July 2003 Sky from the Keeble Observatory
Mars, here we come! Earth orbits closer to the Sun, and moves faster than Mars,
so we're about to lap the red planet . at opposition in late August, a mere 34.6
million miles will separate us. Mars will rise earlier and earlier each night, until
on August 28 it will rise as the Sun is setting. Since the approach to opposition
is the ideal time to launch probes to Mars, it should be no surprise that several
are on their way (and another is preparing for launch, perhaps on the 2nd of July).
They all hope to join Mars Global Surveyor and 2001 Mars Odyssey, which have been
orbiting Mars since 1998 and 2001, respectively. All should be arriving in December
Hope is the translation of the name of a Japanese probe, Nozomi. Hope is also faint
for the success of this mission. Launched in 1998 July, it was supposed to arrive
at Mars in October of the same year. However, its trajectory was flawed and controllers
burned too much fuel trying to adjust. They adopted a strategy of using Earth as
a gravitational slingshot to boost its orbit toward Mars. The latest maneuver in
mid-June sent it on its final trajectory, but the spacecraft is still in trouble.
A solar flare last April shorted out part of its circuitry, in particular the heating
and communications systems were compromised. Controllers are attempting to reprogram
on-board computers to correct for these problems.
Mars Express is the European Space Agency's entry, launched on 3 June and expected
to arrive on Christmas day. The orbiter will study the surface, mapping minerals
and producing a high-resolution stereo image of the surface, able to see features
between 2 and 10 meters in size. Another instrument will use penetrating radar to
study the subsurface structure of the planet to a depth of 2 kilometers.
Hitching a ride with Mars Express is the British lander called Beagle 2. This small
probe (a mere 65 kilograms . 143 pounds) will use a parachute and airbag landing
system similar to 1997's successful Pathfinder probe. It will drill into the surface
some 2 meters, looking for signs of water and/or life. Most of the instruments are
deployed at the end of a robot arm. A camera will take images of the surroundings,
as well as providing close-up views of Martian rocks and soil. A wire-guided mole
will dig under rocks, and a grinding tool will be used to remove surface layers
from rock samples to better study their interiors. The probe is ambitious, as Britain's
first entry into Mars exploration, but its small size precluded building any redundancy
into its systems. If anything goes wrong, the mission will likely fail.
NASA is sending two rovers, named Spirit and Opportunity (more formally, Mars Exploration
Rovers A and B) to opposite sides of the planet. These are more sophisticated than
Beagle 2, essentially upgrades of the Sojourner rover which accompanied Pathfinder.
At 170 kilograms and about the size of a small desk, they are nearly three times
the size They will also use the airbag system to land. Their instruments include
cameras, drills, and microscopes. They should ramble several dozen meters each Martian
day, sampling rocks and soil and returning spectacular images from the surface.
Spirit is already underway, launched on the 10th of June. Opportunity is slated
for launch on the 28th of June.
For more information about these Mars probes, point your web browser to
Lunar phases for 2003 July: First Quarter on the 6th, at 10:33 pm; Full on the 13th,
at 3:22 pm; Last Quarter on the 21st, at 3:02 am; New Moon on the 29th, at 2:54
Saturn passes behind the Sun and moves into the morning sky as Venus vanishes into
the Sun's glare, emerging from twilight by month's end. Mercury also swings behind
the Sun, moving into the evening sky and joining Jupiter in the west later in the
month. As noted above, Mars rises earlier each night - midnight at the beginning
of July, about 10:30 by the end of the month. It will become brighter and brighter
as we approach opposition in late August. Even small telescopes will begin to pick
out surface features, like the polar ice cap.
Looking overhead about an hour after sunset, you'll see the zenith point bracketed
by bright Arcturus (about 30 degrees toward the southwest) and Vega (about the same
angle from zenith, but towards the east). The trapezoidal shape of Hercules is the
closest familiar constellation, about halfway toward Vega. Binoculars and a clear
night may permit you to see the great globular cluster M13 just inside the northwest
corner of Hercules. Low to the west, Leo and bright Regulus accompany the setting
of Jupiter and bid farewell until late fall. To the southwest is the bright star
Spica, in Virgo. Almost due south is bright red Antares - rival of Mars - but don't
be confused, Mars rises later, to the southeast. The summer triangle is now about
halfway to zenith from the eastern horizon. Vega is at the top, Altair to the southeast,
and Deneb to the northeast. From Vega, shift your binoculars or small telescope
to the next star below in Lyra - you'll see that it is actually four stars, known
as the double double. Now shift below and to the right. Between the two stars marking
the other end of the Lyre, you may see the faint circle of the Ring Nebula. Our
own Sun will probably look like this in another 6 billion years. From Deneb, in
Cygnus, sweep your binoculars to the right along the neck of the Swan. The last
star you see in the head is Albireo, a beautiful binary with stars of orange and
For your own monthly star chart, you can direct your web browser to
http://www.skymaps.com. You will find extensive descriptions of what's worth
looking for, and you can download and print a single copy for your personal use.