The informative page shows that the RCM satellites are intended to orbit as follows:

Sun-synchronous circular orbit (dawn-dusk mission), nominal altitude = 592.7 km, inclination = 97.74º, period = 96.4 minutes. The three spacecraft will be spaced at equal distances on the same orbital plane (120º apart) with a repeat cycle of 179 orbits/12days. The orbit selection allows revisiting the same area for coherent change detection every four days, which should enable a whole suite of interferometric applications.

The satellites will be equally spaced in the same orbital plane, following each other with a time separation of ~32 minutes.

enter image description here

Since the satellites were deployed in a single launch as asked about in this question Why does the F9 second stage roll back and forth during deployment of each RADARSAT satellite?, how do they achieve this orbital spacing?

I'm looking for an authoritative answer backed up by references, not speculative "probably" or "potentially" worded answers.

  • $\begingroup$ So you're looking for a precise plan for propulsive maneuvers of the three satellites? In the end it should be as simple as accelerating by ~10 m/s and waiting a couple of days.... $\endgroup$
    – asdfex
    Jun 27, 2019 at 17:20
  • $\begingroup$ I seriously doubt you'd get access to the maneuvering plan/report that the operation team develops. And that would be the only truly "authoritative" answer you could get. But then, why do you need to do that? An option you have downloading TLEs for both satellites from launch until they're in their final orbit. This should allow testing some hypothesis. The basic one being that they'll probably launch the satellites with different semi-major axes, which cause a phasing difference, and upon orbit correction, they'll maneuver into the final orbit. $\endgroup$
    – Mefitico
    Aug 5, 2019 at 20:14
  • $\begingroup$ Then again, an autonomous orbit maintenance system could achieve whatever final orbit by doing its thing. You'd see that by noting slow changes in the TLE's mean motion field. Either case, it wouldn't be conclusive. $\endgroup$
    – Mefitico
    Aug 5, 2019 at 20:16
  • $\begingroup$ Is there a reason this is other than a standard orbit phasing exercise? en.wikipedia.org/wiki/Orbit_phasing. If so, it would be interesting if this were edited into the OP $\endgroup$
    – Woody
    Jan 21 at 4:02
  • $\begingroup$ @Woody last sentence "I'm looking for an authoritative answer backed up by references, not speculative 'probably' or 'potentially' worded answers." From space.skyrocket.de/doc_sdat/radarsat-constellation.htm it seems they have very large cross-sectional area. Did they use thrusters, or differential drag for example? Did they achieve it quickly, or do it slowly to conserve propellants? $\endgroup$
    – uhoh
    Jan 27 at 23:41

1 Answer 1


According to https://spaceflightnow.com/2019/06/11/three-canadian-radar-satellites-ready-for-launch-from-california, these satellites are unremarkable in size at 1430 Kg. They have lots of thrusters and hydrazine:

Propulsion subsystem: The baseline design has a total of six 1 N thrusters, 2 on the -x face and 4 on the -z face (designated the 2X-4Z thruster configuration). A 50 liter nitrogen pressured fuel tank, containing 37 liter of hydrazine, is placed near the -z face of the spacecraft in a manner that fuel usage nominally causes a migration of the centre-of-mass in the +z direction.

Their mission requires them to maintain their orbital trajectory within a 100m “tube” 99% of the time.

With these specifications, it should be well within their capability to deploy over 5 days using a standard 120* orbital phase shift using 2 burns.


News media made no mention of unusual orbital maneuvers.

  • 1
    $\begingroup$ How was it done, not how could it have been done. Facts not guesses. $\endgroup$ Jan 28 at 2:34
  • 1
    $\begingroup$ @OrganicMarble ... yes, I noticed. I've asked CSA how they chose to deploy to dispersed orbital phase angles. I'll post their reply. $\endgroup$
    – Woody
    Jan 28 at 2:37
  • $\begingroup$ You could at least rule out anything besides propulsive maneuver by just mining the TLEs. If the proposed "five day phasing" happened, it would show up there quite clearly in the spread in mean anomaly (evaluated at say 00:00 UTC each day) $\endgroup$
    – uhoh
    Jan 28 at 4:08

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