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Read the Horizons pages the missing moons are written in, and give triaxial bodies their mean radius

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The pages of the moons this branch is about to add state their size and spin in forms the ETL
did not read. Charon's gives "Radius (km, IAU2015) = 606", which none of the radius patterns
matched, so it would have come out at radius 0. Phoebe's gives "Rotational period = 9h 16.438 m",
which the hours-or-days pattern read as 9 hours flat instead of 9.274. Pluto's and the moons' GMs
are now read too ("GM (planet) km^3/s^2 = 869.326" on Pluto's page, "GM (km^3/s^2) = 106.10" on
Charon's), for placing a pair's barycentre.

Miranda and Ariel, like Phobos and Deimos already, give three semi-axes, "240x234.2x232.9". The
first figure was taken as the radius, which is the longest axis. A triaxial body now gets the
radius of the sphere of its volume, the cube root of the product, which is how the IAU states a
mean radius. That changes two bodies already shipped: Phobos 13.1 -> 11.06 km (IAU 11.08) and
Deimos 7.8 -> 6.20 km (IAU 6.2). Nothing else in bodies.json moves.

The page parsers move from tools/etl/lib/horizons.ts to src/app/shared/astro/horizons-page.ts,
as the mean-element parsers did, so the unit suite runs their tests; the ETL imports them. A
small body's command ("1;" for Ceres) is now URL-encoded: sent raw, the semicolon made Horizons
refuse the request ("one or more query parameter was not recognized").

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
This commit is contained in:
Senrokai
2026-09-24 20:41:22 +02:00
co-authored by Claude Opus 5.5
parent 2e5daa0f97
commit cdc0cf4678
4 changed files with 170 additions and 79 deletions
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tools/etl/lib/horizons.ts
+7 -77
View File
@@ -1,4 +1,5 @@
import { OrbitalElements } from '../../../src/app/shared/models/body.model';
import { extractGmKm3PerS2, extractObliquityDeg, extractRadiusKm, extractRotationPeriodHours, isTidallyLocked } from '../../../src/app/shared/astro/horizons-page';
import { fetchTextCached } from './http';
const HORIZONS_URL = 'https://ssd.jpl.nasa.gov/api/horizons.api';
@@ -10,7 +11,7 @@ const REFERENCE_START = '2025-01-01';
const REFERENCE_STOP = '2025-01-02';
export interface HorizonsQuery {
/** Horizons body id, e.g. `'499'` for Mars. */
/** Horizons body id, e.g. `'499'` for Mars, or a small body's number and a semicolon, `'1;'` for Ceres. */
command: string;
/** Horizons coordinate center, e.g. `'500@10'` (Sun) or `'500@399'` (Earth). */
center: string;
@@ -30,70 +31,8 @@ export interface HorizonsResult {
obliquityDeg?: number;
/** The page says "Synchronous" instead of a period: its day is its orbit. */
tidallyLocked: boolean;
}
const RADIUS_PATTERNS = [
/Vol\.?\s*mean\s*radius[^=]*=\s*([\d.]+)/i,
/Mean\s*radius[^=]*=\s*([\d.]+)/i,
/Radius\s*\(IAU\)[^=]*=\s*([\d.]+)/i,
/Radius,?\s*\(km\)\s*=\s*([\d.]+)/i,
/Radius\s*\(gravity\),?\s*km\s*=\s*([\d.]+)/i
];
/**
* How each page states how fast the body turns, in the order they are tried.
*
* The rate in radians per second is preferred wherever it appears: it is unambiguous and it is
* signed: Venus and Uranus carry a negative one. A period in hours or days
* comes next, then the sexagesimal form the giant planets use, and finally the word most moons carry
* instead of a number, Synchronous. Not all do — the Moon's page gives a rate, Titan's nothing —
* so the caller treats every moon it lists as locked whatever its page says.
*/
const ROTATION_RATE_PATTERN = /Rot(?:ational)?\.?\s*Rate\s*[(,]\s*rad\/s\s*\)?\s*=\s*(-?[\d.]+)/i;
const ROTATION_PERIOD_PATTERNS = [
/Sid(?:ereal|\.)?\s*rot\.?\s*period[^=]*=\s*(-?[\d.]+)(?:\+-[\d.]+)?\s*(h|hr|hrs|d|day|days)\b/i,
/Rotation(?:al)?\s*period[^=]*=\s*(-?[\d.]+)\s*(h|hr|hrs|d|day|days)\b/i
];
/** `9h 55m 29.711 s`, as Jupiter and Saturn state it. */
const SEXAGESIMAL_ROTATION_PATTERN = /Sid(?:ereal|\.)?\s*rot\.?\s*period[^=]*=\s*(\d+)\s*h\s*(\d+)\s*m\s*([\d.]+)\s*s/i;
const SYNCHRONOUS_PATTERN = /Rotation(?:al)?\s*period\s*=?\s*:?\s*Synchronous/i;
const OBLIQUITY_PATTERN = /Obliquity\s*to\s*orbit[^=]*=\s*(-?[\d.]+)/i;
const HOURS_PER_DAY = 24;
const SECONDS_PER_HOUR = 3600;
/**
* True where the page gives no number because the body keeps one face to its parent, so its day
* is its orbit. The period itself is then the orbit's, which the caller takes from the body's
* mean motion.
*/
export function isTidallyLocked(text: string): boolean {
return SYNCHRONOUS_PATTERN.test(text);
}
/** Sidereal rotation period, in hours, from whichever form the page states it in. */
export function extractRotationPeriodHours(text: string): number | undefined {
const rate = text.match(ROTATION_RATE_PATTERN);
if (rate && Number(rate[1]) !== 0) {
return (2 * Math.PI) / (Number(rate[1]) * SECONDS_PER_HOUR);
}
const sexagesimal = text.match(SEXAGESIMAL_ROTATION_PATTERN);
if (sexagesimal) {
return Number(sexagesimal[1]) + Number(sexagesimal[2]) / 60 + Number(sexagesimal[3]) / SECONDS_PER_HOUR;
}
for (const pattern of ROTATION_PERIOD_PATTERNS) {
const match = text.match(pattern);
if (match) {
const hours = Number(match[1]) * (match[2].toLowerCase().startsWith('d') ? HOURS_PER_DAY : 1);
return Number.isFinite(hours) && hours !== 0 ? hours : undefined;
}
}
return undefined;
}
export function extractObliquityDeg(text: string): number | undefined {
const match = text.match(OBLIQUITY_PATTERN);
return match ? Number(match[1]) : undefined;
/** The body's own GM, km³/s², where the page states one: what sets where a pair's barycentre lies. */
gmKm3PerS2?: number;
}
/**
@@ -103,7 +42,7 @@ export function extractObliquityDeg(text: string): number | undefined {
*/
export async function fetchHorizonsBody(query: HorizonsQuery): Promise<HorizonsResult> {
const url =
`${HORIZONS_URL}?format=text&COMMAND='${query.command}'&OBJ_DATA='YES'` +
`${HORIZONS_URL}?format=text&COMMAND='${encodeURIComponent(query.command)}'&OBJ_DATA='YES'` +
`&MAKE_EPHEM='YES'&EPHEM_TYPE='ELEMENTS'&CENTER='${query.center}'` +
`&START_TIME='${REFERENCE_START}'&STOP_TIME='${REFERENCE_STOP}'&STEP_SIZE='1d'`;
@@ -113,20 +52,11 @@ export async function fetchHorizonsBody(query: HorizonsQuery): Promise<HorizonsR
orbit: extractOrbitalElements(text),
rotationPeriodHours: extractRotationPeriodHours(text),
obliquityDeg: extractObliquityDeg(text),
tidallyLocked: isTidallyLocked(text)
tidallyLocked: isTidallyLocked(text),
gmKm3PerS2: extractGmKm3PerS2(text)
};
}
function extractRadiusKm(text: string): number | undefined {
for (const pattern of RADIUS_PATTERNS) {
const match = text.match(pattern);
if (match) {
return Number(match[1]);
}
}
return undefined;
}
function extractOrbitalElements(text: string): OrbitalElements {
const startIndex = text.indexOf('$$SOE');
const endIndex = text.indexOf('$$EOE');