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
- 22 September 1928
- Pronunciation
- / ˈ ɑːr n ɪ k ə /
- Named after
- Arnica ( flowering plant )
- Alternative designations
- 1928 SD · 1950 BU, 1976 MK · 1979 HE, A904 XA · A918 RD
- Minor planet category
- main-belt · ( outer ) , Koronis
- Observation arc
- 99.19 yr (36,230 days)
- Aphelion
- 3.0985 AU
- Perihelion
- 2.6991 AU
- Semi major axis
- 2.8988 AU
- Orbital period sidereal
- 4.94 yr (1,803 days)
- Mean anomaly
- 47.143 °
- Mean motion
- 0° 11 58.92 / day
- Inclination
- 1.0342°
- Longitude of ascending node
- 304.12°
- Argument of perihelion
- 24.241°
- Dimensions
- 16.894 ± 0.243 km , 17.234 ± 0.122 km , 17.92 km (calculated)
via Wikipedia infobox
Wikidata facts
- Instance of
- asteroid
- Named after
- Arnica
- Followed by
- Q135934
- Follows
- 1099 Figneria
- Parent body
- Sun
- Minor-planet group
- asteroid belt
- Diameter
- 16.894
- Orbital period
- 1801.90827758539
Show 17 more facts
- discoverer or inventor
- Karl Wilhelm Reinmuth
- site of astronomical discovery
- Heidelberg-Königstuhl State Observatory
- provisional designation
- A918 RD
- time of discovery or invention
- 1928-09-22
- orbital inclination
- 1.030738790771405
- orbital eccentricity
- 0.0700657343472108
- periapsis
- 2.694894406232185
- apoapsis
- 3.100987100167498
- semi-major axis of an orbit
- 2.897940753199842
- mean anomaly
- 289.6233845441876
- longitude of ascending node
- 303.8019912895458
- argument of periapsis
- 21.37831889032936
- absolute magnitude
- 10.91
- albedo
- 0.246
- rotation period
- 14.535
- time of periapsis
- 2461352.756127606
- epoch
- November 21, 2025
Sources (2)
via Wikidata · CC0
~4 min read
Encyclopedic overview
1100 Arnica /ˈɑːrnɪkə/, provisional designation 1928 SD, is a Koronian asteroid from the outer regions of the asteroid belt, approximately 17 kilometers in diameter. It was discovered by Karl Reinmuth at the Heidelberg Observatory in 1928 and named after the herbaceous plant Arnica (aster; daisy). The asteroid is likely of stony composition and has a rotation period of 14.535 hours.
Discovery
Excerpted from Wikipedia’s “Q135927” article, available under the CC BY-SA 4.0 licence.