I just wrote (and have since removed) the following paragraph in this answer to How many times do you have to circle the Earth to break orbit?:
As can be heard in this video SpaceX's launch of the DSCOVR spacecraft to Sun-Earth L1 went there almost directly. The first secondary engine cut-off (SECO-1) was at about
T+ 00:08:40, and after what the announcer says (at about
T+ 00:09:50) would be "in about 21 minutes", the secondary stage's second burn would put it in to a Heliocentric orbit (along the stable manifold of its future SE L1 Halo orbit) on its way to the SE L1. Considering that a LEO orbit is about 90 minutes, DSCOVR was in Earth orbit for roughly half of one Earth orbit. (emphasis added)
DSCOVR would need about four months to arrive in its final orbit, and explained in the answers to Why would a mission to Sun-Earth L1 have an instantaneous launch window? was probably traveling along the most efficient (lowest Δv) path to arrive there.
edit: Based on comments, I should explain that my use of "probably traveling along the most efficient" comes from a reading of the paper Resurrected DSCOVR Propulsion System – Challenges and Lessons Learned that nicely describes DSCOVR's propulsion system and lists the two mid-course corrections used:
The first planned thruster maneuver was the MCC burn, which was designed to correct any launch dispersion in the spacecraft trajectory. Since the Falcon 9 trajectory resulted in a low launch dispersion, the MCC #1 burn only required a burn duration of 37 seconds (0.4895 m/s). The maneuver was performed successfully 32 hours after launch.
MCC #2 was performed on April 28, 2015, as a +Z maneuver with a burn duration of 3.1 minutes (about 2.449 m/s).
Launch was 11-Feb-2015, so MCC #2 happened at around day ~77.
Is the idea that DSCOVR travelled on a trajectory along a CR3BP manifold at least generally correct?
Is the wording at least fairly accurate, or is there a better way to say this? If I understand correctly, DSCOVR is actually in a Lissajous orbit, not technically a halo orbit, although sometimes they get lumped together. In that case is there still a manifold?
Possibly helpful items:
- Lissajous Orbit Control for the Deep Space Climate Observatory Sun-Earth L1 Libration Point Mission
- Fig. 1 of Early Mission Maneuver Operations for the Deep Space Climate Observatory Sun-Earth L1 Libration Point Mission
- page 3 of DSCOVR Halfway to L1