Voyager 1 and Voyager 2 are named in an order that does not match the order they left the ground. That mismatch is documented in NASA's own mission material, which makes it a fair benchmark rather than a trick.
Everything below is drawn from the completed challenge record: clues, evidence, validation searches and the limitations that remain.
The question as published
Two identical NASA probes left Cape Canaveral roughly a fortnight apart in 1977, and the one carrying the higher number in its name departed first. On what date did that earlier launch take place?
- Answer
- 20 August 1977
- Confidence
- High — stated directly on two separate NASA pages
Sources opened and read
Voyager 2 Launched Before Voyager 1
NASA • Government records • Primary
The decisive source: it states the earlier date and explains the counter-intuitive numbering in one place.
Open sourceVoyager Mission Overview
NASA Science • Government records • Primary
Independent NASA page giving the same two dates plus the launch site and vehicle.
Open sourceVoyager 1
NASA Science • Government records • Primary
Confirms the later date on its own page, so the pair can be checked from two separate records.
Open source45 Years Ago: Voyager 1 Begins its Epic Journey to the Outer Planets and Beyond
NASA History (John Uri, Johnson Space Center) • Government records • Primary
Gives the interval as an exact number of days, which lets a solver derive the answer arithmetically from clue C05.
Open sourceGolden Record Overview
NASA Science • Government records • Primary
Confirms the shared payload clue without touching either launch date.
Open sourceTitan/Centaur D-1T TC-6 Voyager Flight Data Report
NASA Lewis Research Center • PDF documents • Primary
A technical document rather than a press page, demonstrating that the chain reaches primary engineering records.
Open source
Searches that were run
Voyager 2 launched August 20 1977 before Voyager 1 September 5 1977 NASA
Web search • 4 September 2026 • Answer exposed: Yes
nasa.gov “Voyager 2 Launched Before Voyager 1”; NASA Science mission overview; Voyager 2 page; JPL 45-years article
Voyager 1 launch September 5 1977 Titan IIIE Centaur Launch Complex Cape Canaveral Golden Record
Web search • 4 September 2026 • Answer exposed: No
NASA Science Voyager 1 page; NASA image article; NASA history 45-years article; TC-6 flight data report; Golden Record overview
which Voyager launched first
Web search • 4 September 2026 • Answer exposed: Yes
NASA image article and mission overview surface immediately.
What the investigation showed
What made the question difficult
The numbering is misleading: Voyager 2 launched before Voyager 1. A solver who assumes the obvious order looks up the wrong date.
Which searches failed
None failed outright — the weakness here is the opposite. A single plain question about launch order is answered immediately, which is why the challenge asks for a date and hides the spacecraft name.
Which source proved decisive
The NASA image article that states both dates and explains why the order was reversed.
How ambiguity was removed
The launch site, the year and the interval together leave exactly one pair of spacecraft and one date.
What an AI browsing agent might get wrong
Returning 5 September 1977 by assuming Voyager 1 flew first, or quoting the interstellar-crossing date instead of a launch date.
Remaining limitations
This benchmark is easier than AIBRC-001: the decisive fact sits on a well-indexed agency page, so it tests care rather than search depth.
Recommended future improvements
Raise the difficulty by requiring a figure that only appears inside the flight-data PDF rather than on a mission summary page.
Read the full case study
The complete record — clue matrix, evidence cards, validation log and the structured JSON output — is published on the case study page.
Open Voyager Launch-Order Benchmark