Galileo Spacecraft: First Orbiter of Jupiter

Artist rendering of Galileo arriving at Jupiter

Artist rendering of Galileo arriving at Jupiter – Credit: NASA

Space Shuttle Atlantis carried a special payload during its STS-34 mission. Commander Don Williams and crew transported the Galileo spacecraft into Earth orbit, from which point it was launched on a years-long voyage to Jupiter. Galileo would become the first spacecraft to orbit an outer planet and would go on to reveal fascinating views of the gas giant and its moons, as well as make monumental discoveries about the nature of the Jovian system.


Quick Facts:

  • Launch Date: October 18, 1989, Shuttle Atlantis STS-34
  • Primary Mission: October ’89 to December ’97.
  • Extended Missions: 3, from ’97 to ’03.
  • Number of Jupiter orbits: 34
  • Total distance traveled during mission: 4,631,778,000 km (approx 2.8 billion miles)
  • Mission End: September 21, 2003

Getting Galileo to Jupiter

Work on the Galileo craft began in 1977, after the exploration of Jupiter was listed as the number one priority in the Planetary Science Decadal Survey published in 1968. Fly-bys of the massive planet were conducted by the twin Pioneer 10 and 11 and Voyager 1 and 2 spacecrafts, but Galileo was set to do more than just perform a fly-by. It would launch an instrument-laden probe into Jupiter’s atmosphere, and then continue to orbit the planet for years. This mission would provide knowledge of the Jupiter system that could hardly even be imagined.

Galileo deploying from Shuttle Atlantis

Galileo deploying from Shuttle Atlantis – Credit: NASA

Galileo suffered a number of postponements. The first planned launch was to be from Space Shuttle Columbia in 1982, but development delays in the Space Shuttle program made that early of a launch unfeasible. The upside is that this gave the Galileo developers more time to work on the probe. Further planned launches and postponements occurred in 1984, 1985, and 1986.

As we all know, 1986 was the year of the Challenger disaster. Galileo would be put on hold during the 32-month hiatus that followed the tragedy, as every detail of the Shuttle program was examined and made safer. Galileo was originally planned to be attached to a liquid hydrogen-fueled Centaur-G booster; however, new safety protocols following Challenger prohibited the booster from being carried in the Space Shuttle’s payload bay. Mission designers had to reconsider how they would get Galileo from the Shuttle’s low Earth orbit to Jupiter. They decided on employing a solid-fuel Inertial Upper Stage booster (IUS). Whereas the Centaur-G would have propelled Galileo on a short and direct trajectory to Jupiter, the IUS would take longer and also require some technical gravitational slingshot maneuvers to make it to the gas giant.

Galileo was finally launched from Space Shuttle Atlantis, during mission STS-34 on October 18, 1989. From there, its IUS booster was started and it began its unique “VEEGA”, or Venus Earth Earth Gravity Assist, maneuvers.

Galileo spacecraft trajectory

Galileo spacecraft trajectory – Source: NASA

  • Galileo flew by Venus on February 10, 1990 at an altitude of 16,000 km (10,000 miles).
  • It then flew by Earth on December 8, 1990 at an altitude 960 km (597 miles).
  • Its trajectory took it near Asteroid Gaspra on October 29, 1991, coming within 1,601 km (1,000 miles).
  • Then it was back to another Earth fly-by on December 8, 1992, this time at an altitude of only 303 km (188 miles).
  • On its way back towards the outer solar system it flew by Asteroid Ida on August 28, 1993, coming within 2,400 km (1,400 miles) of the asteroid.

On its way to Jupiter, Galileo was positioned perfectly to observe the doomed Comet Shoemaker-Levy 9 as it impacted the planet. Pieces of the comet, having been torn into fragments by Jupiter’s immense tidal forces, impacted Jupiter from July 16 – 22, 1994, on the side facing away from Earth. Fortunately, Galileo had a prime view and was able to record the impact. Earth-based telescopes could only observe the impact sites as they rotated into view a few minutes afterwards.

In July, 1995, Galileo released its atmospheric probe component. For the next five months, the probe and orbiter continued their cruise to Jupiter. On December 7, 1995, Galileo had arrived. The orbiter and probe diverged onto their separate missions.

Atmospheric Probe

On December 7, 1995 Galileo’s atmospheric probe sliced into Jupiter’s atmosphere at 47.6 kilometers per second (106,000 miles per hour). As the atmosphere began to slow the probe, it deployed its drogue and main parachutes and dropped its heat shield to expose its scientific instruments. The probe began recording data and transmitting it up to the main Galileo spacecraft orbiting high above, which then re-transmitted the data to Earth. The probe recorded 58 minutes of data on Jupiter’s weather and atmosphere. Towards the end of its descent, the probe measured wind speeds of 724 kilometers per hour (450 miles per hour). The intense heat and pressure of Jupiter’s atmosphere melted and vaporized the probe less than an hour into its journey through Jupiter’s atmosphere.

Orbiter

While the atmospheric probe’s job was complete, the Galileo orbiter still had years of work left to do. The orbiter received its electric power from two radioisotope thermoelectric generators (RTGs). That may sound complicated, but it’s really quite simple. These RTGs carry the radioactive element plutonium-238. As the plutonium decays, it releases energy in the form of heat. That heat can then be easily turned into electricity through the Seebeck effect. This type of energy generation is long-lasting and reliable, as well as impervious to the cold temperatures and strong radiation fields of the Jupiter system. Galileo carried two of these RTGs, with a combined total of approximately 22.7 kilograms (50 pounds) of plutonium-238. While these radioactive components had been used on previous space missions, Galileo drew extra concern due to it being both carried by the Shuttle as well as the multiple Earth fly-bys. Anti-nuclear activists protested Galileo’s launch, fearing a malfunction could cause radiation poisoning for many thousands of people on Earth. NASA, however, argued that the probability of risk was extremely low.

Jupiter's ring system, as observed by Galileo

Jupiter’s ring system, as observed by Galileo – Credit: NASA/JPL/Cornell University

Galileo conducted slow orbits of Jupiter, approximately 2 months long each. The orbits were elongated, and designed to bring the spacecraft within different distances to Jupiter, which allowed it to sample different areas of the planet’s magnetosphere. These orbits were also designed to bring Galileo and its instruments into close fly-bys of Jupiter’s largest moons. Galileo completed its primary mission on December 7, 1997; however, the craft was still functioning extremely well and was able to continue taking measurements and sending valuable data back to Earth. Its mission was extended three times, operating until 2003.

Volcanic activity on Io, as observed by Galileo

Volcanic activity on Io, as observed by Galileo – Credit: NASA/JPL

The orbiter made several discoveries during its mission:

  • It discovered a possible ocean under Europa’s icy crust
  • Revealed Ganymede’s very own magnetic field, the only moon known to have this feature
  • Made the first observations of ammonia clouds in another planet’s atmosphere
  • It created hundreds of images of Jupiter’s large ‘Galilean moons’: Io, Callisto, Europa, and Ganymede
  • It measured the high levels of volcanic activity on Io

Sagan Criteria for Life

The late astronomer Carl Sagan devised a set of experiments to be conducted by Galileo during its first fly-by of Earth. The purpose of the experiments was to see if life could be easily detected from a spacecraft. The results of the experiments were published by Sagan in 1993, in the scientific journal Nature. The experiments were a success, as Galileo was easily able to detect what are referred to as the ‘Sagan requirements for life’. These include strong absorption of light at the red end of the spectrum (indicative of plant photosynthesis), absorption bands of molecular oxygen (again, indicative of plant life), the detection of methane in the atmosphere (a gas created by either volcanic or biological activity), and the detection of narrowband radio wave transmissions (could indicate a technologically advanced civilization).


By the end of its mission, Galileo had conducted 34 orbits of Jupiter and had made multiple fly-bys of Jupiter’s moons: Io 7 times, Callisto 8 times , Ganymede 8 times, Europa 11 times, and one fly-by of Amalthea.

Due in part to Galileo’s discovery of potential oceans on Europa (and possibly other Jovian moons), the decision was made to end the orbiter’s mission by sending it to the same fate as the atmospheric probe eight years prior. Rather than risk contaminating (with either Earth bacteria or radiation from the RTGs) one of Jupiter’s potentially life-harboring moons, Galileo would be ordered to impact Jupiter. On September 21, 2003, Galileo entered Jupiter’s atmosphere at 48.2 kilometers per second (108,000 mph).

The Galilean Moons: Jupiter's four largest satellites

The Galilean Moons: Jupiter’s four largest satellites – Credit: NASA/JPL/DLR

The total mission cost was approximately $1.4 billion USD, had more than 100 scientist partners from many different countries, and involved the work of more than 800 individuals.

In spite of postponements, an antenna that failed to fully deploy, and a tape recorder malfunction, Galileo performed magnificently. It was a mission that brought us up close and personal with our Solar system’s largest planet and provided us with a much more detailed understanding of the Jovian system. Galileo paved the way for future studies of Jupiter and its moons. Its successor, the Juno orbiter, is currently en route and arriving in July of 2016, and plans are being considered to investigate Europa’s oceans. Like the astronomer that the spacecraft took its name from, Galileo Galilei, this mission revealed new worlds that we previously could only distantly wonder about.

 

Soyuz Spacecraft Returns to Earth: Year-In-Space Mission Ends

The image below shows the Soyuz TMA-18M spacecraft’s return to Earth, on March 2nd, 2016. Inside are NASA astronaut Scott Kelly, and Russian cosmonauts Mikhail Kornienko and Sergey Volkov. Both Kelly and Kornienko spent almost an entire year in space aboard the International Space Station, in a research effort to understand the health impacts of long-term spaceflight.

Soyuz TMA-18M spacecraft, floating back to Earth

Soyuz TMA-18M, floating back to Earth – Credit: (NASA/Bill Ingalls)

Click the image for an even gorgeous-er huge version.

Isn’t that image simply amazing?

In Memoriam: Captain Donald Edward Williams

Captain Donald Edward Williams

 

Captain Donald Edward Williams passed away on Tuesday, February 23, 2016. He was 74.

Early Life, Education, and Military Service

Donald Edward Williams was born on February 13, 1942, in Lafayette, Indiana. He grew up working on his father’s farm, spending his time after school running tractors, tending to animals, and completing general repairs. While working, he always took note of the jets flying overhead and thought to himself that being up there looked like a lot more fun that what he was doing down in the dirt. He graduated Otterbein High School, Otterbein, Indiana, in 1960 before earning a bachelor of science degree in Mechanical Engineering from Purdue University. At Purdue, he received his commission through the Naval Reserve Officers Training Corps (NROTC). He completed flight training in Florida, Mississippi, and Texas, earning his pilot wings in 1966.

Williams completed a total of  four deployments to Vietnam, aboard USS Enterprise, as a member of Attack Squadron 113 and Attack Squadron 97. During his deployments, he flew a total of 330 combat missions. After Vietnam, Williams enrolled at the Armed Services Staff College, graduating from the U.S. Naval Test Pilot School in 1974.

Williams was selected as a member of the NASA class of 1978, also known as Astronaut Group 8 or the Thirty Five New Guys (which, I must point out, included gals, too). This was the first new group of astronauts since 1969. He served in various capacities at NASA until being pegged to serve on two separate Space Shuttle missions:

STS-51-D

STS-51-D Mission Patch

STS-51-D Mission Patch

He served as pilot on Space Shuttle mission STS-51-D, which was completed on shuttle Discovery in 1985. That mission included completing a number of experiments (including some utilizing simple toys, with the results being shared with school students), and launching a couple of satellites. One of the satellites malfunctioned upon deployment. As a result, NASA authorized its first unscheduled 3-hour EVA (extravehicular activity).

According to the book, Discovery: Champion of the Space Shuttle Fleet:

The mission became an ingenious effort to avert failure by improvising a difficult rescue without prior training. As engineers and astronauts on the ground devised a solution, they sent instructions to the crew to use on-board materials to make something like a flyswatter and a lacrosse stick.

 

Additionally, that Discovery mission included the first elected government official to fly in space. Utah Senator Edwin Garn joined the crew as Payload Specialist 2, acting as a congressional observer to the program. (Talk about perks of the job!)

STS-34

STS-34 Mission Patch

STS-34 Mission Patch

Williams served as Commander of his second and final spaceflight in 1989, on mission STS-34 aboard shuttle Atlantis. A notable accomplishment of that mission was the deployment of the Galileo spacecraft, which became the first spacecraft to orbit and penetrate the atmosphere of an outer planet.

In a 2002 interview with Rebecca Wright, as part of a NASA Johnson Space Center Oral History Project, Williams reflected on the STS-34 mission:

I really enjoyed that mission probably even more so than the first because it was my goal to command a mission, first of all, and I got to do that. But secondly, because we knew that Galileo was going to be a lasting program as opposed to the first flight, [where] we deployed the two satellites, [but] it turned out to be a unique flight, too, because of the spacewalk. The Galileo mission we knew, if it was successful, the spacecraft was going to end up in orbit around Jupiter several years later and then there [were] going to be several years of data and images sent back. It was going to be a living, ongoing program, and we got to be a part of it. That was a really unique experience.

Post-NASA

Williams retired from the U.S. Navy, having earned the rank of Captain, and left NASA. He completed numerous projects as a Division Manager with Science Applications International Corporation before his retirement in 2006.

During Williams’s career, he earned the following special awards and commendations: The Legion of Merit, Distinguished Flying Cross, Defense Superior Service Medal, 2 Navy Commendation Medals with Combat V, 2 Navy Unit Commendations, a Meritorious Unit Commendation, the National Defense Medal, an Armed Forces Expeditionary Medal, the NASA Outstanding Leadership Medal, the NASA Space Flight Medal, the NASA Exceptional Service Medal, the Vietnam Service Medal (with 4 stars), a Vietnamese Gallantry Cross (with gold star), and the Vietnam Campaign Medal.

From his roots as a rural farm-boy with his eyes in the sky, to serving his country valiantly in four deployments during the Vietnam war, and finally having the honor to fly two space shuttle missions as a Pilot and a Commander, Donald E. Williams was a true American hero. He was among the best of the best and should serve as an inspiration for centuries to come. We thank you for your service and honor your legacy.

Godspeed, Mr. Williams.

NASA Astronaut Don Williams aboard Space Shuttle Atlantis

NASA Astronaut Don Williams aboard Space Shuttle Atlantis – Source: NASA

 

Explorer 1: America's First Space Satellite

Explorer 1

Explorer 1 – Source: NASA

You probably know that Russian Sputnik satellite was the first human-made satellite to be placed into orbit. If not, I’m guessing you’ve at least heard of it. While the Russians beat the United States in that first declaration of space dominancy, America wasn’t far behind. Today we learn the story of the United States’s first orbital satellite: Explorer 1 1.

Towards the end of 1957, news of the Russian’s space accomplishments was rocketing around the world. Their successful Sputnik spacecrafts had recorded new entries in world history: Sputnik 1 was the first human-made object put into Earth orbit; and Sputnik 2 carried the first living creature larger than a microbe, a poor dog sacrificed in the name of science, named Laika.

The United States’s credibility was in question. Could the US compare to the Russian’s space prowess?

News of Sputnik’s milestones kickstarted an otherwise stalled United States space satellite program. The United States Army Ballistic Missile Agency (ABMA), directed by Wernher von Braun, teamed up with the federally-funded research facility, JPL (Jet Propulsion Laboratory) under the direction of Dr. William H. Pickering. JPL designed the Explorer 1 craft, while the ABMA modified one of its Jupiter-C rockets (gaining the designation Juno 1) to carry Explorer 1 payload into orbit.


A few months prior, in December of 1957, the United States Navy had attempted to put the first US satellite in orbit. That rocket made it about four feet above the launchpad before failing catastrophically in a magnificent ball of fire. Its failure earned such laughable nicknames as: Flopnik, Stayputnik, Oopsnik, and my favorite, Kaputnik.


Rapid work began on the satellite and launch system, and in only 84 days they had completed the design, construction, and assembly of Explorer 1 and its complementary rocket.

Explorer 1 schematic

Explorer 1 schematic – Source: NASA

Explorer 1 consisted of two major components: the 37.25 inch scientific portion, containing science and communication instruments, mated to a 45.5 inch rocket booster. This package was placed atop the 70-foot-tall Juno 1: a four-stage, Redstone-family booster rocket.

Explorer 1 launched from Cape Canaveral, Florida, at 10:48pm local time on January 31, 1958.

Explorer 1 entered an eccentric orbit around Earth, with the closest point in its orbit at 358 kilometers (222 miles) and its furthest at 2,550 kilometers (1,580 miles). It completed an orbit every 114.8 minutes. Mercury batteries powered the craft’s high-power transmitter for 31 days, with the low-power transmitter operational for 105 days. Explorer 1’s final transmission was received on May 23, 1958. The silent Explorer 1 continued to orbit for more than 12 years, its orbit finally decaying to the point of re-entry and destruction in the atmosphere over the Pacific on March 31, 1970. By then, it had completed more than 58,000 orbits.

Explorer 1 effectively initiated the Cold War space race. But it did more than just prove that the United States could compete with the Russians in putting things in orbit. Explorer 1 conducted real science and made some important discoveries that would be important to understand as the world progressed into a space-faring society.

Explorer 1 contained two main scientific instruments: one for detecting cosmic rays, and another for studying micrometeorites.

The micrometeorite package consisted of a “wire grid (arrayed around the aft section of the rocket body) and an acoustic detector (placed in contact with the midsection)“. Over the course of the experiment, 145 micrometeorite hits were detected.

The cosmic ray detection equipment made even greater discoveries. This was accomplished by an “Anton 314 omnidirectional Geiger tube detector“, which measured the flux of charged particles hitting the detector. The experiment was overseen by Prof. James A. Van Allen.

A peculiarity was noted in this experiment: the expected radiation count was approximately 30 per second, but the detector would occasionally return a result of zero. It was determined that these zero count intervals coincided with altitudes greater than 2,000 kilometers (1,200 miles). Further research determined that at those altitudes, the detector was actually being over-saturated and overwhelmed by the radiation. This led to the discovery of an energetic belt of charged particles that surround magnetized planets , such as Earth. This belt was named after James Van Allen, and today are known as Van Allen radiation belts. Knowledge of this region would become essential to the survival of humans that would travel through them in later space programs. The discovery was designated as one of the greatest of the International Geophysical Year.

William Hayward Pickering, James Van Allen, and Wernher von Braun at a press conference announcing the orbital insertion of Explorer 1.

William Hayward Pickering, James Van Allen, and Wernher von Braun at a press conference announcing the successful orbit insertion of Explorer 1 – Source: NASA

At around 1:00 am on February 1, 1958, just hours after Explorer 1’s successful orbit insertion was verified, William Hayward Pickering, James Van Allen, and Wernher von Braun were ushered to the National Academy of Sciences building in Washington, D.C.  to conduct a press conference that would make headlines around the globe.

That press conference produced one of the most iconic images of the Space Age. In the image, Pickering, Van Allen, and von Braun stand triumphantly, holding a model of Explorer 1 high above their heads.

A Moment in Time: Explorer 1 – Each of these three men thus represented a component of Explorer 1’s success: the rocket, the satellite and the science payload. Each represented an institutional underpinning crucial to the fledgling American space program: the Army, the Jet Propulsion Laboratory and scientific research as represented by the University of Iowa. Each had converged from his own path to the singular moment depicted in the triumphal image.

 

The success of Explorer 1 can’t be overstated. It proved the efficiency that could be achieved through collaboration between civilian and military agencies, it was one of the major sparks that ignited the Cold War space race, and it confirmed the United States as a powerful contender to the Russians.

  1. At the time of launch, also designated as Alpha 1958

Cosmic Paparazzi: Cat's Eye Nebula

The Cat's Eye Nebula

The Cat’s Eye Nebula – Credit: NASA, ESA, HEIC, and The Hubble Heritage Team (STScI/AURA)

(Click the image for a larger version)

Hubblesite.org: The Cat’s Eye Nebula, one of the first planetary nebulae discovered, also has one of the most complex forms known to this kind of nebula. Eleven rings, or shells, of gas make up the Cat’s Eye.

We recently checked out Supernova 1987A. If you remember, I told you that when massive (8 times the mass of the Sun or greater) stars die they explode in a supernova and leave behind either a neutron star or a black hole, surrounded by a supernova remnant.

When a low mass star (less than 8 times the Sun’s mass) dies, it leaves behind a white dwarf and a planetary nebula. An example of which is shown above, the Cat’s Eye Nebula (also designated NGC 6543). 4 or 5 billion years from now, our own Sun will undergo this very same process.

Perhaps our distant ancestors, or even members of an alien species, will look towards the vicinity of our former home in the galaxy and capture an image just as beautiful.

SN 1987A

2006 Hubble image of SN 1987A

2006 Hubble image of SN 1987A – Source: Hubblesite.org

At about the time our human ancestors started wearing clothes, something amazing was happening in a nearby dwarf galaxy. There, a star about 18 times more massive than our own Sun, was reaching its catastrophic, yet beautiful, end.

This star, named Sanduleak -69° 202, was a blue supergiant located on the outskirts of the Tarantula Nebula in the Large Magellanic Cloud. As is the case with these types of stars, it had the mass to not only fuse hydrogen and helium, like our own Sun, but heavier elements as well. The star would have began fusing those lighter elements, but then progressing through the periodic table until the star had produced a core of iron and nickel.

Up until that point, the energy output of the fusion process would have generated enough outward pressure to keep the star’s mass from caving in on itself. However, once a star begins fusing nickel and iron, there is no net energy output. When this equilibrium is broken, the mass of the outer layers of the star begins compacting onto its core. As the mass continues to, well… amass, there’s a point in which the star can no longer be stable. This is known as the Chandrasekhar limit.

When Sanduleak -69° 202 exceeded the Chandrasekhar limit, a cataclysmic implosion occurred over the course of mere seconds. The outer core, no longer supported by the now-imploded inner core, collapsed. This sudden compression generated temperatures of up to 100 billion kelvin. The resulting physics produced an unimaginable shockwave which had enough force to accelerate the overlying stellar material into an escape velocity. The mass was sent away from what’s left of the star’s core and left behind an expanding cloud of stellar debris and a neutron star (stars with an even higher initial mass can collapse into a black hole). One thing to note here: while the existence of a neutron star is expected as a result of this supernova, searches thus far have been unsuccessful. Check out this link to learn more about the missing neutron star.

About 170,000 years later, the light from that supernova finally reached Earth where it was observable with the naked eye in the southern hemisphere. It was first discovered by Ian Shelton and Oscar Duhalde at the Las Campanas Observatory in Chile, on February 24, 1987 (here’s the telegram that announced the discovery).


Supernovae are named by using the following convention: “SN ” followed by 4-digit year of its discovery, and ending with alpha-sequence indicating the order in which that year’s supernovae were discovered. Thus, this being the first supernova discovered in 1987 was given the designation: SN 1987A.


SN 1987A Today

Today SN 1987A is still there. Actually, I need to be a little more nuanced with this part. When we look at distant objects in space, we’re actually looking into the past. We’re seeing them as they existed however long ago it took the light to get from there to us. SN 1987A is about 170,000 light years from us, which explains why something that happened during the lives of some of our most distant ancestors was only seen by us in 1987. So we don’t know what exactly is going on in the vicinity of SN 1987A today (though physicists could provide with some great theories), we can image exactly what it looked like 170,000 years ago.

Modern image of Supernova SN 1987A

Modern image of Supernova SN 1987A – Source SpaceTelescope.org

SN 1987A as imaged by Hubble in 1994

SN 1987A as imaged by Hubble in 1994. – Source: SpaceTelescope.org

Supernovae are a common occurrence in our universe, if only because of its vast size. In a galaxy such as the size of the Milky Way, you can expect an average of two per century. However, these supernovae are so bright we’re able to identify many of them each year from around the observable universe. When stars explode, the brightness often surpasses that of the entire galaxy from within it occurred.

Play the video below for an artist’s depiction of a collection of distant galaxies.  Watch for the occasional supernova to get an idea of just how bright these can appear.

One could only hope to have as beautiful of a death.

John Glenn’s Orbital Journey

On this day in 1962, the Atlas rocket boosters that John Glenn, inside his Friendship 7 capsule, was strapped to the top of ignited. Millions of Americans watched as the resulting 350,000 pounds of thrust vibrated the vehicle that was about to take the first American into orbit around the Earth.

CAPCOM (Capsule Communicator): 3… 2… 1… 0.
John Glenn: Roger. The clock is operating. We’re underway.

Launch of Friendship 7

Launch of Friendship 7, the first American manned orbital space flight. Astronaut John Glenn aboard, the Mercury-Atlas rocket is launched from Pad 14. / Source: NASA

Minutes later, John Glenn became the fifth human in space and the first American to enter Earth orbit. Previously, Alan Shepard and Gus Grissom became the first and second, respectively, Americans in space; however, John Glenn was the first American to reach the important milestone of completing orbits of the Earth.

For the next 4 hours and 55 minutes, John Glenn completed three orbits of the Earth, reaching speeds greater than 17,000 miles per hour. NASA was still concerned about the effects of spaceflight on humans and this was the longest one an American astronaut had been subjected to yet. John Glenn remarked a number of times during the mission that he felt just fine, and was rather enjoying himself.

Five minutes into the mission:

John Glenn: Oh, that view is tremendous!

View of Earth from Friendship 7

View of earth taken by Astronaut John H. Glenn Jr. during his MA-6 spaceflight. / Source: NASA

John Glenn witnessed three sunsets from space during the flight.

John Glenn: The sky above is absolutely black, completely black. I can see stars though up above.

John Glenn: This is Friendship Seven. At this, MARK, at this present time, I still have some clouds visible below me, the sunset was beautiful. It went down very rapidly. I still have a brilliant blue band clear across the horizon almost covering my whole window. The redness of the sunset I can still see through some of the clouds way over to the left of my course. Over.

Sunset from Friendship 7

Orbital sunset photographed by Astronaut John H. Glenn Jr. aboard the \”Friendship 7\” during his Mercury-Atlas 6 (MA-6) flight. / Source: NASA

From his fantastic vantage point, he observed dust storms and fires in Africa and the lights of Perth, Australia.

And then there was his “fireflies”, which he first noticed at about 1 hour and 15 minutes into the flight:

John Glenn: This is Friendship Seven. I’ll try to describe what I’m in here. I am in a big mass of some very small particles, that are brilliantly lit up like they’re luminescent. I never saw anything like it. They round a little: they’re coming by the capsule, and they look like little stars. A whole shower of them coming by.

They swirl around the capsule and go in front of the window and they’re all brilliantly lighted. They probably average maybe 7 or 8 feet apart., but I can see them all down below me, also.

CAPCOM: Roger, Friendship Seven. Can you hear any impact with the capsule? Over.

John Glenn: Negative, negative. They’re very slow; they’re not going away from me more than maybe 3 or 4 miles per hour. They’re going at the same speed I am approximately. They’re only very slightly under my speed. Over.

They do, they do have a different motion, though, from me because they swirl around the capsule and then depart back the way I am looking.

Are you receiving? Over.

There are literally thousands of them.

These “fireflies”, as Glenn called them after the mission, were later determined to be ice crystals that would accumulate on the craft on the dark side of the Earth and then begin to break off of the capsule when the Sun’s heat returned. 1

Back on the ground, serious considerations were being made. A flight controller received a warning from a sensor on Friendship, indicating a loose heat shield. If the sensor was correct in its reading, the only thing holding the heat shield in place was the straps from the retrorocket package. After debate, a decision was made; Glenn was instructed to refrain from jettisoning the retropack — a normal procedure for re-entry — in hopes that it would hold the heat shield in place during re-entry; the alternative was the craft and Glenn disintegrating in the Earth’s atmosphere. Control offered no explanation for the procedure until after successful re-entry. Glenn suspected a problem with the heat shield, but remained focused on the parts of the craft he could control.

CAPCOM: This is Texas Cap Com, Friendship Seven. We are recommending that you leave the retropackage on through the entire reentry.

John Glenn: This is Friendship Seven. What is the reason for this? Do you have any reason? Over.

CAPCOM: Not at this time; this is the judgment of Cape Flight.

The sensor ultimately proved to be faulty and the heat shield remained securely attached to Friendship. 2

Aside from using more fuel than expected for attitude corrections, a hot spacesuit that had to be regularly adjusted for cooling, and excess cabin humidity, the rest of the flight was essentially flawless.

Glenn fired his retrorockets and descended back to Earth. He splashed down in the Atlantic, 40 miles downrange from the expected landing site. The USS Noa reached Friendship seventeen minutes later and hoisted it onto the ship. Glenn was supposed to exit the capsule from the top hatch, but instead decided to blow the side hatch instead. With a loud bang, the hatch blew open and Glenn emerged and jumped to the deck of the Noa. With a smile, his first words were: “It was hot in there.”

Astronaut John H. Glenn Jr. in his Mercury spacesuit

Astronaut John H. Glenn Jr. in his Mercury spacesuit. / Source: NASA

Glenn returned to a hero’s welcome and a ecstatic ticker-tape parade in New York City. Americans were energized with the progress in the race with the Soviets. And with John Glenn’s help, America — and mankind itself — took another step forward into the uncharted heavens above.

*This post was originally published February 20, 2011. Small updates have been made since then.


  1. In fact, it was solved during the next Mercury mission, Aurora 7, by Scott Carpenter. To test his theory, he banged on the side of the capsule and watched as they broke off of the exterior of the craft!
  2. And it provided a nice fireworks show for Glenn during re-entry. “My condition is good, but that was a real fireball, boy. I had great chunks of that retropack breaking off all the way through.”

Clyde Tombaugh Discovers Pluto

*click* ….. *click* …. *click* …. *click*

On this day in 1930, a 24-year-old man named Clyde Tombaugh was squinting into the Lowell Observatory’s Zeiss Blink microscope. The unique device, also known as a blink comparator, held two photographic plates that each contained the image of a star field taken the previous month–the images showing the same section of sky, taken a few days apart. Tombaugh could rapidly switch between the two images by rotating a dial, allowing him to quickly compare the images and watch for any variations between the two that would indicate a body moving more rapidly than the background stars (eg. planets, asteroids, etc.).

*click* ….. *click*

Late into that February afternoon, a subtle difference between the two images caught his eye.

Animation comparing Tombaugh's star fields.

Can you spot Pluto?  Click on the image to see a version with Pluto identified.   Image Credit: National Air & Space Museum

 

*click* … *click* … *click* .. *click* . *click* *click*

He spent 45 minutes comparing the two images. Convinced of his findings, he contacted his supervisors. Over the next couple of weeks, the observatory focused its attention to the object before confirming Tombaugh’s discovery. On May 1st, 1930, a new planet was introduced to the world: Pluto.

And of course, in 2015, we got to see Pluto in a way that Mr. Tombaugh himself could only have imagined.

NASA’s New Horizons spacecraft captured this high-resolution enhanced color view of Pluto on July 14, 2015.

NASA’s New Horizons spacecraft captured this high-resolution enhanced color view of Pluto on July 14, 2015.        Source: NASA

Dwarf Planet Ceres

PIA19064-Ceres-DwarfPlanet-StillImage-20150414

Previously, I told you the fascinating story of Ceres’s discovery and complicated identity crisis; now I’m ready to tell you about the dwarf planet specifically.

 

Let’s take a quick trip out beyond our Moon, past Mars (if you find yourself at Jupiter, you’ve gone too far), and into the realm that is commonly known as the asteroid belt. Now, contrary to popular depictions, the asteroid belt isn’t crammed full of asteroids. As a kid, I remember seeing illustrations of the asteroid belt that made it look as densely packed as Saturn’s rings. That depiction is a gross exaggeration. In fact, while there are billions of bodies orbiting out in the asteroid belt–it is believed that there are somewhere between 1 and 2 million asteroids with a diameter of 1 kilometer or more–the area is still mostly just empty space. If you were to board a rocket that would fly through the asteroid belt, the chances of actually smacking into anything are extremely slim. Of the asteroids in the belt that have a diameter of 10 km or more, a collision is only likely to occur about once every 10 million years. So anyway, this is the home of one such body, the dwarf planet Ceres.

Compared to the other bodies in the asteroid belt, Ceres is huge. Ceres has a diameter of 950 kilometers (590 miles). This is a little smaller than the width of Texas or Montana. Ceres comprises between a quarter and a third of the mass of the entire asteroid belt. King among the asteroid belt, Ceres falls short when facing up against the other planets in our solar system. Compared to Earth and the Moon, Ceres has the mass of .00015 that of the Earth and .0128 that of the Moon. (For some perspective, it would take almost 80 Cereses to equal the mass of just the Moon.)

Size comparison of Earth, the Moon, and Ceres.

Size comparison of Earth, the Moon, and Ceres.

 

Ceres orbits the Sun at an average distance of 415 million kilometers (257 million miles), in a nearly circular orbit. At this distance from the Sun, and at the speed that Ceres is traveling, one year on Ceres is equivalent to 4.6 years on Earth.

Ceres is believed to consist of a thin, dusty crust situated above a fairly thick layer of water-ice. At the center of the dwarf planet is a thick rocky core.

Cutaway image showing Ceres's layers.

Cutaway image showing Ceres’s layers.
“Ceres Cutaway” by NASA, ESA, and A. Feild (STScI)

 

Ceres, of course, has less mass than the Earth, and thus you would weigh less standing on a scale on Ceres than you would on Earth.  If you weigh 150 pounds on Earth, then you weigh a mere 4.2 pounds on Ceres!

Ceres is one of the latest planets to be explored by high-tech modern spacecraft. NASA’s Dawn spacecraft is currently orbiting the dwarf planet at a just recently arrived distance of only 2,700 miles above its surface. For about a month, Dawn will orbit and study Ceres from this location. The spacecraft will complete an orbit every three days, constantly kicking images and other important data back to Earth. For some perspective, the resolution Dawn can obtain while imaging Ceres is somewhat comparable to what it would be like for you to observe a soccer ball from 10 feet away. Subsequent to the 2,700 mapping orbit, Dawn will venture even closer to the dwarf planet providing better and better views of Ceres. By the end of 2015, Dawn will be concluding its mission at an altitude of only 230 miles. Dawn’s cameras at this distance will be able to produce images with a resolution 850 times greater than that of what Hubble would be able to produce. Now, that soccer ball is a mere 3.3 inches away! At this distance, Dawn will be in a fairly stable orbit around the dwarf planet and is expected to become its satellite into perpetuity.

I’ll have more to share about Dawn soon.

For now, let’s all celebrate the fact that we’re still exploring–exploring not just planets and asteroids and moons, but exploring actual worlds. Let’s celebrate the fact that we’re learning new things about this particular world on a daily basis and that this will continue for many months to come. And, let’s celebrate the fact that with all that we know today, it’s a tiny amount compared to what we still get to learn in the future. Having a lot to learn, I think, is much more exciting than already knowing it all.

Ceres–Either the Most or Second-Most Popular Dwarf Planet

It has been nearly a decade since the International Astronomical Union (IAU) formally defined the word ‘planet’, resulting in the reclassification of Pluto as a ‘dwarf planet’. Some people still remain upset about the decision, considering the new classification as a demotion. If you roll with the kinds of people that I do, battle-lines have been drawn around the issue and many a friendship have been lost in the process. I don’t want to rekindle those debates (this is likely inevitable, however, as Pluto will be in the news quite a bit in the coming months as New Horizons is finally about to have its encounter with the dwa… whatever-you-want-to-call-it), so let’s take a look at a dwarf planet that appears to have finally found comfort in its classification: Ceres.

Color view of Ceres as imaged by Hubble in 2004 - Credit: NASA, ESA, J. Parker (Southwest Research Institute), P. Thomas (Cornell University), L. McFadden (University of Maryland, College Park), and M. Mutchler and Z. Levay (STScI)

Color view of Ceres as imaged by Hubble in 2004 – Credit: NASA, ESA, J. Parker (Southwest Research Institute), P. Thomas (Cornell University), L. McFadden (University of Maryland, College Park), and M. Mutchler and Z. Levay (STScI)

If you thought Pluto’s designation was complicated and controversial, just wait until you Ceres’s story.

Ceres has had a bit of an identity crisis of its own. Italian astronomer Giuseppe Piazzi discovered Ceres on New Years Day, 1801. He at first thought it was a star, but observed its movements against the stellar backdrop over the course of a few days and determined it to be a planet. He took a conservative approach in his announcement however, by referring to it as a comet.

I have announced this star as a comet, but since it shows no nebulosity, and moreover, since it had a slow and rather uniform motion, I surmise that it could be something better than a comet. However, I would not by any means advance publicly this conjecture. – Giuseppe Piazzi in a letter to fellow Italian astronomer Barnaba Oriani

With the help of other astronomers and using a method for calculating orbits developed by Carl Friedrich Gauss, it was confirmed that the object was not a comet, but in fact some sort of small planet. German astronomer Johann Bode had been promoting his hypothesis that planets orbited their host stars at distances that could predicted by mathematics. This hypothesis predicted a planet should exist between Mars and Jupiter. When Bode heard news of Piazzi’s discovery of an object at precisely that location, he rushed to announce that the missing planet had been located and even went as far as to name it himself. The name he gave: Juno. Piazzi, however, had taken the liberty as the new planet’s discoverer to give it the name ‘Ceres Ferdinandea’, honoring the patron goddess of Sicily and King Ferdinand of Bourbon. Piazzi rightfully objected to Bode’s stake on naming rights:

“If the Germans think they have the right to name somebody else’s discoveries they can call my new star the way they like: as for me I will always keep it the name of Cerere and I will be very obliged if you and your colleagues will do the same.” Piazzi in a letter to prominent astronomer and editor of scientific journals, Franz Xaver von Zach.

Piazzi’s name ultimately won out, though it was shortened to its currently-accepted name: Ceres.

"Giuseppe Piazzi" by F. Bordiga - Image from Smithsonian Institute Library

“Giuseppe Piazzi” by F. Bordiga – Image from Smithsonian Institute Library

After more objects were discovered orbiting in the same area, Sir William Herschel, in 1802, labeled these new objects, including Ceres, as asteroids (though the term asteroid, which means “star-like”, wasn’t commonly accepted until the early 1900s).

So thus, Ceres became the first, and largest, of the asteroids that orbit between Mars and Jupiter in a loose collection that we collectively refer to as the asteroid belt. But Ceres’s identity crisis wasn’t over just yet. Ceres was king of the asteroids until 2006, when that controversial IAU reclassified it as a dwarf planet. 1

From star, to comet, to planet, to asteroid, and finally to dwarf planet, Ceres looks to Pluto and remarks, “Psh… and you think you had it bad.”

Now that this introduction is out of the way, stay tuned for more information about Ceres. I’ll tell you about this fascinating world and get you up to speed on NASA’s Dawn spacecraft that will be arriving at Ceres in March of this year.

Animation of Ceres as viewed by the Dawn spacecraft on January 13, 2015. - Source: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

Animation of Ceres as viewed by the Dawn spacecraft on January 13, 2015. – Source: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI

(Much of the information in this post came from Giuseppe Piazzi and the Discovery of Ceres, G. Foderà Serio, A. Manara, and P. Sicoli, published in Asteroids III by the University of Arizona Press)


  1. Since Pluto’s reclassification from planet to dwarf planet was viewed by many as a demotion, I wonder if it’s safe to refer to Ceres’s reclassification from asteroid to dwarf planet as a promotion.