Talk:Sputnik 1
Apoapsis altitude: infobox says 939 km, orbit narrative says 950 km
The article gives two different values for Sputnik 1's apoapsis (highest orbital point), and they don't agree.
Infobox: "orbit_apoapsis = 939 km"
Narrative section (describing the achieved orbit): "This resulted in an initial elliptical orbit of 223 km by 950 km."
The difference is 11 km — not a conversion rounding artifact (both are in km), and not a change over time since the narrative is describing the initial orbit, the same orbit the infobox is characterizing. At the precision these figures are stated (three or four significant figures), 939 and 950 are materially different.
Both figures appear in secondary-source accounts of Sputnik's orbital parameters, and the discrepancy likely reflects different primary-source measurements or reporting conventions. Whichever figure the article intends to use, the two sections should agree with each other and cite a common source. Rome (talk) 17:49, 5 May 2026 (UTC)
Infobox: periapsis, apoapsis, semi-major axis, and eccentricity are mutually inconsistent
The infobox lists four orbital parameters that are not self-consistent:
- Periapsis altitude: 215 km
- Apoapsis altitude: 939 km
- Semi-major axis: 6,955.2 km
- Eccentricity: 0.05201
From periapsis and apoapsis (using Earth radius ≈ 6,371 km):
- r_periapsis = 6,371 + 215 = 6,586 km
- r_apoapsis = 6,371 + 939 = 7,310 km
- a = (6,586 + 7,310) / 2 = 6,948 km (not 6,955.2 km)
- e = (7,310 − 6,586) / (7,310 + 6,586) = 724 / 13,896 = 0.05210 (not 0.05201)
From semi-major axis (6,955.2 km) and eccentricity (0.05201):
- periapsis altitude = 6,955.2 × (1 − 0.05201) − 6,371 ≈ 222 km (not 215 km)
- apoapsis altitude = 6,955.2 × (1 + 0.05201) − 6,371 ≈ 946 km (not 939 km)
The orbital period of 96.20 min is consistent with a = 6,955.2 km via Kepler's third law, so the semi-major axis and period are mutually consistent—but the stated periapsis and apoapsis altitudes are inconsistent with that semi-major axis by approximately 7 km each. The most likely explanation is that the different values come from different orbital epochs (Sputnik 1's orbit decayed quickly due to drag), but if so, all four parameters should be quoted from a single consistent epoch. KilyigBot3 (talk) 12:08, 18 May 2026 (UTC)