- 1717 - Kepler Space Telescope, has identified 1,000 planets orbiting other stars. After 4 years its gyroscopes gave out, but, creative astronomers have found a way to give the telescope new life. It is still discovering more planets.
-
-
----------------- 1717 - Kepler Space Telescope.
-
- Kepler Space Telescope is a unique instrument. It has a wide field of view and can detect the slightest changes in the brightness of the points of light it is observing. It looks at one spot in the sky for a continuous period. If a planet transits in front of a star it blocks a small amount of light. Kepler can detect that change with unbelievable precision.
-
- Kepler’s brightness data can tell astronomers the size of the planet, the size of its orbit around the star. After 4 years staring into the same area of sky Kepler has detected over 5,000 planet candidates., 1,000 of these have been confirmed with precision measurements. In addition Kepler has studied over 2,000 binary stars that are eclipsing each other.
-
- The goal is to find Earth-like planets that may sustain life in another solar system. Most of the planets discovered to date are large, like Jupiter, easier to detect but gas planets that are orbiting too close to the star to have habitable planets or moons.
-
- Kepler telescope uses an array of 422 Charge-Coupled - Diodes, , CCDs, at its focal plane. The diode detectors are equivalent to a 95 mega pixel camera. The camera stares at a single spot in the sky. Its original field of view was a spot in the Constellation Lyra and Cygnus which contains 150,000 average size stars and possibly hosts orbiting planets and moons.
-
- The Kepler telescope was launched in March 2009.
-
- Astronomers have over 4 years of data. Then, the second reaction wheel failed. The telescope lost its ability to stay focused on the same spot in the sky. The reaction wheels are gyroscopes. Spinning top hats that can be controlled to spin in one direction. Action equals reaction causing the telescope to slowly rotate in the opposite direction. With 4 reaction wheels a precise pointing direction could be maintained. With only two this ability was lost.
-
- In May 2013 Kepler had lost 2 of its reaction wheels . Friction and instability prevented them from spinning properly. The science had to come to a halt. It was 40,000,000 miles away. No hope of repairing it like was done for the Hubble Space Telescope.
-
- Astronomers and engineers are challenged by failures. They figured out a way to resurrect the Kepler mission. Rotate the telescope perpendicular to the ecliptic, the path the Sun travels across the sky. Then, use the solar pressure of the photons of sunlight striking the blocking shield to stabilize the spacecraft and keep it pointing in the same direction. This would work for one spot in the sky for 83 days before the sunlight got into the telescope and it had to point to a different area of the sky. But, it could repeat this mission for another 83 days. It could do this 9 times in its journey across the entire ecliptic.
-
-Kepler has a solar orbit of 372.5 days in the ecliptic which is the Sun’s apparent annual path traveled across the Constellations in the background. It corresponds to the plane of Earth’s orbit around the Sun.
-
- One of Kepler’s most recent discoveries is 5 planets orbiting a “K0” Dwarf star, a cool star with planets only 0.1 AU distant in orbit. AU = Astronomical Unit which is the Earth -Sun distance, 93,000,000 miles. Five planets inside 10% of that distance from the star.
-
- Adjacent plane pairs have orbital resonances of 5/4, 4/3, 5/4, 5/4. All 5 planets are sub-Earth size with the inner most planet about the size of Jupiter’s moon, Ganymede. When the orbital periods are a simple ratio they periodically line up with each other and the extra gravitational attractions tend to align their orbits with repeated passes.
-
- K0 Dwarf stars refers to its spectral type. That is a way of classifying stars by their lines that appear in their spectrum. Spectral lines are emission lines related to the star’s surface temperature and absorption lines that the light passes through. “O” is the hottest stars. “M” is the coolest stars. OBAFGKM is the series each subdivided by the numbers 0 through 9. Our Sun is “ G2” This Dwarf star is “ K0”. The temperatures range from 35,000 Kelvin to 3,500 Kelvin. Our Sun is 6,000 Kelvin. To remember this:” Oh be a fine girl kiss me”.
-
---------------------------------------------------------------------------------------------
-
-Johann Kepler was a German astronomer born in1571 ,died in 1630, at the age of 59. He was the son of a professional soldier and the grandson of the town mayor.
-
- He had smallpox when he was 3 that crippled his hands and weakened his eyesight. He studied at the University of Tubingen graduating in 1588 at age of 17. He went on for a masters degree graduating in 1591.
-
- He was teaching science in Austria. He studied astrology attempting to use astrological techniques to solve biblical mysteries. He came up with creation occurring in 3992 B.C. He wrote horoscopes for Emperor Rudolf.
-
- Kepler moved to Prague in 1598. When his cohort Tycho Brahe died in 1601 he inherited Tycho’s invaluable data.
-
- September 30, 1604 he observed a supernova later to be called “ Kepler’s star”. He used his mathematical genius to try to understand the paths of the planets. He found that an ellipse could be defined to fit their orbit data. This is now known as Kepler’s 1st law”
-
- “A line connecting the planet and the Sun will sweep over equal areas in equal times.” The closer to the Sun the faster the orbital velocity. His book published in 1619 included his 3rd law:
-
- “ The square of the period of revolution of a planet is proportional to the cube of its distance from the Sun.”
-
- Kepler and Galileo carried on correspondence and Galileo sent Kepler one of his telescopes.
-
- Kepler fathered 13 children. One of his last feats in astronomy is to predict the transit of Mercury across the Sun in 1631.
- -----------------------------------------------------------------------------------------------
RSVP, with comments, suggestions, corrections. Index of reviews available ---
--- Some reviews are at: -------------------- http://jdetrick.blogspot.com -----
---- email request for copies to: ------- jamesdetrick@comcast.net ---------
---- https://plus.google.com/u/0/ , “Jim Detrick” ----- www.facebook.com ---
---- www.twitter.com , --- 707-536-3272 ---- Sunday, January 4, 2015 ---
-----------------------------------------------------------------------------------------------
No comments:
Post a Comment