This page contains a Flash digital edition of a book.
Cassini flew twice past Venus, then once past Earth and Jupiter. The spacecraft’s


speed


relative to the Sun increased as it approached and swung around each planet, giving Cassini the cumulative boost it needed to reach Saturn with minimal fuel consumption. After reaching Saturn, Cassini fired its main engine for about 96 minutes, reducing the spacecraft’s speed and allowing it to be captured in an orbit around Saturn. On January 5 , 2005 , Cassini released the European-built Huygens probe toward Titan.


Journey to a Distant Moon


> Titan im age. In this infrared view of Titan, features on the leading hem isphere are show n, including the b right, crescent-shaped Hotei arcus ( right of center) , often referred to as “ the sm ile” b y researchers. The view is centered on the


b right region called X anadu. The im age w as tak en w ith the Cassini spacecraft narrow -angle cam era using a spectral  lter sensitive to w avelengths of infrared light centered at 9 3 8 nm . The im age w as acq uired at a distance of approx im ately 1. 3 m illion k m [ 800, 000 m iles] from Titan. ( Im age courtesy of NASA/ J PL/ Space Science Institute. )


With a diameter larger than the planet Mercury, Titan is one of the most interesting moons in the solar system. The surface of this moon lies hidden beneath an opaque atmosphere more than 5 0% denser than that of Earth (left). Titan’s atmosphere is filled with a brownish- orange haze composed of complex organic molecules falling like rain from the sky to the surface. Most scientists agree that conditions on Titan are too cold for life to have evolved— although there are theories concerning the possibility of life forms in covered lakes of liquid hydrocarbons warmed by the planet’s internal heat.


1, 000 5 00


3 00 19 2


Entry speed: 6. 2 k m / s Peak deceleration: 10gn to 25 gn Main chute deploy s


Instrum ent inlet- port


17 0 opens Drogue chute deploy s


Decelerator j ettisons


0 0 2. 5 Tim e, hours after entry


> Descent to Titan. The Huy gens prob e analy zed Titan’ s atm osphere and recorded a signi cant am ount of data and im ages on its j ourney to the surface of Titan. ( Im age courtesy of NASA/ J PL. )


Prob e perform s surface science


Instruments onboard the probe detected a surface temperature of 94K at the landing site. Images taken by the probe while descending showed surface channels that appeared to indicate rain or fluid flow, possibly in the form of liquid methane. Ridges as tall as 100 m were observed near the landing area (next page, top). High quantities of methane were detected in the lower atmosphere, with nitrogen predominating in the upper atmosphere. Oxygen was not detected probably because it is tied up as frozen water. This would also prevent the formation of carbon dioxide.


The Huygens probe entered Titan’s atmos- phere on January 14, 2005 , deployed its parachutes and began its scientific observations during a descent through the moon’s dense atmosphere lasting close to 21 left).4 1


⁄ 2 hours (below


Laboratory tests recreated the impact measurements derived from the onboard penetrometer. These tests indicate that the surface in the landing area may be composed of fine particles with a thin crust. Accelerometer measurements suggest the probe settled 10 to 15 cm [ 4 to 6 in.]


into the surface. Heat from


instruments then evaporated liquid methane in the soil and released it around the spacecraft as methane gas. The Huygens probe continued


5 8


Oilfield Review


Altitude, k m


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68