1521 Seinäjoki

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

Y. Väisälä

Discovery site

Turku Obs.

Discovery date

22 October 1938

Named after

Seinäjoki (Finnish city)

Alternative designations

1938 UB 1 · 1933 UR 1 , 1967 UW

Minor planet category

main-belt · ( outer ) , Brasilia

Observation arc

78.62 yr (28,716 days)

Aphelion

3.2435 AU

Perihelion

2.4633 AU

Semi major axis

2.8534 AU

Orbital period sidereal

4.82 yr (1,760 days)

Mean anomaly

123.44 °

Mean motion

0° 12 16.2 / day

Inclination

15.059°

Longitude of ascending node

12.593°

Argument of perihelion

48.805°

Mean diameter

13.66 ± 3.61 km , 14.813 ± 0.070 km , 16.095 ± 0.070 km , 16.29 ± 0.20 km , 24.30 km (calculated)

Synodic rotation period

4.32 ± 0.01 h , 4.328 159 ± 0.000 001 h

via Wikipedia infobox