Scenario 5 - Ranging Pass

Shift Package

Date: Tuesday 9 November 2027, 1800 Local (0200Z Wednesday) Site: SANDSTORM (SS-01), transportable X-band EA site, high desert Operator on Console: You - contractor, third shift Crew Chief: MSgt Delgado (maintenance tent, radio on channel 2) Mission Direction: 9 EWS ops floor, callsign RAMPART Spacecraft Engineering: TALON ops, callsign LANTERN

Last backup contact - the primary terminal is back at 0600Z. LANTERN has an east-west station-keeping burn on TALON-2 at 0214Z and asked for a ranging arc from us around it: three tones before, the post-burn set loaded when they issue it, three after. The tone is on the TT&C console next to the command stack.

Chain as last night: monitor on the bird, receiver 3 on 1625, modem 1 on 1200, cold. Window T+5:00 to T+40:00.

• Delgado (turnover, 1750)

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Ranging

A ranging tone goes up the command path like a command - key, window, uplink - and comes back with a number: the slant range from the aperture to the bird, to a tenth of a kilometre. One range is one number on one line of sight. A series of them over time, from a known slot, with the pointing angles the tracker already holds, is an arc - and an arc is what an orbit is fitted to.

Reading	What it tells the engineers
One range	Almost nothing on its own
Three timed ranges	A radial track: where the bird is along the line of sight and how that is changing
Three before and three after a known burn	The burn itself, measured from the ground: the step between the two halves
The pointing angles held throughout	The other two dimensions the range cannot see

The Burn

At 0214Z TALON-2 fires its thrusters and moves a tenth of a degree east along its orbit. From SANDSTORM that is about 1.5 km of slant range - the fourth tone comes back longer than the third - with the monitor still on the bird and the telemetry still LIVE.

Caution

Range that steps while pointing and telemetry hold steady is the spacecraft moving, not the station. It is not a tracking error, not a tone fault, and not noise. It also means the element set the station is predicting from now describes where the bird used to be: the Pass Schedule tab reads EPHEMERIS STALE until LANTERN’s post-burn set is loaded from the inbox.

The Contact

Step	Where	What you see
Telemetry LIVE, SOH nominal	Telemetry tab	The bird is healthy before anything goes up
HPA up, modem 1 keyed	TX Chain	Chain ready inside the window
Three tones	TT&C console, TONE	Three ranges, a tenth of a kilometre apart at most
One tone after 0214Z	TT&C console	~1.5 km longer
Load Updated Ephemeris (TALON2-SK)	Pass Schedule inbox	STALE clears; prediction and measurement agree again
Two more tones	TT&C console	Six ranges - the solution badge
Hand-off	The log	Six timed ranges, the step, the sets, the angles
Chain cold	TX Chain	Before the log entry

Note

The pre-burn arc is not obsolete once the set changes. It is the “before” that makes the burn measurable. Give the engineers all six ranges, when each was taken, and which set it was taken against.

TALON-2 Contact Log 2027-314-01

Section	Line
Ranging	The arc: tones, the burn as a step, the set loaded, the hand-off
Contact	Telemetry state, the arc summary, the chain state, the end of the backup role

Three contacts, three logs, one bird handed back healthy. The primary terminal is back at 0600Z.