Monday, February 29, 2016

Tonight's Sky for February 29: Leap Year

Today is February 29, a date that only happens every fourth year. Why do we add a day to the year's shortest month every fourth year? Simple: the year isn't exactly 365 days long, but rather 365 ¼, or pretty close to it. It's that extra ¼ that brought about the Leap Year.

The ancients knew the length of the year was roughly 365 days. Unfortunately, those extra few hours were discounted. So, to set the scene, with the year actually being 365 ¼ days long, every 4 years, the calendar would become 1 day out of sync with real astronomical time. By the end of a century, the calendar would be almost a month off (1 day off every 4 years for 100 years makes for 25 days off of actual time by the end of 100 years). However, none of the ancient civilizations did anything to correct this, but instead merely put up with a calendar that was frequently out of sync with the seasons.

Enter Julius Caesar.

After he won the Roman Civil War and became dictator, Julius Caesar finally decided to do something about the out of sync calendar problem. Knowing that the year was actually 365 ¼ days long, Caesar decreed that there would be an extra day added to every 4th year to eliminate the problem of the inaccurate calendar, hence the start of the leap year.

Sunday, February 28, 2016

Tonight's Sky for February 28: Regulus Due South at Midnight

Today at midnight, Regulus, alpha (brightest) star of Leo the lion, will be just about due South as the clock strikes 12. To see it, go out and look South about two thirds of the way to zenith (directly overhead). 

Saturday, February 27, 2016

Tonight's Sky for February 27: Moon Meets Spica

Want to see Spica, alpha star of zodiac constellation Virgo but don't know where to look? Well, today's your lucky day as the Moon will be parked right next to the star. To see the show, simply go out in the predawn sky and find the Moon. That bright star next to it? That's Spica. 

Friday, February 26, 2016

Tonight's Sky for February 26: Last Total Solar Eclipse for the U.S. (1979)

It was on this date in 1979 that the last total solar eclipse visible over the United States (as of 2015) took place. The eclipse, whose totality lasted for 2 minutes and 49 seconds, was visible in total form over the Pacific Northwest and Southwestern Canada. Needless to say, a partial eclipse was visible over a much larger area of the two countries.

For the record, the next solar eclipse visible in the continental United States will take place on August 21, 2017. 

Thursday, February 25, 2016

Tonight's Sky for February 25: Solar Eclipses from Space

Twice a year around the equinoxes, the Moon will pass directly between the Sun and NASA's Solar Dynamics Observatory (SDO) on a daily basis, thus creating solar eclipses that can only be seen from space. For the record, 2016's spring eclipse season started today. 

Wednesday, February 24, 2016

Tonight's Sky for February 24: Moon Meets Jupiter

Want to see the planet Jupiter but have no idea where to look? Well, no problem because, tonight, the Moon will be parked right next to Jupiter, largest planet in the solar system and fifth from the Sun. To see the show, simply go out tonight and look up to find the Moon. Moon found, notice t hat bright 'star' very close to it? Well, that 'star' is actually Jupiter. For more fun, turn a pair of binoculars on it to see the 4 large moons discovered by Galileo in 1609 or a telescope to see the cloud patterns on the planet itself.

Tuesday, February 23, 2016

Tonight's Sky for February 23: First Naked Eye Supernova in Almost 400 Years (1987)

It was on this date in 1987 that the Earth was treated to the first supernova visible to the naked eye in nearly 400 years. Officially dubbed supernova 1987A, the stellar explosion, located in the Large Magellanic Cloud, peaked at a brightness of magnitude +3 in May and would remain visible into late summer.

Before this event, the last naked eye core collapse supernova observed was in 1601 and studied by, most notably, Johannes Kepler. To date, Kepler's Supernova is the last core collapse supernova observed within the Milky Way. Though not as bright, 1987A provided a lot of insight to scientists about the nature of these events. First: the star that exploded was a blue supergiant, a class of star that was previously thought to be stable, like our Sun (but only much, much bigger).Another insight: stars about to go supernova emit a wave of neutrinos before they explode, thus serving as a method to detect them a few hours before light from the actual explosion can be seen. 

Monday, February 22, 2016

Tonight's Sky for February 22: More Chances for Aurora

Tonight into tomorrow morning, Earth is set to enter a stream of highly charged particles coming from the Sun called the solar wind. NOAA is accordingly advising high-latitude dwellers to be alert for aurora, also known as the Northern Lights.

Sunday, February 21, 2016

Tonight's Sky for February 21: Full Moon Meets Regulus

Tonight, the Moon will reach its full phase, which means that, as seen from Earth, it is directly opposite the Sun in the sky as seen from Earth and is at the half way point in its current orbit.

As for lunar mechanics, the Moon is always half lit. The reason we don't always see it as such is thanks to orientation in relation to us. Right now, when the Moon is opposite the Sun and on the far side of Earth, we can see all of its lit side, which is why it appears to be “full.” In the coming nights, we will start to see less of the Moon as its lit side starts to turn away from us as seen from Earth and heads toward Third Quarter. 

Saturday, February 20, 2016

Tonight's Sky for February 20: Be Alert for Aurora

Yesterday, the solar wind poured into a crack in the Earth's magnetosphere, sparking brilliant displays of aurora, also known as the Northern Lights. Tonight, though odds are falling, NOAA is still predicting a 30% chance of geomagnetic activity, and hence aurora, for Northerly dwellers tonight.

Friday, February 19, 2016

Tonight's Sky for February 19: Russia Launches Mir (1986)

It was on this date in 1986 that Russia launched the first module of its long-lived Mir space station. Originally planned a decade earlier as an improved Salyut (1-piece) station, it would take the better part of a decade for Mir to hit the production phase due to plan changes (into a multi-module station) and financial troubles, with the goal of a first module launch by the 27th Communist Party Congress, set to open February 25, 1986.

The launch met the goal by 6 days.

In the intervening decade, Mir would come to include 7 modules, the last of which was attached in 1996. At the same time, with the collapse of the Soviet Union and end of the Cold War in 1991, Mir became an unofficial international space station, hosting astronauts from other countries, including the United States. By 1997, the 11-year old station (designed to fly for only 5years) had really started to show its age as it was plagued by constant mechanical problems to the point where visitors were openly questioning the station's safety.

The beginning of the end for Mir would come on June 25, 1997 when an unmanned supply ship crashed into the space station after a failed docking attempt. The result: a smashed solar panel resulting in a power loss and a punctured module. Additionally, the station was spent into an uncontrolled spin, which was only stopped after the crew estimated the rate of spin by visual estimate (the computers were knocked out) and radioing the guess to mission control, which was able to fire the station's rockets and stabilize the station because the guess, based on the apparent motion of the stars, was right.

After the accident, Mir would continue to fly as a manned station for another 3 years. During that time, the Russians expressed optimism that Mir could be retrofitted and used for future research or, in a preview of things to come, as a commercial venture wherein rich space tourists would pay to be flown to the station aboard Soyuz rockets. However, previous commitments to the then in-planning International Space Station left Russia with no money to fix Mir, which the nation reluctantly abandoned in 2000 before it was eventually de-orbited in 2001. 

Thursday, February 18, 2016

Tonight's Sky for February 18: Pluto Discovered (1930)

It was on this date in 1930 that Clyde Tombaugh, yet to earn a college degree, discovered Pluto, the former 9
th planet in the solar system.

In the decades since the discovery of Uranus in 1781, astronomers noticed that its orbit seemed to exhibit 
some unexpected eccentricities. This observation led to the discovery of Neptune in 1846. When Neptune, too, seemed to exhibit similar orbital disturbances and following the logic that led to its discovery, the implication was that there was an even more distant planet tugging on Neptune, too.

So, the search was on for the mysterious 9th planet, which was apparently found by Tombaugh on February 18, 1930.

Initially, astronomers had a very hard time determining the size of Pluto as it was so far away and the tools available at the time of discovery were primitive by today's standards when it came to their planet-measuring capabilities. However, as time progressed, Pluto only seemed to get smaller and smaller, eventually reaching the point where it was estimated to be smaller than many of the moons in the solar system, including our own. By 1978 and the discovery of its first known moon, Charon, Pluto was known to be only about 1/500th the mass of Earth, far from the 1 Earth mass first suggested shortly after discovery. By virtue of its size alone, some scientists started to question whether Pluto deserved to be called a planet at all.
The next blow for Pluto came with the advent of digital imaging technology. For astronomers, digital CCD chips, which came into mass use in the 1990s, were far more sensitive than film and could reveal much greater details. With the advances in imaging technology, many objects at Pluto's distance from the Sun were found. Now, with the fact known that Pluto was not unique at all, scientists were faced with a dilemma: start adding more planets to the solar system (and thus overwhelm the mind of schoolchildren the world over) or reconsider the definition of a planet. As history shows, astronomers were able to kick the proverbial can down the road thanks to the fact that none of these new bodies were anywhere near as large as Pluto, realizing that, while Pluto was no longer alone in the outer, it was an anomaly in that it was a relative giant among dwarfs.

However, the road on which to kick the can was not endless.

The final blow to Pluto's status as a planet came on July 29, 2005, when the existence of Eris, a body 3 times more distant but nearly 30% more massive than Pluto, was confirmed. Eris was discovered by astronomer Mike Brown, who, in a TV interview, recalled calling his wife immediately after the discovery to announce that he had discovered the 10
th planet. Unfortunately for Brown, he would not enter the Pantheon of astronomers occupied by the other planet finders: Tombaugh, Gallee (Neptune), and Herschel (Uranus). Instead, Brown's 'planet' was merely classified as the largest in a series of Trans-Neptunian objects discovered since the advent of digital imaging, which is far more adept at low-light photography than film. It was because of this problem, how could the larger of two distant bodies be considered not a planet while the smaller one was a planet, that the scientific community began to reassess the definition of the word 'planet.'

Result: on August 24, 2006, the International Astronomical Anion (IAU) came up with the following definition of the word 'planet,' which reads: “a body that circles the sun without being some other object's satellite, is large enough to be rounded by its own gravity (but not so big that it begins to undergo nuclear fusion, like a star) and has "cleared its neighborhood of other orbiting bodies.” Obviously, Pluto met the first 2 conditions (it orbits the Sun and nothing else, it is round), but not the third, as it has failed to clear its neighborhood thanks to the fact that its moon, Charon, is not a true moon in that Charon does not orbit Pluto, but both bodies orbit a point in space between them where their gravitational fields meet, making for more of 
a double planet system than a planet-moon one.

For many people, both scientists and especially members of the public, the demotion of Pluto was a tough pill to swallow as most everyone alive (save the people 77+ years of age at the time) grew up on the notion of 9, not 8, planets. In fact, there was even a massive 'save Pluto' petition being circulated online, but to no avail as the IAU refused to budge on this question of what defines a planet.

Still, regardless of what one chooses to call it, Pluto was revealed in stunning detail by the
New Horizons mission last July, the data from which is expected to continue trickling back to Earth for the remainder of 2016. 

Wednesday, February 17, 2016

Tonight's Sky for February 17: Ranger 8 Launched (1965)

It was on this date in 1965 that NASA launched its Ranger 8 Moon probe, which was designed, along with its fellow Rangers, to photograph as much of the lunar surface as possible in order to locate possible landing sites for the then-future Apollo program. In all, Ranger 8 would transmit 7,137 photos of the lunar surface until it impacted the Moon. The last picture had a resolution of 1.5 meters and the crater created by the probe's impact was estimated to be around 40 feet in diameter after it was photographed by a later probe: Lunar Orbiter 4.

Tuesday, February 16, 2016

Tonight's Sky for February 16: 9th Recorded Perihelion of Halley's Comet (374)

It was on this date in 374AD that the 9th recorded perihelion approach (exact date of perihelion determined far later) of Halley's Comet took place. Aside from the fact that its appearance was recorded, virtually nothing else is known about this appearance as seen from Earth. Instead, what makes this interesting is the tale (sorry) behind the comet.

Looking through astronomical records, English astronomer Edmund Halley (1656-1742) noticed that there seemed to be a pattern to sightings of a Great Comet, namely that one was seen every 76 years. Using the past to predict the future, Halley theorized that these several comets were, in fact, a single comet returning every 76 years. Halley then boldly predicted that a great comet would be seen again in 1758. Unfortunately, Halley died before he was vindicated. 

For the record, the comet's next return is set for 2061.

Monday, February 15, 2016

Tonight's Sky for February 15: Moon Meets the Hyades

Tonight, the
Moon will be among one of the closest to Earth star clusters: the Hyades, located in the zodiac constellation of Taurus. To see the show, go out and find the Moon. Moon found, look around the Moon to spot a 'V' of stars, set off by bright orange Aldebaran, that constitute the brightest stars of the cluster and also the bull's nose. To see more stars, grab a pair of binoculars. 

Sunday, February 14, 2016

Tonight's Sky for February 14: First Quarter Moon

Today, the Moon, second brightest object in the sky, has reached the First Quarter phase, which means that it is exactly 90 degrees around its orbit of Earth and is one quarter finished with its current orbit. 

As for lunar mechanics, the Moon is always half lit. The reason we don't always see it as such is thanks to orientation in relation to us. Right now, with the Moon at a 90 degree angle relative to the Earth-Sun line, we only see half of the lit side.

After today, we will see more of the Moon each night as its lit side turns more toward from us and heads toward Full in a week. 

Saturday, February 13, 2016

Tonight's Sky for February 13: Tycho Brahe Develops his 'Tychonic' Solar System (1583)

It was on this date in 1578 that the great Danish astronomer Tycho Brahe unveiled his model of what he believed the solar system to look like, which would later come to be dubbed the 'Tychonic Model.' Never heard of the Tychonic Model? Well, don't feel bad as it is now considered a footnote in scientific history created as a compromise between the geo and heliocentric models of the solar system.

Explain, please?

In 1578, an all-out scientific debate was raging as to how the solar system worked. Since Ancient Greece, all models of the solar system were geocentric, or Earth-centered (except for that proposed by Aristarchus of Samos, which was Sun-centered). Yes, there were variances but the overall picture, namely that of the Earth being at the middle with everything else revolving around it, remained the same. This is the picture of the solar system that would hold sway for 2000 years.

In 1542, the ancient wisdom was challenged when Nicholas Copernicus published his book On the Revolutions of the Heavenly Orbs, which put forth the revolutionary, and to the Catholic Church heretical, idea that the Sun, not the Earth was at the center of the solar system. As evidence for the geocentric model were the observations that there was no woosh of air created by the Earth moving through space, objects don't land to the West when dropped, and a lack of observed stellar parallax. Going for the heliocentric model was the observation that it predicted the motions of the planets just as well as the geocentric one and the fact that it was much simpler than the geocentric model, which had grown quite complicated in order to explain retrograde motion and which the heliocentric view explained much more simply.

Then cue Tycho Brahe.

Tycho Brahe was the greatest of the pre-telescopic astronomers. Thanks to his noble birth and connections to people in high places, Brahe was able to found and fund the first modern observatory, one outfitted with large, permanently-mounted instruments and manned by a staff of trained assistants. In his 30+ year career, Brahe and his staff compiled around 10 times more observational data than all previous astronomers in recorded history combined. With a resume like that, when Brahe spoke, people listened, which is exactly what happened when he put forth his solar system model, one with the Earth at the center, the Sun revolving around the Earth, and everything else revolving around the Sun.

Ironically, rather than end the debate, the Tychonic model only served to prolong it because, when Galileo published his observations of the phases of Venus, which proved that Venus orbited the Sun, die-hard geocentrists switched allegiance from the pure geocentric to the Tychonic model because it explained the phases of Venus while still allowing for the Earth to be at the center of everything.

In the end, it would not be until the 1660s and the physics of Issac Newton that the geocentric and Tychonic models would finally be proven incorrect.

Friday, February 12, 2016

Tonight's Sky for February 12: Venera 1 Launched (1961)

It was on this date t hat Russia launched its Venera 1 space probe, which was the first spacecraft designed to travel to another planet, Venus. Launched on February 12, the satellite was set for a Venus flyby on May 19. Unfortunately, before the flyby, communication with the satellite was lost. However, in the days immediately after launch, it did return some then groundbreaking data on the solar wind and Earth's magnetic field.

Thursday, February 11, 2016

Tonight's Sky for February 11: Japan Becomes Fourth Space-Faring Nation (1970)

It was on this date in 1970 that Japan became the fourth nation to successfully launch a satellite on its own rocket after it launched its Osumi satellite into orbit, thus becoming the fourth space-faring nation after Russia, the United States, and France. While most space programs up to that time were government-run, this launch was unique in that it was accomplished by the University of Tokyo's Institute of Space and Aeronautical Science.

Wednesday, February 10, 2016

Tonight's Sky for February 10: Moon at Perigee

Tonight, the Moon is about as big as it will ever get thanks to the fact that the Moon is at perigee, a point in its orbit that is closest to Earth.

What many people may not realize is the fact that the Moon (and all other celestial bodies) do not orbit their parent bodies in circles, but ellipses, which are slightly elongated circles. Result: any given day of an orbital period, any orbiting body will be at a slightly different distance from its parent body. As for the Moon, this variance in orbit amounts to about 20,000 miles.

As for tonight, the Moon will be about as close to Earth as it is going to get. When it comes to practical implications, the difference will be hard to notice with the naked eye to all but an experienced observer but, in a telescope, the difference will be obvious.

Tuesday, February 9, 2016

Tonight's Sky for February 9: Young Moon

How thin of a
Moon have you seen? How about one that's just barely over a day old and only 3% illuminated? Well, if you have never seen a Moon this thin, this is your chance to do so as such a Moon will be making an appearance in this evening's sky just after sunset. 

To see the Moon, you'll need a good Western horizon. How good? One with less than 10 degrees of obstruction. To simulate this, hold your fist vertically at arm's length to simulate 10 degrees. Hint: if you can't think of a good location off-hand, scout out one during the day. Location found, head there at sunset and start looking, preferably with optical aid, and start scanning the sky. The Moon may not be visible at first, often seeming to suddenly pop into visibility as if it were flipped on like a light.

Believe me, when this happens, it's an exhilarating experience.

Monday, February 8, 2016

Tonight's Sky for February 8: New Moon

Today, the Moon, second brightest object in the sky, has reached the New Moon phase, which means that it is directly between the Sun and Earth, and thus invisible for us Earthlings as of now.

As for lunar mechanics, the Moon is always half lit. The reason we don't always see it as such is thanks to orientation in relation to us. Right now, with the Moon directly between the Earth and Sun, e can't see any of its lit side.

After today, we will see more of the Moon each night as its lit side turns more toward from us and heads toward first quarter.

Sunday, February 7, 2016

Tonight's Sky for February 7: Old Moon

How thin of a Moon have you seen? How about one that's just barely a day before New and only 2% illuminated? Well, if you have never seen a Moon this thin, tonight's your chance to do so as such a Moon will be making an appearance in this morning's sky just before sunrise.

To see the Moon, you'll need a good Eastern horizon. How good? One with less than 3 degrees of obstruction. To simulate this, hold two fingers vertically at arm's length to simulate 3 degrees. Hint: if you can't think of a good location off-hand, scout out one during the day. Location found, arrive there about 15 minutes before sunrise and start looking, preferably with optical aid. The bad news: you'll have to hurry because, as soon as the Sun clears the horizon, you can forget about seeing the Moon.

Saturday, February 6, 2016

Tonight's Sky for February 6: Moon Meets Mercury and Venus

This morning, there will be quite a sight in the predawn sky as the Moon will form a triangle with the two inferior planets: Venus, third brightest object in the sky, and Mercury, closest planet to the Sun. To see the show, go out about 30 minutes before sunrise and look low in the Eastern sky. The Moon and Venus should be easy to spot. As for Mercury, optical aid in the form of binoculars will be useful here.

Friday, February 5, 2016

Tonight's Sky for February 5: Apollo 14 Lands on the Moon (1971)

It was on this date in 1971 that Apollo 14 landed on the Moon. After the Apollo 13 near-disaster the year before, public confidence in NASA was shaken and the space agency knew it needed a slam-dunk mission to re-instill public confidence in the Apollo program. To lead the mission, NASA selected a seasoned veteran, Alan Shepard, Mercury 7 member and first American in space. Joining Shepard were Stuart Roosa and Edgar Mitchell. The mission lifted off on January 31 and successfully landed on February 5. While a smashing success in the science department, Apollo 14 is most-remembered for something that definitely wasn't in the mission plan: Moon golf.

An avid golfer, Alan Shepard wanted to hit a golf ball on the Moon and, at the same time, he realized that such a show could mean some positive public relations for NASA. Knowing that by-the-book NASA management would probably never go for the plan, Shepard, with the help of a club pro, rigged up a 6-iron head to fit the collapsible shaft of an excavation tool, which Shepard then smuggled aboard in his space suit. Once on the Moon and with cameras rolling, Shepard pulled out the collapsible club, extended it to its full length, and, after a few practice swings, sent a golf ball flying for “miles and miles!” over the lunar surface in what could have been termed one small swing for man, one giant drive for mankind.

As Shepard hoped, his impromptu stunt captured public imagination, put NASA back in the headlines for all the right reasons, and has continued to be one of the most talked about moments in NASA history. 

Thursday, February 4, 2016

Tonight's Sky for February 4: Mars Due South at Dawn

Today at dawn, Mars, fourth planet from the Sun, will be just about due South as the sky starts to brighten. To see it, go out as the sky is getting bright and look South about a third of the way to zenith (directly overhead). 

Wednesday, February 3, 2016

Tonight's Sky for February 3: Moon Meets Saturn

Want to see Saturn but have no idea where to look? Well, today's your lucky day as Saturn will be parked right next to the Moon this morning. To find Saturn, simply go out in the predawn hours and find the Moon and the bright 'star' next to it, which is, in fact, Saturn.

Tuesday, February 2, 2016

Tonight's Sky for February 2: Happy Groundhog's and Cross-Quarter Day

Today is Groundhog's Day and also a cross-quarter day. What is a cross-quarter day? It's the mid way point of any season and was, like the solstices and equinoxes, an important time for early civilizations as these days served as another natural way to divide up the year into periods of time, which became a matter of life and death with the advent of large scale agriculture around 5000BC. 

Monday, February 1, 2016

The February Sky

With new month of February upon us, we quickly hit the mid point of astronomical winter on the 2nd and the lengthening of the days will be noticeable at the start and plainly obvious by month's end as we get closer and closer to the equinox, which will come on March 20. Besides the rapidly lengthening days (and thus, shortening nights), February marks the last full Month of Standard Time, with DST returning the first Sunday of next month. All in all, there should be a sense of urgency to get out and see the winter sky, especially considering the often still lousy weather in much of the country.

Cool Constellations
By nightfall in February the fall constellations are all extremely low in the Western sky. Hint: don't dilly dally when it comes to viewing them, they'll be gone by month's end. In the Northwest, ‘W’-shaped Cassiopeia is still high up, house-like Cepheus is low, and the mythological hero Perseus Is still reasonably well-placed for early evening viewing. Moving away from the past and into the present celestial landmarks for this time of year, the Big Dipper is perpendicular to the horizon by the time the sky gets dark and things will only be getting better for Dipper fans as the next few months go along. Almost at zenith is the bright Capella, alpha Auriga. The cloudy patch that is the Pleiades is also very high come nightfall this time of year, as is the V-shaped Hyades cluster. Looking in the South, you'll see all the winter favorites like unmistakable Orion, which also serves as a winter signpost to the stars. From Orion, follow a line from his belt down to blazing blue Sirius, alpha Canis Major. Following that line up will bring one to Aldebaran, alpha Taurus the bull. Aldebaran is also right in the midst of the Hyades. Imagining a line starting at bright blue Rigel (Orion's left foot) through red Betelgeuse (Orion's right shoulder) will bring you to Castor and Pollux, alpha and beta Gemini. Other winter favorites to look for include Canis Minor, Cancer, and even Leo if you wait into the night a little longer. Early birds? Well, getting up just before the Sun will bring a spring preview in the form of Virgo, Bootes, Corona, Hercules, Corvus, and even the Summer Triangle along with the front half of Scorpius, highlighted by fiery red Antares, the rival of Mars.

Planetary Perceptions
On the planet front, you'll need to be an early bird to catch 4 of the 5 naked eye planets. The one exception: Jupiter, which is up just about all night as it nears opposition, which is set to take place n March 8. Moving into the night, Mars is next to break the horizon, albeit in middle of the night, followed by Saturn roughly 2 hours later. Moving to the immediate predawn sky, the two inferior planets, Venus and Mercury, finally make their appearances, the former lingering low in the predawn sky all month and the latter making an appearance for the first half of the month before dropping out of visibility on the road to becoming an evening object early next month. Tip: since they're close, use the brighter, higher Venus to spot the far dimmer, lower Mercury. For even better news, a pair of 7x50 binoculars should fit them in the same field (or be very close to doing so).

Tonight's Sky for February 1: Columbia Disaster

It was on this date in 2003 that the space shuttle Columbia, first of the shuttle fleet, disintegrated upon reentry, killing the crew of 7 astronauts.

At the time of the Columbia's flight, there was a growing chorus of whispers suggesting that the space shuttles were ending their useful lives and needed to be retired. When development began in the early 1970s parallel with Skylab, the space shuttles were (and arguably still are) the most complex machines ever built. Shoved to the back burner to focus on Skylab, the shuttles became top priority in the late 1970s and early 80s. Finally, in 1981, Columbia made the first orbital flight. In the following years NASA would add 4 more shuttles. Aside from the Challenger disaster in 1986 (which could have been avoided if NASA management had listened to the engineers' warnings about launching in cold temperatures), the shuttles performed flawlessly, which is how Columbia's final mission went until the crucial re-entry phase, during which the shuttle disintegrated, killing the crew, and scattering thousands of pieces of debris across a stretch of the American South hundreds of miles long. After a months-long investigation, it was determined that a piece of insulating foam had broken away from the main fuel tank, impacted Columbia's wing, and dislodged some of the thermal tiles used to protect the shuttle from the extreme heat of reentry. The result: the heat caused by friction of the Earth's atmosphere at the high speed of atmospheric reentry caused the shuttle's wind to melt off, sending the Shuttle out of control. End result: total disintegration.

Following the Columbia disaster, the whispers about retiring the shuttle turned to shouts. The following year, President Bush called for the creation of the Constellation Program and a return to the Moon. The chosen craft for Constellation: rockets, which are nowhere near as complex as the shuttles. Shortly thereafter, it was announced that the shuttles would be retired. Finally, on July 26, 2005, Discovery made the first post-Columbia flight (Discovery also made the return flight after Challenger). For these final missions, post-launch inspections of the shuttles' underbellies and heat tiles were mandatory. Still, old as they were, the shuttle fleet continued to perform admirably, so much so that there was an intense lobbying effort to keep them flying until a replacement craft for manned spaceflight became operable.