Tuesday, April 08, 2008

The Little Spacecraft That Could

A few weeks ago, there was a story in the New York Times about the imminent death of the Ulyses spacecraft. Usually, a story like this relates a NASA failure. In this case, though, it is about an astounding NASA success.


The Ulysses got off to a less-than-stellar beginning. It was originally scheduled to be launched in 1986. The Challenger disaster forced a delay of several years for the mission, not only to fix the systemic problems in the Space Shuttle, but to wait for the right planetary alignments to take place.

Why was this? Because Ulssyes was going on a long, long, unique journey-- a journey that was a lot longer than was originally expected.

Ulysses was originally supposed to be two missions by NASA and the European Space Agency, the Solar Polar Mission. One spacecraft would fly over Jupiter and under the sun, the other would fly under Jupiter and over the sun. The overall purpose was to study the poles of the sun; because earth's orbit is approximately around the sun's equator, it was easier to study that region. Little was known about the sun's polar regions.

Because of budgetary constraints, the two spacecraft were merged into one and the resulting spacecraft was dubbed the Ulysses because it was going to travel an indirect and untried path to its mission.

The biggest obstacle to Ulysses' mission was fuel constraints-- getting it in a position to orbit the sun in a non-equatorial manner. NASA had been having success in using the gravitational pull of planets rather than precious fuel to change the direction of flight (the Voyager I and Voyager 2 spacecraft were both launched in the seventies and are now exiting the solar system after passbys of several planets, were notable examples of this.)

Ulysses' original launch date of February, 1983 was delayed to May of 1986. It was supposed to go up in the Challenger, so when the Challenger was destroyed in January of 1986, and the whole shuttle fleet grounded for some time, Ulysses finally went up in a shuttle in October, 1990. It was launched with a solid-fuel booster toward Jupiter. Imagine the math required to get the trajectory right-- to change the path of the spacecraft to put it in a polar orbit around the sun.

The Ulysses was powered with a Radioisotope Thermoelectric Generator, or RTG, which is powered by the decay of Plutonium-238. This engine, which also heats up the fuel used to change the attitude of the craft so that its antenna points toward the earth so that it can transmit its data, is finally failing. When it fails, as is expected in the next month or so, it will end a mission that has lasted years longer-- more than a decade longer, in fact-- than was expected.

Two years after it was launched, in 1992, Ulysses passed by Jupiter, changing its attitude to set it up to fly toward the sun and enter an orbit where it would be able to pass by the solar poles. In 1994 and 1995, it explored the northern polar region of the sun. In 2000 and 2001, it explored the southern region of the sun. In between, however, was a bonus; Ulysses unexpectedly passed through the tail of Comet Hyakutake.

In all three cases, the two polar explorations and the pass through Hyakutake's tail, the results were unexpected.

Ulysses made some observations afterward of Jupiter and then last year, NASA was able to pass it through the tail of another comet, Comet McNaught. Once again, there were unexpected results.

A few months ago, NASA tried a command to extend the life of the RTG power source. It failed, and NASA technicians realized that the mission was going to come to an end. On February 22, NASA announced that the mission was coming to an end. However, the mission was more than a success. A mission that was supposed to last about 4 years lasted 17 years and 4 months, more than 4 times the original length. Ulysses gathered much more data than was expected, data that has changed the view of the sun and our universe, and will be analyzed for years.

It takes years for a spacecraft to be designed, built, deployed. This lag means that spacecraft always have a lag in technology. Ulysses went up with early-eighties electronics and other technology. Once you design and start building the spacecraft, you have to bite the bullet and send it up with the technology it was designed around; the math and physics of its flight is planned around the mass of the computers and parts it was designed with. Think about the difference in electronics between say 1983 and now. The data on Ulysses was stored on a tape recorder! In the early eighties, there weren't even hard drives with enough capacity that were small enough to fit into this spacecraft!

And imagine what we could could do with today's technology. Or that of five years from now.

Occasionally, I read criticisms of money spent on space exploration. Compare the cost (versus success) of the Ulysses program-- $250 million-- to the cost of a single B-2 stealth bomber, an aircraft that the military had pointedly stated it did not want. A single B-2 costs $2 billion. We built 20 of them. Compare it to the cost of the pointless war in Iraq-- over $500 million a day. Compared to this, it seems a bargain.

My fellow space geek, Skyler's Dad, once pointed out that we human beings are, by nature, explorers. As I've drifted into middle age and as I've become a parent, I think a lot of the future. As a parent, I hope that there is a future for my kids in which we solve some of the many, many short-term problems we're dealing with right now-- the huge amount of violence inflicted upon earth's population by our flawed political and economic system, and by fighting over religion. I hope and dream of a day in which children everywhere grow up to be the mathematicians, scientists, engineers, tool and die makers, managers, technicians, teachers, manufacturers, farmers-- and astronauts-- and other professions that will make our planet a safe, sustainable place from which we can pursue our destiny-- to reach beyond our planet, as we've done in baby steps the last few decades.

A few years ago, Kim and I went to Chicago's Museum of Science and Industry, and we discovered that the capsule from Apollo 8 was there. Apollo 8 was commanded by Frank Borman, along with Jim Lovell (later the commander of the near-disasterous Apollo 13) and William Anders. Apollo 8 was the first manned spacecraft to leave earth's orbit. It left earth's orbit and orbited around the moon. As they orbited the moon for the first time, they were completely cut off from earthly communication.

As they came around from the dark side of the moon, the crew beheld a site no one in history had seen before-- an earthrise. They snapped a picture, showing our planet, beautiful, warm and blue, a tiny oasis in a huge cold, hostile universe. The photo is often credited with being the beginning of environmentalism; it showed how beautiful, unique and fragile our planet was and is.

On Christmas Day, the crew carried out a plan. They each read from the Bible, the book of Genesis. I remember that day, as a seven year old kid, hearing that message on that Christmas day. In the year of tumult that 1968 was-- the Tet offensive and the worst year of the Vietnam War, the assasinations of Martin Luther King and Bobby Kennedy, the Chicago Convention riots, the demonstrations and murder of demonstrators in Mexico City, the Paris riots, the crushing of the Prague Spring and many other things-- it was a beautiful coda to a troubled year. It was not so much about religion but about the beauty and uniqueness of the human race, and the importance of hope.

That day at the museum, that capsule reached out to me. It had crossed hundreds of thousands of miles and a couple of decades to cross paths with me and remind me of the importance of what Lovell, Borman and Anders and all the thousands of people who supported them, did that day.

In the next few weeks, the Ulysses will cease operating and will be a piece of metal and plastic floating through space. It will probably never be in a museum. However, as we plot out the next few baby steps of our reach into space and our ultimate future as a species, the data that Ulysses sent back, long after it was expected to, will be invaluble, providing answers and raising new questions. It will be an artifact, like the Surveyor spacecraft and parts of Apollos 11, 12, 14, 15, 16 and 17 sitting on the moon, the Voyagers I and II and a handful of other bits of our earthly machinery that will be out there for future explorers to perhaps gaze at like you or I might look at the now-primitive, but then groundbreaking Wright flyer in the Smithsonian. Well done, Ulysses. And hats off to all the men and women who had the vision and determination to dream, design, fund, build, launch, maintain her-- and had the imagination to extend her mission.


Dave said...

That thing is gonna become super-intelligent and destroy the Earth!

Dr. Zaius said...

Great post! I remember when Apollo went to the Moon as well. I was just a little kid. It was amazing.

Anonymous said...

tag, you're it, if you wish, no pressure.

SkylersDad said...

Great post JY!! I too, share in your dream that we may someday solve the problems of flawed political and economic system, and fighting over religion. And perhaps we may just see that Mars mission, and discover that we are probably not alone out here.

cheer34 said...

Thanks for an inspiring post...we are not alone....we just have not found the others that are out there, they may not have found us either...or maybe they have but we do not know it yet...

Distributorcap said...

that was great... i love space and space exploration. i remember when Voyager flew by Uranus and Neptune and could not get enough it

and now Cassini......

when we put our minds and money towards the right stuff (no pun intended) -- look at what we can do....

but no...

STPTT said...

Nice post! For what it cost to play Armageddon in Iraq we could have financed several missions and probably cured cancer as well. I'm sure some Blackwater board member uses a B-2 to take his kids to school...

sexy said...