02 - Full Moon
at 19:14 UT
05 - Taurid
(south) meteor shower peaks. Active
between 25 Sept and 25 Nov.
Associated with Comet 2P/Encke.
09 - Moon near
Mars (morning sky) at 14h UT. Mag. +0.3.
12 -Taurid (north) meteor
shower peaks. May produce the occasional
17 -Leonid meteor shower
peaks at 9h UT. Arises from debris ejected
Comet Tempel-Tuttle in 1533. Expect about 25
to 30 meteors per hour under
dark skies. Predictions of enhanced activity
between 21-22h UT on 17 Nov
(favours sky watchers in Asia).
21 -Alpha Monocerotid meteor
shower peaks at 15:25 UT. A usually minor
shower active 15-25 Nov. Radiant is near Procyon.
Predictions of enhanced
activity this year. Timing favours Far East
Asia, Australia and across the
Pacific to Alaska.
00 0 0
0 0 0//
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Wednesday, June 30, 2004
Journey to the Ringed Planet
Sorry for lack of updates - too lazy to be true :p but this time now I come up with Cassini grand tour to planet Saturn. A long post tho..
Tomorrow, Cassini spacecraft will mark an history as it will enter orbit of the ringed planet of Saturn. The first ever attempt made by human to put an orbiter on the planet. This is so outstanding moment because of its travel distance taken by the Cassini spacecraft to reach the planet. Such a long journey that the Cassini has travelled - 2.2 billion miles! Launched in October 1997 (it is when my first nephew was born, now he is at the first grade of Elementary school :D - imagine that!), to travel to Saturn, Cassini had to manouver by circling the Sun twice, made two flybys of Venus and one of Earth in order to get advantage of gravity force of the planets, that hence can boost the spacecraft's velocity. Then, made a last flyby of Jupiter before firing up a nuclear-powered spacecraft engine directed to the ringed-planet. To get a clear view of the path to Saturn, click here.
Well, I am so excited to watch the moment of the Saturn insertion tomorrow. I hope everything goes well with the spacecraft when it enters the Saturn orbit. The critical point of the journey, however, is heart-beating moment. Because to be able to get into orbit and captured by the Saturn gravity, the spacecraft firstly have to pass the ring of the planet. The ring itself is formed by billions of ice and rocks, which can has a size as big as a house). But cleverly, the spacecraft engineers have already designed the spacecraft to pass a gap between F ring and G ring, which actually has less density of ice and rock accumulation. They had succesfully sent Voyager 1 and Pioneer spacecraft to pass the ring space. So, they believe the Cassini will follow their predecessors passing this ardous journey! I really hope so. :)
Before made a final trip to the ringed-planet, Cassini previously made an historic flyby at Phoebe - one of 31 known moons of Saturn and the outer-most satellite of the Saturn moon system. Capturing a few shots with high resolution camera attached to the body of spacefraft from close proximity at about 13 thousand km, the spacecraft sent outstanding pictures back to earth. And it really amazed folks here because of its crisp and detailed quality of those images, ten times much better then those taken by Voyager in 1980. I was just thinking when I first saw the object... it is alot like an asteroid origin. But my thought was wrong. When NASA held a briefing shortly after publishing the pictures to public, they made analysis that this satellite is not asteroid-like moon but rather an object originated from the outer solar system, perhaps from Kuiper Belt region. They made a analysis after seeing the composition of the landscape of the moon. They used a tool called Spectrometer, that was also in action when the spacecraft made the flyby, to get the data necessary to unveil the composition.
In early January 2005, Cassini will make a flyby at Titan, the largest moon on the planet and drop a piggybacked lander, called Huygens. Huygens was developed by European Space Agency. The moon is so interesting that engineers agreed to send a lander on it. It is the only moon in our solar system that has atmosphere, and it is believed the planet has an ocean of liquid methane, methane is a key ingredient to sustain life. But to get to the surface is not an easy task, the lander must pass through thick clouds. It is so thick that no available telescopes on Earth can see the surface of the Titan. That is why the only way to get upclose of the surface is to send a device/lander to it.
Scheduled to orbit Saturn for 4 years, the Cassini is expected to gain scientific data, make new discovery and perhaps re-shape our prior perception of the planet. That is true because what we know about the planet details are merely from scientific research made from distance. Now, with the presence of orbiter on the planet, we could refine and enrich our understang of the planet even more.
Oh well, what a long post. Honestly, I enjoy writing this short article, as much as I enjoy watching the journey of Cassini spacecraft to Saturn and Titan. I'll will post again tomorrow, and I will keep you informed later that day.
Oh ya, I've just received a newsletter from Nasa Jet Propulsion Laboratory in Pasadena, saying that Cassini is at Saturn's Doorstep (June 29, 2004).
Here's the script of the newsletter I got:
On June 30 at 7:36 p.m. Pacific Time (10:36 p.m. EDT), Cassini will
begin executing a series of commands to enter orbit around the ringed
planet. The spacecraft will fire its main engine for a crucial 96
minutes to slow down and be captured in orbit about Saturn.
During the orbit insertion, Cassini will fly closer to Saturn than at
any other time during the spacecraft's planned four-year tour of
Saturn. This provides an unprecedented opportunity to study the planet
and rings at close range. It will pass approximately 20,000 kilometers
(12,427 miles) above Saturn's cloud tops, closer than any other
spacecraft in history. It will also be flying about 10 times closer to
the rings than at any other point in the mission
Eighty-five minutes before the engine burn, Cassini will rotate to
point its main antenna dish forward. The Italian-built antenna, 4
meters (13 feet) in diameter, will offer shielding against dust
particles the spacecraft may hit as it crosses a gap in the rings. The
spacecraft will continue transmitting a monotone "carrier" signal with
a secondary antenna for tracking from Earth. Cassini will pass twice
through a known gap between the F and G rings, first while ascending
shortly before the burn, then while descending shortly after the burn.
The engine burn will slow the spacecraft by 626 meters per second
(1,400 miles per hour). Five science instruments will be on during the
burn, and others will be used shortly after the engine cuts off. The
magnetometer will measure the strength and direction of the magnetic
field to understand the physics of Saturn's magnetic dynamics.
Lightning may also be detected. Another instrument will provide a
record of the dust hits as the spacecraft flies through the ring
plane. These observations may tell scientists the size of these tiny
particles and the thickness of that ring region. The remote sensing
instruments will assess the rings' composition, temperature, and
structure. Then the spacecraft will be oriented for the outbound ring
plane crossing. After crossing the ring plane in the descending mode,
Cassini will look back at the sunlit face of the rings to take more
data before turning to Earth to transmit its data.
Oort cloud, is a postulated spherical cloud
of comets situated about 50,000 to 100,000 AU from
the Sun. This is approximately 1000 times the distance
from the Sun to Pluto or roughly one light year, almost
a quarter of the distance from the Sun to Proxima
Centauri, the star nearest the Sun. The Oort cloud
would have its inner disk at the ecliptic from the
Kuiper belt. Although no direct observations have
been made of such a cloud, it is believed to be the
source of most or all comets entering the inner solar
system (some short-period comets may come from the
Kuiper belt), based on observations of the orbits
of comets. Source: Wikipedia