1991 29c Space Exploration: Mercury

# 2568 - 1991 29c Space Exploration: Mercury

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US #2568
1991 Mercury

  • Part of set picturing nine planets and Earth’s moon
  • Issued as part of Stamp Collecting Month

Category of Stamp:  Commemorative
Set: 
Space Exploration
Value: 
29¢
First Day of Issue: 
October 1, 1991
First Day City: 
Pasadena, California
Quantity Issued: 
33,394,800
Printed by: 
Bureau of Engraving and Printing
Printing Method:
Photogravure
Format: 
Booklets – 2 panes of 10 in each
Perforations: 
11

Reason the stamp was issued:  The set of Space Exploration stamps was issued in honor of the Voyager 2 space probe passing Neptune and the 11th annual Stamp Collecting Month.

About the stamp design:  The Mercury stamp pictures the planet and the Mariner 10 space probe.  Launched in 1973, it flew by Mercury for the first time in March 1974, then passed the planet two additional times.

These stamps were the first by Ron Miller, a former artist for the Smithsonian Institution’s National Air and Space Museum.  He was asked to picture each of the Sun’s nine planets and the Earth’s moon with a spacecraft.  This was to tie in the idea of America’s exploration of space.  His original acrylic paintings were larger than those normally used for stamp art.  This was to show all the details of the spacecraft.

Special design details:  While most of the stamps name the spacecraft shown, the Pluto stamp has “not yet explored,” because no spacecraft had reached that planet at the time.  (The space probe New Horizons explored Pluto in 2015.)

First Day City:  The First Day of Issue ceremony took place at the Jet Propulsion Laboratory in Pasadena, California, on October 1, 1991, the start of Stamp Collecting Month.

Unusual thing about this stamp:  The USPS partnered with Paramount Studios to promote the stamps.  The studio was celebrating the 25th anniversary of the Star Trek movies and television series.  The stamp designs were unveiled on the bridge of the Starship Enterprise, the space vehicle featured in the series.  Flyers promoting the stamps were included in the packaging of Star Trek video cassettes.

About National Stamp Collecting Month stamps: October has been designated by the US Postal Service as National Stamp Collecting Month.  The first celebration occurred in 1981 as a way to promote the hobby of collecting stamps.  Each year, new stamps are issued in early October to stimulate additional interest, and many philatelic organizations hold special programs during the month.  The theme for the 1991 celebration was “Journey to a New Frontier… Collect Stamps.”

History the Space Exploration stamps represent:  Uncovering the mysteries of the universe has been a pursuit of scientists and dreamers for all time.  With the invention of telescopes, astronomers discovered some of the wonders of space.  With the space age, researchers began sending spacecraft outside of Earth’s orbit to gain further insight into the planets of our solar system.  Manned missions were followed by unmanned missions with the capability of traveling to distant planets.  These stamps show some of the spacecraft and the images of the planets they captured as they flew by.  Discoveries continue to be made with the space probes that still travel through our solar system.

History this stamp represents:

On March 29, 1974, Mariner 10 became the first space probe to fly by Mercury.

NASA launched the Mariner program in 1962 to build and send probes to investigate Mars, Venus, and Mercury. Prior to the launch of Mariner 10, earlier missions explored Mars and Venus.

Because Mariner 10 was destined to orbit Mercury, the planet closest to the sun, scientists faced new challenges in its design. The probe would have to withstand 4.5 times more solar radiation than when it departed Earth, requiring extra shielding to protect it. Mariner 10’s designers installed thermal blankets and a sunshade on the main body and made the solar panels adjustable so they wouldn’t overheat.

Mariner 10 was also the first spacecraft to use an interplanetary gravitational slingshot maneuver. In doing so, it would use Venus’ gravitational pull to bend its flight path into Mercury’s orbit. This would also put Mariner 10 in an orbit that would repeatedly bring it back to Mercury. In order for this to work, Mariner 10 couldn’t change its trajectory more than 120 miles, so mission planners stocked the probe with three times the amount of fuel as previous models. This would also allow it to make two additional flybys.

The probe was fitted with a number of instruments to gather information to send back to Earth. These included several cameras, which used more power than all the other instruments combined.   There was also an infrared radiometer to detect infrared radiation given off by both planets, which would help scientists to calculate their temperatures. Ultraviolet spectrometers were included to test whether Mercury had an atmosphere and to study the interstellar background radiation of Earth and Venus. Plasma detectors were added to study gases in the solar wind and observe Mercury’s magnetic field. However, a part of the probe didn’t open correctly, so not all of this information was collected. There were also charged particle telescopes and Magnetometers, both of which also studied Mercury’s magnetic field.

Construction on Mariner 10 was completed in June 1973, after which it underwent testing. After Mariner 10 completed it’s testing, NASA had a one-month window to launch it. They selected November 3, as it would provide the best imaging conditions when Mariner 10 was supposed to reach Mercury. The probe was launched that day at 12:45 a.m.

After a partial orbit of Earth, Mariner 10 was set on its path toward Venus. In its first week in space, Mariner 10 took five photomosaics of Earth and six of the Moon. It provided some of the best photos up to that time of the Moon’s North Pole region.

Item #M5470 – Mariner and Pioneer 10 First Day Covers set.

The journey to Venus was filled with technical malfunctions. According to one NASA scientist, “It seemed as if we were always just patching Mariner 10 together long enough to get it on to the next phase and next crisis.” Flaking paint repeatedly interrupted tracking and the on-board computer frequently reset itself. Mariner 10 approached Venus on February 5, 1974. Though several other probes had reached the planet before, Mariner 10 was the first to successfully send images back to Earth. The probe then dropped its velocity, setting it on course to orbit Mercury.

Although it experienced difficulties along the way, Mariner 10 finally reached Mercury on March 29, 1974. It was the first of three flybys (the others on September 21, 1974, and March 16, 1975) that revealed a wealth of information about the planet. Photographs revealed that Mercury looked a lot like our moon, with bare ground and lots of craters. It differed from the moon, though, by the presence of “scarps”, markings which suggest that the planet’s crust had shrunk at some point in its history. The probe’s tests also revealed that Mercury has a small magnetic field – about 1/60th as strong as Earth’s. Mariner 10 also detected a faint helium atmosphere and a large iron-rich core. The probe’s findings estimate that Mercury has a nighttime temperature of -297º Fahrenheit and a daytime temperature of 369º Fahrenheit. Because of its orbit, Mariner 10 photographed the same side of Mercury on each flyby, so the 2,800 photos only capture about 40-45% of the planet’s surface.

On March 24, 1974, shortly after Mariner 10’s final flyby of Mercury, its transmitters were turned off. Though the probe has run out of fuel, scientists believe it could still be orbiting the Sun today. The information gathered by Mariner 10 led to even more questions, many of which were answered with the launch of the MESSENGER probe in 2004.

Click here to see some of the images captured by Mariner 10.

 
 

 

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US #2568
1991 Mercury

  • Part of set picturing nine planets and Earth’s moon
  • Issued as part of Stamp Collecting Month

Category of Stamp:  Commemorative
Set: 
Space Exploration
Value: 
29¢
First Day of Issue: 
October 1, 1991
First Day City: 
Pasadena, California
Quantity Issued: 
33,394,800
Printed by: 
Bureau of Engraving and Printing
Printing Method:
Photogravure
Format: 
Booklets – 2 panes of 10 in each
Perforations: 
11

Reason the stamp was issued:  The set of Space Exploration stamps was issued in honor of the Voyager 2 space probe passing Neptune and the 11th annual Stamp Collecting Month.

About the stamp design:  The Mercury stamp pictures the planet and the Mariner 10 space probe.  Launched in 1973, it flew by Mercury for the first time in March 1974, then passed the planet two additional times.

These stamps were the first by Ron Miller, a former artist for the Smithsonian Institution’s National Air and Space Museum.  He was asked to picture each of the Sun’s nine planets and the Earth’s moon with a spacecraft.  This was to tie in the idea of America’s exploration of space.  His original acrylic paintings were larger than those normally used for stamp art.  This was to show all the details of the spacecraft.

Special design details:  While most of the stamps name the spacecraft shown, the Pluto stamp has “not yet explored,” because no spacecraft had reached that planet at the time.  (The space probe New Horizons explored Pluto in 2015.)

First Day City:  The First Day of Issue ceremony took place at the Jet Propulsion Laboratory in Pasadena, California, on October 1, 1991, the start of Stamp Collecting Month.

Unusual thing about this stamp:  The USPS partnered with Paramount Studios to promote the stamps.  The studio was celebrating the 25th anniversary of the Star Trek movies and television series.  The stamp designs were unveiled on the bridge of the Starship Enterprise, the space vehicle featured in the series.  Flyers promoting the stamps were included in the packaging of Star Trek video cassettes.

About National Stamp Collecting Month stamps: October has been designated by the US Postal Service as National Stamp Collecting Month.  The first celebration occurred in 1981 as a way to promote the hobby of collecting stamps.  Each year, new stamps are issued in early October to stimulate additional interest, and many philatelic organizations hold special programs during the month.  The theme for the 1991 celebration was “Journey to a New Frontier… Collect Stamps.”

History the Space Exploration stamps represent:  Uncovering the mysteries of the universe has been a pursuit of scientists and dreamers for all time.  With the invention of telescopes, astronomers discovered some of the wonders of space.  With the space age, researchers began sending spacecraft outside of Earth’s orbit to gain further insight into the planets of our solar system.  Manned missions were followed by unmanned missions with the capability of traveling to distant planets.  These stamps show some of the spacecraft and the images of the planets they captured as they flew by.  Discoveries continue to be made with the space probes that still travel through our solar system.

History this stamp represents:

On March 29, 1974, Mariner 10 became the first space probe to fly by Mercury.

NASA launched the Mariner program in 1962 to build and send probes to investigate Mars, Venus, and Mercury. Prior to the launch of Mariner 10, earlier missions explored Mars and Venus.

Because Mariner 10 was destined to orbit Mercury, the planet closest to the sun, scientists faced new challenges in its design. The probe would have to withstand 4.5 times more solar radiation than when it departed Earth, requiring extra shielding to protect it. Mariner 10’s designers installed thermal blankets and a sunshade on the main body and made the solar panels adjustable so they wouldn’t overheat.

Mariner 10 was also the first spacecraft to use an interplanetary gravitational slingshot maneuver. In doing so, it would use Venus’ gravitational pull to bend its flight path into Mercury’s orbit. This would also put Mariner 10 in an orbit that would repeatedly bring it back to Mercury. In order for this to work, Mariner 10 couldn’t change its trajectory more than 120 miles, so mission planners stocked the probe with three times the amount of fuel as previous models. This would also allow it to make two additional flybys.

The probe was fitted with a number of instruments to gather information to send back to Earth. These included several cameras, which used more power than all the other instruments combined.   There was also an infrared radiometer to detect infrared radiation given off by both planets, which would help scientists to calculate their temperatures. Ultraviolet spectrometers were included to test whether Mercury had an atmosphere and to study the interstellar background radiation of Earth and Venus. Plasma detectors were added to study gases in the solar wind and observe Mercury’s magnetic field. However, a part of the probe didn’t open correctly, so not all of this information was collected. There were also charged particle telescopes and Magnetometers, both of which also studied Mercury’s magnetic field.

Construction on Mariner 10 was completed in June 1973, after which it underwent testing. After Mariner 10 completed it’s testing, NASA had a one-month window to launch it. They selected November 3, as it would provide the best imaging conditions when Mariner 10 was supposed to reach Mercury. The probe was launched that day at 12:45 a.m.

After a partial orbit of Earth, Mariner 10 was set on its path toward Venus. In its first week in space, Mariner 10 took five photomosaics of Earth and six of the Moon. It provided some of the best photos up to that time of the Moon’s North Pole region.

Item #M5470 – Mariner and Pioneer 10 First Day Covers set.

The journey to Venus was filled with technical malfunctions. According to one NASA scientist, “It seemed as if we were always just patching Mariner 10 together long enough to get it on to the next phase and next crisis.” Flaking paint repeatedly interrupted tracking and the on-board computer frequently reset itself. Mariner 10 approached Venus on February 5, 1974. Though several other probes had reached the planet before, Mariner 10 was the first to successfully send images back to Earth. The probe then dropped its velocity, setting it on course to orbit Mercury.

Although it experienced difficulties along the way, Mariner 10 finally reached Mercury on March 29, 1974. It was the first of three flybys (the others on September 21, 1974, and March 16, 1975) that revealed a wealth of information about the planet. Photographs revealed that Mercury looked a lot like our moon, with bare ground and lots of craters. It differed from the moon, though, by the presence of “scarps”, markings which suggest that the planet’s crust had shrunk at some point in its history. The probe’s tests also revealed that Mercury has a small magnetic field – about 1/60th as strong as Earth’s. Mariner 10 also detected a faint helium atmosphere and a large iron-rich core. The probe’s findings estimate that Mercury has a nighttime temperature of -297º Fahrenheit and a daytime temperature of 369º Fahrenheit. Because of its orbit, Mariner 10 photographed the same side of Mercury on each flyby, so the 2,800 photos only capture about 40-45% of the planet’s surface.

On March 24, 1974, shortly after Mariner 10’s final flyby of Mercury, its transmitters were turned off. Though the probe has run out of fuel, scientists believe it could still be orbiting the Sun today. The information gathered by Mariner 10 led to even more questions, many of which were answered with the launch of the MESSENGER probe in 2004.

Click here to see some of the images captured by Mariner 10.