GETTING SPACEY

By Pam Eastlick

Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond. Visit our website at www.thedeepradioshow.com

Well, it’s time to clean out the file that’s perhaps nearest and dearest to my heart, the space stories. I also like to correct misconceptions and the first item has a doozy!

THE STATES OF MATTER

So . . . name the three states of matter for me. That’s simple you say; there’s solid, liquid and gas. Interestingly enough, your teachers neglected to tell you about the fourth state of matter. It’s interesting because the fourth state of matter is the most abundant in the universe. At least 98% of the atoms in the universe exist in this state and you’ve probably never heard of it even though there’s a very good chance that this state of matter is allowing you to read this article.

The fourth state of matter is called plasma and it’s not the same kind of stuff that liquefies your blood. Plasmas are ionized gases and they don’t behave like regular gases. They can be as commonplace as the contents of a fluorescent light bulbs, or as exotic as a thermonuclear explosion. The Earth’s upper atmosphere is a plasma; so are lightning bolts. The reason that plasma is the most abundant state of matter? All stars, including the Sun, are made of plasma.

Physicists have worked for nearly a hundred years to understand plasma, but detailed knowledge what they’re made of and how they work has been hard to come by. Conventional plasmas are hot, complex and difficult to characterize either in the natural world or in the laboratory.

Recently, work has begun on a new class of plasmas so simple that it promises to take our understanding to a new level. They’re called ultracold plasmas, and they start with trapped atoms, cooled to a fraction of a degree above absolute zero, to form clouds of ions and electrons that are nearly standing still. Using these ultracold plasmas scientists can study the elementary steps by which atomic plasmas are born and grow.

Recently, researchers found a way to make ultracold plasmas out of molecules. Starting with a gaseous sample cooled in a supersonic molecular beam, a team formed a plasma of nitric oxide that had ion and electron temperatures as cold as plasmas made from trapped atoms. Their technique not only produces plasmas three orders of magnitude denser than those made with trapped atoms, but produces plasmas that have a liquid-like motion.

The researchers hope that further understanding of ultracold plasma on a molecular level could lead to new knowledge about gas planets (Jupiter, Saturn, Uranus, and Neptune in our solar system), white dwarf stars, thermonuclear fusion and X-ray lasers.

The Earth’s upper atmosphere is a plasma, as are lightning bolts and all stars. (Credit: iStockphoto/Chee Ming Wong)

Tuning in on the most common state of matter in the universe will certainly expand our knowledge but recently astronomers have tuned in on a different kind of signal that seems to be muddying the waters. Read on!

I CAN’T HEAR YOU. THE RADIO’S TOO LOUD!

Just as there are several different states of matter, energy comes in several different flavors depending on its wavelength. We’re familiar with most of them; we see in visible light, doctors see our insides with x-rays, we cook our food with microwaves, and we listen to radio waves. (OK, technically, we listen to sound waves, which are a whole other ball game; but the waves that arrive at our radio that give it the information to produce the sound are radio waves.)

Well, listening to the early universe just got a lot harder. A team from NASA’s Goddard Space Flight Center in Greenbelt, Md., recently announced the discovery of cosmic radio noise that booms six times louder than expected.

The finding comes from a balloon-borne instrument named ARCADE, which stands for the Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission. ARCADE was launched from NASA’s Columbia Scientific Balloon Facility in Palestine, Texas, and flew to an altitude of 120,000 feet, where the atmosphere thins into the vacuum of space. ARCADE’s mission was to search the sky for heat from the first generation of stars. Instead, it found a cosmic puzzle.

Instead of the faint signal they had hoped to find, the researchers detected a booming noise six times louder than anyone predicted. Detailed analysis ruled out an origin from those early stars or from other known radio sources, including gas in the outermost halo of our own galaxy. The source of this cosmic radio background remains a mystery.

Many objects in the universe emit radio waves. Jupiter is the loudest source of radio waves in our own solar system, producing much more radio energy than all the transmitters on Earth. In 1931, American physicist Karl Jansky first detected radio static from our own Milky Way galaxy. Similar emission from other galaxies creates a background hiss of radio noise.

The problem is that there don’t appear to be enough radio galaxies to account for the signal ARCADE detected. One of the mission scientists said, "You’d have to pack them into the universe like sardines. There wouldn’t be any space left between one galaxy and the next."

The sought-for signal from the earliest stars remains hidden behind the newly detected cosmic radio background. Nevertheless, this cosmic static may provide important clues to the development of galaxies when the universe was less than half its present age. Unlocking its origins should provide new insight into the development of radio sources in the early universe.

ARCADE is the first instrument to measure the radio sky with enough precision to detect this mysterious signal. To enhance the sensitivity of ARCADE’s radio receivers, they were immersed in more than 500 gallons of ultr
a-cold liquid helium. The instrument’s operating temperature was just 2.7 degrees above absolute zero.

This is the same temperature as the cosmic microwave background (CMB) radiation, the remnant heat of the Big Bang that was itself discovered as cosmic radio noise in 1965. ARCADE was the same temperature as the microwave background, sothe instrument’s heat didn’t contaminate the cosmic signal.

Of course, I have my own theory about this mysterious signal. It’s all the little green men out there and they have their radios turned up REALLY loud. OK, I know that’s not the real explanation. But who knows what the real explanation will be?

It’s stuff like this, of course that makes science so exciting. You start out on a path to measure something, in this case, the heat from the very first stars, but run into something else entirely, something unexplained. Someone once said that real scientific progress comes not from all the labs and all the research equipment but when someone says “Hmmmm. That’s funny . . . . “

A mysterious extra-loud radio noise permeates the cosmos, preventing astronomers from observing the heat from the first stars. The balloon-borne ARCADE instrument discovered this cosmic static (white band, top). The noise is six times louder than expected. Astronomers have no idea what’s producing the noise. (Credit: NASA/ARCADE/Roen Kelly)

GALILEO’S EYES

Four centuries ago in 1609, the Italian scientist Galileo Galilei revolutionized our understanding of our position in the Universe when he used a telescope for the first time to study the heavens. He drew new sketches of the Moon, discovered that the Milky Way was made from uncountable stars and dethroned the Earth as the center of the Universe when he discovered four large moons, which orbit not the Earth, but the planet Jupiter.

As a part of the International Year of Astronomy (IYA), which marks the 400th anniversary of Galileo’s discoveries, a group of astronomers and curators from the Arcetri Observatory and the Institute and Museum of the History of Science, in Florence, Italy, are recreating both Galileo’s telescope and the conditions that led to Galileo’s world-changing observations.

Astronomers will be using the recreated apparatus to catalogue all the objects recorded in Galileo’s ‘Sidereus Nuncius’ (translated into English as “The Starry Messenger”), the treatise that Galileo published in 1610 that included many of his early observations.

The team has already observed the Moon and Saturn and are now recording images of Jupiter’s moons and the phases of Venus. Both the existence of Jupiter’s moons and the phases of Venus confirmed the heliocentric hypothesis, which says that the objects in the solar system orbit the Sun and not the Earth.

To recreate Galileo’s telescope, the team examined the lens of a telescope given to Galileo’s patron, the Grand Duke of Tuscany, Cosimo II, in 1610. They measured the shape and refractive index of the lens, and used X-ray fluorescence to determine the condition of the glass. Unfortunately the team can’t build an exact replica of the telescope actually used by Galileo to make the observations reported in Sidereus Nuncius as only one lens of that instrument survives.

The project, however, is more ambitious than just recreating one of Galileo’s telescopes. The ultimate aim is to reproduce what Galileo himself might have seen. Galileo died blind and the researchers hope to open Galileo’s tomb to retrieve DNA and diagnose his optical affliction in order to recreate conditions that resemble looking through Galileo’s very own eyes.

Most members of the scientific community suspect that Galileo was gradually blinded because he used his telescope to observe the Sun. Today we realize just how dangerous that is. We all know it hurts to look at the Sun, but what Galileo didn’t know is that the focusing capabilities of his lenses allowed the Sun’s light to burn multiple holes in his retinas. Since the back of the eye has no pain sensors; he didn’t realize his danger until far too late.

NEVER look at the Sun with any kind of focusing instrument like binoculars, a spotting scope or a telescope. You don’t want to end up like Galileo!

Cruise on over to the Deep Website at www.thedeepradioshow.com to learn more about space and many other topics. Enjoy!