Idaho Skies

October 2007

Vol. 4 No. 10

Idaho Skies is a column for beginning amateur astronomers and those interested in astronomy. Suggestions about the column are gladly accepted by the columnist, at paul.verhage@boiseschools.org

This month look for the star Enif, which is the lucida or brightest star of Pegasus the Flying Horse. Astronomers call Enif, Epsilon Pegasi, which would lead you to believe it’s the fifth brightest star in Pegasus (but it’s not, it’s the brightest). Pegasus is the flying horse of Greek mythology. Pegasus sprang from the blood of the dying Gorgon, Medusa who was killed by the Greek hero Perseus. Please note that Perseus did not ride the Pegasus to rescue Andromeda as some stories might lead you to believe. Perseus flew in on his winged sandals. The word Enif is Arabic for Nose, since this star represents the nose of Pegasus. Calling this star Enif doesn’t make sense until you realize that the Greeks placed Pegasus upside down in the sky.

Enif is a giant star, but not the largest star visible from earth. The star is a cool orange and 150 times larger than the sun. That’s so large that Enif would engulf Mercury if it replaced our sun. Our sun spans ½ degree in the sky, but Enif would span one quarter of our sky if it replaced our sun. In other words, Enif would appear larger than the Great Square of Pegasus if it replaced the sun.

Enif is ten times more massive than our sun. As a result of its immense gravity, it fuses its hydrogen fuel faster than the sun. Its fusion overdrive pushes its outer layers over 60 million miles from its center. While the core of Enif is hotter than our sun’s, Enif’s bloated atmosphere dilutes that heat until the star takes on an orange color (versus the hotter yellow color of our sun). However, since the star is so huge, it’s still over six thousand times more luminous than the sun. Enif will end its life as a supernova or, if it can shed some of its mass, a very hot white dwarf. Enif is 670 light years away. So you’re seeing Enif as it was in 1337, or the year the 100 year war between France and England began.

Let Enif be your guide star to a globular cluster called M-15. Put Enif in the bottom left of the view of your 7X50 binoculars at about 10:30 PM and you’ll see this.

In binoculars, M-15 looks like a fuzzy star. However, through your telescope in dark skies, you’ll see M-15 as a soft round glow peppered with faint stars. Through a large telescope in dark skies, M-15 looks like a pile of salt poured on blackest velvet. M-15 is 175 light years across and 33,600 light years away. It’s probably the densest globular cluster in the Milky Way; half of its stars reside within ten light years of its center.

October 1 – 7

The moon is at last quarter the morning of the 3^rd. If you like seeing the greatest amount of surface detail visible on the moon, than this is one of the moon phases you want. For your best lunar views, look along the boundary between day and night, the lunar terminator.

The moon, Mars, and M-35 star cluster rise close together after midnight on the 3^rd. While the moon is too far from Mars for your binoculars, the M-35 star cluster is close enough to fit neatly in your binoculars along with Mars. Locate Mars in your binoculars, which is the bright orange colored star to the right of the moon. Less than one degree to the upper left of Mars (your binoculars probably has a field of view of seven degrees) you’ll see the M-35 star cluster as a sprinkled of stars.

One of the original Mercury astronauts died a couple of months back. That astronaut, Wally Schirra, rode Sigma 7 into orbit 45 years ago on the 3^rd. He was the fifth American into space and the third to go into orbit. Later he would fly onboard the Gemini and Apollo spacecraft (he’s the only astronaut to fly all three). Schirra’s flight was perfect; he orbited the earth six times in nine hours. His flight was also the highest altitude Mercury flight with an apogee 176 miles above the earth. Schirra was more of a pilot and engineer than a scientist. He had very little interest in performing experiments in space, he just wanted to test and fly spacecraft.

The space age began 50 years ago on the 4^th. The year 1957 was the beginning of the International Geophysical Year (IGY), an 18 month period where nations of the world explored the planet and shared their findings. In 1955, both the United States and the Soviet Union stated their plans to launch a satellite into orbit during IGY. However not many people took the Soviet Union claim seriously. They considered the Soviet Union a backwards country with little technical skill. So on October 4, 1957, the Soviet Union shook the world with the news of the launch of Sputnik.

A modified R-7 ICBM launched Sputnik 1 into its initial 134 by 583 mile orbit. The R-7 booster is still in use today in Russia; it’s the rocket booster that launches crews and supplies to the International Space Station. Sputnik 1 was a surprisingly heavy satellite with a weight of 184 pounds. The satellite, a polished aluminum sphere two foot diameter, contained batteries and two radio transmitters. The radios’ frequencies of 20 and 40 MHz allowed amateur radio operators around the world to hear the satellite’s beep-beep. Sputnik 1 remained in orbit for three months until atmospheric drag brought it down on January 4, 1958. The successful launch of Sputnik 1 ignited the space race between the Soviet Union and United States. It was a race that culminated with Neil Armstrong stepping on the moon’s surface less than 12 years later.

World Space Week runs from October 4^th to the 10^th this year. You can guess why it begins on the 4^th, but why does it end on the 10^th? That’s because the Outer Space Treaty was ratified on that date, forty years ago (October 10, 1967). You’ll find more information on World Space Week at its website, http://www.spaceweek.org/

The moon passes within one degree of the Beehive star cluster on the morning of the 5^th. This is another perfect event for your binoculars. So on the morning of the 5^th, point your binoculars at the thin crescent moon. To its right you’ll see a scattering of stars covering an area larger than the moon. Since the moon is a crescent, its light shouldn’t interfere greatly with the faint stars making up the Beehive star cluster.

Guess who celebrates a birthday on the 5^th? If he were alive today, Robert Goddard would be 125 years old on the 5^th. Starting in 1907, Goddard experimented with rocket propulsion. At the time, the only successful rockets used solid fuel. To achieve higher altitudes, Goddard realized that a liquid fuel rocket, with its higher energy (and speed), was needed. His experiments led to the first liquid fueled rocket launch on March 16, 1926. The location was his aunt’s farm in Auburn, Massachusetts. However, because of unhappy neighbors and unwanted media attention, Goddard eventually moved his work to Roswell, New Mexico.

Look for the moon, Venus, Saturn, and Regulus shortly before sunrise on the 7^th at 5:00 AM. All four will fit within the field of view of your binoculars. In case you didn’t know, Regulus is the alpha star of Leo the Lion and is 77 light years away. In binoculars, you’ll see this scene.

October 8 – 14

Fifteen years ago on the 8^th, the Pioneer Venus Orbiter (some times called Pioneer 12) mission ended with its entry into the atmosphere of Venus. The Pioneer Venus Orbiter (PVO) was the orbiting half of the two American spacecraft launched to Venus in 1978. The other half was the atmospheric probe that released four additional probes into the Venusian atmosphere. PVO orbited Venus for 14 years. During most of its time orbiting Venus, its instruments studied the planet’s upper atmosphere, including its ionosphere. PVO generated low resolution maps of the planet’s surface with its radar. Years later Magellan generated higher resolution maps of Venus from its orbital perch.

The moon is new on the 10^th. Without moon light, this is great night to observe faint objects in the sky.

The Outer Space Treaty was ratified 40 years ago on the 10^th. The treaty’s goal is to promote the peaceful use and exploration of outer space. To that end, it requires countries to, explain the nature of their space exploration, protect earth and celestial bodies from contamination, render assistance to astronauts in need, and prohibits the deployment of nuclear weapons in space and on other celestial bodies. Countries with nuclear weapons delivered via missiles get around the Outer Space Treaty by flying them on ballistic trajectories that don’t enter into orbit. Oh well, the treaty is a good start.

The distance to the moon on the 13^th is 252,582 miles away. Since this is the moon’s greatest distance from earth this month, the moon is at apogee. On the other side of its orbit, the moon’s at its closest to earth, or at perigee.

October 15 – 21

Cassini, the spacecraft currently in orbit around Saturn, left earth on a Titan IVB ten years ago on the 15^th. It took nearly seven years for Cassini to arrive at its destination. Cassini is the largest spacecraft ever sent to another planet. The spacecraft weighs 12,500 pounds, is 22 feet long, and is 13 feet wide (think of a bus). Six months after arriving at Saturn, Cassini released its 700 pound Huygens probe for its landing on Saturn’s largest satellite, Titan. With its camera and infrared filter, Cassini can glimpse surface details below the clouds of Titan. On its flyby’s of the satellite Enceladus, Cassini discovered geysers blowing water ice into space. Cassini’s close up images of another Saturnian satellite, Iapetus, show it to be a world of black and white. One hemisphere is bright as freshly fallen snow while the opposite hemisphere is pitch black. Around its equator is a mountainous budge unlike anything seen in the rest of the solar system. In less than a year, Cassini will complete its 70^th orbit around Saturn. If it remains healthy, NASA will extend Cassini’s mission. So here’s to a healthy Cassini. You can read more about Cassini’s mission to Saturn at its website, http://saturn.jpl.nasa.gov.

There was once a time when we only knew of four terrestrial planets, the asteroid belt, four gas giants, oddball Pluto, and a vast reservoir of comets. Well, on October 18, 1977 (30 years ago), American astronomer Charles Kowal changed all that when he announced the discovery of a celestial body between the orbits of Saturn and Uranus. Kowal proposed the name Chiron for his discovery. Later, astronomers discovered other objects like Chiron in orbits between Saturn and Neptune. These objects, call Centaurs, are icy bodies in unstable orbits. Because their orbits are unstable of the long run, they could not have originated in this region of the solar system. Most likely, they’re refugees from the Kuiper Belt. In time, the gas giants will either eject Centaurs back into the Kuiper Belt or into the inner solar system. Since Chiron measures 120 miles across, or ten times larger than the nucleus of comet Halley, Chiron would become a fantastically large and bright comet if sent to the inner solar system. On the other hand, it could also be a very dangerous object should it be sent on a collision course with earth.

The first spacecraft to make it alive to another planet was Venera 4 (the previous Venera spacecraft made it to Venus, but it stopped transmitting before reaching the planet’s atmosphere). Forty years ago on the 18^th, this spacecraft entered the Venusian atmosphere and transmitted data until it was 15-1/2 miles above the surface. At this altitude, high atmospheric temperatures and pressures destroyed the 840 pound Venera 4 probe. The probe returned data on the composition, temperature, and pressure of the Venusian atmosphere as it descended. The spacecraft that carried Venera 4 to Venus flew past the planet on its own mission. It returned data on magnetic fields and radiation surrounding Venus.

The moon is at first quarter on the 19^th. So tonight would be a great time to go moon watching (and a lot more convenient that moon watching during third quarter). Be sure to invite a neighbor over to look through your telescope.

Mariner 5, a converted Mars flyby probe, passed 2,500 miles from Venus 40 years ago on the 19^th, or one day after Venera 4 descended into the planet’s atmosphere. JPL designed the Mariner 5 as a flyby spacecraft and not as an atmospheric probe. During its flyby, Mariner 5 measured the radiation and magnetic fields of Venus. It also looked for ultraviolet emissions from its atmosphere.

From the 20^th until early November, the Zodiacal Light is visible early in the morning. Since the moon is at first quarter, it sets well before morning so its light doesn’t interfere with the faint Zodiacal Light. Autumn mornings are good times to look for this light since the plane of the solar system (the imaginary disk on which the planets orbit around the sun) is tilted at its greatest vertical angle.

The Orionid meteor shower peaks on the night of the 20^th and morning of the 21^st. Typically, 20 meteors per hour are visible from this shower. The moon is first quarter, so you’ll need to observe this shower after midnight. The moon sets at 2:20 AM and the sun rises at 8:00 AM today, so the hours between 2:30 and 6:00 AM would be a good time. Meteoroids in the Orionid shower have orbits similar to the Eta Aquarids, and both streams are debris from the tail of comet Halley.

October 22 – 30

The moon is full on the 25^th. What makes this full moon special is that it’s the same day the moon’s at perigee. That makes this year’s Hunter’s Moon the largest full moon of 2007. The moon’s distance from earth tonight is 221,676 miles. Because the moon is full (and therefore opposite the sun in the sky) and at its closest to earth (were its tidal forces are greatest), coastal dweller can expect larger than average tides today.

Just as it’s getting dark on the 27^th, look for the nearly full moon in the east. There to its right will be the Pleiades star cluster, or Seven Sisters. The moon’s light will wash out some of its stars, but it should still be nice to see in binoculars.

Venus reaches greatest western elongation on the morning of the 28^th. So the Morning Star will be well above the horizon as you drive to work this morning. The planet rises at 4:14 AM for Boise and sports a third quarter phase in a telescope.

This Month’s Topic

Vostok

The first spacecraft to carry a human into space was the Vostok, a Soviet built spacecraft. Vostok (which is Russian for East) was a one-man spacecraft, making it the equivalent of American’s Mercury spacecraft. However, Vostok shared some similarities with the later American two-man Gemini.

Design of the Vostok

Work designing and building the Vostok spacecraft began in early 1959. The final design was a two part spacecraft consisting of an eight foot diameter sphere mounted on top of a double cone module. The total length of the Vostok was 14-1/2 feet and it weighed just over five tons. Its designer was Sergei Korolev, the Soviet space program’s Chief Designer. Because the Vostok had multiple modules, it is more similar to the two-man Gemini (a three module spacecraft) than to the one man Mercury (a single module spacecraft).

The cosmonaut resided inside the eight foot diameter sphere that the Soviets called the Sharik (Russian for sphere). The cosmonaut could not leave the Sharik until the end of reentry, as will be described later. Between the reentry and instrument modules ran a ring of spherical tanks and also a bundle of wires and pipes. The tanks contained air for the cosmonaut to breathe and the cable bundle was the Vostok’s umbilical. Four metal bands across the Sharik reentry module held it tightly against the double-cone instrument module. At the time of reentry, all four bands split apart and the umbilical disconnected, freeing the Sharik from the instrument module.

The instrument module contained the supplies and power for the flight. Covering the bottom cone of the instrument module were radiators that kept the module cool. They open and close automatically, depending on the temperature inside the module. At the very bottom of the instrument module was the Vostok’s retro engine, the TDU-1 (from the Russian abbreviation for Breaking Rocket Installation-1). The TDU-1 was a liquid fueled rocket engine capable of producing 3,500 pounds of thrust. With its 600 pound fuel supply, its thrust slowed the Vostok by 350 miles per hour, enough to cause it to reenter the earth’s atmosphere.

The instrument module burned up upon reentry while the cosmonaut sat in an ejector seat inside the Sharik. A layer of ablation material coating the Sharik melted as it returned to earth, protecting the cosmonaut inside. A manned Vostok reentry module was is too heavy for the parachute that fit inside. Therefore, to protect the cosmonaut from the hard landing, he ejected out of the module with his own parachute.

Vostok carried enough supplies (food, air, and water) for a ten day mission. However, every Vostok had an orbit that naturally decayed from orbit in less time. The ten day supply of food, water, and air was insurance against a failure of the Vostok retro engine.

Early Tests of Vostok

Before launching cosmonauts into space, the Soviets performed several tests with the Vostok design. These space flight tests were given the name Korabl-Sputnik, or spaceship satellite. The first was Vostok test was an unmanned test. Following it were six additional test flights carrying animals, most often, dogs. The last two Vostok tests also carried a mannequin named Ivan Ivanovich. In all, there were seven Vostok test flights before Yuri Gagarin’s flight.

The Six Vostok Missions

The six cosmonauts that flew onboard Vostoks were military plot recruited in 1959, just like the seven Mercury astronauts. The first cosmonaut was Yuri Gagarin who became the first human to go into space on April 12, 1961. His Vostok 1 entered into a 203 by 112 mile orbit that took 89 minutes to complete. Since it wasn’t known how a cosmonaut would react in weightlessness, the spacecraft controls of Vostok 1 were locked, leaving Gagarin just a passenger. However, if he should run into a problem, he carried an envelope containing the combination to unlock the controls. That combination was 1-2-5. Yuri made a single orbit before returning to earth.

After firing the TDU-1 reentry engine, his entry module did not separate as expected from the umbilical connecting it to the instrument module. The weight of the instrument module hanging off the umbilical put Yuri’s reentry module into a tumble. Eventually reentry heat burned through the cables in the umbilical, freeing the reentry module. The reentry module then assumed its rightful orientation and successfully completed reentry. To be an official record, a pilot must land with his ship. Therefore, it’s understandable that the Soviets were hesitant to mention the fact that Gagarin ejected from his spacecraft. Hearing this might make the rest of the world think that Yuri abandoned ship, losing him the international record.

The second cosmonaut was Gherman Titov. Originally, his mission was to be a three orbit flight. However, under political pressure, the flight became a 24 hour flight. Titov’s flew into orbit about six months before John Glenn’s orbital flight. Titov has the distinction of being the first person to experience space sickness.

Vostok 3 carried cosmonaut Nikolayev on a four day mission on 12 Aug 1962. One day later, Vostok 4 was launched from the same launch pad (that’s a quick turn around). The Soviets spoke of this as a space rendezvous. In actuality, Vostok had no ability to maneuver in orbit (except to rotate itself to the proper orientation for entry). Without the ability to maneuver in orbit, there could be no space rendezvous. Instead, Vostok 3 and 4 passed four miles from each other, which was close enough for the cosmonauts to talk to each other over their radios. These flights mark the first time that two human beings were in orbit at the same time.

Vostok 5 and 6 was another dual mission. However, this time, Vostok 6 carried Valentina Tershkova, the first woman to fly into space. Vostok 5 carried cosmonaut Bykovskiy on a five day mission and Tershkova remained in orbit for three days. Vostok 5 and 6 passed within three miles of one another.

It should be noted, for the Soviets to launch two manned spacecraft so close together in time and get them to pass so close together in space was a pretty impressive feat for the time. However, Gemini would do much better just three years later.

After Vostok 6

Evidence suggests that the Soviets planned additional Vostok missions, but they never launched. As a gap filler (since the more advanced Soyuz was behind schedule), Korolev bowed to political pressure once again and modified the Vostok into a two and three man spacecraft. This allowed the Soviets to launch multi-man crews before Americans launched the two-man Gemini. The spacecraft was renamed Voskhod to give the impression that it was a new spacecraft. Voskhod 1 carried the first multi-manned mission (three cosmonauts in this case) and cosmonaut Alexei Leonov performed the first space walk on Voskhod 2. The Soviets continued to use the Vostok design for biological payloads and spy satellites (called Zenith).

This Month’s Sources

Observer’s Handbook 2007, The Royal Astronomical Society of Canada

Space Calendar, Baalke, Ron, <www.jpl.nasa.gov/calendar/>

Night Sky Explorer (software)

Stars, Kaler, James, <www.astro.uiuc.edu/~kaler/sow/>

Mercury Atlas 8, 29 July 2007, 31 July 2007, <en.wikipedia.org/wiki/Mercury_8>

Sputnik 1, 28 July 2007, 31 July 2007, <en.wikipedia.org/wiki/Sputnik_1>

NASA Facts Robert H. Goddard: American Rocket Pioneer, 31 July 2007, <www.gsfc.nasa.gov/gsfc/service/gallery/fact_sheets/general/goddard/goddard.htm>

Pioneer Venus Orbiter, 31 July 2007, <nssdc.gsfc.nasa.gov/nmc/tmp/1978-051A.html>

Draconids (Giacobinids), 31 July 2007, <meteorshowersonline.com/showers/draconids.html>

Cassini-Huygens Overview, 31 July 2007, <saturn.jpl.nasa.gov/home/index.cfm>

Venera 4, 31 July 2007, <nssdc.gsfc.nasa.gov/nmc/tmp/1967-058A.html>

Mariner 5, 31 July 2007, <nssdc.gsfc.nasa.gov/nmc/tmp/1967-060A.html>

Orionids, 31 July 2007, <meteorshowersonline.com/orionids.html>

Outer Space Treaty, <www.state.gov/t/ac/trt/5181.htm>

The Encyclopedia of Soviet Spacecraft, Hart, Douglas, Exeter Books, 1987

The Soviet Manned Space Program, Clark, Phillip, Orion Books, 1988

Dark Skies and Bright Stars,

Your Interstellar Guide