Firefly Mission to Study Terrestrial Gamma-ray Flashes

High-energy bursts of gamma rays typically occur far out in space, perhaps near black holes or other high-energy cosmic phenomena. So imagine scientists' surprise in the mid-1990s when they found these powerful gamma ray flashes happening right here on Earth, in the skies overhead.

They're called Terrestrial Gamma-ray Flashes, or TGFs, and very little is known about them. They seem to have a connection with lightning, but TGFs themselves are something entirely different.

An artist's concept of TGFs.

"In fact," says Doug Rowland of NASA's Goddard Space Flight Center, "before the 1990s nobody knew they even existed. And yet they're the most potent natural particle accelerators on Earth."
Individual particles in a TGF acquire a huge amount of energy, sometimes in excess of 20 mega-electron volts (MeV). In contrast, the colorful auroras that light up the skies at high latitudes are powered by particles with less than one thousandth as much energy.

At this stage, there are more questions about TGFs than answers. What causes these high-energy flashes? Do they help trigger lightning--or does lightning trigger them? Could they be responsible for some of the high-energy particles in the Van Allen radiation belts, which can damage satellites?

To investigate, Rowland and his colleagues at GSFC, Siena College, Universities Space Research Association, and the Hawk Institute for Space Sciences are planning to launch a tiny, football-sized satellite called Firefly in 2010 or 2011. Because of its small size, Firefly will cost less than $1 million — about 100 times cheaper than what satellite missions normally cost. Part of the cost savings comes from launching Firefly under the National Science Foundation's CubeSat program, which launches small satellites as "stowaways" aboard rockets carrying larger satellites into space, rather than requiring dedicated rocket launches.

An artist's concept of Firefly on the lookout for TGFs above a thunderstorm. Firefly will make simultaneous measurements of energetic electrons, gamma rays, and the radio and optical signatures of the lightning discharge.

If successful, Firefly will return the first simultaneous measurements of TGFs and lightning. Most of what's known about TGFs to date has been learned from missions meant to observe gamma rays coming from deep space, such as NASA's Compton Gamma Ray Observatory, which discovered TGFs in 1994. As it stared out into space, Compton caught fleeting glimpses of gamma rays out of the corner of its eye, so to speak. The powerful flashes were coming--surprise!--from Earth's atmosphere.

Subsequent data from Compton and other space telescopes have provided a tantalizingly incomplete picture of how TGFs occur:

In the skies above a thunderstorm, powerful electric fields generated by the storm stretch upward for many miles into the upper atmosphere. These electric fields accelerate free electrons, whisking them to speeds approaching the speed of light. When these ultra-high speed electrons collide with molecules in the air, the collisions release high-energy gamma rays as well as more electrons, setting up a cascade of collisions and perhaps more TGFs.

Doug Rowland, principal investigator for Firefly stands next to the a life-sized model of the tiny satellite.

To the eye, a TGF probably wouldn't look like much. Unlike lightning, most of a TGF's energy is released as invisible gamma rays, not visible light. They don't produce colorful bursts of light like sprites and other lightning-related phenomena. Nevertheless, these unseen eruptions could help explain why brilliant lightning strikes occur.

A longstanding mystery about lightning is how a strike gets started. Scientists know that the turbulence inside a thundercloud separates electric charge, building up enormous voltages. But the voltage needed to ionize air and generate a spark is about 10 times greater than the voltage typically found inside storm clouds.

"We know how the clouds charge up," Rowland says, "we just don't know how they discharge. That is the mystery."

TGFs could provide that spark. By generating a quick burst of electron flow, TGFs might help lightning strikes get started, Rowland suggests. "Perhaps this phenomenon is why we have lightning," he says.

If so, there ought to be many more TGFs each day than currently known. Observations by Compton and other space telescopes indicate that there may be fewer than 100 TGFs worldwide each day. Lightning strikes millions of times per day worldwide. That's quite a gap.

Then again, Compton and other space telescopes before Firefly weren't actually looking for TGFs. So perhaps it's not surprising that they didn't find many. Firefly will specifically look for gamma ray flashes coming from the atmosphere, not space, conducting the first focused survey of TGF activity. Firefly's sensors will even be able to detect flashes that are mostly obscured by the intervening air, which is a strong absorber of gamma rays (a fact that protects people on the ground from the energy in these flashes). Firefly's survey will give scientists much better estimates of the number of TGFs worldwide and help determine if the link to lightning is real.

Year's Best Mars View Tonight

Red planet to pass closest to Earth

Mars shines brightly over Mount Taftan in southeast Iran. This phenomena will be seen tonight at the East after sunset. <<>>

Mars is zooming in for a close approach to Earth tonight, offering backyard astronomers their best views of the red planet until 2014.
For the past few months Mars has appeared at night as a ruddy, starlike beacon rising in the east.

Tonight Mars will pass within 61 million miles (98 million kilometers) of Earth—close enough for well-equipped sky-watchers to make out details on the Martian surface.
"With a small telescope of about 6 inches (15.2 centimeters), the polar ice caps and other surface features are visible," said Raminder Singh, staff astronomer at the H.R. MacMillan Space Centre in Vancouver, British Columbia.

(Related: "Mars Pole Holds Enough Ice to Flood Planet, Radar Study Shows.")
"Even a pair of binoculars will show it as a disk, as opposed to a star, which looks like a pinpoint of light."

And on January 29 Mars will reach opposition, which means it will rise in the east just as the sun sets in the west, making the red planet visible all night long.
"When opposition occurs, Mars is on the opposite side [of Earth] from the sun. If viewed from above the solar system, the sun, Earth, and Mars would be in a straight path," Singh said.
(Find out what happens when Mars is on the opposite side of the sun from Earth, aka in solar conjunction.)

Adding to the cosmic spectacle, on the night of opposition Mars will appear fairly close to the full moon, and the pair will glide together across the sky.

Mars Easy to See

The exact distance between Mars and Earth changes over time, because the orbits of the planets are not perfect circles, but elongated ellipses.

This orbital setup means Mars makes a close pass by Earth roughly every two years.
In August 2003 Mars made its closest pass by Earth in 60,000 years, swinging by at a mere 35 million miles (56 million kilometers) away. That event created spectacular views for astronomers but also seems to have spawned the recurring "Mars Spectacular" email hoax.

Tonight's approach won't be a particularly close pass. Still, the "flyby" will highlight how easy it is to spot Mars even with the naked eye, Singh noted.

"It's the third brightest object in the night sky, aside from the moon and the star Sirius," Singh said.

"People should really go outside and look at it, as it's an easy thing to see in the sky."

Close Encounter of Earth and Mars

A red planet in our solar system, Mars will be seen on 29 January 2010, after sunset. The Mars will be in 99 million kilometers distance away from Earth, and without using any telescope or the binocular, we can see the planet clearly with our naked eye!

The sky map of the red planet observation event is shown below.

The planet will just be seen on January 2010 only. If you missed the chance to observe this planet on January 2010, you must be patient to observe it next on March 2012.

Happy enjoyed the show and thanks to Dragon X for the observation and investigation.

End Of The World 2012 - 2012 Doomsday

For more details, logon to: End Of The World 2012 - 2012 Doomsday to watch the homepage! Get ready!!!!!!!!!!

Space Shuttle

For the latest news of the Space Shuttle Endeavour launch onto STS-130 mission, please click on the hyperlink to the NASA home page for the Nodes 3 reached LC 39A. <<Space Shuttle>>

Annular Solar Eclipse of 15 January 2010

Headline:
The first eclipse of 2010 will begin by the Annular Solar Eclipse on 15 January 2010. The first solar eclipse of 2010 occurs at the Moon’s ascending node in western Sagittarius. An annular eclipse will be visible from a 300-km-wide track that traverses central Africa, the Indian Ocean and eastern Asia (Espenak and Anderson, 2008). A partial eclipse is seen within the much broader path of the Moon’s penumbral shadow, which includes Eastern Europe, most of Africa, Asia and Indonesia.

Description:
The annular path begins in western most Central African Republic at 05:14 UT. Because the Moon passes through apogee two days later (17 January 2010 at 01:41 UT), its large distance from Earth produces an unusually wide path of annularity. Traveling eastward, the shadow quickly sweeps through Uganda, Kenya and Somalia while the central line duration of annularity grows from 7 to 9 minutes.

For the next two hours, the antumbra crosses the Indian Ocean, its course slowly curving from east-southeast to northeast. The instant of greatest eclipse occurs at 07:06:33 UT (15:06:33pm GMT+8) when the eclipse magnitude will reach 0.9190. At this instant, the duration of annularity is 11minutes 08seconds, the path width is 333 kilometers and the Sun is 66° above the flat horizon formed by the open ocean. Such a long annular duration will not be exceeded for over 1000 years (23 December 3043).

The central track continues northeast where it finally encounters land in the Maldive Islands (07:26 UT). The capital city Male experiences an annular phase lasting 10minutes 45seconds. This is the longest duration of any city having an international airport in the eclipse track.

When the antumbra reaches Asia the central line passes directly between the southern tip of India and northern Sri Lanka (07:51 UT). Both regions lie within the path where maximum annularity lasts 10minutes 15seconds. Quickly sweeping over the Bay of Bengal the shadow reaches Burma where the central line duration is 08minutes 48seconds and the Sun’s altitude is 34°.

By 08:41 UT (16:41pm GMT+8), the central line enters China. The shadow crosses the Himalayas through Yunnan and Sichuan provinces Chongqing lies directly on the central line and witnesses a duration of 07minutes 50seconds with the Sun 15° above the horizon. Racing through parts of Shaanxi and Hubei provinces, the antumbra’s speed increases as the duration decreases. In its final moments, the antumbra travels down the Shandong Peninsula and leaves Earth’s surface (08:59 UT) (16:59pm GMT+8).

During the course of its 3 ¾-hour (3hours 45minutes) trajectory, the antumbra’s track is approximately 12,900km long that covers 0.87% of Earth’s surface area. Path coordinates and central line circumstances are presented in Table 1.
Partial phase of the eclipse are visible primarily from Africa, Asia and Indonesia. Local circumstances for a number of cities are found in Table 2. All times are given in Universal Time (UT). The Sun’s altitude and azimuth, the eclipse magnitude and obscuration 3 are all given at the instant of maximum eclipse.

This is the 23rd eclipse of Saros 141 (Espenak and Meeus, 2006). The family began with a series of 6 partial eclipses starting on 19 May 1613. The first annular eclipse took place on 04 August 1739 and had a maximum duration just under 04minutes. Subsequent members of Saros 141 were all annular eclipses with increasing durations, the maximum of which was reached on 14 December 1955 and lasted 12minutes 09seconds. This event was the longest annular eclipse of the entire Second Millennium. The duration of annularity of each succeeding eclipse is now dropping and will dwindle to 01minutes 09seconds when the last annular eclipse of the series occurs on 14 October 2460. Saros 141 terminates on 13 June 2857 after a long string of 22 partial eclipses. Complete details for the 70 eclipses in the series (29 partial and 41 annular) may be found at:
[NASA Saros 141]

Eclipse Viewer:
On 15 January 2010, Friday morning, there will be an Annular Solar Eclipse occurs. The eclipse will be occurring at the Ecliptic Conjunction of 07:12:28.5 TD (07:11:22.4 UT), and the Greatest Eclipse of 07:07:39.0 TD (07:06:33.0 UT). At the moment, the Eclipse Magnitude will be at 0.9190 and the Gamma of 0.4002. The Saros Series will be at 141 and the member will be at 23 of 70.

Easy Capture (1):
Ecliptic Conjunction = 07:12:28.5 TD (07:11:22.4 UT)
Greatest Eclipse = 07:07:39.0 TD (07:06:33.0 UT)

Eclipse Magnitude = 0.9190
Gamma = 0.4002

Saros Series = 141
Member = 23 of 70

Sun at Greatest Eclipse (Geocentric Coordinates):
When the eclipse occur, the Sun will be in the Right Ascension for 19hours 47minutes 51.1seconds. The Declination of the Sun will be in -21°07’38.7”, Apparent Semi-Diameter of 00°16’15.5”, and the Horizontal Parallax of 00°00’08.9”.

Easy Capture (2):
R.A. = 19h47m51.1s
Dec. = -21°07’38.7”
S.D. = 00°16’15.5”
H.P. = 00°00’08.9”

Moon at Greatest Eclipse (Geocentric Coordinates):
When the eclipse occur, the Moon will be in the Right Ascension for 19hours 47minutes 25.3seconds. The Declination of the Sun will be in -20°46’54.8”, Apparent Semi-Diameter of 00°14’44.3”, and the Horizontal Parallax of 00°54’05.4”.

Easy Capture (3):
R.A. = 19h47m25.3s
Dec. = -20°46’54.8”
S.D. = 00°14’44.3”
H.P. = 00°54’05.4”
External/Internal (Contacts of Penumbra):
P1= 04:05:27.5 UT
P2= 06:50:06.7 UT
P3= 07:22:37.6 UT
P4= 10:07:35.1 UT

External/Internal (Contacts of Umbra):
U1= 05:13:54.8 UT
U2= 05:21:15.8 UT
U3= 08:51:40.3 UT
U4= 08:59:03.7 UT

Eclipse Occur Duration:
Kota Bharu, Malaysia: 16:30pm ~ 16:41:08pm
Observation Started: 15:22:37.6pm

Constant & Ephemeris:
ΔT = 66.0s
k1 = 0.2725076
k2 = 0.2722810
ΔB= 0.0”
ΔL= 0.0”
Eph. = JPL DE200/LE200

Geocentric Libration (Optical + Physical):
L= 1.48°
B= -0.48°
C= -8.81°
Brown Lun. No. = 1077

Local Circumstances at Greatest Eclipse:
Latitude= 01°37.4’N
Longitude= 069°17.4’E
Sun Altitude= 66.4°
Sun Azimuth= 164.9°
Path Width= 333.1 km
Duration= 11minutes 07.8seconds

Why Won't the Supernova Explode?

A massive old star is about to die a spectacular death. As its nuclear fuel runs out, it begins to collapse under its own tremendous weight. The crushing pressure inside the star skyrockets, triggering new nuclear reactions, setting the stage for a terrifying blast. And then... nothing happens.

At least that's what supercomputers have been telling astrophysicists for decades. Many of the best computer models of supernova explosions fail to produce an explosion. Instead, according to the simulations, gravity wins the day and the star simply collapses.
Clearly, physicists are missing something.

"We don't really understand how supernovas of massive stars work yet," says Fiona Harrison, an astrophysicist at the California Institute of Technology. The death of relatively small stars is better understood, but for larger stars — those with more than about 9 times the mass of our sun — the physics just doesn't add up.

A supercomputer model of a rapidly-spinning, core-collapse supernova. NuSTAR observations of actual supernova remnants will provide vital data for such models and help explain how massive supernovas manage to explode.

Something must be helping the outward push of radiation and other pressures overcome the inward squeeze of gravity. To figure out what that "something" is, scientists need to examine the inside of a real supernova while it's exploding — not a particularly easy thing to do!

But that's exactly what Harrison intends to do with a new space telescope she and her colleagues are developing called the Nuclear Spectroscopic Telescope Array, or NuSTAR.

After it launches in 2011 aboard a Pegasus rocket, NuSTAR will give scientists an unprecedented view of high-energy X-rays coming from supernova remnants, black holes, blazars, and other extreme cosmic phenomena. NuSTAR will be the first space telescope that can actually focus these high-energy X-rays, producing images roughly 100 times sharper than those possible with previous telescopes.

Using NuSTAR, scientists will look for clues to conditions inside the exploding star etched into the pattern of elements spread throughout the nebula that remains after the star explodes.

An artist's concept of NuSTAR. Focusing X-ray optics require long focal lengths--hence the 10-meter deployable mast, which is extended after launch.

"You don't get the opportunity to watch these explosions very often, ones that are close enough to study in detail," Harrison says. "What we can do is study the remnants. The composition and distribution of the material in the remnants tells you a lot about the explosion."

One element in particular is of keen interest: titanium-44. Creating this isotope of titanium through nuclear fusion requires a certain combination of energy, pressure, and raw materials. Inside the collapsing star, that combination occurs at a depth that's very special. Everything below that depth will succumb to gravity and collapse inward to form a black hole. Everything above that depth will be blown outward in the explosion. Titanium-44 is created right at the cusp.

So the pattern of how titanium-44 is spread throughout a nebula can reveal a lot about what happened at that crucial threshold during the explosion. And with that information, scientists might be able to figure out what's wrong with their computer simulations.

NuSTAR will map the distribution of titanium-44 in supernova remnants like this one, Cassiopeia A, to search for evidence of asymmetries.

Some scientists believe the computer models are too symmetrical. Until recently, even with powerful supercomputers, scientists have only been able to simulate a one-dimensional sliver of the star. Scientists just assume that the rest of the star behaves similarly, making the simulated implosion the same in all radial directions.

But what if that assumption is wrong?

"Asymmetries could be the key," Harrison says. In an asymmetrical collapse, outward forces could break through in some places even if the crush of gravity is overpowering in others. Indeed, more recent, two-dimensional simulations suggest that asymmetries could help solve the mystery of the "non-exploding supernova."

If NuSTAR finds that titanium-44 is spread unevenly, it would be evidence that the explosions themselves were also asymmetrical, Harrison explains.

To detect titanium-44, NuSTAR needs to be able to focus very high energy X-rays. Titanium-44 is radioactive, and when it decays it releases gamma rays with an energy of 68 kilo-electronvolts (keV). Existing X-ray space telescopes, such as NASA's Chandra X-Ray Observatory, can only focus X-rays up to about 15 keV.

Normal lenses can't focus X-rays at all. Glass bends X-rays only a miniscule amount, so for a glass lens to bend X-rays enough to focus them, it would have to be so thick that it would adsorb the X-rays instead.

X-ray telescopes use an entirely different kind of lens. Called a Wolter-I optic, it consists of many cylindrical shells, each one slightly smaller and placed inside the last. The result looks a bit like the layers of a cylindrical onion (if there were such a thing), with small gaps between the layers.

The x-ray "light path" of the EPIC camera of the XMM-Newton satellite, a Wolter-I design similar to that used by NuSTAR.

Incoming X-rays pass between these layers, which guide the X-rays to the focal surface. It's not a lens, strictly speaking, because the X-rays reflect off the surfaces instead of passing through them the way light passes through a glass lens. But the end result is the same.

NuSTAR's Wolter-I optic has a special atomic-precision coating that enables its layers to reflect X-rays with energies as high as 79 keV. Harrison and her colleagues have spent years perfecting the delicate manufacturing techniques for making these high-precision layers. Together with a new sensor that can tolerate these high energies, these finely crafted layers are what enable NuSTAR to image these relatively unexplored, high-intensity X-rays.And the discoveries won't stop with supernovas. High-energy X-rays are emitted by many of the universe's most extreme phenomena, including supermassive black holes and blazars. NuSTAR will give us a new window on the universe at its most extreme.

Kepler Discovers Five New Exoplanets

NASA's Kepler space telescope, designed to find Earth-size planets in the habitable zone of sun-like stars, has discovered its first five new exoplanets.

Named Kepler 4b, 5b, 6b, 7b and 8b, the planets were announced Monday, Jan. 4, by the members of the Kepler science team during a news briefing at the American Astronomical Society meeting in Washington.

An artist's concept of the Kepler space telescope on a mission to discover habitable planets outside our own Solar System.

"The discoveries show that our science instrument is working well," says William Borucki of NASA's Ames Research Center in Moffett Field, Calif. Borucki is the mission's science principal investigator. "Indications are that Kepler will meet all its science goals."

The five planets are quite a bit larger than Earth. Known as "hot Jupiters" because of their high masses and extreme temperatures, the new exoplanets range in size from similar to Neptune to larger than Jupiter. They have orbits ranging from 3.3 to 4.9 days. Estimated temperatures of the planets range from 2,200 to 3,000 degrees Fahrenheit, hotter than molten lava and much too hot for life as we know it.

Kepler's first five exoplanets are large and hot. As the mission proceeds and Kepler has time to gather more data, smaller and cooler planets can be found leading, perhaps, to the discovery of planets like Earth.

"It's gratifying to see the first Kepler discoveries rolling off the assembly line," says Jon Morse, director of the Astrophysics Division at NASA Headquarters in Washington. "We expected Jupiter-size planets in short orbits to be the first planets Kepler could detect. It's only a matter of time before more Kepler observations lead to smaller planets with longer period orbits, coming closer and closer to the discovery of the first Earth analog."

Launched on March 6, 2009, from Cape Canaveral Air Force Station in Florida, the Kepler mission continuously and simultaneously observes more than 150,000 stars. Kepler's science instrument, or photometer, already has measured hundreds of possible planet signatures that are being analyzed.

Kepler looks for the signatures of planets by measuring dips in the brightness of stars. When planets cross in front of, or transit, their stars as seen from Earth, they periodically block the starlight. The size of the planet can be derived from the size of the dip. The temperature can be estimated from the characteristics of the star it orbits and the planet's orbital period.

While many of the signatures detected so far are likely to be something other than a planet, such as small stars orbiting larger stars, ground-based observatories have confirmed the existence of the five exoplanets. The discoveries are based on approximately six weeks' worth of data collected since science operations began on May 12, 2009.

The five planets were discovered when they passed in front of (or "transited") their parent stars, causing the stars' apparent brightness to dip.

Kepler will continue science operations until at least November 2012. It will search for planets as small as Earth, including those that orbit stars in a warm habitable zone where liquid water could exist on the surface of the planet. Since transits of planets in the habitable zone of solar-like stars occur about once a year and require three transits for verification, it is expected to take at least three years to locate and verify an Earth-size planet.

According to Borucki, Kepler's continuous and long-duration search should greatly improve scientists' ability to determine the distributions of planet size and orbital period in the future.
"Today's discoveries are a significant contribution to that goal," Borucki said. "The Kepler observations will tell us whether there are many stars with planets that could harbor life, or whether we might be alone in our galaxy."For more information about the Kepler mission, visit the mission home page at http://www.nasa.gov/kepler.

Spirit Faces Uncertain Future as New Year Dawns

This Sunday, NASA's Mars rover Spirit will mark six years of unprecedented exploration of the Red Planet. However, the upcoming Martian winter could end the roving career of the beloved, scrappy robot.

Spirit landed on Mars at 8:35 p.m. PST on Jan. 3, 2004, and its twin Opportunity arrived at 9:05 p.m. Jan. 24, 2004. The rovers began missions intended to last for just three months but which have instead gone on for six Earth years, or 3.2 Mars years. During this time, Spirit has found evidence of a steamy and violent environment on ancient Mars that was quite different from the wet and acidic past documented by Opportunity, which has been operating successfully halfway around the planet.

An artist's concept of Spirit on Mars.

A sand trap and balky wheels are challenges to Spirit's mobility that could prevent NASA's rover team from using a key winter-survival strategy. The team might not be able to position the robot's solar panels to tilt toward the sun to collect power for heat to survive the severe Martian winter.

Nine months ago, Spirit was driving across a place called "Troy" when its wheels broke through a crusty surface layer into loose sand. Efforts to escape this sand trap barely have budged the rover. The rover's inability to use all six wheels for driving has worsened the predicament. Spirit's right-front wheel quit working in 2006, and its right-rear wheel stalled a month ago. Surprisingly, the right-front wheel recently resumed working, though intermittently. Drives with four or five operating wheels have produced little progress and the latest attempts have resulted in the rover actually sinking deeper in the soil.

"The highest priority for this mission right now is to stay mobile, if that's possible," says Steve Squyres of Cornell University in Ithaca, N.Y. He is principal investigator for the rovers.

If mobility is not possible, the next priority is to improve the rover's tilt, while Spirit is able to generate enough electricity to turn its wheels. Spirit is in the southern hemisphere of Mars, where it is autumn, and the amount of daily sunshine available for the solar-powered rover is declining. This could result in ceasing extraction activities as early as January, depending on the amount of remaining power. Spirit's tilt, nearly five degrees toward the south, is unfavorable because the winter sun crosses low in the northern sky.

The latest attempt to dislodge Spirit, pictured above, was not successful. On Dec. 26th the rover actually sunk 6 mm deeper into the sandtrap.

Unless the tilt can be improved or winds lessen the gradual buildup of dust on the solar panels, the amount of sunshine available will continue to decline until May 2010. During May, or perhaps earlier, Spirit may not have enough power to remain in operation.

"At the current rate of dust accumulation, solar arrays at zero tilt would provide barely enough energy to run the survival heaters through the Mars winter solstice," says Jennifer Herman, a rover power engineer at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

The team is evaluating strategies for improving the tilt even if Spirit cannot escape the sand trap, such as trying to dig in deeper with the wheels on the north side. In February, NASA will assess Mars missions, including Spirit, for their potential science versus costs to determine how to distribute limited resources. Meanwhile, the team is planning additional research about what a stationary Spirit could accomplish as power wanes.

"Spirit could continue significant research right where it is," says Ray Arvidson of Washington University in St. Louis, deputy principal investigator for the rovers. "We can study the interior of Mars, monitor the weather and continue examining the interesting deposits uncovered by Spirit's wheels."

A topographic map of Spirit's surroundings at Troy. For more information about the science Spirit is able to do there, read the Science@NASA story "Sandtrapped Rover Makes Big Discovery."

A study of the planet's interior would use radio transmissions to measure wobble of the planet's axis of rotation, which is not feasible with a mobile rover. That experiment and others might provide more and different findings from a mission that has already far exceeded expectations.
"Long-term change in the spin direction could tell us about the diameter and density of the planet's core," says William Folkner of JPL. He has been developing plans for conducting this experiment with a future, stationary Mars lander. "Short-period changes could tell us whether the core is liquid or solid."