Recovery Map — How It Works

A Walking Map That Knows Where Your Rocket Landed

You've watched your rocket descend somewhere into the next field over. You know roughly where it came down, and now you have to walk there. The Recovery Map is the tool for that walk: a heading-rotated map that shows you, your rocket, and the line between you, updating live with every step.

The Idea

Recovery is a navigation problem with two GPS fixes — yours and the rocket's. Every other number on the screen is something we can compute from those two points if we trust the geometry of the Earth. The map's job is to turn that geometry into an honest picture you can walk by.

We treat the world as a sphere of mean radius 6,371 km and compute the distance and bearing between your position and the rocket's using the great-circle formulas. Distance comes from the haversine identity; bearing is the initial heading along that great-circle path. At recovery distances — typically under a few kilometers — the difference between a sphere model and the WGS-84 ellipsoid is well under one part in a thousand, so the spherical math is honest enough to drive a walking display.

The map itself is drawn on a standard mercator projection. The colored line connecting you to the rocket is rendered straight on that projection, which at recovery scales is visually indistinguishable from the great-circle path. The numbers driving the camera, the badge, and the accuracy circle all come from the geodesic math underneath — not from the projected pixels.

What You See and Why

Your position. A standard blue dot, refreshed from the device's GPS as you walk. The map's camera is rotated to match your compass heading, so "ahead" on screen always means "ahead in real life." This is a deliberate choice — you don't have to mentally rotate the map, you just look at the line and walk.

The rocket marker. A red-orange diamond at the rocket's last reported GPS position. It updates whenever the rocket transmits a new fix; if telemetry stops, the marker stays where the last good fix put it. We do not move it, smooth it, or guess where the rocket might have drifted after signal loss.

The route line. A straight, colored line from your position to the rocket. Watching the line shorten as you walk is immediate visual feedback that you're heading the right way.

The direction badge. Lower right of the screen: a short, plain-language phrase like "120 m ahead" or "47 m right 30°" or "12 m nearby." This is the relative bearing between the way you're currently facing and the bearing toward the rocket — a single number that tells you whether to keep walking, turn, or start scanning the ground.

The phrasing is more careful than it looks. The badge has an adaptive dead zone: at 200 m out, "ahead" means within roughly 2° of the rocket's bearing; at 20 m out, the dead zone widens to about 20°, because the GPS error on both ends of the line is large compared to the distance between them. Below about 7 m, the badge gives up on direction entirely and just says "nearby" — at that range, the bearing between two GPS points is mostly noise, and we'd rather tell you that honestly than point you confidently at a random direction.

The GPS accuracy circle. A dashed circle around the rocket marker showing the real horizontal accuracy of the rocket's GPS fix, scaled from the satellite geometry reported in telemetry. With many satellites in good view, the circle tightens to a few meters; with a poor sky view or few satellites, it grows. We don't inflate the circle to make it more visible on the map — what you see is the actual error budget the GPS is reporting. The only floor we apply is around 3 m, because consumer GPS doesn't honestly resolve sub-meter accuracy; below that, a small visible circle is more truthful than a tighter one.

The map shows only the rocket's accuracy circle, not yours. Your phone's GPS has its own error floor of a few meters in good conditions, but we don't draw a circle around the blue dot. Keep that in mind when you're inside the rocket's circle and looking around — the actual search area is a bit larger than the dashed circle suggests, by however far off your own position estimate is.

Auto-zoom. The camera frames both you and the rocket with sensible padding. As you close in, it tightens. There is no manual zoom you have to fiddle with mid-walk.

How to Read It

The badge and the map agree by construction, but they answer slightly different questions. The line is "where the rocket is in the world." The badge is "how should I steer right now relative to the way I'm facing." Most of the walk is the line; the badge becomes the primary instrument once you're close enough that small angle errors matter.

When the badge says "nearby," stop walking by GPS and start using your eyes. Two consumer GPS receivers — yours and the rocket's — each carry a few meters of error in good conditions. Inside the sum of those two error floors, no map can resolve "left" from "right" honestly.

If the badge starts flickering wildly between left and right while you're walking, your phone's compass is being interfered with — usually by metal you're carrying or standing near. Walk a few meters in a straight line, ignore the badge for a moment, and watch the line shorten on the map instead. The line uses GPS, not the compass, and is always the more trustworthy reference when the magnetic environment is uncertain.

When It Earns Its Keep

The Recovery Map is your primary navigation tool for the bulk of the walk — roughly from a few hundred meters out down to about a hundred meters. At that range you can see terrain, roads, fences, and the line you need to cross them, and you can plan a sensible foot route around obstacles instead of bushwhacking straight at a bearing.

It also earns its keep when the rocket is across an obstacle you can't go through — a fence, a creek, a property line. The top-down view lets you see the obstacle, find the gate or the crossing, and re-plan without losing track of the destination.

For the final close-in scan, when you're within sight of the rocket but it's hidden in cover, the AR Recovery HUD takes over. The map is for the walk; the HUD is for the find.

What This Isn't

It is not a navigation system that tells you to turn left at the next driveway. It draws a straight line through obstacles. You read the terrain and choose the route.

It is not a precision instrument near zero distance. The "nearby" threshold exists because two GPS fixes can't honestly resolve direction inside their combined error. If the badge says "nearby," the rocket is somewhere inside the accuracy circle and you should look, not walk.

It is not a substitute for keeping eyes on the rocket during descent. The map shows the rocket's last reported GPS position. If telemetry was lost on the way down — under chute, behind a hill, antenna-down on the ground — the last good fix might be hundreds of meters from where the rocket actually came to rest. The map cannot know what it didn't receive.

It is not bulletproof to magnetic interference. The map's heading-rotated camera and the badge both use the device compass. Steel structures, vehicles, and your own metallic gear can swing the heading by tens of degrees. Walk a few meters away from interference and the heading recovers.

It is not online-only. When the device has a network connection, the map uses Apple Maps tiles. When the network is gone, it switches to whatever offline tiles you've pre-downloaded for your launch site. Outside the area you've cached, an offline device shows a featureless background — your position and the rocket marker still work, but the terrain context is gone.

What You Need

• GPS location services enabled on the device
• An active telemetry connection to a flight computer with a GPS receiver (TeleMega, TeleMetrum, or TeleGPS)
• For offline use at launch sites without cell coverage: pre-download the recovery area in the app's offline maps settings before you leave home

This is an experimental feature. We're refining it from real recovery walks and would like to hear what worked, what didn't, and what surprised you.