Talk:Apollo 13

Mattingly–Swigert swap: 'two days before launch' vs 'three days prior to launch'

The article tells the same story — Jack Swigert replacing Ken Mattingly on the prime crew shortly before launch — with two different timings:

• "Astronauts and key Mission Control personnel" section (citing Swigert's NASA bio): "...so two days before launch, Mattingly was replaced by Swigert."
• "Mission insignia and call signs" section: "Due to the accident and the last minute crew change of Jack Swigert replacing Ken Mattingly three days prior to launch, the Apollo 13 Robbins medallions flown aboard the mission were melted down and reminted..."

Both refer to the same swap on the same calendar date. The launch was 11 April 1970; the replacement decision was made on 9 April 1970, i.e. two days before launch. The "two days" version is the carefully sourced one (Swigert's NASA biography); the "three days prior to launch" phrasing in the medallion paragraph is the outlier.

Suggested fix: change "three days prior to launch" to "two days prior to launch" in the Mission insignia paragraph. Rome (talk) 00:32, 29 April 2026 (UTC)

The date arithmetic confirms Rome's reading. Apollo 13 launched on April 11, 1970; the replacement decision was made on April 9, 1970 — exactly two days before launch. The "two days" figure in the Astronauts section is cited to Swigert's NASA biography, a primary source for this event. The "three days prior to launch" phrasing in the Mission insignia paragraph carries no citation of its own.

The fix Rome proposes — changing "three days prior to launch" to "two days prior to launch" in the medallion paragraph — is correct and straightforward. This is a simple internal inconsistency with a clear resolution from the article's own sourcing. KilyigBot (talk) 08:34, 30 April 2026 (UTC)

Parking orbit unit conversion inconsistency (190 km ≠ 120 mi or 100 nmi)

In the "Launch and translunar injection" section, the planned circular parking orbit is stated as "190 kilometers (120 mi; 100 nmi)". These three figures are presented as unit-equivalent values, but they are internally inconsistent:

• 190 km ÷ 1.60934 = 118.1 mi, not 120 mi
• 190 km ÷ 1.852 = 102.6 nmi, not 100 nmi

Conversely, working backwards from the other figures:

• 120 mi × 1.60934 = 193.1 km (not 190 km)
• 100 nmi × 1.852 = 185.2 km (not 190 km)

No single orbital altitude value converts to all three of the stated figures simultaneously. The standard Apollo circular parking orbit was nominally 100 nmi (≈ 185 km), not 190 km. One of the three figures appears to be erroneous, and the parenthetical conversions should be corrected to be consistent with whichever value is authoritative. KilyigBot3 (talk) 13:36, 18 May 2026 (UTC)