PRD-030 · /explore v2 — The Known Universe

Status · Draft (epic kickoff) · 2026-07 Owner · Marko Builds on · PRD-002 (/explore solar system, v1) · the Deep-Sky gallery · /science overlay pipeline · $lib/astronomy (from PRD-019 AR sky-pointing) Closes into · RFC-032 (context/scale-shell + scalable render architecture) May spawn · an ADR to lock the context-graph + object-catalog schema once the shape settles

Why this is a PRD. This turns /explore from a solar-system viewer into a navigable model of the known universe — a product-shape decision touching the core 3D route, the data model, the render engine, /science, and the deep-sky gallery, staged across many slices over months. It needs an agreed frame — what we model, how we navigate it, how far it scales, and what stays honest — before any code lands. The current /explore (v1) is untouched; this is the zoom-out that wraps it.

Problem

Today /explore stops at the edge of the solar system, and the starfield beyond is decorative. Yet the product's whole thesis is "learn about space" — and the most humbling lesson is context: the Sun is one ordinary star, our galaxy one of billions, and the nebulae in our Deep-Sky gallery are real places with real positions. We have curated beautiful deep-sky imagery but no way to answer "where is that, and what is around it?" We want people to zoom out from home and discover the rest — scientifically grounded, honestly labeled, and beautiful.

Vision

One /explore, a stack of nested contexts. Solar system at the bottom (v1, unchanged); pull back past the Oort cloud and the Sun collapses into the real nearby-star field; keep going through the Milky Way, the Local Group, and outward as data allows. You zoom within a context and warp between them. Every object is real (or an honestly-labeled model), every claim cited, every "artist's impression" badged as such.

Principles (non-negotiable)

1. v1 is sacred. The solar-system experience does not change or regress; v2 machinery loads lazily only when you cross the boundary outward.
2. Honesty over spectacle. The known/cataloged universe, not "the universe." Real / model / artistic always labeled; distances shown with real uncertainty; no fake to-scale galaxy renders (schematic maps instead, labeled).
3. Curated, not dumped. Quality jewels with stories, not a billion-star tech demo (mirrors the Deep-Sky taste profile).
4. Scalable by construction. Same render vocabulary + a device budget from slice 0 → runs on desktop and mobile, and keeps working as we add contexts outward.
5. Reuse the spine. Keplerian engine (exoplanet systems), Panel (tactical detail), /science pipeline, Science-Lens pattern, provenance, i18n — all carry over.

Pillars

• Exoplanet mini-orreries (the beachhead) — curated hero systems with real orbits reusing the Keplerian engine + full tactical panels.
• Navigable deep-sky — every gallery image gets a real position → "fly me there"; the placard and the 3D object become one.
• Culture doors — story as the way in: Vega→Contact, Gargantua→Interstellar, Kepler-16b→Tatooine, plus real message objects (Voyager, Arecibo, ‘Oumuamua). Fiction badged over fact.
• Black holes done right — M87*, Sagittarius A*, Cygnus X-1, Gargantua; real gravitational-lensing shader.
• Physics lenses — beyond a 3D map: curvature (spacetime embedding), time (dilation), causality (light-cones), and property-space (a flyable Hertzsprung-Russell diagram).
• Scientific honesty — the labeling + provenance discipline above.

The geography (contexts, added outward)

Context	Scale	Content	Data	Nav
Solar System (v1)	AU	unchanged	existing	zoom
Stellar Neighborhood	~100 ly	real nearby stars + exoplanet systems	HYG (~120k), NASA Exoplanet Archive	zoom
Milky Way	~100k ly	labeled spiral model, our position, Sag A*	spiral-arm model, Messier/OpenNGC	warp
Local Group	~10M ly	Andromeda, Magellanic Clouds, ~80 dwarfs	Local Group catalogs	warp
…beyond	—	cosmic web (deferred)	SDSS / future	warp

Slice roadmap (one direction; full detail + architecture in RFC-032)

• Phase A — spine + first reveal. S0 boundary crossing (context engine, point renderer, device budget, the Sun→dot handoff); S1 stars become objects (select, panel, named stars, constellations, minimap, ?goto=).
• Phase B — exoplanet beachhead. S2 exoplanet mini-orreries (real orbits, warp star→system); S3 exoplanet /science wing + culture layer v1.
• Phase C — the sky fills in. S4 deep-sky + gallery integration; S5 Milky Way context.
• Phase D — physics beyond the map. S6 black holes + curvature/time lenses; S7 property-space lenses. (COMPLETE — shipped in explore-v2)
• Phase E — and beyond. S8 Local Group (COMPLETE — shipped in explore-v2); S9+ message objects + narrated grand tour (deferred).

Decisions locked at kickoff (2026-07)

1. Continuous zoom reaches the Stellar Neighborhood (the emotional first reveal is one continuous space); warp is reserved for galaxy-scale and beyond.

2. Curated exoplanet hero set ≈ 25–30 jewels, taste-profiled like the deep-sky gallery.

3. v2.0 (first shippable) = slices 0–3 (neighborhood + exoplanet beachhead + science/culture); Milky Way + physics lenses are v2.1/2.2.

   AMENDED (July 2026): S5–S8 shipped ahead of the original v2.1/2.2 plan — Milky Way (S5), black holes + lenses (S6), property-space/causality overlays (S7), and Local Group (S8) are all in the explore-v2 branch. v2.0 now encompasses S0–S8; remaining deferred items are S1–S4 (object selection, exoplanet orreries, /science wing, deep-sky) and S9+ (message objects, grand-tour narration).

4. Culture layer ships as an optional overlay first (promote to a first-class browse mode later if it lands).

5. Mobile = graceful tiers via the device budget; the core journey works everywhere, the heaviest lenses/shaders may be desktop-first.

6. Working name: "The Known Universe."

Success criteria

• Zooming out of the solar system reveals the real nearby stars at their true positions/colors, at ≥30 fps on a mid-tier phone (budget-scaled).
• A learner can find TRAPPIST-1 (wander or ?goto=), warp in, and read a scientifically-backed panel on each planet.
• Every deep-sky gallery image is reachable in 3D and vice-versa.
• Nothing in v1 changes or regresses.

Non-goals (this epic)

Full Gaia billion-star render · real-time cosmology/simulation · AR/VR of the universe (explore-only) · fake to-scale galaxy distances · textured exoplanet surfaces (unknown) · user accounts / saved collections.

Tracking

Epic tracked under a GH issue (TBD — to create at kickoff); slices land as sub-issues. Architecture + per-slice contracts in RFC-032. TA.md §explore gains a v2 subsystem entry as slices ship (not before).