Thursday, 8 February 2018

There's a Starman Waiting in the Sky

image: SpaceX

This is the freakiest, most surrealistic image related to Space I have ever seen.

On February 6/7, as part of the Maiden Flight of the SpaceX Falcon Heavy, a Tesla Roadster with a dummy called Starman behind the wheel (and various other references to pop-culture tucked in the car) has been orbiting Earth in a 180 x 6950 km orbit for 6 hours, after which it was boosted into a heliocentric Apollo orbit with aphelion near the orbit of Mars.

Yep, that's right: a car in space! That is something beyond my wildest dreams.

Image: M. Langbroek

Above is the  ground track of the slightly under 6 hours earth orbit. Launch was at 20:45 UT (6 February) from pad 39A at Cape Canaveral; SECO 2 was over Africa 28m 52s later, boosting it into a 180x 6950 km, 29 degree inclined elliptical coasting orbit. After just under two orbital revolutions, a third and final boost sent it into heliocentric orbit. The boost was widely observed from the US West Coast (see for example this hefty 256 Mb movie shot by Derek Breit in Morgan Hill, California).

The heliocentric orbit is below. It has perihelion at 0.98 AU, aphelion at 1.67 AU and an orbital inclination of 1.05 degrees. The orbital period is 1.53 year. If this was an asteroid instead of a rocket stage and a car, we would call it an Apollo orbit.

image: M. Langbroek
The aphelion distance of the orbit is similar to the aphelion of Mars, but located near the perihelion of Mars.

The rocket stage and car will periodically come back to Earth's orbit. Near 27 January 2073, the rocket stage and car might make an actual close approach to Earth. My current orbit integration with MERCURY 6 has it passing at a nominal distance of ~0.004 AU or ~1.6 Lunar distances, and likely will be in reach of telescopes on Earth then. [EDIT 15 Feb 2018: after new orbit updates based on optical observations, the 2073 close approach is off the table]. The real distance might be more (or less) as the current orbit probably isn't very accurate (SpaceX earlier presented an orbit that was dead wrong) and the object(s), being of low area-to-mass ratio and shiny, moreover will be strongly influenced by Solar Radiation Pressure, which will perturb the orbit and is difficult to model over a 55 year timespan.

A  less close approach (nominal values in the order of 9 Lunar distances) will happen in March 2137. Close approaches to Mars will not happen over the next three centuries.

image: SpaceX

image: SpaceX
image: SpaceX

To me, this was the most exciting launch since I watched the first Shuttle launch on tv when I was a teenager. That big Falcon Heavy roaring into the sky was very impressive. Even more impressive was the synchonous return of both side boosters, landing smoothly and brotherly next to each other. The core booster alas did not fare that well, and smashed to bits in sea.

And then there were those surreal images of the Tesla orbiting earth, with "Starman" at the steering wheel. I reckon these will be iconic images for a very long time.

The whole idea of launching a car into orbit is crazy of course, and it has drawn critique from some people. I do not share that critique. This is one of the daring, crazy, whimsical things that is so characteristic of humanity, and it fits iconic moments in exploration. The World needs people who are a bit crazy, in a good way. Otherwise it would remain dull and boring, with very little progress.

Say what you want of Elon Musk, and of course this is primarily a publicity stunt (and brilliant marketing), but it appears Elon Musk is giving the human space program a real boost of the kind we haven't seen in a long time. After this stunt, I for the first time in my life get the feeling that I might really see humans walk on Mars in my lifetime. After all, if we can send a Tesla Roadster towards the orbit of Mars, we can send more. To my mind, this was absolutely awesome!

UPDATE: see more in my follow-up post here with my telescopic imagery of the Falcon Heavy/Tesla Roadster in Space!

And I am quotes (and some of my imagery features) in this article on the CNN website.
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5 comments:

  1. Jig8/2/18 22:28

    Great post, thanks.

    I wanted to ask - I used a tracking site to know when and where to look as the 2nd stage and Starman passed to the south of CA, and as a result, I was lucky enough to witness one of the burns in person. I was looking at the orbital data for NORAD 43205.

    So, that object is still showing as orbiting the earth with an elliptical orbit (closest altitude about 180km, furthest altitude about 7000km).

    My question is: do you know if what I'm seeing is just a projection of the last orbital data for that object, or is NORAD still tracking maybe the second stage as it decays eventually?

    I can't make sense of it. The second stage only has battery for about 12 hours, and if it had any fuel left, I would think it would have been directed to splash down once the payload was released towards Mars. However, some have mentioned that they expended all the fuel in the second stage, so if it separated (which was the published plan by SpaceX), maybe it's still being tracked in an orbit around earth. But then... how did the payload reach escape velocity, separate from the second stage, if the second stage used up all its fuel to boost Starman towards Mars? Endless questions.

    Maybe there's a simpler question - how often does NORAD clear out tracking data for things that have left their planned orbit? It seems like it happens pretty quickly - things that deorbit are typically not updated pretty much immediate, in the site I'm looking at to track NORAD 43205.

    If it's not the second stage, then what is NORAD 43205? Unfortunately, due to the battery issue, it probably isn't sending out any radio signals. But, maybe if it passes over you sometime, you have some optical way to try to pick up if there's actually an object up there, and not just an orbital ghost?

    Thanks!

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  2. SatTrackCam Leiden9/2/18 00:11

    Kevin: the 2nd stage is in Heliocentric orbit, so no longer in orbit around Earth.
    On-line tracking sites are never "live", they show positions based on a catalogue of orbital elements.
    If an on-line tracker still shows it as in earth orbit, then the tracking website is using outdated orbital elements from when it was still in earth orbit. I.e. the website has not updated the database (it should remove the 2nd stage, but hasn't).
    That is very common with on-line tracking websites: the orbital elements on which they base their prediction, can be outdated.

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  3. Jig9/2/18 01:35

    Thanks! The strange issue is that I think I saw the orbital elements change almost in real time as the second stage burned - it seemed to change the shape of the ellipse relative to the continents, and satflare appeared to pick that up right away. Certainly, satflare had things correct enough for me to pick out the second stage in the sky when it burned (the plume was beautiful).

    Aside from that, there are things that satflare tracks until they deorbit, and those seem to be removed from its catalog within an hour? of burning up.

    Maybe NORAD is continuing to broadcast the last good orbital elements, or satflare is just continuing them for fun, or they treat deorbit-->spash different from deorbit-->Mars. ;)

    Or, possibly, there's some leftover junk from the launch orbiting under 43205.

    Thanks much for the reply.

    ReplyDelete
  4. Jig9/2/18 01:59

    Of course, almost as we are discussing this, satflare removes it from its catalog. I checked on space-track and it shows, as you say, heliocentric orbit. Thanks again.

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  5. Hephaestus9/2/18 04:20

    Marco —

    I agree with you completely that this was a silly, self-serving stunt. Of course, so was most of the early space program. It's moments like this when everyone stops what they are doing and stares at the television (or their phones) and shares a moment with complete strangers. It's when we stop being American or Dutch or Chinese or whatever and have a chance to be humans together.

    One of the best comments that I read said simply, "A million kids decided that they want to be scientists today." I remember watching Apollo as a kid and knowing that I was going to have a part in the future. Every science classroom and every grad student office is going to have a poster of the Starman with the Earth behind him. That will be the legacy of Falcon Heavy: the knowledge that if you want something badly enough, you can make it happen.

    Even if it is silly.

    ReplyDelete

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