FRIENDS OF THE PLANETARIUM NEWSLETTER – DECEMBER 2014
Season’s greetings everyone. If you are looking for some last minute gift ideas, how about a 2015
Almanac or a 2015 Lunar Calendar. Both are available at the Planetarium along with a nice selection
of books for all ages. The Planetarium is open to the public this Sunday evening from 7 to 9 pm. It
will also be open for shoppers only on Christmas Eve between 10 am and 2 pm.
In our last newsletter we mentioned the Rosetta mission and its ambitious plan to send a lander to
land on Comet 67P / Churyumov-Gerasimenko. Well, they managed to pull it off, sort of. The Philae
lander made it to the surface as
you can see from this montage
of images. Unfortunately, the
harpoon system designed to
anchor the lander didn’t work
and the lander bounced a
couple of times before settling
in next to the shaded interior
wall of a crater. It did send
back images and data but
couldn’t use its solar panels to
recharge its batteries. It is now
in hibernation as scientists
wait patiently for a more
favourable sun angle in hopes
that the increase in solar
radiation will bring the little
guy back to life.
In the meantime, the Rosetta spacecraft orbiting the comet has made some interesting discoveries.
The question about the origin of oceans on Earth is one of the most important questions with respect
to the formation of our planet and the origin of life. The most popular theory is that water was
brought by impacts of comets and asteroids. Data from the Orbiter Spectrometer for Ion and Neutral
Analysis (ROSINA) instrument aboard the spacecraft indicate that terrestrial water did not come
from comets like 67P/Churyumov-Gerasimenko. Researchers agree that water must have been
delivered to Earth by small bodies at a later stage of the planet's evolution. It is, however, not clear
which family of small bodies is responsible. There are three possibilities: asteroid-like small bodies
from the region of Jupiter; Oort cloud comets formed inside of Neptune's orbit; and Kuiper Belt
comets formed outside of Neptune's orbit. The key to determining where the water originated is in
its isotopic "flavour", that is, by measuring the level of deuterium, a heavier form of hydrogen. By
comparing the ratio of deuterium to hydrogen in different objects, scientists can identify where in
the solar system that object originated. And by comparing the D/H ratio in Earth's oceans with that
in other bodies, scientists can aim to identify the origin of our water. The ROSINA instrument on the
Rosetta spacecraft has found that the composition of comet 67P/Churyumov-Gerasimenko's water
vapour is significantly different from that found on Earth. The value for the D/H ratio on the comet is
more than three times the terrestrial value. This is among the highest-ever-measured values in the
solar system. That means it is very unlikely that comets like 67P/Churyumov-Gerasimenko are
responsible for the terrestrial water. The D/H ratio is the ratio of a heavier hydrogen isotope, called
deuterium, to the most common hydrogen isotope. It can provide a signature for comparison across
different stages of a planet's history.
Comets are time capsules containing primitive material left over from the epoch when the sun and
its planets formed. Rosetta's lander obtained the first images taken from a comet's surface and will
provide analysis of the comet's possible primordial composition. Rosetta will be the first spacecraft
to witness at close proximity how a comet changes as it is subjected to the increasing intensity of the
sun's radiation. Observations will help scientists learn more about the origin and evolution of our
solar system and the role comets may have played in seeding Earth with water, and perhaps even
life.
The search for evidence of a watery past on Mars continues as the Curiousity rover continues its
journey up the slope of Mount Sharp in Mars’ Gale Crater. Observations by the rover indicate Mars'
Mount Sharp was built by sediments deposited in a large lake bed over tens of millions of years. This
interpretation of Curiosity's finds in Gale Crater suggests ancient Mars maintained a climate that
could have produced long-lasting lakes at many locations on the Red Planet. Why this layered
mountain sits in a crater has been a challenging question for researchers. Mount Sharp stands about
5 kilometers tall, its lower flanks exposing hundreds of rock layers. The rock layers, alternating
between lake, river and wind deposits, bear witness to the repeated filling and evaporation of a
Martian lake much larger and longer-lasting than any previously examined close-up.
Curiosity currently is investigating the lowest sedimentary layers of Mount Sharp, a section of rock
150 meters high, dubbed the Murray formation. Rivers carried sand and silt to the lake, depositing
the sediments at the mouth of the river to form deltas similar to those found at river mouths on
Earth. This cycle occurred over and over again. After the crater filled to a height of at least a few
hundred meters and the sediments hardened into rock, the accumulated layers of sediment were
sculpted over time into a mountainous shape by wind erosion that carved away the material
between the crater perimeter and what is now the edge of the mountain. Despite earlier evidence
from several Mars missions that pointed to wet environments on ancient Mars, modeling of the
ancient climate has yet to identify the conditions that could have produced long periods warm
enough for stable water on the surface. NASA's Mars Science Laboratory Project uses Curiosity to
assess ancient, potentially habitable environments and the significant changes the Martian
environment has experienced over millions of years. This project is one element of NASA's ongoing
Mars research and preparation for a human mission to the planet in the 2030s.
Finding Earthlike planets beyond our solar system has largely been the work of space-based
telescopes, but new observations from a remote island suggest that could change. The Nordic Optical
Telescope on La Palma, one of the Canary Islands off the west coast of Africa, observed 55 Cancri e, a
planet twice the size of Earth, as it passed in front of its parent star and caused a dip in the star's
brightness, according to a new study. This is the first time a planet in this "super-Earth" size
category orbiting a sunlike star has been observed by a ground-based telescope using this detection
method, the researchers say. First identified in 2004 by a space-based telescope, 55 Cancri e has a
diameter of about 26,000 kilometers, about twice that of Earth. The alien world is eight times as
massive as Earth, making it a so-called super-Earth, a planet more massive than Earth but
significantly smaller than gas giants like Neptune and Uranus. While not habitable, the planet's size
and position around a sunlike star make it similar to planets that might support life, researchers say.