# Why hasn't DSCOVR's trajectory determination been updated in JPL's Horizons after 2015-Aug-4?

I tried to download orbital positions for the DSCOVR spacecraft in its Lissajous orbit around Sun-Earth L1 from JPL's Horizons web page but I was surprised to see the following!

No ephemeris for target "DSCOVR (spacecraft)" after A.D. 2017-JAN-03 12:06:08.1840 TDB

Question: According to the output, nothing has been done in Horizons for this NASA spacecraft after 2015-Aug-4? The data between then and 2017 is only a prediction, and there's nothing after that Why not?

Is there a plan to drop DSCOVR from Horizons, or conversely to update its trajectory there? Or is current tracking data not of sufficient precision to warrant including in Horizons?

Surely the spacecraft is still being tracked regularly somehow! See Where are post-2017 EPIC images of Earth and the DSCOVR spacecraft coordinates available for download?

SPACECRAFT TRAJECTORY:
Concatenated trajectories (DSN)
Based on tracking data through 2015-Aug-4, prediction thereafter.

Trajectory name                            Start (TDB)          Stop (TDB)
------------------------------------    -----------------   -----------------
DSCO-2015-02-11-Nominal_withMCC.V0.1    2015-Feb-11 23:46   2015-Mar-09
23month_20150309_01.V0.1                2015-Mar-09         2015-Jul-13
21day_20150803_01.V0.1                  2015-Jul-13         2015-Aug-03
21day_20150803_01.V0.1                  2015-Aug-03         2015-Aug-04
18month_20150804_01.V0.1                2015-Aug-04         2017-Jan-03 12:06


• – uhoh
Jun 27, 2020 at 4:51

## 2 Answers

No new DSCOVR spacecraft trajectory data has been made available by this non-NASA (NOAA) mission since May 2017.

(Flight projects are not required to provide trajectory data to Horizons and, in this case, the original 2015 trajectory data was provided to the DSN for tracking support).

If there is a source of current DSCOVR trajectory information (no doubt it is maintained -somewhere- for internal mission use), it could be updated into Horizons.

However, the last apparent delivery to the DSN I can find included a 6-year prediction on 2017-May-30 that extends to 2023. This has been added to Horizons, though its useful-accuracy past 2017 is open to question.

• Wow, welcome to Stack Exchange. Thank you for the information and for updating Horizons so quickly! I see the data is there already; NASA Rocks!
– uhoh
Jun 27, 2020 at 10:15
• – uhoh
Sep 22, 2020 at 1:04

While the DSCOVR attitude may not be in JPL's Horizons database, you can find attitude/orbit information from the Space Physics Data Facility (SPDF) at: https://spdf.gsfc.nasa.gov/data_orbits.html