Picture of the Day · NASA

Pathfinder on Mars
2026-07-04
On July 4th, 1997, using its own array of fireworks, a parachute, and a cocoon of airbags, the Mars Pathfinder spacecraft bounced like a giant beach ball at least 15 times before it came to rest on the surface of Mars at 10:07 AM Pacific Daylight Time. After its then novel airbag-assisted landing sequence was completed, Pathfinder transmitted this color mosaic to mission operators on Earth. In the scene from another world, the Mars Sojourner robot rover is visible in the foreground, crouched on top of the unfolded Pathfinder. About the size of a large house cat, the six-wheeled, solar-powered Sojourner became the first successful Martian rover. Surrounding Pathfinder are deflated airbags and the rock-strewn terrain of the Ares Vallis floodplain. In the distance Martian hills appear against a dusty brownish sky. The Pathfinder lander was subsequently renamed the Carl Sagan Memorial Station.
via NASA APOD
Key facts
- Discovered by
- K. Reinmuth
- Discovery site
- Heidelberg Obs.
- Discovery date
- 17 August 1936
- Pronunciation
- / ˈ eɪ dʒ æ k s /
- Named after
- Ajax (Greek mythology)
- Alternative designations
- 1936 QW
- Minor planet category
- Jupiter trojan , Greek · background
- Adjectives
- Ajantian / ə ˈ dʒ æ n t i ə n /
- Observation arc
- 81.76 yr (29,864 d)
- Aphelion
- 5.9044 AU
- Perihelion
- 4.6992 AU
- Semi major axis
- 5.3018 AU
- Orbital period sidereal
- 12.21 yr (4,459 d)
- Mean anomaly
- 247.16 °
- Mean motion
- 0° 4 50.52 / day
- Inclination
- 18.005°
- Longitude of ascending node
- 332.92°
- Argument of perihelion
- 59.772°
via Wikipedia infobox
Wikidata facts
- Instance of
- asteroid
- Named after
- Ajax the Great
- Followed by
- 1405 Sibelius
- Follows
- Q138797
- Parent body
- Sun
- Minor-planet group
- asteroid belt
- Diameter
- 83.99
- Orbital period
- 4435.52638672312
- Image
- 001404-asteroid shape model (1404) Ajax.png
Show 18 more facts
- discoverer or inventor
- Karl Wilhelm Reinmuth
- site of astronomical discovery
- Heidelberg-Königstuhl State Observatory
- provisional designation
- 1936 QW
- time of discovery or invention
- 1936-08-17
- orbital eccentricity
- 0.1124052870928298
- albedo
- 0.048
- orbital inclination
- 18.03163071086053
- periapsis
- 4.689348758553304
- apoapsis
- 5.877070104384973
- semi-major axis of an orbit
- 5.283209431469139
- mean anomaly
- 112.570143838859
- longitude of ascending node
- 332.8772857573175
- argument of periapsis
- 61.74117568804254
- absolute magnitude
- 9.29
- Commons category
- 1404 Ajax
- rotation period
- 29.411
- time of periapsis
- 2459613.5337684597
- epoch
- November 21, 2025
via Wikidata · CC0
~4 min read
Encyclopedic overview
1404 Ajax /ˈeɪdʒæks/ is a carbonaceous Jupiter trojan from the Greek camp, approximately 83 kilometers (52 miles) kilometers in diameter. It was discovered on 17 August 1936, by German astronomer Karl Reinmuth at Heidelberg Observatory in southern Germany, and named after the legendary warrior Ajax from Greek mythology. The assumed C-type asteroid belongs to the 40 largest Jupiter trojans and has a longer than average rotation period of 29.4 hours.
Orbit and classification
Excerpted from Wikipedia’s “Q138810” article, available under the CC BY-SA 4.0 licence.