After two mission extensions, the Phoenix Lander has been on the Martian surface for five months. But with an approaching winter, the Lander is already beginning to lose power, as it must now sit in five hours of freezing darkness each day. The rover will slowly lose power until the end of October when it will no longer be able to use its robotic arm. Even though its days are numbered the Phoenix Lander is still making discoveries.

For the first time in Martian history, Phoenix observed Martian snowfall. The snow observed at an altitude of about 4km above the Lander, and it appears to have vaporized before reaching the surface. The Lander has also discovered several minerals that, on Earth, would typically form in the presence of water.

Potentially, the most exciting mineral discovered is Calcium Carbonate, (CaCO₃). Calcium Carbonate is the main component of chalk, which forms in deep marine conditions from the gradual accumulation of calcite plates called coccoliths, which are shed from microorganisms called cocolithosphores. The discovery was made by the combined data of two instruments onboard the Phoenix Lander. The Thermal and Evolved Gas Analyzer,(TEGA), discovered that Carbon Dioxide was released from soil samples when exposed to high temperatures. The temperature at which the CO₂ was released is a temperature which is known to breakdown CaCO₃ into CO_2. The Microscopy, Electrochemistry and Conductivity Analyzer, (MECA), found concentration of (Ca) in the soil; this confirms the presence of CaCO3 in the soil. The presence of Calcium Carbonate does not immediately imply that chalk or microorganisms have been discovered, future tests will have to be done to determine if the CaCO₃ was formed due to ancient marine life.

Both MECA and TEGA discovered have smooth-faced layered particles which resemble clay. Clay minerals have a crystal structure which allows them to store water between Silicon and Oxygen Bonds. These bonds are relatively weak, this allows the bonds to expand and contrast depending on the water content of the environment they are in. These weak bonds also break easily along the bonding planes which give them the smooth and layered surfaces which were observed by the Lander.

Currently, Phoenix is beginning to analyze the soil found in a region called “Galloping Hessian”. This area is being explored because of its high concentration of salts. On Earth Salts are also commonly found in dried up sea beds. As the darkness and the cold settles in over the Lander its days of discovery are nearing an end. Because of the extreme conditions of the Martian winter, which loom in the Landers very near future, scientists do not think that they will be able to resurrect it when spring finally returns.

On October 6th the MESSENGER spacecraft will perform a Mercury flyby for the second time this year. MESSENGER (MErcury Surface, Space, Environment, GEochemistry and Ranging) will fly past Mercury at an altitude of 201 km while taking over 1200 images of the cratered surface.

The spacecraft made its first flyby on Jan 14th, during which it took over 1200 photos, and made several startling discoveries. Some of which demonstrated that the innermost planet is not as similar to the Earth’s Moon as once was believed. MESSENGER photographed craters which are very different from the craters on the Moon. For instance, the Caloris basin is a crater with a diameter of approximately 1545km. The floor of this crater has a surface which is more reflective than the material surrounding the crater. This is exactly opposite of the Moon, whose crater floors are darker than the surrounding material. MESSENGER also observed that Mercury’s magnetic field has changed since it was first observed by Mariner 10. MESSENGER also observed large cliffs which contain ancient faults, these faults act as a recording of the paleotectonics which occurred early in the planets history. MESSENGER also observed the mineral makeup of the planet’s surface, and discovered sodium and hydrogen in the planets exosphere.

On March 18th 2011 MESSENGER will enter Mercury’s orbit where it will gather data for an entire year. MESSENGER hopes to answer several questions. The first question: “Why is Mercury so dense?” Mercury has a density of 5.427g/cm3 which implies that the mass of mercury’s core accounts for 60% of the planets total mass. MESSENGER will gather mineralogical and compositional data to help determine why. Like on Earth, part of this core must be liquid if it is to have the dynamo necessary to generate a magnetic field.

Question 2: “What is the geologic history of Mercury?” MESSENGER will photograph and observe the planet in great detail in an attempt to better understand the processes which have shaped the planet. Specifically areas such as the faults observed on the large cliffs I described earlier. Because Mariner 10 was only able to observe 45% of the planet’s surface, MESSENGER is sure to discover more geologic splendors.

Question 3: “Is there water on Mercury?” Some of the permanently shadowed craters on Mercury’s poles contain a highly reflective material that could be ice. Mercury is the closest planet to the Sun, but it also has the largest daily temperature gradient of the terrestrial planets. Surface temperatures range from -83°C to 427°C, with the coldest temperatures recorded at the bottom of the polar craters.

MESSENGER will not begin collecting this exciting data for a couple more years, but it is sure to tease with some good photographs and interesting data while we wait. The second flyby is scheduled for next week and a third a third and final flyby is scheduled for September 28th 2009.

The solar cycle was first discovered in 1843 by Samuel Heinrich Schwabe, who noticed a periodic change from year to year in the number of sunspots. This cycle has been determined to last an average of 11 years, but it has been recorded as low as 9 years and as high as 14 years. This cycle is responsible for several space-weather phenomena such as shaping the structure of the Sun’s atmosphere, corona, and wind. The number of solar flares, mass ejections, and high energy particles are modulated by the solar cycles.

The sun is currently experiencing the lowest solar minimum observed in the last 50 years. This is also the longest lasting solar minimum ever observed, already six months longer than last cycle. A solar minimum impacts the entire solar system, and directly effects life on Earth. During a solar minimum less UV radiation reaches the Earth. This results in reduced ozone layer, because ozone is produced when UV radiation spits the O₂ molecules in the stratosphere. A smaller ozone layer means that more UV light will reach the Earth’s surface potentially causing sunburns and skin cancer.

Changes in the solar cycle could also affect the Earth’s climate. During a solar minimum less energy reaches the Earth, on an average year the Earth receives about 1366.7 W/m² during a solar maximum, and 1365.6 W/m² during the solar minimum. Some scientists argue that this difference may be too small to significantly affect the Earth’s climate. (Although it is interesting that in 2008 we experienced the largest world-wide temperature drop ever recorded in a 12 month period, not to mention Minneapolis celebrated its coldest Easter in 33 years, which is a factor of 11.) In 1991 E. Friis-Chritensen published a study which demonstrated a direct correlation between solar cycles and Land air temperature in the Northern hemisphere.

Another side effect of solar minimums is a reduced heliosphere. The heliosphere is a large magnetic bubble generated by the sun which protects the solar system from harmful cosmic rays. The Voyager spacecrafts inadvertently provided proof of the shrinking helioshpere when Voyager 2 reached the termination shock after traveling 10 AUs less than Voyager 1 had to travel in order to reach the same boundary. Because of fluctuations in solar activity Voyager 1 actually crossed the terminal shock 5 times!

By studying the Sun and its cycles, scientists are gaining a better understanding of stellar phenomena, and how it affects us here on Earth. Such knowledge will aid in the development of better climate models, and in evaluated and eliminating some of the radiation risks which would hinder future colonies on the Moon or Mars.

Saturn’s rings were first discovered by Galileo Galilei in 1610, but he was unable to identify them as rings, instead he called then “ears”. In 1655 Christiaan Huygens became the first person to identify Saturn’s “ears” as Rings. Since the discovery of the rings in 1610, there have been many theories which have attempted to describe the formation of the rings.

The most popular theory is that Saturn’s rings are only 100 million years old. These young rings would have formed by a commit that was ripped apart by Saturn’s tidal forces, or by a moon which was destroyed by a large asteroid impact. The strong evidence for this theory is that the rings are much too bright to be very old, because as time passes the rings should accumulate dust which would slowly darken the rings.

Recent simulations, based on data gathered by the Cassini mission, show that the rings might be much larger and much older than previously thought, perhaps as old as four billion years. These simulations show that the particles in the rings form clumps and are not evenly distributed particles. This could mean that there is an ongoing warfare between formation and destruction within the rings. The particles slowly clump together and a blasted apart by micro-meteors. The researchers believe that the reason for the relative brightness of the rings could be that the dust is incorporated into the centers of the clumps after reformation.

The rings consist of eleven major sub-rings. For the most part the rings have been given lettered names in the order of their discovery. The D ring is the closest to Saturn and is very faint. Voyager 1 discovered that the D ring consists of three ringlets: D73, D72, and D68. Recently Cassini has discovered that D73 has moved 200 km towards Saturn since its discovery. The C ring is about 5 meters thick and it has a mass of about 1.1×10¹⁸ kg. If viewed from above or below the ring appears transparent because 5 to 12 percent of the light perpendicular to the ring is blocked. The B ring is the thickest ring, about 5 to 15 meters. Voyager discovered “spokes” inside the B ring; these spokes were not observed again until Cassini observed them in 2007. These spokes may be seasonal phenomena, as they disappear in midsummer then reappearing around equinox, and disappearing again around midwinter. The A Ring is 10 to 30 meters thick and has a mass of about 6.2 x 10¹⁸ kg. In 2006 4 small tiny moons were discovered inside the A ring. There is now estimated to be over 1000 such moonlets inside the A ring. The F was discovered in 1979 by Pioneer 11. The ring is the most active of the rings, and is the very thin outermost ring. The ring is held together by two moons, Prometheus and Pandora. Occasionally during Prometheus’s orbit, it approaches the ring causing kinks and knots. It also steals material from the ring leaving behind a dark channel.

Besides their formation, there is still much to learn about the rings. For instance, what causes the seasonal spokes which occur inside the B ring? Why is some of the material accreted into tiny moonlets, while the rest remains as independent particles or clumps? Why has the ringlet D73 moved in towards Saturn? Whatever the answers may be, anyone who looks at Saturn through a telescope knows one thing for sure–Saturn is one of the most amazing and beautiful objects in our solar system.