990 Yerkes

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

G. Van Biesbroeck

Discovery site

Williams Bay

Discovery date

23 November 1922

Pronunciation

/ ˈ j ɜːr k iː z /

Alternative designations

1922 MZ

Observation arc

102.46 yr (37425 days)

Aphelion

3.2477 AU (485.85 Gm )

Perihelion

2.0916 AU (312.90 Gm)

Semi major axis

2.6696 AU (399.37 Gm)

Orbital period sidereal

4.36 yr (1593.2 d )

Mean anomaly

216.84 °

Mean motion

0° 13 33.456 / day

Inclination

8.7872°

Longitude of ascending node

353.971°

Argument of perihelion

9.4832°

Mean radius

9.23 ± 0.6 km

Synodic rotation period

24.56 h (1.023 d )

Sidereal rotation period

24.45 ± 0.05 h

via Wikipedia infobox

Wikidata facts

Instance of

asteroid

Named after

Yerkes Observatory

Followed by

991 McDonalda

Follows

989 Schwassmannia

Parent body

Sun

Minor-planet group

asteroid belt

Diameter

21.428

Orbital period

1592.406158625063

via Wikidata · CC0