Astronomy Picture of the Day 07-12-04

Explanation: What are Saturn's rings made of? In an effort to find out, the robot spacecraft Cassini that entered orbit around Saturn two weeks ago took several detailed images of the area surrounding Saturn's large A ring in ultraviolet light. In the above image, the bluer an area appears, the richer it is in water ice. Conversely, the redder an area appears, the richer it is in some sort of dirt. This and other images show that inner rings have more dirt than outer rings. Specifically, as shown above, the thin rings in the Cassini Division on the left have relatively high dirt content compared to the outer parts of Saturn's A ring, shown on the right. This dirt/ice trend could be a big clue to the ring's origin. The thin red band in the otherwise blue A ring is the Encke Gap. The exact composition of dirt remains unknown.

NASA crew goes under water to study outer space
NASA NEWS RELEASE
Posted: July 11, 2004

Four NASA crewmembers will look to the deep seas this month to help prepare for journeys into deep space. They'll use an undersea laboratory to study what it may be like to live and work in other extreme environments, such as the Moon and Mars.

Astronaut John Herrington will lead the crew in an undersea mission July 12-21 that will field-test equipment and technology for the International Space Station as part of the NASA Extreme Environment Mission Operations (NEEMO) project. Astronauts Doug Wheelock and Nick Patrick will join Herrington, a veteran space flier and spacewalker, and biomedical engineer Tara Ruttley in the Aquarius Underwater Laboratory off the coast of Key Largo, Fla., for the mission.

University of North Carolina at Wilmington (UNCW) systems engineers Craig Cooper and Joe March will work side by side with the NASA crew in Aquarius. The facility is owned by the National Oceanic and Atmospheric Administration (NOAA), operated by UNCW and funded by NOAA's Undersea Research Program. The NEEMO missions are a cooperative project of NASA, NOAA and UNCW. Aquarius is similar in size to the International Space Station's (ISS) living quarters.

This will be the sixth NASA mission to Aquarius to practice long-duration life in space. It will study life in extreme environments in support of future human exploration beyond Earth orbit, evaluate equipment that may be used on the ISS and perform scientific research on the human body and coral reefs. The crew also will build undersea structures to simulate ISS assembly.

As the current NEEMO "aquanauts" conduct their mission, a former Aquarius aquanaut is living on the Space Station. Mike Fincke arrived April 21 for a six-month tour as Expedition 9 flight engineer and NASA science officer. Schedulers for both crews are looking for a ship-to-ship conversation opportunity.

"NEEMO is not a simulation. It's a real mission with real risks in a hazardous environment. If we're going to send humans back to the Moon and on to Mars, we're going to need economical ways to get our feet wet here on Earth," said NEEMO 6 Mission Director Marc Reagan. "With NEEMO we have an analog of such high fidelity that we can field-test equipment and procedures before we try them in space. On this mission we'll focus on exercise equipment, anti-microbial technology and wireless tracking technology that are likely to be found on the Space Station in the near future," he added.

Aquarius is the world's only underwater habitat and research laboratory. The 45-foot long, 13-foot diameter complex is three miles off Key Largo in the Florida Keys National Marine Sanctuary. It rests about 62 feet beneath the surface.

A buoy on the surface that provides power, life support and communications capabilities supports Aquarius. A shore-based mission control for the Aquarius laboratory in Florida and a control room at NASA's Johnson Space Center, known as the Exploration Planning Operations Center, will monitor the crew's activities.

Atmospheric observatory ready to launch Tuesday
A Boeing Delta 2 rocket is poised to launch NASA's latest environmental research satellite early Tuesday from Vandenberg Air Force Base, California. The Aura spacecraft will study the atmosphere as part of the Earth Observing System constellation of satellites.

MONDAY, JULY 12, 2004
1700 GMT (1 p.m. EDT)

The weather forecast for tomorrow's launch of the Delta 2 rocket with Aura is still calling for a 90 percent chance of acceptable conditions. Although Vandenber's trademark fog and low visibility will hamper spectators watching the liftoff, meteorologists say only gusty launch pad winds are of concern for violating the weather rules.

Here is the outlook from Capt. Paul Lucyk, the Air Force launch weather officer:

"Vandenberg is currently under the influence of high pressure centered in the Four Corners region. A ridge of high pressure extends from northern Arizona through the southern Los Angeles basin. This ridge is just south of Los Angeles and, combined with an upper level trough in the Pacific-Northwest, will tend to bring upper level winds from the southwest for the next 3-5 days.

"The forecast for Tuesday has tended more toward fog as upper level temperatures continue to warm in response to the ridge in the southwest. As of this morning, models have kept dry air in place at all but the lowest levels. This, combined with upper level warming will push the marine layer lower, which will drive our visibility down."

The launch time forecast calls for stratus clouds at 200 feet with 8/8ths sky coverage and tops at 800 feet, visibility of one-half to one-mile with fog, a temperature between 55 and 60 degrees F, northerly ground-level winds from 340 to 020 degrees at 8 to 12 knots and upper level winds from the southwest with maximum of 55 knots near 42,000 feet.

Should the launch be delayed 24 hours, there is a 90 percent chance of favorable liftoff weather.

"The forecast for Wednesday still calls for a slight change to favor the high pressure in the desert southwest. This raises a concern for monsoon moisture moving through the Los Angeles basin and into eastern Ventura county," Lucyk says.

"Our primary concern for scrub is the 102-foot winds (at the launch pad), but with this moisture, anvil clouds associated with thunderstorm development to the southeast of Vandenberg may be a factor. The anvil concern is slight, as steering winds aloft will continue out of the southwest keeping the majority of the mid and upper level moisture to our east.

"The forecast continues to call for drier air in place but will keep the marine layer stratus at the very lowest levels. Surface winds continue from the northwest at 8-12 knots. Upper level winds will continue from the southeast with maximum of 40 knots at 40,000 feet."

Ring/Gap	Start radius (km) from the center of Saturn	End radius (km)	Width (km)
D	67,000 km	74,500 km	7,500 km
C	74,500 km	92,000 km	17,500 km
Maxwell Gap	87,500 km	87,770 km	270 km
B	92,000 km	117,500 km	25,500 km
Cassini Division	117,500 km	122,200 km	4,700 km
A	122,200	136,800	14,600
Encke Gap	133,570 km	133,895	.
Keeler Gap	136,530	136,565	35
F	140,210	140,240-140,710	30-500 km
G	165,800	173,800	8,000
E	180,000	480,000	300,000

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