A probe network

Fly two rockets with nobody aboard. The first leaves a relay high over Earth; the second is a probe down low that talks home through it. At the end you can watch your own commands take the long way round on the map.

What you need

• You can reach orbit. Reaching orbit builds the two-stage rocket this guide flies twice, and buys the Launch Pad's second level, which both of these ships fit inside.
• You are in the shared world, not sandbox. Nothing is bought, spent or claimed in sandbox.
• Your Research Centre is at level 2, which costs 200 discovery and 2,500 credits. Every node below is tier 2 and cannot be bought until it is.

At the end you will own a relay satellite that keeps working while you are not looking at it, a probe flying through it, and a run of achievements paid out along the way.

Buy four tech nodes

From the hangar, tap Center, then the Research Centre, then Open tech tree. All four hang off Probe Control, so buy that one first.

That is 148 discovery altogether. See Buy a tech node if a node will not sell to you.

Build the relay

Start from the two-stage rocket in Reaching orbit and change the top of it.

1. Take the Command Pod and the Parachute off. Nobody is riding this one and it is not coming home. Drag each one off the canvas to delete it.
2. Put a Sat Controller where the pod was. Open the Pods tab and pull one onto the top of the upper tank. It is the part that flies the ship, and it steers on a reaction wheel of its own.
3. Hang the kit on the upper tank's flanks. From the Comms tab, a CR-1 Relay Whip. From Electrical, an SP-1 Solar Panel and a PB-20 Battery. Spread them round the tank rather than stacking them on one side.

   Part	Why	Price
   Sat Controller	Flies the ship with nobody in it	200 cr
   CR-1 Relay Whip	Carries other ships' commands, which a plain whip will not	200 cr
   SP-1 Solar Panel	Makes 0.03 u/s, three times what the relay whip draws	70 cr
   PB-20 Battery	Holds 20 u for the dark half of the orbit	60 cr

4. Check the ship fits. The strip at the top of the hangar gives the mass, and this ship is lighter and shorter than the crewed one you flew to orbit, so the pad that took that one takes this.
5. Set the staging. Open Stages and leave the two engine stages as they were. Add one more stage after them holding the SP-1 Solar Panel, so one tap of STAGE opens the wing when you are ready for it.

Fly the relay high

1. Tap Fly, then STAGE. Fly the same ascent as before. A new chip is in the top left this time, reading "LINK" and "DIRECT": you are flying by radio now, and the ground station is right underneath you.
2. Coast up and circularise as before. Get a low orbit first. A relay that never made orbit is a launch paid for with nothing to show. Once the orbit settles, a toast pays out Repeater, for putting an uncrewed relay up there.
3. Raise it. Open the map, plan a burn at periapsis that lifts the apoapsis to 500 km, fly it, then plan a second at the new apoapsis to circularise there. Plan a maneuver node and Execute a node walk through both.
4. Fire the panel's stage. The wing swings out and the ELECTRICITY row in the readout turns positive in sunlight. A toast says Power in the Dark: unfolding a panel this high is an achievement of its own.
5. Leave it there. Tap ≡ and then ⌂ HANGAR. That wording means the ship stays in the world exactly where you left it, on its orbit, working.

Build the probe

The second rocket is the same again, with the cheap antenna instead of the relay.

1. Swap the CR-1 for a CW-1 Whip. Everything else stays: Sat Controller, SP-1 Solar Panel, PB-20 Battery, the same two engine stages and the same panel stage. The CW-1 costs 90 cr against the relay's 200 cr, and it reaches just as far. What it cannot do is carry anyone else's traffic, and this ship does not need to.
2. Fly it to a low orbit and stop there. No second burn this time. You want this one down where Earth gets in its way.
3. Fire the panel's stage once the orbit is settled.

Watch the chain

1. Open the map. Tap MAP in the top right of the flight screen.
2. Tap the comms chip on the left twice. The first tap gives you CHAIN, the second NETWORK. Now every link you own is drawn, and the one carrying this ship is drawn brighter and thicker than the rest.

   

3. Follow the probe round its orbit. While it is on your side of Earth, the bright line runs straight down to the ground station and the chip reads "LINK DIRECT". As it goes round the back, watch the line jump: it now runs up to the relay and down from the relay to the station, and the chip reads "LINK 2 HOPS".
4. Collect the reward. Flying an uncrewed ship whose link runs through a relay of your own, above 70 km, is the Through the Chain achievement. It lands as a toast the moment the second hop appears.

What you should see

Two ships of yours in the world, one working for the other. The probe's chip swings between "LINK DIRECT" and "LINK 2 HOPS" as it goes round, without ever going red, and every control stays live the whole way. Between the two flights you are paid for launching with an antenna aboard, for launching with a battery aboard, for flying with nobody aboard, for unfolding a panel in space, for parking a relay, and for using it.

What went wrong?

The chip says "NO ANTENNA" on the pad. The whip's Antenna on toggle is off, or there is no antenna on the ship at all. Tap the part and look at its sheet.

The controls died during the ascent. You lost the link. That close to the pad it is almost always the antenna: check it is fitted, switched on and, if it is a dish rather than a whip, deployed.

The probe never shows 2 HOPS. The relay has to be in view of both ends at the same time. Give it a lap or two, and check on the map that the relay is not ringed in red, which means nothing can reach it either.

The relay's charge is falling. Its panel is stowed. Switch to the relay from the map and deploy it, or fly the next one with the panel staged.

A node will not sell to you. The Research Centre is still at level 1, so tier 2 is shut. Its card says so.

Next

One relay is a chain, not a network. The same satellite built with a CR-2 Relay Dish instead is rated two hundred times as far, which is what a probe at the Moon talks through. Extending the Comm Station on Earth — the one home station, wherever you launch from — does the same job from the ground and lifts everything you already have flying, with no launch at all. Read Communications for how far each pairing gets you, and Upgrade a building for the station.