Category Archives: Space

Exploring Jupiter

Jupiter, taken by the Cassini satellite

With all the excitement the last few weeks of watching the new Mars Curiosity rover get packed up and on the first leg (JPL in California to Florida) of its long journey to Mars, it’s easy for me to forget that there is a lot of other space exploration stuff going on this summer. Juno, which I wrote a bit about last month, is another JPL-based NASA mission, heading out in August for the planet Jupiter. I realized in reading about Juno that I know very little about Jupiter so it’s time to remedy that deficit of knowledge. I knew Jupiter was the biggest planet in our solar system, and that it had some moons, but that’s really about it. So time to learn more about Jupiter.

First, why study Jupiter at all?  Because learning more about this huge planet can help us understand how our Sun and solar system formed over 4.5 billion years ago. From active volcanoes to icy moons, Jupiter and its moons are almost a solar system in themselves. Studying how these bodies interact, and the atmosphere and magnetic fields of Jupiter itself, will hopefully give us more information to understand our planet and our little corner of the universe.

Great Red Spot as seen by Voyager

Juno won’t be the first satellite to study Jupiter in detail. Voyager 1 and 2, Ulysses, Galileo and Cassini have all provided data information about this gas giant of a planet. In 1979, the separate visits of the Voyagers sent back detailed photos of the weather activity on Jupiter, discovering the Great Red Spot, as well as our first close-up views of its moons, including the first active volcano found outside of Earth on the moon Io.

In 1992, the Ulysses spacecraft, designed to explore our Sun, used Jupiter’s gravity to position itself to explore the Sun’s poles. During its fly-by, Ulysses identified changes in Jupiter’s gravity and recorded fewer active volcanos on Io than observed by the Voyagers 13 years earlier.

Galileo, the first spacecraft devoted to long-term exploration of Jupiter, was launched from the space shuttle Atlantis in October 1989 and reached Jupiter in December 1995, becoming the first satellite to orbit a planet in the outer solar system. Credited with a long list of discoveries, one of the most startling finds was evidence of subsurface salt water on three moons: Europa, Ganymede, and Callisto. Galileo’s mission ended in 2003 when it crashed into Jupiter’s atmosphere.

Cassini (artist's rendition, courtesy NASA)

Cassini did a fly-by in 2001 on its way to Saturn, sending back over 1,200 detailed photographs taken over 70 days that — strung together by JPL scientists into a time-lapse movie –showed how storms on Jupiter behave. The Cassini movie showed persistent storms moving across the planet’s surface by bands of latitude, with the storms lasting the entire 70 days covered by the photographs. In all, Cassini took over 26,000 photographs as it flew by Jupiter, and those photographs are being used to develop insights into the faint rings and the moons of Jupiter. Cassini’s single fly-by sent more than enough information to keep scientists busy for years.

Imagine, then, what Juno will do. Thirty-seven years after the Voyager spacecraft first sent back detailed images, Juno will observe Jupiter with cameras and instruments designed to capture information about the planet’s gravity, magnetic fields, and atmosphere. It is in studying these elements that scientists will work on determining the properties of Jupiter and how it evolved over billions of years.

I’ve saved the best for last. Go here to see a breathtaking video opening, then learn more about the Juno mission from a dedicated website:  The history of our planet lives on this planet. 

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50 years of humans in space

Today, when a space shuttle takes off or a Soyuz rocket launches people towards the International Space Station, it barely makes the news. It’s become ordinary, commonplace, to have people in orbit around the Earth, blasting off and landing without much fuss or fanfare.

Half Moon

50 years ago today, the first of those people, the Russian cosmonaut Yuri Gagarin, was launched into orbit, an accomplishment that even the New York Times finds worthy of remembering this day.

Imagine, a man in space, something no one had ever done. I’m old enough that I remember following the the Space Race, learning the names of the Mercury Seven (Shepard, Grissom, Cooper; front row: Schirra, Slayton, Glenn, Carpenter), and watching the Apollo launches, hoping that nothing would go wrong. In July of 1969, I remember sitting close to the TV with my family, watching the grainy black-and-white video of Armstrong coming down the ladder and setting foot on the moon. I don’t know which was more amazing: that there were two men on the moon or that we were watching video of the whole thing. Technology, although I didn’t realize it then, would continue to pull at me until I finally gave in and became first a geek then, late in life, a space geek.

30 years ago today, the first Space Shuttle to make orbit took off, the Columbia (which was later destroyed over Texas in 2003). In only 20 years, humans had gone from nothing to sending an oversized plane into orbit with a crew that could number from 4 to 7 people. Now that is progress. It shows what we can do when we have a clear goal, a lot of commitment, and dogged determination to make things happen.

Yuri Gagarin died in a jet crash in 1968, so he never saw men land on the moon, or witnessed a Soyuz launch, or a Shuttle landing. He never saw the International Space Station, which at this moment is hosting 3 cosmonauts, two US astronauts, and an Italian astronaut. As Yuri sat in his tiny Vostok 1, I wonder if he imagined the places we would go in 20 years, in 50 years. Who knows where we’ll be in 100 years?

SOFIA: The Mission

On to the second of two NASA missions that will be covered in the #NASATweetup on February 11th, the SOFIA Mission.

Imagine taking a Boeing 747, putting a 20-ton telescope in the rear section with a door that can expose it to the heavens during flight, and then flying it anywhere from 39,000 to 45,000 feet (that would be the stratosphere) on a regular basis. You don’t have to imagine it, because it’s real. It’s SOFIA, the Stratosphereic Observatory For Infrared Astronomy and it’s the world’s largest airborne astronomical observatory. How big is the telescope? It’s 100 inches in diameter! You can see how it looks inside the 747 in the picture just to the left.SOFIA joins other innovative telescopes in space: the Hubble, the Spitzer (launched in 2003), the Herschel (launched in 2009) and the James Webb (to be launched in 2014). SOFIA is the only telescope that can see certain wavelengths in the mid-infrared range, and that will help fill in gaps about how stars and planets are born, how things form in space, and how black holes grow.

Why fly a telescope way up high or launch a telescope into space? Water vapor in Earth’s lower atmosphere limits what ground-based telescopes can see in the infrared and sub-millimeter spectral range. Higher is better for SOFIA because flying in the stratosphere gets the telescope above the  99% of the water vapor in the lower atmosphere, meaning SOFIA will provide better image quality and more sensitive observations than any ground-based telescope.

The advantage of SOFIA over permanently flying telescopes like the Hubble is that scientists can change or adjust SOFIA’s telescope fittings for each series of flights. For example, the first science flight used the Faint Object Infrared Camera for the SOFIA Telescope (FORCAST) to take infrared pictures of the Messier 42 nebula in the constellation Orion. In February, the dual-channel German Receiver for Astronomy at Terahertz Frequencies (GREAT) will be installed for three flights, where scientists will observe submillimeter and far-infrared spectral frequency bands in the intersteller medium (ISM). The ISM is the gas and dust in space between star systems in a galaxy; it’s also the place where stars form, so it’s a pretty interesting thing to study. You can learn more about the ISM by clicking on the link in this sentence.

You might have heard of SOFIA’s first science flight, since it just happened in November 2010, a 10-hour flight out of NASA’s Dryden Flight Research Center in Palmdale, CA. I thought it was quite cool when I read about it and never dreamed I would be getting the chance in 2011 to meet some of the SOFIA team, which is based at the NASA Ames Research Center.

Kepler: The Discoveries

In my last post, I wrote a bit about Kepler’s search for habitable planets, ones that had the right conditions for human life to exist on them.  So what exactly makes a planet the “right” one for us to survive on it? Two conditions, really:

(1) It has to be the “right” size.
(2) It has to be in “right” distance from its sun (star).

What’s the right size for a habitable planet? Anywhere between one-half to twice the size of our Earth is the simple answer. But why that size range and not any bigger or smaller?

We need air to breathe, which means we need the planet to have an atmosphere. If the planet is too small (think Mars), then it does not have enough gravity to hold onto air molecules. So that’s why there’s no atmosphere on Mars — I always wondered about that and I just new that Red Planet wasn’t telling the story right! If the planet is too big (think Neptune), then it will have too much gravity and too much atmosphere for us to survive in. Earth, then, is just the “right” size to hold onto the perfect amount of atmosphere (for us, at least, if not the Klingons and Vulcans).


Now, let’s look at the “right distance” condition, which is more commonly referred to as the habitable zone. Think of this habitable zone in terms of our own solar system orbiting around our own big star (the Sun). Mercury is too close to the Sun, so it’s baked and fried in terms of us trying to live there. Jupiter? Too far away, so too cold. Hard for us to live there without a lot of external support systems in place. Earth? Just the right distance to keep us warm and happy. Look at the Planet Temperature and Size graphic to see some fun facts: lead melts on the planet Mercury. Ouch, that’s hot.

To put this whole concept of “right” conditions in terms of a childhood fairy tale:
Size
Mars? Too small
Neptune? Too big
Earth? Just right

Habitable zone
Mercury? Too close
Mars? Too far
Earth? Just right.

So now you know all that, what has Kepler found so far in its almost two years of searching that small patch of sky in the Cygnus starfield? Over 700 planet candidates! Out of these, so far they have 8 planets confirmed. They call them “exoplanets” because they our outside our own solar system. None of these confirmed exoplanets is the right size as you can see. As a matter of fact, they are all rather huge compared to Earth (that little white dot on the right side of the graphic). We’re feeling kind of small right now.

(Both graphics are courtesy of the Kepler Mission web site.)

Kepler: The Mission

The Kepler Mission is to find new planets that are close to Earth in size and composition. The scientific equipment is designed to detect planets as they pass in front of their stars, which causes a tiny dip in the stars’ light.

Think of standing way out beyond the edge of our solar system and just staring at the tiny face of the Sun for a decade or more. You would see regular patterns of tiny dots moving across the face of the Sun. Those dots would be Earth, Mars, and the other planets of our solar system. Every time one of those dots moved across the sun, there would be a change in the light output from the Sun.

Now, think of the Sun as just another star in the Milky Way galaxy. Kepler is simultaneously watching over 100,000 stars, every 30 minutes, waiting for the tiny little winks of light that happen when a planet crosses in front of its sun and changes the light. The change can last an hour or a half-day, depending on the planet’s orbit and the star.

100,000 stars! Think about that for a minute. Kepler is watching 100,000 stars, searching for those stars that have planets circling them. Even more precisely, Kepler is looking for habitable planets with approximately 1-year orbits (more on that below). What are the odds of finding those planets? Pretty good, actually! The Kepler team hopes to find

  • About 50 planets the same size as Earth.
  • About 185 planets that are 1.0 to 1.3 times larger than Earth.
  • About 12% of star/planet systems will contain 2 or more planets.

So why is Kepler focusing on planets with approximately 1-year orbits? It’s practicality, actually. Kepler is staring at the same section of space for 3 or 4 years (the longer the spacecraft can last, the better for observation purposes). It is looking for repeatable “winks” of light (same dimness and position every time) and it has to see those “winks” at least 2 or 3 times to determine there is a pattern – an orbit. Any wink that is seen less than 3 times is discounted. It may be a planet with a really long orbit but Kepler won’t be around long enough to ascertain if it is or not. Any wink that is seen more than 2 or 3 times (a shorter orbit than Earth’s) probably indicates a planet too close to its star to support our kind of life. So those get discounted too. What’s left are planets that are most similar to ours in size and in distance from their stars (their Suns). And Kepler is hoping to find over 200 planets in that category. 200 planets in a tiny section of a single galaxy.

And here’s what’s really amazing. Kepler is only looking at those stars from one angle. There may be planets that don’t show up in that angle of view. So the “200+ planets” figure is even more amazing because it’s a tiny bit of space viewed from a single viewpoint. Imagine what else is out there, beyond what we can see or measure now? It’s truly mind-boggling.

Kepler: The Man

In today’s example of synchronicity, I’ve been working my way (very slowly) through The Grand Design, by Stephen Hawking and Leonard Mlodinow and today I learned why the Kepler mission is named after Johannes Kepler. I guess if I was a deep reader of astronomy, I would already know about Kepler. But I’m not, so I didn’t. Until now. It’s time to rectify this gap in my (limited) knowledge of the history of astronomy. Today, the subject of my study (prior to the Feb 11th Tweetup) is Johannes Kepler. So who was this Kepler guy and why did NASA choose his name as the Mission name?

Johannes Kepler (1571AD – 1630AD) was a German mathematican, astronomer, and astrologer, back when the latter two were  much more closely related than they are now. He was a key figure in the 17th-century scientific revolution that repudiated much of what people had believed since the time of Ancient Greece and provided the foundation for much of modern science. Kepler contributed two very notable ideas to this revolution of knowledge (1) the Kepler laws of planetary motion and (2) the Keplerian refracting telescope, which led to the modern refractive telescopes in use today.

There are three of Kepler laws of planetary motion. The first two were published in 1609 after he had analyzed astronomical observations of his mentor, Tycho Brahe (a Danish noble who was a noted astronomer as well). I understand Kepler’s first two laws:

1. The orbit of every planet is an ellipse with the Sun at one of the two foci.

2. A line joining a planet and the Sun sweeps out equal areas during equal intervals of time.

It took him a while to formulate the third law, and he didn’t publish it until 1619. This one I don’t really understand, being the non-math-brained person that I am:

3. The square of the orbital period of a planet is directly proportional to the cube of the semi-major axis of its orbit.

(For you science lovers that want to learn more, Wikipedia has a basic explanation of Kepler’s three laws.)

Isaac Newton later used Kepler’s laws in his own theory of gravity, about a century later. Kepler’s work was that important.

The design of the Keplerian Telescope, published as Dioptrice, was an improvement on Galileo’s original design, published in 1609. Instead of using a concave lens (as Galileo had done), Kepler’s design proposed using a convex lens. This widened the field of view significantly although it did invert the image. Why was this telescope design such a breakthrough? Kepler originally felt that this design improved on Galileo’s design because it collected more light, which increased the magnification, allowing the viewer to see more detail in the small area of sky where he was pointing the telescope. It also allowed a way to insert a measuring device into the area being viewed, the first time anyone could then measure the distance between two objects over time.

The big downside of both Galileo’s and Kepler’s designs were that they required really long telescopes to overcome the abberations of the simple objective lens, along the lines of 130 to 150 feet for a lens was six inches across. Kepler never actually built a telescope using his design; he considered his design as purely theoretical. People did later build a Keplerian telescope, but it was hard to use, given the very long tube length required (the drawing above shows a 45-meter version built in 1673). Given the materials of the day used to construct the tube, it was almost impossible to keep it from bending and therefore affecting the images. (In 1668, Robert Hooke demonstrated the use of mirrors inside the tube to reflect the images and shorten the tube, a major breakthrough. A telescope formerly 60 feet long could now be shortened to 12 feet long, and that was much easier to support and stabilize.)

As part of his study of optics, Kepler wrote Astronomiae Pars Optica (The Optical Part of Astronomy) in 1604, which is generally regarded as the first description of how humans see images as inverted and reversed by the lens of our eye onto the retina.

Kepler was into a lot of things. He also explained that tides are caused by the Moon, discovered that Sun rotates about its axis, investigated the formation of pictures with a pin hole camera, and designed eyeglasses for near- and far-sightedness. (I especially appreciate that last bit, being someone who has needed vision correction since third grade!)

In one more example of synchronicity, an European unmanned resupply spacecraft is scheduled to deliver cargo to the International Space Station in February 2011. The name of that vehicle? The Johannes Kepler ATV-002 (Automated Transfer Vehicle).

It’s an amazing thing to dive into the life and work of someone I never heard about, not being the scientific type in school or in life. I’m playing catchup now, and the two hours I’ve just spent reading an introduction to Kepler’s life and work makes me realize how much I have to learn. It’s a journey, though, and today is just the second step on what I think will be a deepening of my fascination with the starry, starry night sky and the worlds we have yet to find and explore.

Kepler: First Contact

I’m so excited — I’m going to the NASA Tweetup at Ames Research Center on February 11! I am one of only 100 tweeters invited (it was a lottery drawing from all applicants) so I want to study up on what they’re doing at Ames and be able to really absorb everything I can while I’m there.

The two projects we’ll be focusing on are the Kepler and SOFIA missions. I am studying Kepler first because its mission statement really grabbed me: Kepler: A Search for Habitable Planets. Wow, like something out of sci-fi movie, only it’s reality right NOW! The picture here is of a Kepler-10b, a rocky planet about 1.4 times the size of Earth, announced on January 10, 2011. It took eight months of Kepler data to make the calculations that discovered Kepler-10b. I’m reading up on how the Kepler telescope works tomorrow.

Kepler is only looking at a very small part of the Milky Way. How small? Well, check out this graphic from NASA that shows the Kepler’s area of concentration. Go on, click on the graphic and it will display larger and then you can really try to grasp how huge our galaxy is (and we’re only one galaxy, there are so many more out there, it’s mind-blowing, seriously!).

Next time you look up in the night sky and see the constellations of Cygnus and Lyra constellations in our Galaxy, think of Kepler, looking there for more planets, more chances to find new places, and perhaps, new races.

Interested in reading more about Kepler’s mission? Here you go: Kepler Mission on the NASA web site.