Pluto Probe Proposals Propositioned

Space.com; Dec. 20, 2000; Missions: "NASA Revives Pluto Mission; 2004 Launch Possible"

Cosmiverse.com; Dec. 21, 2000; Space News: "NASA Seeks Proposals for Pluto Mission"

Old PKE -- NASA.

NASA has revived hopes for a Pluto probe with it's upcoming mid-January "Announcement of Opportunity" for scientist to develop a mission to Pluto, its moon Charon, and objects beyond in the Kuiper-belt.  Open to anyone, this is the first time that the Office of Space Science has put up for competitive bidding a mission to the outer planets.  The process will be modeled on the agency's "Discovery Program" that attempts to lower costs through the rapid development of highly focused missions. 

"In the past decade a number of organizations outside NASA have gained the expertise to successfully fly deep space missions, and in the past few months we have heard the calls from many in the scientific community in favor of open competition in our outer planet program," said Dr. Edward Weiler, the NASA associate administrator for the Office of Space Science. "I think it's time to try this new approach. We hope that opening these missions to competition will greatly benefit science and space exploration."

This announcement from NASA is in response to the recent outcry in the science community over the cancellation of the Pluto-Kuiper Express (PKE) due to cost overruns (see NewsNotes: 09.01.00 Pluto Probe Procrastination and 10.01.00 Pluto Probe Pulled).  PKE was part of a JPL managed outer planet program that included an orbiter to Jupiter's moon Europa.  When costs escalated in both programs Europa got the priority and the Pluto missions was cut. 

This new mission will have a budget cap of $500-million compared with the original PKE budget of $350-million. This Pluto mission will still be "budget bundled" with the Europa Orbiter mission -- with Europa still having priority. "Europa may harbor the only ocean in the solar system, other than on Earth. If you have water, energy, and hydrocarbons, you have life," says Dr. Weiler. "Europa is a very, very important mission."

Competitors will have to design a full mission that includes launch vehicle and spacecraft, with associated science instrumentation, by the March 2001 proposal deadline.  Ideas that NASA likes will be funded for further research, but not necessarily launched.  "We are not making a commitment to do a Pluto mission or to select any of the proposals," Weiler said.  "We just want to see if we have any viable options," he said.  Final decision to proceed with a mission will be in August of 2001.  A Workshop will be held in February to discuss techniques, innovations, and novel methods of reaching and studying the outer planets.

Speedy mission development is driven by the opportunity to use Jupiter in a cost-savings gravity assist to reach Pluto.  Planetary alignment requires a spacecraft launch by 2006 to utilize this technique.  But even with unlimited money and power the race is on to reach the planet before its atmosphere freezes over -- which is estimated to happen in 2020 -- as the planet's highly elliptical orbit takes it further from the sun.  Pluto is the only major planet not to be visited by a spacecraft."  This is likely the last chance to get to Pluto for a decade or more," Weiler said.

Child's Play to Pay-Day

SpaceDaily.com; Dec 4, 2000; Tech Space: "Water Rockets Are Go"

There are toy rockets that fly using air pressurizing by hand-pump or a stream of water from a garden hose.  So why not employ these systems to launch real rockets?  An article originally printed in New Scientist posits this question with its description of the " Hydro Pneumatic Accelerator" (Hypacc).  

Hypacc is essentially a long, vertical, and mostly submerged tube in the ocean kept dry by a seal at the bottom.  Below that seal is an air filled chamber that is open to the water  -- sort of like a diving bell.  The longer the tube length to the surface the greater the air is compressed in the chamber.  A space rocket rests nice and dry above the seal at the bottom of the tube.  One scenario envisions the tube 1-km long and 10-m wide. 

At launch the seal between the dry tube and compressed air chamber is broken.  The compressed air pocket propels the rocket upward with great force as it is chased up the tube by the high-pressure water.  Pressure equalizes as the air and water reach the surface: at that point the speed of the rocket is an amazing 1,000-km/hr!  With that massive initial boost the onboard rocket engines fire and the rocket continues on to space.  

"I'm not a rocket scientist and I know there must be thousands of wackos out there all pushing their ideas."
-- Scott Taylor, father of Hypacc

The system is envisioned as a weight and cost saving way of accomplishing most of the work of the first stage in a conventional launch system.  What is most impressive is that the envisioned 1-km long tube could send the mass of five Space Shuttles out the top!  

And who's idea was it to scale up "amateur" rocket technology?  Why, an amateur rocketeer named Scott Taylor.  "I'm not a rocket scientist and I know there must be thousands of wackos out there all pushing their ideas.  But I'm just trying to establish if there's anything to this idea," says Taylor.

A launch expert interviewed for the article points out the enormity of the project (i.e., costs) and the likelihood that air resistance and friction will prevent large payloads from achieving the envisioned speeds.  But in the future, if it does work, Taylor may ask users to pay a nice sum to "play" with his "toy". 

"Mars Millennium" Roundup

The space press has been buzzing all year with discoveries on Mars and coverage of the flotilla of upcoming missions to the Red Planet.   It is quite clear that our close neighbor will get a lot of scrutiny in the new Millennium -- perhaps that long-dreamt of human landing will come true this century.  In honor of the "Martian Millennium" the news section below contains recent Mars news.

Take Me to Your North Pole

SpaceScience.com; Dec. 20, 2000; NASA Science News: "Martian Micro-Magnets"

Mars  magnetite.

The 4-year-old scientific controversy surrounding the possibility of residual Martian life-signs in the Allen Hills meteorite (ALH84001) has now tilted back a bit in favor of the Martian microbes.  Scientists recently revealed the the Martian meteorite contains magnetite in a pure and defect-free crystal form that is only produced on Earth by bacteria that prefer a watery, low-oxygen environment.  The material is employed by the bacteria to detect magnetic field-lines for use in navigation.   

While the magnetite content of the meteor was touted as one of the main proofs of fossil life in 1996, much more now is known about the specific physical properties of these biogenic crystals.  For instance the bacterial magnetite is elongated along a particular axis and exhibits a distinct faceting pattern.  The properties are unusual enough to make this form of magnetite distinguishable from the geologically occurring form of the mineral.  The article quotes Dr. Dennis Bazylinski, a geobiologist at Iowa State University, as saying: "Finding this type of magnetic crystal in any material from another planet is an amazing and important finding."  

Evidence that Mars could host an environment for the magnetic-seeking aqueous bacteria has grown since 1996.  Recently the Mars Global Surveyor spacecraft detected what appears to be layers of sedimentary rock on Mars.  This type of rock requires water to lay down the layers.  The spacecraft has also detected residual magnetic fields on the surface from when Mars had a planet-wide magnetic field 4-billion years ago.

Scientists don't believe the magnetite is of terrestrial origin because the samples examined were from deep inside the meteorite and the recovery location of the meteorite in the Antarctic, where it lay for 13,000-years, was not environmentally suited for the magnetite producing bacteria.  Intriguingly the magnetite in ALH84001 was formed about 3.9- billion years ago while the earliest consensus for life on Earth dates back only 3.6 and 3.7-billion years.

While the scientists that studied the magnetite samples don't tout there existence as definitive proof of Martian life, they think the meteorite evidence is hard to explain away as non-biogenic in origin. 

Martians Have Landed?

SpaceDaily.com; Oct. 26, 2000; Mars Daily: "Getting A Cooler Ride To Earth"

The possibility that Martian meteorite ALH84001 exhibits remains of Martian life, brought to the forefront the theory that living microbes may have made the journey from Mars to Earth cocooned inside meteorites in the distant past.  One version of this "panspermia" theory holds that conditions for life were more favorable on Mars than Earth in the early evolution of our solar system.  In fact computer simulations indicate that of all the Martian material blasted into space by asteroid impacts, about 1-billion tons of it made it to Earth -- some within 1-year of departure!  The dynamics of the simulations indicate that a reverse crossing from Earth to Mars would have been more rare.

While radiation-resistant organism, that hibernate without energy and water for at least a year, are known on Earth, one roadblock in proving this theory is the heat the Martian microbes were subject to on ejection from Mars and passage through our atmosphere.  Researchers at Vanderbilt and McGill universities looked at this question when they ran thin slices of ALH84001 through an Ultra-High Resolution Scanning Superconducting Quantum Interference Device Microscope -- a unique machine developed at Vanderbilt.  This device is 10,000 times more sensitive than existing machines in determining differences in the magnetic field lines of rock samples.  The machine found that, while the exterior of ALH84001 had a strongly aligned magnetic field, the interior had randomly aligned magnetic fields.  Heating a sample of the meteorite's interior revealed that the weakly magnetic rock demagnetized at 40°C (105° Fahrenheit) and magnetizing along Earth's magnetic field on cool-down.  The university researchers interpreted the results as meaning the outer layer of the Martian meteorite was subject to high-heat which caused its magnetic field lines to align with that of Earth.  But the inner part of ALH84001 never reached 40° C -- cool enough for bacteria, fungi, or even seeds to survive. 

"So there is at least a chance that we are in part descended from Martian microbes."
--Professor Joseph Kirschvink of Caltech

Professor Joseph Kirschvink of Caltech, who organized the study, believes that, "The Martian biosphere, if it ever evolved, would most likely have been brought to Earth billions of years ago, and could have participated in the evolution and diversification of bacterial life here."  Further Kirschvink says: "So there is at least a chance that we are in part descended from Martian microbes."

2003: "The Beagle Has Landed" 

ESA; Dec. 20, 2000; Press Release: "Beagle 2 landing site selected"

Beagle 2 Site -- ESA

The European Space Agency (ESA) has issued a press release detailing the intended landing site of their Beagle 2 Mars Express lander.  The probe is slated for a June 2003 launch with arrival in December of that year.  The lightweight lander has a mass of only 30-kg and is packed with instruments to detect organic material in the soil, study the geology of the region, and monitor the weather.  

The site chosen is a large flat region called Isidis Planitia.  This region is the third largest impact basin on Mars and spans from Mars latitude 5° to 20° North; the landing spot is centered near 10° North.  Isidis Planita appears to be a sedimentary basin that once was filled with water.  This may be one of the locations where traces of ancient Martian life has been preserved.

One of the major constraints in landing site selection was the need for an area big enough to accommodate the 500-km x 100-km maximum size of the landing zone.  This entire area needs to be at a low elevation to allow landing parachutes to grab into the thin Martian atmosphere.  Also the terrain must have few steep slopes and little dust.  Finally, for the experiments to operate correctly, the landing zone for Beagle 2 must be in a warm-area during the Martian early-Spring. 

The precise location of the landing spot will be determined by a novel technique.  In February 2004 the Martian moon Phobos cast its shadow over Isidis Planitia as it passes in front of the Sun in a partial eclipse.  Timing the shadow position from the ground will determine the position of the lander. 

Attracted to That Ol' Martian Magnetism

SpaceDaily.com; Dec. 18, 2000; Mars Daily: "Mars' Magnetic Patchwork May Protect Atmosphere"

Artist concept of crustal magnetic fields -- NASA.

Current Martian theories point to a planet that had flowing surface water early in its history before the atmosphere thinned and all that water evaporated.  Data from Mars Global Surveyor (MGS), as analyzed by researcher at the University of California, Berkeley, has shed light on how the past and current magnetic fields of Mars play a role in protecting the atmosphere from erosion by the solar wind. 

MGS carries instruments that detect when it is orbiting through the Martian ionosphere or through an ionosphere- less region buffeted by the solar wind.  A magnetometer measures the magnetic fields emanating from the crust of the planet.

The magnetometer has mapped areas of strong crustal magnetism and areas devoid of a magnetic field.  The non-magnetic regions coincide with craters 4-billion or more years old.  Presumably Mars started out with a molten metal core "dynamo" that generated a magnetic field that magnetized the crust.  The age of the de-magnetized craters indicate that 4-billion years ago that dynamo shut-down.  After that event any surface crust heated by asteroid impact was demagnetized and could not be re-magnetize as it cooled.

Prior to shut-down the dynamo generated a magnetosphere around the whole planet that trapped ionized hydrogen and helium from the solar wind.  This global ionosphere extended to high-altitude and prevented those particles from ionizing atmospheric gasses and sweeping them away.  This research leads to speculation that, lacking a dynamo-generated ionosphere, the solar wind stripped-off a large part of the Martian atmosphere and caused the surface water to evaporate into space.  This is why Mars today is a "dead" planet. 

This MGS data also revealed that ionospheric patches that remain today are generated by remnant crustal magnetism.  When MGS passes over areas of strong crustal magnetism it also detects an ionospheric region in space.  Where crustal magnetism was lacking there was no ionosphere.  So the residual magnetism in the crust plays an important role in protecting the remains of the Martian atmosphere.  "The ionosphere is what shields the densest part of Mars' atmosphere from being swept away by the solar wind," said David Mitchell, of Berkeley's Space Sciences Laboratory.  He says that, "These fields are like umbrellas scattered over the surface protecting the atmosphere."  In the future this data will be used to model how fast the Martian atmosphere eroded away.