TCM-14: Helping to Clear Out the Lines and get to Phoebe

Not to belittle TCM-14, but there's still quite some time between this maneuver and Jupiter. It's not so incredibly crucial, in fact, this and a few following it are mostly to clear old propellant out of the propulsion system. Sorry, No. 14, but it's the truth...

That may be what I wrote when I first sat down to this page about a year ago, TCM-14 has become a little more than that. It's still only about half a meter per second, but now it changes the Jupiter swingby just a touch; merely enough to bring the spacecraft closer to Phoebe in 2004.

Yes, I said 2004. The encounter with Phoebe, however brief, happens on the approach to Saturn. There will be a maneuver, the Phoebe targeting maneuver, to fine tune the flyby, but if you don't fly by Jupiter at the right point, you'll need a little more fuel.

The difference can be seen in the following targets. The column "goes to Phoebe" shows the maneuver target parameters for TCM-14. The column "does not go to Phoebe" shows the old target parameters for TCM-14. The old target parameters do result in a trajectory that approaches Phoebe, but the distance is so much further that you might as well say it doesn't fly by.

For those of you who are wondering "B-dot-R" and "B-dot-T" are dot products between the miss distance vector (the one perpendicular to V-infinity) of the hyperbolic orbit with unit vectors we call R and T. R and T are both perpendicular to the V-infinity vector while points south (Earth's south) and is perpendicular to Earth's Mean Equatorial Plane on at 0 hours on Jan 1, 2000 (J2000.0). Why use Earth's Mean Equatorial plane? As far as I know so far, it's just a convention :)

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