Communications
A rocket with somebody in it answers the hand on its stick. A rocket with nobody in it answers a radio, and if the radio stops so do you. This is how that link is made, what it costs, and what to build so it never breaks.
Who needs a link
Only a machine. Put a Command Pod or a Crew Capsule on a rocket, seat somebody in it, and the ship flies wherever it goes with no radio at all: the pilot is aboard and needs permission from nobody. Nothing about contact appears on the flight screen, because there is nothing to lose.
Build the same rocket around a Sat Controller instead and it is a remote-controlled machine. Everything you do to it — the throttle, the turn buttons, the stage button, tapping a part — is a command sent from the ground, and it only arrives while the ship is in contact.
The Sat Controller has a small aerial built in, rated at 3,000 km, which is enough to fly a probe up from the pad and into a low orbit with no antenna fitted, for as long as it is in sight of the ground station. Anything further needs a real one. See Parts: Comms for the six.
A link is a pair, not a number
Every antenna has a range on its card, and reading it as "how far this reaches" is the one mistake worth avoiding. A link is made between two aerials, and what it reaches depends on both of them.
Two aerials reach the square root of their two ratings multiplied together. So a small antenna talking to a big dish reaches far more than the small antenna's own rating, and a big dish on the ground lifts everything small that is already in the sky.
| Aerial | Its own rating | Talking to a new Comm Station |
|---|---|---|
| Sat Controller, built in | 3,000 km | 12 Mm |
| CW-1 Whip | 50 Mm | 50 Mm |
| CD-2 Dish | 10.0 Gm | 707 Mm |
| CD-3 Deep Space Dish | 500.0 Gm | 5.0 Gm |
Every antenna's info card carries that second column itself, as a row labelled VIA L1 STATION: what this part manages against a Comm Station nobody has upgraded. Ranges are written in Mm, a thousand kilometres, and Gm, a million.
The ground end is the Comm Station, and it is on Earth
Every chain finishes at the Comm Station: one dish, standing at the space center on Earth, turning round with the planet under it. You have it from your first day, at level 1, without buying it — and there is only ever the one. Opening the Moon or Mars founds a Launch Pad there and no dish, so a world you fly to is a world you have to carry your own radio to.
That is what relay satellites are for. Earth turns, and a planet or a moon blocks the line, so anything out of Earth's sight is reached only through relays of yours in between — a probe on the Moon's far side talks to a relay in lunar orbit, and that relay talks home.
Its level is its reach, and because a link is a pair, extending it lifts every antenna you already have flying without launching anything.
| Level | Rated | Costs | Needs |
|---|---|---|---|
| 1 | 50 Mm | free | Nothing |
| 2 | 10.0 Gm | 3,500 credits | Deep Space Comms |
| 3 | 500.0 Gm | 12,000 credits | Interplanetary Comms |
It is bought once and it lifts everything you have flying, anywhere in the system. See the Comm Station's entry and The Space Center, and Keep a probe in contact for what to do when the link drops.
A relay passes a signal on
An antenna is one of two kinds, and its card says which on the ROLE row.
- Transmit — the ship carrying it can be flown through it, and that is all. Nobody else's commands go through this ship.
- Transmit + relay — the same, plus it carries other ships' traffic. The relays are the CR parts: the CR-1 Relay Whip, the CR-2 Relay Dish, the CR-3 Deep Space Relay.
That difference is the whole reason to build a network. Your commands flood outward from the ground station, and they can pass through a relay of yours and on to the next ship, but they stop dead at a plain antenna. Two plain antennas never talk to each other at all. So the middle of any chain is relays, always, and the far end can be the cheap part.
A relay is worth more the higher and the further out it sits, because it lifts the small aerials near it and it can see over a world that would otherwise be in the way. A relay parked in a low orbit is behind the planet as often as your probe is.
What breaks a link
Two things, and only two.
Distance. The two ends are further apart than the pair reaches. A chain is only as strong as its worst hop, so one long gap in the middle drops the whole thing however good the ends are.
A world in the way. If any world's body crosses the straight line between two aerials, that hop is blocked. Air does not block anything and neither does a cloud; the solid ball does. This is what puts a probe out of contact on the far side of a planet with no special rule for it, and it is what most low-orbit blackouts really are. Near Earth, range is rarely the problem. Earth is.
Once a link is up it survives a little past its own limit before it drops, so a ship parked exactly at the edge does not flicker in and out. That grace does not get you anything you can plan around; treat the rated figure as the limit.
The radio chip
A ship that needs a link carries a chip in the top left of the flight screen. A crewed ship never shows it, because there would be nothing on it to read.
| What the chip says | What it means |
|---|---|
| "LINK DIRECT" over "SIGNAL 92%" | Straight to a ground station, with plenty of reach to spare. The waves beside the mast are the same reading. |
| "LINK 2 HOPS" | Your commands are going through one relay of yours on the way. Three hops means two relays, and so on. |
| "WEAK — SIGNAL 12%" | The chip turns amber once the worst hop has used 85 % of its reach. This is your warning; on an ordinary orbit it is tens of seconds long. |
| "NO LINK" over "OUT OF RANGE" | There is an aerial aboard and it cannot get through. Either something is in the way or the gap is too wide. |
| "NO LINK" over "NO ANTENNA" | Nothing aboard can talk at all. The antenna is switched off, still folded in its housing, or was never fitted. |
Losing contact
Losing the link takes the ship away from you completely, exactly as though the command part had fallen off. No steering, no throttle, no staging, no tapping a part for its actions. The thruster pad goes with them.
What does not stop is the flight. A burn already running keeps running at the throttle you left it at, gravity keeps pulling, the air keeps dragging, and a probe on a course into the ground stays on it. Everything you can only look at still works: the instruments read, the map opens, the trajectory is drawn, and you can still set a reminder for the moment the ship comes back round.
Contact comes back on its own the moment the geometry allows it, and every control comes back with it.
Seeing the network
The map draws the radio. In flight, a chip on the left cycles through three states each time you tap it: off, then CHAIN, then NETWORK.
CHAIN draws only the hops carrying this ship's commands, plus the ground station they land on, so you can see at a glance whether you are talking straight home or through something. NETWORK draws every link between everything of yours, and rings in red any relay of yours that nothing can reach. A dead relay is invisible from anywhere else, and that ring is how you find it.
