.25389 (J2000 ecliptic)
    n 0.64230639 Peri. 180.09192
    a 1.33037645 Node 317.25015
    e 0.2585965 Incl. 0.74743
    P 1.53/560.47d q 0.98634572 Q 1.67440719

    These are completely "unofficial" at this point.

  7. #7
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    Quote Originally Posted by ngc3314 View Post
    From Bill Gray of Project Pluto, tweaked with images during the escape burn, preliminary orbital elements were:

    Orbital elements: 2018-017X
    Perigee 2018 Feb 7.108542 +/- 0.000217 TT = 2:36:18 (JD 2458156.608542)
    Epoch 2018 Feb 8.0 TT = JDT 2458157.5 Gray
    q 7131.80034 +/- 1.97 (J2000 equator)
    Peri. 152.15202 +/- 0.024
    Node 285.31375 +/- 0.0012
    e 1.2024743 +/- 0.000383 Incl. 29.21177 +/- 0.0018

    Orbital elements: 2018-017X
    Perihelion 2018 Feb 6.490939 TT = 11:46:57 (JD 2458155.990939)
    Epoch 2018 Feb 10.0 TT = JDT 2458159.5 Earth MOID: 0.0002 Ma: 0.0114
    M 2.25389 (J2000 ecliptic)
    n 0.64230639 Peri. 180.09192
    a 1.33037645 Node 317.25015
    e 0.2585965 Incl. 0.74743
    P 1.53/560.47d q 0.98634572 Q 1.67440719

    These are completely "unofficial" at this point.
    I wonder how long the roadster will last out there before it turns into a big lump of lithium circling the sun. That's if the main batteries are still in it. It would be an interesting thing to visit when it comes back around. Any guesses when it might be back in our neighborhood?
    Last edited by DaCaptain; 2018-Feb-08 at 03:24 PM.
    I know that I know nothing, so I question everything. - Socrates/Descartes

  8. #8
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    Heard on the news that the looped music would only last about 6 hours before the battery was drained, was wondering if the music had a solar power source to last for decades or not.

  9. #9
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    Quote Originally Posted by Spacedude View Post
    Heard on the news that the looped music would only last about 6 hours before the battery was drained, was wondering if the music had a solar power source to last for decades or not.
    Musk missed a co-branding opportunity to put some Tesla solar panels on the car or the mating platform.

  10. #10
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    Thanks for posting those orbital elements!

  11. #11
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    Quote Originally Posted by DaCaptain View Post
    I wonder how long the roadster will last out there before it turns into a big lump of lithium circling the sun. That's if the main batteries are still in it. It would be an interesting thing to visit when it comes back around. Any guesses when it might be back in our neighborhood?
    I thought I heard someone on TV or on-line saying it would have a close approach to Earth in 2030, but I can't find a reference now and I don't know how close "close" is.

    The best I could find was this.
    For most of its orbit, the car will be floating between Mars and Jupiter. But it will pass through Earth’s orbit every once in a while and have “very rare close approaches to the Earth and Mars,” explained Alan Fitzsimmons, an astronomer at Queen's University Belfast.
    At night the stars put on a show for free (Carole King)

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  12. #12
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    Slightly updated elements as of the next morning (also circulated by Bill Gray)

    Orbital elements: Sped-up
    Perihelion 2018 Jan 28.639832 TT = 15:21:21 (JD 2458147.139832)
    Epoch 2018 Feb 9.0 TT = JDT 2458158.5 Earth MOID: 0.0000 Ma: 0.0934
    M 4.63650 (J2000 ecliptic)
    n 0.40813685 Peri. 168.57287
    a 1.79997100 Node 317.89354
    e 0.4554736 Incl. 3.36051
    P 2.41/882.04d q 0.98013165 Q 2.61981035

    Orbital elements: Sped-up
    Perigee 2018 Feb 7.107275 TT = 2:34:28 (JD 2458156.607275)
    Epoch 2018 Feb 8.0 TT = JDT 2458157.5 Gray
    q 7133.54306km (J2000 equator)
    Peri. 148.15635
    Node 285.92927
    e 1.7405665 Incl. 28.92091

    (called 'Sped-up' because it requires a boost in speed over the
    earlier C3=12 km^2/s^2 solution.)

    (Also, the payload is now recognized by the JPL Horizons system for coordinate predictions - under the list of spacecraft select Tesla Roadster!)

  13. #13
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    Best headline so far from the Register in the UK:

    MY GOD, IT'S FULL OF CARS: SpaceX parks a Tesla in orbit (just don't mention the barge)
    And this from Jonathan McDowell, astronomer at the Harvard-Smithsonian Center for Astrophysics (several tweets joined together):

    Revised heliocentric orbit using the JPL ephemeris is 0.986 x 1.667 AU x 1.05 deg. (My estimate used a simple patched conic approximation, JPL do the proper job).

    Using the JPL ephemeris, the closest predicted approach to Mars between now and 2030 is 7 million km on 2020 Oct 8. This is still well outside Mars' gravitational sphere of influence.

    In contrast, the Roadster will not return anywhere near Earth by 2030; closest it gets after this month is Mar 2021 at a distant 45 million km.

    Summary: Starman will be lonely for a long time to come.
    ETA: And Alan Fitzsimmons has created a graph which shows how Jupiter affects the Tesla's orbit over time.
    Last edited by schlaugh; 2018-Feb-08 at 05:31 PM.

  14. #14
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    so, bear with me, I mess with this stuff in Starry Night every couple of years, so there's always a re-learning curve.

    It looks like you're giving two sets of data, two possible orbits for the object?

    So, say, call it 2018-017X-version1 and 2018-017X-version2?

  15. #15
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    Quote Originally Posted by algomeysa View Post
    Anybody have the orbital characteristics for the Tesla Roadster/Starman?

    I wanted to enter them into my Starry Night program. So I could ride along!
    Here is a simulation of the Tesla's orbit using the latest data from JPL Horizons.
    If you want to see the orbital elements for Starry Night, with the simulation paused, click menu Objects > Edit Objects Orbital Elements
    http://orbitsimulator.com/gravitySim...9Horizons.html

  16. #16
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    Amateur astronomers are still tracking it.

    spaceweather.com (I suspect the story will only be on that page for a day or so)

    Using that ephemeris, along with a remote-controlled telescope in Siding Spring, Australia, amateur astronomer Adriano Valvasori photographed the Roadster on Feb. 8th. It is the faint speck circled in red:

    At the time, the car was 493,000 km (306,000) away, not far beyond the orbit of the Moon, receding from Earth about 3.7 km/s (8,300 mph). Reflecting sunlight, it shone about as brightly as a 16th magnitude star.
    The image (click to magnify)
    At night the stars put on a show for free (Carole King)

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  17. #17
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    Here is a little video of it. Odd, I'm pretty sure one of those lights were red, but it didn't stop. [2nd pun]
    We know time flies, we just can't see its wings.

  18. #18
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    I'm seeing two specks on the same trajectory there. Is one the payload and the other (presumably the brighter one) the second stage?
    Cum catapultae proscriptae erunt tum soli proscript catapultas habebunt.

  19. #19
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    Cool, this guy's youtube video https://www.youtube.com/watch?v=OQgDUrNOkVs
    gave me the info I've been looking for...
    that Tesla Roadster/Starman's designation in the JPL database is

    -143205

    So I emailed the JPL email-bot and it spat back this:

    Revised: Feb 20, 2018 Tesla Roadster (spacecraft) -143205
    (solution #8)

    Tesla Roadster (AKA: Starman, 2018-017A)

    NOTE:
    The trajectory estimate will be updated here in the days ahead if more
    measurement data is reported.

    Visibility: 20th magnitude until Feb 20, 22nd magnitude through early April,
    brighter than 26th magnitude into June.

    LAUNCHED:
    2018-Feb-06 20:45 UTC by Falcon Heavy (FH-1) from Kennedy Space Center, USA
    (launchpad 39A)

    BACKGROUND:
    Dummy payload from the first launch of SpaceX Falcon Heavy launch vehicle.
    Consists of a standard Tesla Roadster automobile and a spacesuit-wearing
    mannequin nicknamed "Starman".

    Also includes a Hot Wheels toy model Roadster on the car's dash with a
    mini-Starman inside. A data storage device placed inside the car contains
    a copy of Isaac Asimov's "Foundation" novels. A plaque on the attachment
    fitting between the Falcon Heavy upper stage and the Tesla is etched with
    the names of more than 6,000 SpaceX employees.

    After orbiting the Earth for 5 hours, a third burn by the second stage was
    completed at approximately 02:30 UTC Feb 7, placing the dummy payload in a
    heliocentric orbit having a perihelion of 0.99 au and aphelion ~1.67 au.

    The object stack consists of a Merlin 1D Vacuum second stage with Extended
    Nozzle, Payload Attachment Fitting, and Tesla Roadster on mount.

    Roadster mass: ~1250 kg (with batteries), ~800 kg (without ESS/batteries)

    TRAJECTORY:
    This trajectory is based on JPL solution #8, a fit to 330 ground-based
    optical astrometric measurements spanning 2018 Feb 8.2 to 18.3

    Trajectory name Start (TDB) Stop (TDB)
    -------------------------------- ----------------- -----------------
    tesla_s8 2018-Feb-07 03:00 2048-Jan-01 00:00

    Encounter predictions for s8 (with gravity-only dynamics):

    Date (TDB) Body CA Dist MinDist MaxDist Vrel TCA3Sg Nsigs P_i/p
    ----------------- ----- ------- ------- ------- ------ ------ ------ ------
    2018 Feb 08.09700 Moon .000936 .000936 .000936 3.962 0.42 40889. 0.000
    2020 Oct 07.27671 Mars .049248 .048632 .049996 8.132 29.03 6.68E5 0.000
    2035 Apr 22.31261 Mars .021004 .007334 .035038 8.315 142.40 37596. 0.000
    2047 Jan 12.52967 Earth .029674 .019448 .039078 4.422 4391.7 73261. 0.000
    2050 Mar 19.02367 Earth .113309 .089472 .135482 7.215 2540.6 2.42E5 0.000

    Date = Nominal encounter time (Barycentric Dynamical Time)
    CA_Dist = Highest probability close approach distance to body, au
    MinDist = 3-sigma minimum encounter distance, au
    MaxDist = 3-sigma maximum encounter distance, au
    Vrel = Relative velocity at nominal encounter time, km/s
    TCA3Sg = 3-sigma uncertainty in close enocunter time, minutes
    Nsigs = Number of sigmas to encounter body at nominal encounter time
    P_i/p = Linearized probability of impact

    NOTE:
    How to obtain optional statistical uncertainty output & generate an SPK file:

    Since this is a spacecraft and not part of the asteroid and comet database
    which normally holds orbit covariance data, some functions like statistical
    output and SPK file generation aren't automatically available for this object.

    However, with some extra steps, such optional extended output is possible
    in this case.

    To propagate statistical uncertainties for this object, the full statistical
    orbit solution (given below) can be manually input back into Horizons as a
    "user-defined object" using the telnet or e-mail interfaces (not possible
    with the browser interface).

    To do this and activate statistical or SPK file output ...

    Using the telnet interface (command-line "telnet ssd.jpl.nasa.gov 6775"),
    enter ";" to drop into user-input mode then cut-and-paste each line shown
    below, one at a time. The lines of numbers after SRC must be in the order
    shown.

    For SPK file generation, only the first three lines need be input; the
    EPOCH and orbital element lines starting with "EC" and "OM".

    SRC lines are needed only for statistical output, the H & G values only
    for visual magnitude output.

    EPOCH= 2458161.5
    EC= .2605617969679692 QR= .986061946474019 TP= 2458153.658830588476
    OM= 317.4100916677914 W = 177.3002372702468 IN= 1.096465162480806
    SRC= 2.215648860985859E-7 -6.978166940838508E-9 1.747703101626183E-9
    6.838107985591074E-7 -2.785083038219253E-9 1.623752951763019E-6
    2.676579519565857E-7 4.428313428313642E-9 2.245727600074333E-5
    3.906772819853299E-7 7.548892835768459E-7 6.893942303902765E-9
    -2.440888593071481E-5 -2.00112779439303E-6 1.694365063698046E-6
    2.774779936165686E-5 2.475181137432366E-8 .0002597834543639343
    2.183107215200873E-6 2.157965362478634E-6 1.889595619028567E-6
    H= 25.257 G= 0.15

    When done, press a blank return to exit input mode.

    Enter "J" at the prompt to indicate heliocentric J2000 ecliptic data has
    been supplied. Then at the next prompt, input an arbitrary name
    (i.e., Roadster).

    Horizons will then proceed as usual, but with statistical output and SPK
    file generation now available as options.

    A basic and identical tracking ephemeris can be produced without doing any
    of this, but statistical uncertainty quantities requested will be marked
    "n.a.", meaning not available, and SPK generation won't be an option..

    NOTE: long-term predictions

    Over time, trajectory prediction errors could increase more rapidly
    than the formal statistics indicate due to unmodeled solar pressure,
    thermal re-radiation, or outgassing accelerations that are not currently
    characterized but may exist.
    ************************************************** *****************************


    ************************************************** *****************************
    Ephemeris / MAIL_REQUEST Thu Mar 1 10:27:41 2018 Pasadena, USA / Horizons
    ************************************************** *****************************
    Target body name: SpaceX Roadster (spacecraft) (-143205) {source: tesla_s8}
    Center body name: Sun (10) {source: DE431mx}
    Center-site name: BODY CENTER
    ************************************************** *****************************
    Start time : A.D. 2018-Mar-02 13:25:00.0000 TDB
    Stop time : A.D. 2018-Mar-02 13:25:01.0000 TDB
    Step-size : 60 minutes
    ************************************************** *****************************
    Center geodetic : 0.00000000,0.00000000,0.0000000 {E-lon(deg),Lat(deg),Alt(km)}
    Center cylindric: 0.00000000,0.00000000,0.0000000 {E-lon(deg),Dxy(km),Dz(km)}
    Center radii : 696000.0 x 696000.0 x 696000.0 k{Equator, meridian, pole}
    Keplerian GM : 1.3271244004193930E+11 km^3/s^2
    Output units : KM-S, deg, Julian Day Number (Tp)
    Output type : GEOMETRIC osculating elements
    Output format : 10
    Reference frame : ICRF/J2000.0
    Coordinate systm: Ecliptic and Mean Equinox of Reference Epoch
    ************************************************** *****************************
    JDTDB
    EC QR IN
    OM W Tp
    N MA TA
    A AD PR
    ************************************************** *****************************
    $$SOE
    2458180.059027778 = A.D. 2018-Mar-02 13:25:00.0000 TDB
    EC= 2.563932000786699E-01 QR= 1.475121159297403E+08 IN= 1.080002051466089E+00
    OM= 3.172299386700017E+02 W = 1.773818012354794E+02 Tp= 2458153.549923829734
    N = 7.470539034750749E-06 MA= 1.711042235902635E+01 TA= 2.937830245190548E+01
    A = 1.983738125382210E+08 AD= 2.492355091467017E+08 PR= 4.818929374779865E+07
    $$EOE
    ************************************************** *****************************
    Coordinate system description:

    Ecliptic and Mean Equinox of Reference Epoch

    Reference epoch: J2000.0
    XY-plane: plane of the Earth's orbit at the reference epoch
    Note: obliquity of 84381.448 arcseconds wrt ICRF equator (IAU76)
    X-axis : out along ascending node of instantaneous plane of the Earth's
    orbit and the Earth's mean equator at the reference epoch
    Z-axis : perpendicular to the xy-plane in the directional (+ or -) sense
    of Earth's north pole at the reference epoch.

    Symbol meaning:

    JDTDB Julian Day Number, Barycentric Dynamical Time
    EC Eccentricity, e
    QR Periapsis distance, q (km)
    IN Inclination w.r.t XY-plane, i (degrees)
    OM Longitude of Ascending Node, OMEGA, (degrees)
    W Argument of Perifocus, w (degrees)
    Tp Time of periapsis (Julian Day Number)
    N Mean motion, n (degrees/sec)
    MA Mean anomaly, M (degrees)
    TA True anomaly, nu (degrees)
    A Semi-major axis, a (km)
    AD Apoapsis distance (km)
    PR Sidereal orbit period (sec)

    Geometric states/elements have no aberrations applied.

    Computations by ...
    Solar System Dynamics Group, Horizons On-Line Ephemeris System
    4800 Oak Grove Drive, Jet Propulsion Laboratory
    Pasadena, CA 91109 USA
    Information: http://ssd.jpl.nasa.gov/
    Connect : telnet://ssd.jpl.nasa.gov:6775 (via browser)
    http://ssd.jpl.nasa.gov/?horizons
    telnet ssd.jpl.nasa.gov 6775 (via command-line)
    Author : Jon.D.Giorgini@jpl.nasa.gov
    ************************************************** *****************************

  20. #20
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    Wow, very interesting stuff. Thanks for sharing.
    I know that I know nothing, so I question everything. - Socrates/Descartes

  21. #21
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    So....

    So, plugging these into my very ancient Starry Night (1.0 probably) I have 7,
    but I'm more comfortable using the old one.
    New orbiting object, asteroid

    Near-circular Eliptic 2000
    1 mean distance (a) in AU
    2 eccentricity (e)
    3 inclination (i)
    4 ascending node
    5 arg of pericenter
    6 Mean Anomaly L
    7 epoch (julian day)
    1 A = 1.983738125382210E+08 in kilometers, convert to AU:

    2 eccentricity EC= 2.563932000786699E-01
    3 IN= 1.080002051466089E+00
    4 OM= 3.172299386700017E+02
    5 W = 1.773818012354794E+02
    6 MA= 1.711042235902635E+01
    7 EPOCH= 2458161.5
    -------
    so, 1: 198373812.5382210 kilometers / # of kilometers in an AU 1.496e+8
    198373812.5382210 / 149600000 = AU 1.326028158677948
    2. eccentricity .2563932
    3 inclination 1.080002051466089
    4 ascending node 317.2299386700017
    5 arg of pericenter 177.3818012354794
    6. MA 17.11942235902635
    7 EPOCH= 2458161.5

    Now I make it 1 kilometer across (sue me, I exagerate) asteroid
    and paint it with a JPG of starman

    Looks right to me. I'm at least in the ballpark.

    https://planettom.dreamwidth.org/6431.html

    I guarantee I'm not off by more than the width of 1 solar system!

  22. #22
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    Hmmmm....

    9/7/2020 .310 AU
    9/17/2020 .281
    9/24/2020 .268
    9/28/2020 .265 AU
    9/29/2020 .264 AU
    9/30/2020 .264 AU
    10/1/2020 .264 AU
    10/2/2020 .264 AU
    10/3/2020 .264 AU
    10/4/2020 .264 AU
    10/5/2020 .265 AU
    10/7/2020 .266 AU
    11/1/2020 .342 AU

    "In 2020, the car will pass about 6.9 million kilometers from Mars"

    .264 Au= 39,493,838 kilometers

    I can't get it to come closer than 39 million kilometers, so something's not quite right.

    Oh, what's 32 million kilometers, give or take...

    Maybe I should try it in Starry Night 7.

    Maybe my ancient 1.0 or whatever Starry Night is putting *MARS* in the wrong place!

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