October 1999 Sky from Keeble Observatory
One of our spacecraft is missing. Mars exploration has never been easy, and we shouldn't be surprised when such a difficult undertaking doesn't always work out as planned. The $125 million Mars Climate Observer was probably destroyed as it attempted to brake into orbit around the Red Planet. After a near-flawless flight which began last December, an apparent navigation error brought it too low into the atmosphere where it either broke up, burned up, or both.
With the spectacular images from Mars Global Surveyor (still alive and well) and the singular success of Mars Pathfinder and its plucky rover, Sojourner, we were all a bit complacent. They worked. Global Surveyor has even survived complicated aerobraking and a contrary solar array and a cranky high-gain antenna to carry out its mission. Not so for Climate Observer. Somehow, that probe missed its target by about 100 km, plowing into the thin Martian atmosphere 60 km above the surface, rather than 160 km as designed.
And, how did this happen? If it weren't so embarrassing, it might almost be silly. What apparently occurred was that engineers at Lockheed-Martin, the prime contractor that built the spacecraft, used English engineering units in their specifications. Rocket and thruster firings were rated in pounds of force. Flight controllers at NASA's Jet Propulsion Laboratory, which had operational responsibility for the mission, did their calculations in metric units, with forces in newtons. Oops.
However, all is not lost! The current onslaught of Mars probes has been planned so that failure of a single component does not doom the rest of the missions, nor cost so much as to endanger future missions. At $125 million and with only a 4-year time span from design to flight, this probe was a bargain. The Mars Observer probe, which exploded as it was pressurizing its fuel system for braking into orbit in 1993, cost over $1 billion. By separating the science into smaller, cheaper packages, NASA is able to keep sending missions. Also, although the Climate Observer was supposed to double as a relay station for telemetry from the Polar Lander (scheduled to arrive at Mars in December), that mission will continue using back-up systems, including the Global Surveyor already in orbit.
And, still more probes are in the pipeline, slated for launch to Mars roughly every 26 months.
Lunar phases for October: Last Quarter on the 2nd, at 12:02 EDT, and again on the 31st at 7:04 am STANDARD TIME (don't forget to turn your clocks back!); New Moon at 7:34 am on the 9th at 7:34 am EDT; First Quarter on the 17th at 11:00 am EDT; Full Moon on the 24th at 5:02 pm.
In the pre-dawn twilight you can see Venus, high and bright to the east-southeast. It will be at its greatest elongation, 46 degrees west of the Sun on the 30th. Binoculars will show it in a "half moon" phase. Jupiter is bright to the west, and Saturn is visible about 15 degrees above and to the left of its larger planetary cousin.
In the evening dusk you can find Mars to the SSW, while Jupiter rises north of east about an hour after sunset in the early part of October. By the 23rd, when it is at opposition, Jupiter will rise at sunset. Saturn's rising follows Jupiter's by about 45 minutes. Mercury is barely visible on the horizon at sunset, about 20 degrees south of due west.
Our overhead view at midmonth at about 9:30 shows the sky bisected NE to SW by the Milky Way. Deneb, Vega, and Altair form the bright triangle just west of zenith. This part of the sky is a rich target for binoculars. The Big Dipper (Ursa Major) is low on the horizon to the north. To the east of zenith we find the large, empty "great square" of Pegasus. Between Pegasus and Perseus to the northeast, you may be able to pick out the Andromeda Galaxy on a clear, moonless night. Taurus is just on the eastern horizon, presaging Orion's return to the night sky for the winter.