File:Орбита_астероида_101.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
- James Craig Watson
- Discovery date
- 15 August 1868
- Pronunciation
- / ˈ h ɛ l ə n ə /
- Named after
- Helen of Troy
- Alternative designations
- A868 PA
- Minor planet category
- Main belt
- Observation arc
- 145.07 yr (52986 d)
- Aphelion
- 2.94606 AU (440.724 Gm )
- Perihelion
- 2.22353 AU (332.635 Gm)
- Semi major axis
- 2.58480 AU (386.681 Gm)
- Orbital period sidereal
- 4.16 yr (1517.9 d )
- Average orbital speed
- 18.44 km/s
- Mean anomaly
- 236.265 °
- Mean motion
- 0° 14 13.823 / day
- Inclination
- 10.1976°
- Longitude of ascending node
- 343.419°
- Argument of perihelion
- 348.030°
- Earth moid
- 1.21369 AU (181.565 Gm)
via Wikipedia infobox
Wikidata facts
- Diameter
- 65.84
- Mass
- 300
- Orbital period
- 1516.881535580736
Show 15 more facts
- time of discovery or invention
- 1868-08-15
- orbital inclination
- 10.19192324479905
- albedo
- 0.1898
- Commons category
- 101 Helena
- provisional designation
- A868 PA
- rotation period
- 23.08
- absolute magnitude
- 8.39
- orbital eccentricity
- 0.1405228690058763
- semi-major axis of an orbit
- 2.583660776023355
- periapsis
- 2.220597351238604
- apoapsis
- 2.946724200808105
- longitude of ascending node
- 343.3578097821223
- argument of periapsis
- 347.7568457539488
- mean anomaly
- 323.6524488136242
- time of periapsis
- 2461153.6525812726
Sources (2)
via Wikidata · CC0
~1 min read
Article
101 Helena is a large, rocky main-belt asteroid. It was discovered by Canadian-American astronomer J. C. Watson on August 15, 1868, and was named after Helen of Troy in Greek mythology.
This object is orbiting the Sun with a period of 4.16 years and an eccentricity of 0.14. Its orbital plane is inclined by 10.2° to the plane of the ecliptic. Radar observations were made of this object on Oct 7 and 19, 2001 from the Arecibo Observatory. Analysis of the data gave an estimated ellipsoidal diameter of 71×63×63 ± 16% km. The mean diameter estimated from IRAS infrared measurements is 66 km, in agreement with the radar findings. It is classified as an S-type asteroid in the Tholen system, suggesting a predominantly silicate composition. 101 Helena is spinning on its axis with a period of 23 hours.