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
- Max Wolf
- Discovery site
- Heidelberg Observatory
- Discovery date
- 20 March 1915
- Alternative designations
- 1915 WQ; A924 OD;, 1925 RG; 1970 GS1
- Observation arc
- 101.08 yr (36918 d)
- Aphelion
- 2.8087 AU (420.18 Gm )
- Perihelion
- 2.4007 AU (359.14 Gm)
- Semi major axis
- 2.6047 AU (389.66 Gm)
- Orbital period sidereal
- 4.20 yr (1535.4 d )
- Mean anomaly
- 47.6362 °
- Mean motion
- 0° 14 4.056 / day
- Inclination
- 14.130°
- Longitude of ascending node
- 185.973°
- Argument of perihelion
- 335.076°
- Earth moid
- 1.41172 AU (211.190 Gm)
- Jupiter moid
- 2.17333 AU (325.126 Gm)
- Mean radius
- 16.615 ± 1.25 km
- Synodic rotation period
- 23.93 h (0.997 d )
via Wikipedia infobox
Wikidata facts
- Instance of
- asteroid
- Followed by
- 802 Epyaxa
- Follows
- 800 Kressmannia
- Parent body
- Sun
- Minor-planet group
- asteroid belt
- Diameter
- 32.404
- Orbital period
- 1535.783454418186
Show 18 more facts
- discoverer or inventor
- Max Wolf
- site of astronomical discovery
- Heidelberg-Königstuhl State Observatory
- provisional designation
- A915 FH
- time of discovery or invention
- 1915-03-20
- albedo
- 0.031
- rotation period
- 23.93
- asteroid spectral type
- X-type asteroid
- absolute magnitude
- 11.57
- orbital eccentricity
- 0.076794270773605
- semi-major axis of an orbit
- 2.605079842252994
- periapsis
- 2.405024635460157
- apoapsis
- 2.80513504904583
- orbital inclination
- 14.14027217088045
- longitude of ascending node
- 185.8929634791679
- argument of periapsis
- 337.449420316529
- mean anomaly
- 122.2646076491264
- time of periapsis
- 2460478.9112180877
- epoch
- November 21, 2025
Sources (2)
via Wikidata · CC0
~1 min read
Encyclopedic overview
801 Helwerthia is a C-type asteroid orbiting in the Main belt near the Eunomia family. However, it is not a family member but an un-related interloper in the region because its composition is inconsistent with membership. Its diameter is about 33 km, its albedo around 0.038. An international team of astronomers observed this minor planet photometrically in 2012, determining a rotation period of 23.93±0.01 h with an amplitude of 0.15±0.03 in magnitude.
References
Excerpted from Wikipedia’s “Q157172” article, available under the CC BY-SA 4.0 licence.