Category: NASA Space Place

by Dr. Tony Phillips

Jupiter and Earth just had a close encounter—and it was a good one. In late September 2010, the two worlds were 31 million km (about 19 million miles) closer than at any time in the past 11 years. Soaring high in the midnight sky, Jupiter shone six times brighter than Sirius and looked absolutely dynamite through a backyard telescope.

Planetary scientist Scott Bolton of the Southwest Research Institute isn’t satisfied. “I’d like to get even closer,” he says.

Bolton will get his wish in July 2016. That’s when a NASA spacecraft named “Juno” arrives at Jupiter for a truly close-up look at the giant planet. Swooping as low as 5,000 km (about 3,000 miles) above the cloud tops, Juno will spend a full year orbiting nearer to Jupiter than any previous spacecraft.

The goal of the mission is to learn what lies inside the planet.

Astronomers have been studying Jupiter since the invention of the telescope 400 years ago, but in all that time the planet’s vast interior has remained hidden from view. Even the Galileo probe, which dived into the clouds in 1995, penetrated no more than about 0.1% of Jupiter’s radius.

“Our knowledge of Jupiter is truly skin deep,” says Bolton, Juno’s principal investigator. “There are many basic things we just don’t know—like how far down does the Great Red Spot go? And does Jupiter have a heavy core?”

Juno will improve the situation without actually diving into the clouds. Bolton explains how. “Juno will spend a full year in close polar orbit around Jupiter, flying over all latitudes and longitudes. We will thus be able to fully map Jupiter’s gravitational field and figure out how the interior is structured.”

But that’s not all. Researchers have good reason to believe that much of Jupiter’s interior is filled with liquid metallic hydrogen, an exotic metal that could form only in the high-pressure, hydrogen-rich core of a giant planet. Jupiter’s powerful magnetic field almost certainly springs from dynamo action inside this vast realm of electrically conducting metal.

“Juno’s magnetometers will precisely map Jupiter’s magnetic field,” says Bolton. “This map will tell us a great deal about planet’s inner magnetic dynamo—what it’s made of and how it works.”

Finally, Juno will probe Jupiter’s atmosphere using a set of microwave radiometers. “Our sensors can measure the temperature 50 times deeper than ever before,” says Bolton. Researchers will use that information to figure out how much water is underneath Jupiter’s clouds. “Microwave measurements of Jupiter’s water content are particularly exciting because they will help discriminate among competing theories of the planet’s origin.”

Now that’s a close encounter. Stay tuned for Juno.

Find out more about the Juno mission at http://www.nasa.gov/mission_pages/juno. Play the new Solar System Explorer super game, which includes the Juno Recall mini-game at http://spaceplace.nasa.gov/en/kids/solar-system. It’s not just for kids!

This article was provided courtesy of the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Caption:

The Juno mission, arriving at Jupiter in July 2016, will help to solve the mystery of what’s inside the giant planet’s core.

By Carolyn Brinkworth

The world of astronomy was given new direction on August 13, 2010, with the publication of the Astro2010 Decadal Survey. Astro2010 is the latest in a series of surveys produced every 10 years by the National Research Council (NRC) of the National Academy of Sciences. This council is a team of senior astronomers who recommend priorities for the most important topics and missions for the next decade.

Up near the top of their list this decade is the search for Earth-like planets around other stars—called “extrasolar planets” or “exoplanets” —which has become one of the hottest topics in astronomy.

The first planet to be found orbiting a star like our Sun was discovered in 1995. The planet, called “51 Peg b,” is a “Hot Jupiter.” It is about 160 times the mass of Earth and orbits so close to its parent star that its gaseous “surface” is seared by its blazing sun. With no solid surface, and temperatures of about 1000 degrees Celsius (1700 Fahrenheit), there was no chance of finding life on this distant world. Since that discovery, astronomers have been on the hunt for smaller and more Earth-like planets, and today we know of around 470 extrasolar planets, ranging from about 4 times to 8000 times the mass of Earth.

This explosion in extrasolar planet discoveries is only set to get bigger, with a NASA mission called Kepler that was launched last year. After staring at a single small patch of sky for 43 days, Kepler has detected the definite signatures of seven new exoplanets, plus 706 “planetary candidates” that are unconfirmed and in need of further investigation. Kepler is likely to revolutionize our understanding of Earth’s place in the Universe.

We don’t yet have the technology to search for life on exoplanets. However, the infrared Spitzer Space Telescope has detected molecules that are the basic building blocks of life in two exoplanet atmospheres.  Most extrasolar planets appear unsuitable for supporting life, but at least two lie within the “habitable zone” of their stars, where conditions are theoretically right for life to gain a foothold.
We are still a long way from detecting life on other worlds, but in the last 20 years, the number of known planets in our Universe has gone from the 8 in our own Solar System to almost 500. It’s clear to everyone, including the Astro2010 decadal survey team, that the hunt for exoplanets is only just beginning, and the search for life is finally underway in earnest.

Explore Spitzer’s latest findings at http://www.spitzer.caltech.edu. Kids can dream about finding other Earths as they read “Lucy’s Planet Hunt” at http://spaceplace.nasa.gov/en/kids/storybooks/#lucy.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Caption:

Artist’s rendering of hot gas planet HD209458b. Both the Hubble and Spitzer Space Telescopes have detected carbon dioxide, methane, and water vapor—in other words, the basic chemistry for life—in the atmosphere of this planet, although since it is a hot ball of gas, it would be unlikely to harbor life.

by Dr. Tony Phillips

Grab your cell phone and take a good long look.  It’s indispensible, right?  It tells time, surfs the web, keeps track of your appointments and, by the way, also makes phone calls. Modern people can hardly live without one.

One good solar flare could knock it all out.

“In the 21st century, we’re increasingly dependent on technology,” points out Tom Bogdan, director of NOAA’s Space Weather Prediction Center in Boulder, Colorado. “This makes solar activity an important part of our daily lives.”

Indeed, bad space weather can knock out power systems, telecommunications, financial and emergency services—basically, anything that needs electronics to work.  That’s why NOAA is building a new fleet of “space weather stations,” the GOES-R satellites.

“GOES-R will bring our existing fleet of weather satellites into the 21st century,” says Bogdan.  “They’re designed to monitor not only Earth weather, but space weather as well.”

NOAA’s existing fleet of Geostationary Operational Environmental Satellites (GOES) already includes some space weather capabilities: solar ultraviolet and X-ray telescopes, a magnetometer and energetic particle sensors.  GOES-R will improve upon these instruments and add important new sensors to the mix.

One of Bogdan’s favorites is a particle detector named “MPS-Low,” which specializes in sensing low-energy (30 ev – 30 keV) particles from the sun.

Who cares about low-energy particles?  It turns out they can be as troublesome as their high-energy counterparts.  Protons and other atomic nuclei accelerated to the highest energies by solar flares can penetrate a satellite’s exterior surface, causing all kinds of problems when they reach internal electronics.  Low-energy particles, particularly electrons, can’t penetrate so deeply.  Instead, they do their damage on the outside.

As Bogdan explains, “Low-energy particles can build up on the surfaces of spacecraft, creating a mist of charge.  As voltages increase, sparks and arcs can zap electronics—or emit radio pulses that can be misinterpreted by onboard computers as a command.”

The Galaxy 15 communications satellite stopped working during a solar wind storm in April 2010, and many researchers believe low-energy particles are to blame. GOES-R will be able to monitor this population of particles and alert operators when it’s time to shut down sensitive systems.

“This is something new GOES-R will do for us,” says Bogdan.

The GOES-R magnetometer is also a step ahead. It will sample our planet’s magnetic field four times faster than its predecessors, sensing vibrations that previous GOES satellites might have missed.  Among other things, this will help forecasters anticipate the buildup of geomagnetic storms.

And then there are the pictures. GOES–R will beam back striking images of the sun at X-ray and extreme UV wavelengths. These are parts of the electromagnetic spectrum where solar flares and other eruptions make themselves known with bright flashes of high-energy radiation.  GOES-R will pinpoint the flashes and identify their sources, allowing forecasters to quickly assess whether or not Earth is in the “line of fire.”

They might also be able to answer the question, Is my cell phone about to stop working?

The first GOES-R satellite is scheduled for launch in 2015.  Check www.goes-r.gov for updates. Space weather comes down to Earth in the clear and fun explanation for young people on SciJinks, http://scijinks.gov/space-weather-and-us.

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Caption:

In spite of Earth’s protective magnetosphere, solar storms can wreak havoc with Earth satellites and other expensive electronics on the ground.