API VERSION: 1.2
API SOURCE: NASA/JPL Horizons API

*******************************************************************************
 Revised: Nov 05, 2020                Tianwen-1                        -9901491
                  https://www.nature.com/articles/s41550-020-1148-60

 MISSION LAUNCH DATE:                                           MARS LANDING:
  Jul 23, 2020 04:41 UTC (in flight)                            February 2021

 LAUNCH VEHICLE:
  Long March 5 from Wenchang (Hainan Island) Peoples Republic of China

 BACKGROUND:
  This mission includes an orbiter, lander, and rover. Science objectives:

   - Map the morphology and geological structure 
   - Investigate the surface soil characteristics and water-ice distribution
   - Analyze the surface material composition
   - Measure the ionosphere and the characteristics of the Martian climate
   - Detect the physical fields (electromagnetic, gravitational) and 
      internal structure of Mars

  The mission includes 13 science instruments, with seven mounted to the 
  orbiter and six on the solar-powered, six-wheeled rover. The rover is 
  designed to operate for 90 Martian days.

 LANDER
  The Tianwen-1 lander and rover will stay in Mars orbit through April or May,
  of 2021, then descend to the surface using a combination of aeroshell, 
  parachute and thruster. Candidate landing site is Utopia Planitia
  (also location of the US Viking 2 lander from 1976).

 TRAJECTORY: 
  This trajectory is an UNOFFICIAL one based on optical and radio ground 
  observations collected by numerous volunteers. 

  It does not include FUTURE maneuvering events that will take place en-route 
  to Mars (no information on them has been made public), so will likely be 
  accurate only for days or weeks into the future past the "revision date" 
  noted above.  It terminates an hour after Mars closest-approach since the
  spacecraft would likely have been maneuvered into orbit by that time.

  This as-is trajectory is being made available through Horizons by request, 
  to support volunteer ground-based radio tracking efforts described here:

   https://destevez.net/2020/07/tracking-tianwen-1s-orbit-to-mars/
   http://www.r00t.cz/Sats/Tianwen1
   https://amsat-dl.org/chinese-mars-probe-tianwen-1-successfully-received-by-amsat-dl/

  References for trajectory segment data:
   Jul23-Aug01: https://www.projectpluto.com/pluto/mpecs/tianwea.htm#o001
   Aug01-Sep20: https://destevez.net/2020/08/tianwen-1-tcm-1/
   Sep20-Oct09: https://destevez.net/2020/09/tianwen-1-tcm-2/
   Oct09-Oct28: https://destevez.net/2020/10/tianwen-1-dsm-final-trajectory/
   Oct28-Mar21: https://destevez.net/2020/11/tianwen-1-tcm3-final-trajectory/

  Trajectory (data from ground-based volunteers)       Start         End 
  -------------------------------------------------  -----------   -----------
  tianwen-1_p-mpec     (Bill Gray)                   2020-Jul-23   2020-Aug-01
  tianwen-1_post_tcm-1 (Amateur DSN)                 2020-Aug-01   2020-Sep-20
  tianwen-1_post_tcm-2 (Amateur DSN)                 2020-Sep-20   2021-Oct-09    
  tianwen-1_post_dsm   (Amateur DSN)                 2020-Oct-09   2021-Mar-21
  tianwen-1_post_tcm-3 (Amateur DSN)                 2020-Oct-28   2021-Feb-10
*******************************************************************************