Telescopes Follow Mystery Jupiter Spot

July 22, 2009

 

Since I last reported on the strange spot that suddenly appeared on Jupiter last Sunday, it has been the “splat” or rather “splash” seen ‘round the world. 

An unknown interplanetary object did a “cannonball” by plunging into Jupiter’s atmosphere, disintegrating, and splashing debris above the cloud tops.

There was a sense of “déjà vu all over again” about this because it was exactly 15 years ago that I reported on a day-by-day basis the sequential impacts of over 20 fragments of comet Shoemaker Levy 9 that carpet-bombed Jupiter. A belt of dark bruise-looking features grew in the atmosphere following each subsequent impact.

Has a Comet Hit Jupiter?

July 19, 2009

This is a little too mystical for my tastes, but on the cusp of Walter Cronkite’s passing, and the Apollo 11 moon landing 40th anniversary, a mysterious dark spot has appeared on Jupiter.

The dark feature was first observed at approximately 13:30 universal time today by amateur astronomer Anthony Wesley from his home observatory just outside Murrumbateman NSW Australia. Wesley photographed Jupiter through a 14.5 inch Newtonian reflector.

Science fiction fans will remember the closing chapters of Arthur C. Clarke’s 2010: Odyssey Two when black alien monoliths began popping up in Jupiter’s atmosphere.

The explanation for this one is a bit more down to Earth, per the observer’s posting tonight: 

“Preliminary image showing a black mark in Jupiters South Polar Region (SPR) which is almost certainly the result of a large impact - either an asteroid or comet - similar to the Shoemaker-Levy impacts in 1994.”

Let me caution that as of this writing the spot has not been reported being sighted independently by anyone else. Also, it is too near the pole to be a satellite shadow, and also moves with the planet’s rotation according to Wesley.

Beginning on July 20 1994, a string of comet pieces, from the breakup of comet Shoemaker-Levy 9, bombarded Jupiter for nearly a week. Each fragment exploded in Jupiter’s atmosphere and blew black material above the cloud tops. Now, the new spot is reminiscent of the scars let behind by SL9 exactly 15 years ago.

The SL9 event was considered a once in 10,000-year spectacle. But individual comet or asteroid collisions may happen much more frequently on Jupiter. Prior to SL9 dark spots had been occasionally reported in Jupiter's atmosphere. But their origin was not understood. 

This will reinvigorate 2012 soothsayers that strange cosmic events are coming becasue of the end of the Mayan calendar. But for the rest of us more pragmatic observers, this unusual event will be followed closely by telescopes all over the world over the next few days. 

Europa or Bust: Next Potential Harbor For Life

February 09, 2009

Many of my posts have focused on the search for life on Mars.  And like detectives sorting through clues, astrobiologists are meticulously closing in on what I predict will be the first confirmation of life off the planet Earth.

But Mars isn’t the only game in town. The Jovian moon Europa -- four times farther away than Mars -- beckons astrobiologists. Since the Voyager flybys of the late 1970s, scientists have hypothesized that a global ocean with more fresh water that on all on Earth exists miles beneath the rock-hard icy crust. Why? Observational evidence for that ocean has been mounting.

Life might be able to subsist by extracting energy from possible hydrothermal vents at the seafloor, as some species do on Earth. Brown material filling a cobweb of cracks on the moon's surface might contain organic compounds, too -- Europa could be the solar system’s biggest cesspool.

Its greater distance from Earth than Mars aside, exploring Europa will be technologically more daunting, more expensive, and more scientifically challenging. 

Europa is embedded in a radiation field maintained by Jupiter’s powerful magnetic field that bakes unshielded spacecraft electronics. Temperatures on the moon’s surface are a frigid -250 degrees Fahrenheit -- challenging mechanical operation and power generation. The feeble sun, 500 million miles away, is just 4 percent as bright as seen from Earth.

This week, planetary scientists meeting at a conference in Moscow are discussing the science goals and experiments to be performed by a Europa lander.

Funding for such a mission, however, is problematic.

NASA scheduled the Jupiter Icy Moons Orbiter (JIMO) for a 2017 launch but was canceled in 2005. (NASA recently did approve a Jupiter orbiter Discovery-class mission for arrival at Jupiter in 2016). Now under consideration is the Europa Joint Systems Mission (EJSM) an ESA/NASA program. But given NASA’s flat space science budget, it’s going to be a stiff competition with other planetary programs standing in the food line.

Nevertheless, we will eventually explore Europa because it is just too enticing to pass up.  

Based on various concept studies this is how a mission might unfold:

Completing a decade-long voyage, a Europa orbiter spirals into the Jovian system (the vehicle has low thrust ion engines, so it simply can’t “hit the brakes” when it reaches Jupiter). During the 65-day spiral-in the orbiter’s cameras scrutinize Europa to search for a safe but scientifically interesting looking landing site. By then astrogeologists may be confident that Europa’s large cracks and smooth “ponds” are sites of recent chaotic activity where water has reached the surface.

After entering orbit about Europa, the mothership releases a small lander probe that has traveled piggyback along the journey. The probe deploys airbags and free-falls under Europa’s gravitational pull, which about 1/6th Earth gravity. The saucer-shaped lander touches down and the airbags are jettisoned.

The lander performs the functions of any robotic space tourist: monitoring surface temperature, seismic activity, and radiation flux from Jupiter. A pair of spectrometers use laser light to illuminate, and sometimes vaporize, surface ices to study Europa’s chemistry and look for organic compounds. The camera sends back images of an exotic, tortured looking terrain.

During the mission Jupiter eclipses the sun once every 3.5 days. An on-board nuclear generator not only provides power to keep the lander operating, but warm too, especially during the blackout. But nothing can protect the craft from the blistering radiation that would kill any human in 10 minutes.  The radiation-hardened probe is doomed to a life expectancy of only 30 days on Europa.

With luck, the Europa landing site has relatively recent breaks in the surface due to a melting of the crust by a subsurface "lava-lamp" water plume, tectonics, or a meteorite impact.

The Europa lander has a  baggage weight limit of 40 pounds of science experiments. Unlike the Mars Viking Landers from the 1970s, the lander can accommodate just a single astrobiology lab. It is dedicated to studying any organic chemistry present and identifying any sources of chemical disequilibrium on the surface – the driving energy flow for life.  

Before the lander fizzles out, a tiny pocket-sized probe melts its way down to a depth of just a few inches and then is retracted into the lander with a water sample. The water is filtered, and chemically analyzed for organic matter.

The first results are likely be ambiguous when it comes to finding life on Europa, unless the probe’s camera photographs Europa whales beached and frozen stiff on the surface. 

The water sample may not be large enough to capture a single microbe if they are thinly dispersed in the Europa ocean.  But if we get lucky, there could be nutrient-rich regions near the boundary between ice and water near Europa’s surface.

Whatever the astrobiology data – or lack thereof -- comes from the lander, it serves to guides the follow-on mission: An autonomous, robotic, ocean-exploring spacecraft.

This next and far pluckier lander will carry a torpedo-shaped cryobot that will melt its way through the ice and come face-to-face with anything that might be within the subterranean ocean.

Photos: NASA