SenrokaiandClaude Opus 5.5
28fa79e1e0
The frozen Horizons tests ran on a hand copy of seventeen records, so an ETL that lost Standish's a, e and i rates, or Io's and Europa's backward periapses, wrote a bodies.json that passed both its own validators and the whole unit suite: the data-refresh job's "Unit tests against the new data" read none of it. record() now takes kind, orbit, rates, laplacePole, parentBodyId and massRatio from src/assets/data/bodies.json, read with node:fs as texture-catalog.spec.ts reads its JPEG, and the copy is gone. Today's data passes as the copy did (all seventeen were identical). The parser test checked only the mean motion and the periapsis rate on Earth's row. It now checks the node, a, e and i rates too, against Standish's Table 2a (-0.24123856, -0.00000003, -0.00003661, -0.01337178 a century). Dropped, those rates move Saturn 0.66 degrees at AD 1 (node) and 0.36 at AD 3000 (a, e, i), where no date from 1950 to 2100 shows more than 0.036. Guarded mutants, each run on the full suite: - bodies.json without the a, e and i rates, as that ETL writes it: 'puts saturn within 0.1 degrees of Horizons on JD 2816787.5' and Earth's fail (and the new orbit-line test, on the same data). - bodies.json with Io's and Europa's periapsis rates turned positive: Io's and Europa's 1950 tests fail. - the parser without its a, e and i rates, and with a node rate of 0: 'gives the rates per day' fails, and only it. Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
194 lines
10 KiB
TypeScript
194 lines
10 KiB
TypeScript
import { describe, expect, it } from 'vitest';
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import { parsePlanetMeanElements, parseSatelliteMeanElements, parseSmallBodyElements, SbdbAnswer } from './mean-elements';
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/** Standish's p_elem_t2.txt, cut to the lines that matter here, as JPL published them. */
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const TABLE_2 = `Keplerian elements and their rates, with respect to the mean ecliptic and equinox of J2000,
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valid for the time-interval 3000 BC -- 3000 AD. NOTE: the computation of M for Jupiter through
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Pluto *must* be augmented by the additional terms given in Table 2b (below).
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EM Bary 1.00000018 0.01673163 -0.00054346 100.46691572 102.93005885 -5.11260389
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-0.00000003 -0.00003661 -0.01337178 35999.37306329 0.31795260 -0.24123856
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Jupiter 5.20248019 0.04853590 1.29861416 34.33479152 14.27495244 100.29282654
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-0.00002864 0.00018026 -0.00322699 3034.90371757 0.18199196 0.13024619
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Pluto 39.48686035 0.24885238 17.14104260 238.96535011 224.09702598 110.30167986
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0.00449751 0.00006016 0.00000501 145.18042903 -0.00968827 -0.00809981
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Table 2b.
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Jupiter -0.00012452 0.06064060 -0.35635438 38.35125000
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Pluto -0.01262724
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`;
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/** The satellite page's markup around three rows, as the 2021 page served it. */
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const SATELLITES = `
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<td align="left" nowrap><b>Satellites of Earth</b></td>
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<td align="right" nowrap><b>jump to:</b> <a href="#earth">Earth</a>, <a href="#mars">Mars</a></td>
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<H3>Mean <a href="?glossary&term=ecliptic">ecliptic</a> orbital elements</H3>
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Epoch 2000 Jan. 1.50 TT<BR>
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<TR ALIGN=right><TD ALIGN=left>Moon</TD>
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<TD>384400.</TD><TD>0.0554</TD><TD>318.15</TD><TD>135.27</TD><TD>5.16</TD><TD>125.08</TD>
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<TD>13.176358</TD><TD>27.322</TD><TD>5.997</TD><TD>18.600</TD>
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<TD ALIGN=right><A HREF="#ref1">1</A></TD></TR>
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<td align="left" nowrap><b>Satellites of Jupiter</b></td>
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<td align="right" nowrap><b>jump to:</b> <a href="#earth">Earth</a>, <a href="#mars">Mars</a></td>
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<H3>Mean orbital elements referred to the local <a href="?glossary&term=lp">Laplace planes</a></H3>
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Epoch 1997 Jan. 16.00 TT<BR>
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<TR ALIGN=right><TD ALIGN=left>Io</TD><TD>421800.</TD><TD>0.0041</TD>
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<TD>84.129</TD><TD>342.021</TD><TD>0.036</TD><TD>43.977</TD><TD>203.4889583</TD>
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<TD>1.769</TD><TD>1.625</TD><TD>7.420</TD><TD>268.057</TD><TD>64.495</TD>
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<TD>0.000</TD>
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<TD ALIGN=right><A HREF="#ref11">11</A></TD></TR>
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<td align="left" nowrap><b>Satellites of Neptune</b></td>
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<td align="right" nowrap><b>jump to:</b> <a href="#earth">Earth</a>, <a href="#mars">Mars</a></td>
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<H3>Mean orbital elements referred to the local <a href="?glossary&term=lp">Laplace planes</a></H3>
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Epoch 2000 Jan. 1.50 TT<BR>
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<TR ALIGN=right><TD ALIGN=left>Triton</TD><TD>354759.</TD><TD>0.0000</TD>
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<TD>66.142</TD><TD>352.257</TD><TD>156.865</TD><TD>177.608</TD>
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<TD>61.2572638</TD><TD>5.877</TD><TD>386.371</TD><TD>687.446</TD>
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<TD>299.456</TD><TD>43.414</TD><TD>0.010</TD>
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<TD ALIGN=right><A HREF="#ref54">54</A></TD></TR>
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<td align="left" nowrap><b>Satellites of Uranus</b></td>
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<td align="right" nowrap><b>jump to:</b> <a href="#earth">Earth</a>, <a href="#mars">Mars</a></td>
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<H3>Mean equatorial orbital elements</H3>
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Epoch 1980 Jan. 1.0 TT<BR>
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<TR ALIGN=right><TD ALIGN=left>Titania</TD><TD>436300.</TD><TD>0.0011</TD>
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<TD>284.400</TD><TD>24.614</TD><TD>0.079</TD><TD>99.771</TD><TD>41.3514246</TD>
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<TD>8.706</TD><TD>161.525</TD><TD>195.369</TD>
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<TD ALIGN=right><A HREF="#ref10">10</A></TD></TR>
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`;
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/** Ceres as the SBDB API answers `sstr=Ceres&phys-par=1&full-prec=1`, cut to what is read. */
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const CERES: SbdbAnswer = {
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orbit: {
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epoch: '2461200.5',
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elements: [
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{ name: 'e', value: '.07969229514816586' },
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{ name: 'a', value: '2.765552595034094' },
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{ name: 'q', value: '2.545159361382861' },
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{ name: 'i', value: '10.58802780183462' },
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{ name: 'om', value: '80.24862682043221' },
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{ name: 'w', value: '73.29421453021587' },
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{ name: 'ma', value: '274.4193463761342' },
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{ name: 'tp', value: '2461599.841466614066' },
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{ name: 'per', value: '1679.853119758983' },
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{ name: 'n', value: '.21430445064843' },
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{ name: 'ad', value: '2.985945828685327' }
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]
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},
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phys_par: [
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{ name: 'H', value: '3.34' },
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{ name: 'diameter', value: '939.4' },
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{ name: 'GM', value: '62.6284' },
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{ name: 'rot_per', value: '9.074170' }
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]
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};
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describe('parsePlanetMeanElements', () => {
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it('turns Standish’s longitudes into the argument of periapsis and mean anomaly', () => {
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const { orbit } = parsePlanetMeanElements(TABLE_2, 'jupiter');
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expect(orbit.argumentOfPeriapsisDeg).toBeCloseTo(14.27495244 - 100.29282654, 8);
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expect(orbit.meanAnomalyAtEpochDeg).toBeCloseTo(34.33479152 - 14.27495244, 8);
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expect(orbit.epochJd).toBe(2451545);
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});
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it('gives the rates per day, the mean motion being the mean longitude’s', () => {
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const { rates } = parsePlanetMeanElements(TABLE_2, 'earth');
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// 35 999.373 degrees a century is the sidereal year.
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expect(360 / rates.meanMotionDegPerDay).toBeCloseTo(365.2564, 4);
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expect(rates.argumentOfPeriapsisDegPerDay * 36525).toBeCloseTo(0.3179526 + 0.24123856, 8);
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// And every other rate the row gives, a century's worth: dropped, Saturn moved 0.66 degrees by
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// AD 1 without its node's and 0.36 by AD 3000 without its a, e and i, where no date from 1950 to
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// 2100 shows more than 0.036.
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expect(rates.longitudeOfAscendingNodeDegPerDay * 36525).toBeCloseTo(-0.24123856, 8);
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expect(rates.semiMajorAxisAuPerDay! * 36525).toBeCloseTo(-0.00000003, 8);
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expect(rates.eccentricityPerDay! * 36525).toBeCloseTo(-0.00003661, 8);
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expect(rates.inclinationDegPerDay! * 36525).toBeCloseTo(-0.01337178, 8);
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});
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it('carries Table 2b’s terms for Jupiter and beyond, and none for the inner planets', () => {
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expect(parsePlanetMeanElements(TABLE_2, 'jupiter').rates.meanAnomalyTerms).toEqual({ b: -0.00012452, c: 0.0606406, s: -0.35635438, f: 38.35125 });
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expect(parsePlanetMeanElements(TABLE_2, 'earth').rates.meanAnomalyTerms).toBeUndefined();
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});
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it('reads Pluto’s row, not the note above the table that starts a line with its name', () => {
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const pluto = parsePlanetMeanElements(TABLE_2, 'pluto');
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expect(pluto.orbit.semiMajorAxisAu).toBe(39.48686035);
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expect(pluto.rates.meanAnomalyTerms).toEqual({ b: -0.01262724, c: 0, s: 0, f: 0 });
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});
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});
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describe('parseSatelliteMeanElements', () => {
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it('reads a Laplace-plane row with its pole and its section’s epoch', () => {
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const io = parseSatelliteMeanElements(SATELLITES, 'Jupiter', 'Io', true);
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expect(io.laplacePole).toEqual({ raDeg: 268.057, decDeg: 64.495 });
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expect(io.orbit.epochJd).toBe(2450464.5);
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expect(io.rates.meanMotionDegPerDay).toBe(203.4889583);
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expect(io.orbitSource).toBe('JPL SSD satellite mean elements, epoch 1997 Jan 16');
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});
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it('reads the Moon against the ecliptic, with no pole', () => {
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const moon = parseSatelliteMeanElements(SATELLITES, 'Earth', 'Moon', false);
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expect(moon.laplacePole).toBeUndefined();
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expect(moon.orbit.epochJd).toBe(2451545);
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expect(moon.orbit.semiMajorAxisAu * 149597870.7).toBeCloseTo(384400, 3);
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});
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it('regresses a prograde node and advances a periapsis, as the planet’s oblateness turns them', () => {
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const { rates } = parseSatelliteMeanElements(SATELLITES, 'Earth', 'Moon', false);
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expect(rates.longitudeOfAscendingNodeDegPerDay).toBeCloseTo(-360 / (18.6 * 365.25), 9);
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expect(rates.argumentOfPeriapsisDegPerDay).toBeCloseTo(360 / (5.997 * 365.25), 9);
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});
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it('advances the node of a retrograde orbit', () => {
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const { rates } = parseSatelliteMeanElements(SATELLITES, 'Neptune', 'Triton', false);
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expect(rates.longitudeOfAscendingNodeDegPerDay).toBeCloseTo(360 / (687.446 * 365.25), 9);
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});
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it('reads a section referred to the planet’s equator against the pole it is given', () => {
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const pole = { raDeg: 77.311, decDeg: 15.175 };
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const titania = parseSatelliteMeanElements(SATELLITES, 'Uranus', 'Titania', false, pole);
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expect(titania.laplacePole).toEqual(pole);
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expect(titania.orbit.epochJd).toBe(2444239.5);
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expect(titania.rates.meanMotionDegPerDay).toBe(41.3514246);
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// Read as ecliptic elements, which is what a missing pole would mean, Titania is 88 degrees
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// from Horizons on 2025-01-01.
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expect(() => parseSatelliteMeanElements(SATELLITES, 'Uranus', 'Titania', false)).toThrow(/equator/);
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expect(() => parseSatelliteMeanElements(SATELLITES, 'Jupiter', 'Io', true, pole)).toThrow(/equator/);
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});
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it('turns the periapsis backwards where a resonance holds it', () => {
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const { rates } = parseSatelliteMeanElements(SATELLITES, 'Jupiter', 'Io', true);
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expect(rates.argumentOfPeriapsisDegPerDay).toBeCloseTo(-360 / (1.625 * 365.25), 9);
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});
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});
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describe('parseSmallBodyElements', () => {
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it('carries a dwarf planet on its osculating elements at their own mean motion', () => {
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const ceres = parseSmallBodyElements(CERES);
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expect(ceres.orbit).toEqual({
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semiMajorAxisAu: 2.765552595034094,
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eccentricity: 0.07969229514816586,
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inclinationDeg: 10.58802780183462,
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longitudeOfAscendingNodeDeg: 80.24862682043221,
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argumentOfPeriapsisDeg: 73.29421453021587,
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meanAnomalyAtEpochDeg: 274.4193463761342,
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epochJd: 2461200.5
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});
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expect(ceres.rates).toEqual({ meanMotionDegPerDay: 0.21430445064843, longitudeOfAscendingNodeDegPerDay: 0, argumentOfPeriapsisDegPerDay: 0 });
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expect(ceres.laplacePole).toBeUndefined();
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expect(ceres.orbitSource).toBe('JPL SBDB osculating elements, epoch 2026 Jun 9');
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});
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it('takes half the diameter as the radius, and the rotation period in hours', () => {
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const ceres = parseSmallBodyElements(CERES);
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expect(ceres.radiusKm).toBe(469.7);
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expect(ceres.rotationPeriodHours).toBe(9.07417);
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});
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it('leaves out what the answer does not publish', () => {
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const eris = parseSmallBodyElements({ ...CERES, phys_par: [{ name: 'rot_per', value: '25.9' }] });
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expect(eris.radiusKm).toBeUndefined();
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expect(eris.rotationPeriodHours).toBe(25.9);
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});
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});
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