File:69Hesperia_(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
- G. Schiaparelli
- Discovery date
- April 29, 1861
- Pronunciation
- / h ɛ ˈ s p ɪər i ə /
- Named after
- Hesperia
- Minor planet category
- Main belt
- Adjectives
- Hesperian / h ɛ ˈ s p ɪər i ə n /
- Aphelion
- 3.471 AU (519.3 Gm )
- Perihelion
- 2.489 AU (372.3 Gm )
- Semi major axis
- 2.980 AU (445.8 Gm )
- Orbital period sidereal
- 1,879 days (5.14 a )
- Inclination
- 8.59°
- Longitude of ascending node
- 184.99°
- Argument of perihelion
- 288.8°
- Dimensions
- 138 km ( IRAS ) , 110 ± 15 km
- Mass
- (5.86 ± 1.18) × 10 kg
- Mean density
- 4.38 ± 0.99 g/cm
- Synodic rotation period
- 5.655 h
- Spectral type
- M
via Wikipedia infobox
~2 min read
Encyclopedic overview
69 Hesperia is a large, M-type main-belt asteroid. It was discovered by the Italian astronomer Giovanni Schiaparelli on April 29, 1861 from Milan, while he was searching for the recently discovered 63 Ausonia. It was his only asteroid discovery. Schiaparelli named it Hesperia in honour of Italy (the word is a Greek term for the peninsula). The asteroid is orbiting the Sun with a period of 5.14 years, a semimajor axis of 2.980 AU, and eccentricity of 0.165. The orbital plane is inclined by an angle of 8.59° to the plane of the ecliptic.
Hesperia was observed by Arecibo radar in February 2010. Radar observations combined with lightcurve-based shape models, lead to a diameter estimate of 110 ± 15 km (68 ± 9.3 mi). The radar albedo is consistent with a high-metal M-type asteroid. In the near infrared, a weak absorption feature near a wavelength of 0.9 μm can be attributed to orthopyroxenes on the surface. A meteorite analogue of the reflectance spectra from 69 Hesperia is the Hoba ataxite.
Excerpted from Wikipedia’s “69 Hesperia” article, available under the CC BY-SA 4.0 licence.