So, usually a few days after every launch, I go out and check out the published TLE data for each satellite, made public courtesy of CelesTrak. It generally includes all the orbital parameters for each satellite, and more importantly, the rocket body, as I like to see how accurately SpaceX places their payloads into the predetermined orbits.

However, for the launch of DSCOVR, no TLE (or more correctly, an incomplete TLE) has been published for either. Plugging in the International Designators for DSCOVR and the Falcon 9 R/B (which are 2015-007A and 2015-007B, respectively) into the SatCat search form, which I acquired from the raw SatCat database here (warning, large text file), returns this:

No TLE found

Furthermore, this is reflected on the n2yo.com tracking site, which does not show any orbital path for DSCOVR or the Falcon 9 R/B.

  • Why is this? Is it simply a case of the TLE having not been published yet, or will they not publish it as it is beyond Earth's SOI (which is not technically true, the Falcon 9 R/B is in Earth orbit still).

  • If they don't track objects beyond Earth's SOI, how does one follow their orbital positions?


TLEs are (as far as I know) only issued for Earth-orbiting spacecraft. Since DSCOVR is placed in L1 and not in a near-Earth orbit that's probably why its TLE are missing. I checked for TLEs of SOHO and ACE, which are also placed in L1, and SatCat gives the same output.

P.S: The fact that there's no TLEs does not mean that the spacecraft is not tracked. TLEs are just a type of low-precision ephemerides (+ something else such as information on the orbital lifetime) kindly issued by NORAD to the general public. There's more options to retrieve spacecraft position and velocity, such as HORIZONS.

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    $\begingroup$ However, as I say, there should at least be a TLE for the Falcon 9 R/B which is in Earth orbit. $\endgroup$ – ReactingToAngularVues Feb 17 '15 at 16:58
  • $\begingroup$ Yes, I have no idea about the Falcon 9 R/B actually. Perhaps it will re-enter soon, therefore they decided not to release its TLEs? I don't know enough about its orbit to make a guess. $\endgroup$ – LeWavite Feb 17 '15 at 17:08
  • $\begingroup$ I honestly have no idea about which spacecraft are tracked in HORIZONS and which are issued TLEs and what's the relation between the two databases. My Two-Line-answer is: "TLEs were not issued for DSCOVR because it is not in Earth orbit". As for the Falcon 9, I guess that the R/B was the stage which re-entered and tried the landing on their drone ship, i.e. it could not be in orbit anymore. The second stage should still be there, but probably not in Earth's orbit anymore. $\endgroup$ – LeWavite Feb 17 '15 at 17:19
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    $\begingroup$ Falcon 9 R/B is the second stage, and should still be in Earth orbit. $\endgroup$ – ReactingToAngularVues Feb 17 '15 at 17:29
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    $\begingroup$ R/B stands for "Rocket Body" and is designated NORAD Catalog Number only if it reaches orbit, so that would be F9 upper stage. As it injected DSCOVR towards SEL1, it will end up in a heliocentric orbit at an altitude below 1 AU. BTW, your "Two-Line-answer" in the comment is good, but I'm not sure it's apparent or properly supported in the answer. If you wanna go with "TLE are only issued by NORAD for tracked object orbiting the Earth, which neither DSCOVR nor FALCON 9 R/B will", that would be an answer then. For DSCOVR you already say that, but not also for FALCON 9 R/B. ;) $\endgroup$ – TildalWave Feb 17 '15 at 17:30

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