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
- August Kopff
- Discovery site
- Heidelberg
- Discovery date
- 4 January 1908
- Alternative designations
- 1908 BM
- Observation arc
- 108.29 yr (39553 d)
- Aphelion
- 2.8288 AU (423.18 Gm )
- Perihelion
- 1.7653 AU (264.09 Gm)
- Semi major axis
- 2.2970 AU (343.63 Gm)
- Orbital period sidereal
- 1,271.6 d (3.48 yr)
- Mean anomaly
- 51.9052 °
- Mean motion
- 0° 16 59.196 / day
- Inclination
- 18.125°
- Longitude of ascending node
- 278.460°
- Argument of perihelion
- 214.008°
- Mean radius
- 63.70 ± 1.95 km , 63.915 ± 2.615 km
- Mass
- (1.35 ± 0.14) × 10 kg
- Mean density
- 1.23 ± 0.19 g/cm
- Synodic rotation period
- 31.735 h (1.3223 d )
via Wikipedia infobox
~2 min read
Encyclopedic overview
654 Zelinda is a minor planet orbiting the Sun that was discovered on 4 January 1908 by German astronomer August Kopff. It is orbiting the Sun at a distance of 2.297 AU with an orbital eccentricity of 0.23 and a period of 3.48 yr. The orbital plane is inclined at an angle of 18.1° to the plane of the ecliptic. On favorable oppositions, it can be as bright as magnitude 10.0, as observed on January 30, 2016.
In 1988, this object was detected with radar from the Arecibo Observatory at a distance of 0.89 AU. The measured radar cross-section was 2,200 km. Measurements made using the adaptive optics system at the W. M. Keck Observatory give a diameter estimate of 131 km. This is 13% smaller than the diameter estimated from the IRAS observatory measurements. It is roughly triangular in shape, and spins with a synodic rotation period of 31.735 h.
Excerpted from Wikipedia’s “654 Zelinda” article, available under the CC BY-SA 4.0 licence.