Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2004 February 15 
Posted on 02/14/2004 11:19:06 PM PST by petuniasevan
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2004 February 15
Explanation: How did this spherule come to be on the Moon? When a meteorite strikes the Moon, the energy of the impact melts some of the splattering rock, a fraction of which might cool into tiny glass beads. Many of these glass beads were present in lunar soil samples returned to Earth by the Apollo missions. Pictured above is one such glass spherule that measures only a quarter of a millimeter across. This spherule is particularly interesting because it has been victim to an even smaller impact. A miniature crater is visible on the upper left, surrounded by a fragmented area caused by the shockwaves of the small impact. By dating many of these impacts, some astronomers estimate that cratering on our Moon increased roughly 500 million years ago and continues even today.
At a meeting in Paris on February 11 and 12, ESA's Science Programme Committee unanimously approved a proposal to continue operating the highly successful Ulysses spacecraft until March 2008.
 An artist's concept of Ulysses. Credit: NASA/ESA |
Unlike the recent high-latitude passes in 2000 and 2001 that brought Ulysses over the solar poles near the maximum of the Sun's activity cycle, conditions for the third set of polar passes are expected to be much quieter. In fact, they are likely to be similar to those in 1994/1995 when Ulysses first visited the Sun's poles. There will be an important difference, however.
While the Sun's activity follows the well-known 11-year sunspot cycle, conditions in the heliosphere are driven by the 22-year solar magnetic (or Hale) cycle.
"The Sun's magnetic field is rather like that of a bar magnet, with a north and a south pole," says Richard Marsden, ESA's Mission Manager for Ulysses.
"The north and south poles changed places at the time of the recent solar maximum, so the Sun's magnetic polarity in 2007/2008 will be opposite to that of the previous solar minimum."
The magnetic field of the Sun influences the way in which charged particles (cosmic rays, solar energetic particles, and even interstellar dust grains) move through the heliosphere.
"We'll be looking for differences in behaviour related to the magnetic reversal," says Marsden.
There is another difference between the solar minimum polar passes in 2007/2008 and those in 1994/1995. During its first high-latitude exploration, Ulysses did not have the benefit of being part of a fleet of solar and heliospheric spacecraft that now includes SOHO, Cluster, and NASA's ACE and Cassini. These missions did not come on line until later. The launch of new missions like NASA's dual-spacecraft STEREO, and Solar Dynamics Observatory, will add a further dimension over the next few years.
The study of our solar system's local neighbourhood using data from Ulysses has proven to be remarkably fruitful. Several of the instruments on board Ulysses are able to measure the properties of the gas and dust clouds that surround the heliosphere by detecting individual atoms and grains that are able to penetrate into the heliosphere. Many of the key measurements, however, can only be made when Ulysses is close to its maximum distance from the Sun. The period 2004-2006 represents a unique opportunity to extend these studies.
"The best way to improve the precision of our measurements is to detect as many atoms and dust grains as we can," says Marsden.
Because Ulysses is a joint project with NASA, programmatic decisions have to be agreed on by both agencies. A proposal was presented to NASA's 2003 Sun-Earth Connection Senior Review Panel who recommended continuing the mission until 2008. Based on this recommendation, NASA has already indicated its intention to go ahead. So things are all set for a new round of solar polar adventures.
"We're all excited by the wonderful scientific opportunities that Ulysses will give us in the next four years," says Richard Marsden.
Titan 4B rocket launches U.S. military satellite
SUNDAY, FEBRUARY 15, 2004
0203 GMT (9:03 p.m. EST Sat.)
MISSION SUCCESS! The Inertial Upper Stage completed its second firing and then released the 5,200-pound Defense Support Program-22 satellite into geostationary orbit tonight for the U.S. Air Force.
The $507 million Titan 4B/IUS vehicle lifted off at 1:50 p.m. EST from the Cape Canaveral Air Force Station's Complex 40. About nine minutes later, the Lockheed Martin Titan second stage deployed the Boeing-made IUS kick motor and attached DSP satellite into a low-Earth orbit. Over the course of the last six hours, the solid-fueled IUS fired its two stages to deliver the Northrop Grumman-built DSP spacecraft into a perch about 22,000 miles up.
The DSP spacecraft -- the 22nd launched since 1970 -- will undergo about 30 days of checks before being handed to Air Force Space Command for operational use. The Pentagon operates a constellation of DSP satellites to detect missile launches and nuclear explosions anywhere in the world, providing early warning to the U.S. and its allies.
"For 34 years, the Defense Support Program satellites have been the mainstay of this great nation's space-based strategic missile warning and surveillance capability," said Col. Robert "Bo" Reese, deputy system program director for the Air Force's Space Based Infrared Systems. "During the past 13 years, relatively inexpensive computer resources allowed us to expand that DSP mission to tactical missile warning and support commanders deployed worldwide."
Today's mission was the final for the IUS motor and next-to-last Florida launch for the Titan rocket fleet. The East Coast Titan finale is scheduled for October 1 when a classified satellite cargo will be launched for the U.S. National Reconnaissance Office.
One additional Titan 4 will fly after that, lifting off from Vandenberg Air Force Base in California next February.
The 23rd and last DSP satellite is scheduled for launch next March aboard a Boeing Delta 4-Heavy rocket from the Cape. Meanwhile, a new generation of orbiting surveillance satellites is being readied to fly.
"As we transition to more capable systems that will succeed DSP, these satellites will remain the backbone for this nation's missile warning needs for the foreseeable future, at least for the next decade," Reese said.
"The need to replenish the constellation and provide the cornerstone for this important transition is dependent upon the successful launch and deployment of the two remaining DSP satellites -- DSP-22 and 23."
SATURDAY, FEBRUARY 14, 2004
2028 GMT (3:28 p.m. EST)
The Inertial Upper Stage has fired its first stage, boosting the DSP spacecraft payload from the low-altitude parking orbit achieved by the Titan 4B toward geostationary orbit 22,000 miles up, officials are reporting. The solid-fueled IUS will now coast for the next several hours before discarding the first stage and igniting the second stage to deliver DSP-22 into the proper orbit.
The launch should conclude around 8:45 p.m. EST tonight. Confirmation of mission success is expected to be announced around 9 p.m. We will update this page as soon as official information is released.
1906 GMT (2:06 p.m. EST)
T+plus 16 minutes. "Everything has gone remarkably well," Lockheed Martin spokesman Dave Welch says. "We got through a few hiccups in the pre-launch planning and preparation of the vehicle, and Mother Nature gave us a break and allowed us to get off the ground today."
1900 GMT (2:00 p.m. EST)
T+plus 10 minutes. The upper stage and spacecraft payload have embarked on an hour-long coast period. That will be followed by ignition of the IUS' first stage at T+plus 73 minutes, 30 seconds after liftoff, raising one side of the orbit to geosynchronous altitude 22,000 miles above Earth.
The rocket then coasts up to the high point of the orbit before separating the spent first stage at T+plus 6 hours, 30 minutes. Ignition of the IUS second stage is expected at T+plus 6 hours, 33 minutes to circularize the orbit.
Separation of the DSP satellite to complete this launch is scheduled for roughly 6 hours, 55 minutes after liftoff.
1859 GMT (1:59 p.m. EST)
T+plus 9 minutes, 12 seconds. Retrofire motors have fired and the spent second stage has separated from the Inertial Upper Stage. The IUS and attached DSP spacecraft are now coasting in a parking orbit around Earth.
1859 GMT (1:59 p.m. EST)
T+plus 9 minutes, 1 second. The Titan 4 rocket's second stage has shut down. Standing by for separation of the Titan and IUS.
1858 GMT (1:58 p.m. EST)
T+plus 8 minutes, 20 seconds. Shut down systems enabled on the second stage.
1857 GMT (1:57 p.m. EST)
T+plus 7 minutes, 55 seconds. No problems have been reported by Lockheed Martin as the Titan streaks to space
1856 GMT (1:56 p.m. EST)
T+plus 6 minutes, 45 seconds. The liquid-fueled second stage engine continues to fire, producing just over 100,000 pounds of thrust.
1856 GMT (1:56 p.m. EST)
T+plus 6 minutes, 5 seconds. The vehicle is 92 miles in altitude, 352 miles downrange from the launch pad, traveling at 15,937 feet per second.
1855 GMT (1:55 p.m. EST)
T+plus 5 minutes, 34 seconds. The first stage has shut down and the spent stage has dropped away to fall into the Atlantic Ocean. And the second stage liquid-fueled engine has now ignited!
1854 GMT (1:54 p.m. EST)
T+plus 4 minutes, 30 seconds. About a minute left in the first stage burn.
1853 GMT (1:53 p.m. EST)
T+plus 3 minutes, 39 seconds. The 56-foot long payload fairing enclosing the DSP spacecraft atop the Titan 4B rocket has separated. First stage continues to fire.
1852 GMT (1:52 p.m. EST)
T+plus 2 minutes, 36 seconds. Solid rocket booster separation has occurred. The spent motors will fall into the Atlantic below.
1852 GMT (1:52 p.m. EST)
T+plus 2 minutes, 20 seconds. First stage main engine start. The liquid-fueled engine package is up and burning. The first stage produces about 550,000 pounds of thrust. Engine ignition is a precursor to burnout and separation of the twin solid rocket boosters that have propelled the Titan 4 rocket to this point in the flight.
1851 GMT (1:51 p.m. EST)
T+plus 1 minute, 30 seconds. The rocket has passed through maximum dynamic pressure. All continues to go well.
1850 GMT (1:50 p.m. EST)
T+plus 45 seconds. The twin solid rocket motors are firing normally on the Titan 4 rocket. The vehicle just punched through the cloud deck over the launch site, disappearing from view. The thunderous liftoff is giving the Cape a good shaking as the rocket ascends.
1850 GMT (1:50 p.m. EST)
T+plus 15 seconds. The pitch and roll programs are now underway as the rocket maneuvers to the eastward trajectory for the trek downrange.
1850 GMT (1:50 p.m. EST)
LIFTOFF! Liftoff of the Titan 4 rocket launching another Defense Support Program satellite -- a orbiting sentry for U.S. national security. And the vehicle has cleared the tower!
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