File:694Ekard_(Lightcurve_Inversion).png · Wikimedia Commons · See Wikimedia Commons
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
- Joel Hastings Metcalf
- Discovery site
- Taunton, Massachusetts
- Discovery date
- 7 November 1909
- Alternative designations
- 1909 JA
- Observation arc
- 106.44 yr (38878 d)
- Aphelion
- 3.5372 AU (529.16 Gm )
- Perihelion
- 1.8114 AU (270.98 Gm)
- Semi major axis
- 2.6743 AU (400.07 Gm)
- Orbital period sidereal
- 4.37 yr (1597.4 d )
- Mean anomaly
- 201.11 °
- Mean motion
- 0° 13 31.332 / day
- Inclination
- 15.849°
- Longitude of ascending node
- 230.116°
- Argument of perihelion
- 111.400°
- Mean radius
- 45.39 ± 2 km , 45.39 km
- Synodic rotation period
- 5.925 h (0.2469 d )
- Geometric albedo
- 0.046 , 0.0460 ± 0.004
via Wikipedia infobox
~1 min read
Encyclopedic overview
694 Ekard is a minor planet orbiting the Sun that was discovered by American astronomer Joel Hastings Metcalf on November 7, 1909. The asteroid's name comes from the reverse spelling of Drake University in Des Moines, Iowa, where Seth Barnes Nicholson and his wife calculated its orbit.
Photometric observations of this asteroid gave a light curve with a period of 5.925 hours and a brightness variation of 0.50 in magnitude. Measurements of the thermal inertia of 694 Ekard give a value of around 100–140 J m K s, compared to 50 for lunar regolith and 400 for coarse sand in an atmosphere.
Excerpted from Wikipedia’s “694 Ekard” article, available under the CC BY-SA 4.0 licence.