This artist's rendering depicts NASAs Voyager 2 spacecraft as it studies the outer limits of the heliosphere - a magnetic 'bubble' around the solar system that is created by the solar wind. Image credit: NASA/JPL-Caltech
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What could be happening out near the edge of the solar system? The 33-year-old Voyager 2 spacecraft has experienced an anomaly where the data it sends back is unreadable. To try and understand the problem, engineers at JPL have shifted the spacecraft into a mode where it transmits only spacecraft health and status data. Preliminary engineering data received on May 1 show the spacecraft is basically healthy, and that the source of the issue is the flight data system, which is responsible for formatting the data to send back to Earth.
Voyager team members first noticed changes in the return of data packets from Voyager 2 on April 22, and have been working since then to troubleshoot the problem and resume the regular flow of science data. Because of a planned roll maneuver and moratorium on sending commands, engineers got their first chance to send commands to the spacecraft on April 30. It takes nearly 13 hours for signals to reach the spacecraft and nearly 13 hours for signals to come down to NASA’s Deep Space Network on Earth.
Voyager 2 is about 13.8 billion kilometers, or 8.6 billion miles, from Earth, and launched on August 20, 1977. Its twin, Voyager 1 is about 16.9 billion kilometers (10.5 billion miles) away from Earth, and launched almost two weeks after Voyager 2.
The original mission was a four-year journey to Saturn, and later the flybys of Uranus and Neptune were added to give us a “Grand Tour” of the outer solar system. If all goes well, Voyager 2 should leave the solar system and enter interstellar space in about five years.
When considering how the solar system formed, there are a number of problems with the idea of planets just blobbing together out of a rotating accretion disk. The Nice model (and OK, it’s pronounced ‘niece’ – as in the French city) offers a better solution.
In the traditional Kant/Laplace solar nebula model you have a rotating protoplanetary disk within which loosely associated objects build up into planetesimals, which then become gravitationally powerful centres of mass capable of clearing their orbit and voila planet!
It’s generally agreed now that this just can’t work since a growing planetesimal, in the process of constantly interacting with protoplanetary disk material, will have its orbit progressively decayed so that it will spiral inwards, potentially crashing into the Sun unless it can clear an orbit before it has lost too much angular momentum.
The Nice solution is to accept that most planets probably did form in different regions to where they orbit now. It’s likely that the current rocky planets of our solar system formed somewhat further out and have moved inwards due to interactions with protoplanetary disk material in the very early stages of the solar system’s formation.
It is likely that within 100 million years of the Sun’s ignition, a large number of rocky protoplanets, in eccentric and chaotic orbits, engaged in collisions – followed by the inward migration of the last four planets left standing as they lost angular momentum to the persisting gas and dust of the inner disk. This last phase may have stabilised them into the almost circular, and only marginally eccentric, orbits we see today.
The hypothesized collision between 'Earth Mk 1' and Theia may have occurred late in rocky planet formation creating the Earth as we know it with its huge Moon of accreted impact debris
Meanwhile, the gas giants were forming out beyond the ‘frost line’ where it was cool enough for ices to form. Since water, methane and CO2 were a lot more abundant than iron, nickel or silicon – icy planetary cores grew fast and grew big, reaching a scale where their gravity was powerful enough to hold onto the hydrogen and helium that was also present in abundance in the protoplanetary disk. This allowed these planets to grow to an enormous size.
Jupiter probably began forming within only 3 million years of solar ignition, rapidly clearing its orbit, which stopped it from migrating further inward. Saturn’s ice core grabbed whatever gases Jupiter didn’t – and Uranus and Neptune soaked up the dregs. Uranus and Neptune are thought to have formed much closer to the Sun than they are now – and in reverse order, with Neptune closer in than Uranus.
And then, around 500 million years after solar ignition, something remarkable happened. Jupiter and Saturn settled into a 2:1 orbital resonance – meaning that they lined up at the same points twice for every orbit of Saturn. This created a gravitational pulse that kicked Neptune out past Uranus, so that it ploughed in to what was then a closer and denser Kuiper Belt.
The result was a chaotic flurry of Kuiper Belt Objects, many being either flung outwards towards the Oort cloud or flung inwards towards the inner solar system. These, along with a rain of asteroids from a gravitationally disrupted asteroid belt, delivered the Late Heavy Bombardment which pummelled the inner solar system for several hundred million years – the devastation of which is still apparent on the surfaces of the Moon and Mercury today.
Then, as the dust finally settled around 3.8 billion years ago and as a new day dawned on the third rock from the Sun – voila life!
Japan Aerospace Exploration Agency (JAXA) astronaut Naoko Yamazaki, STS-131 mission specialist, works inside the Window Observational Research Facility (WORF) in the Destiny laboratory of the International Space Station while shuttle Discovery was still docked. WORF is a platform for cameras, multispectral scanners, and other sensors to capture science imagery of Earth imagery through Destiny's earth facing window. WORF is named after the Klingon character Worf beloved in the Star Trek Universe (top left). The WORF patch (lower left) is inscribed with Commander Worf’s name in Klingon script and was created by Tony Boatright. Credit: NASA images. WORF Patch: NASA/Tony Boatright. Mosaic: Ken Kremer
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WORF has finally joined the crew aboard the International Space Station (ISS). That’s great news for NASA as well as members and fans of the Klingon High Council who are delighted to occupy a prime location for exquisite surveillance of the Earth and Federation activities.
WORF is the acronym for the Window Observational Research Facility, a new science imaging platform on the ISS, which is named after the popular Klingon character from the “Star Trek: The Next Generation” science fiction television series. The surface panel on WORF sports a beautiful patch with a Klingon language inscription – spelling out the name WORF in Klingon script (see photo). Although seemingly innocent, Universe Today has learned that the Klingon High Council may have more sinister plans afoot for WORF involving future imperial undertakings.
WORF was designed by Earthlings to function as a photographic darkroom for precision remote space sensing of the Earth. As such, it’s also the only rack on the station that ISS astronauts and cosmonauts can actually physically float into and then maneuver equipment around to conduct their science research. “The working volume to accommodate instruments is about 23 cubic ft (0.8 cubic m)”, according to Dennis Toney of Boeing, Huntsville, Al, who I interviewed at the Kennedy Space Center during the STS 131 launch.
Panels, shelving and brackets inside WORF provide numerous attach points for digital cameras, multispectral and hyperspectral scanners, camcorders, sensors and other instruments to capture Earth imagery through Destiny’s nadir – Earth facing – window.
The experiments will focus on studies of atmospheric and climate properties, land and sea formations, geology, agriculture, ranching, environmental and coastal changes, and also be linked to public outreach and education efforts.
“EarthKAM is an example of a remotely controlled digital camera system that will be commanded to take pictures by middle school students across the US using web based tools”, Toney explained to me. The kids will learn how to work as real scientists. See WORF graphics provided to the author by Boeing/Denis Toney.
Graphics show WORF ‘darkroom’ science rack loaded with cameras and spectral payloads (left) and after closing with hatch (right) to exclude stray light from entering the payload volume. Crewmembers control the experiments loaded inside WORF using a laptop computer mounted on the front of the rack. NASA will use WORF for high resolution Earth observation experiments. Middle school students will be able to remotely control the EarthKAM digital camera payload inside WORF to take photos of the earth and learn how to work as real scientists. Graphics courtesy of Boeing/Dennis Toney were specially provided to the author for this story.
Astronauts installed the WORF darkroom inside the US Destiny Laboratory module and purposely “placed it in a bay directly over the labs 20 inch (508 mm) diameter observation window to provide direct access to the window from inside WORF”, said Toney.
“WORF provides the infrastructure to maximize the usability of the window. Up to 5 science payloads can be accommodated at once”, explained Toney. Numerous instrument connector ports and jacks for Ethernet computer connections, power, video and cooling are built directly into the rack to transmit the multispectral and high resolution experimental imaging data to the ground.
The Destiny window is the highest quality optical glass science window ever flown on any manned spacecraft. The window is constructed from 4 panes of optical quality glass pressed together that permit greater than 95% transmission across most of the visible spectrum and 90% transmission in the near infrared.
Jeff Williams, Expedition 13 Science Officer, at the U.S. Destiny Laboratory Science Window on the ISS. Williams recently served as the ISS Expedition 22 Commander.WORF was mounted on top of the Destiny window by the STS 131 crew.
The photographic and spectral gear – up to 350 mm aperture – mounted inside WORF can be remotely operated from Earth or by astronauts on board, who may also work in a hand held mode as required by the particular piece of equipment to maximize the scientific return.
An external shutter protects the window from micrometeoroid and orbital debris floating outside the station. The hinged cover can be manually opened and closed by the crew inside the cabin with a hand crank.
The “Leonardo’ Multi-purpose Logistics Module (MPLM) weighs over 27,000 pounds and is one of three such modules built by the Italian Space Agency. The module serves as a space moving van and was loaded with 16 science and storage racks – including WORF – holding over 17,000 pounds of science supplies and experiments, crew life support provisions, spare parts, a new astronaut sleep quarter and a minus 80 degree freezer to stow science samples collected by the resident ISS crew.
The Leonardo resupply module and Ken Kremer inside the Space Station Processing Facility at the Kennedy Space Center as the module was being prepared for launch aboard shuttle Discovery on the STS 131 mission. WORF science rack and over 17,000 pounds of science equipment and supplies were loaded inside Leonardo. Credit: Ken Kremer
After Discovery docked to the ISS, Leonardo was hoisted out of Discovery’s cargo bay and berthed to the station for the duration of the flight. The massive orbiting outpost is 98% complete – by habitable volume – and weighs in at 800,000 pounds and spans the length of an American football field.
Space Shuttle Discovery undocked from the ISS on Saturday morning (April 17) in preparation for a Monday April 19 landing at 8:51 AM. Credit: NASAThe STS 131 mission of Space Shuttle Discovery is nearing a close. Discovery undocked from the ISS early this morning at 8:52 AM and about 213 miles above earth and is set to land at KSC on Monday morning at 8:51 AM, weather permitting.
Authors Note: This paragraph is just for fun excepting Federation Counterintelligence agents. Unbeknownst to the crew members and NASA, top secret Klingon military surveillance technology was embedded deep within the WORF unit, according to a source who requested anonymity. Whilst the STS 131 crew was innocently hooking up umbilical line connections to the ISS electrical and computer systems, they unwittingly activated the Klingon Empires cloaking chip previously hidden inside WORF by time traveling Klingon spies dispatched by the High Council. The chip instantaneously began transmitting encoded data via sub space frequencies to eagerly waiting intelligence operatives working for the Klingon Chancellor. Stay tuned for more on WORF and the Klingon infiltration of the ISS.
Dennis Toney (Boeing) and Ken Kremer discuss the science goals of the WORF facility at the Kennedy Space Center Press Site during the STS 131 launch of shuttle Discovery on April 5, 2010. Discovery delivered WORF to the ISS. Credit: Ken Kremer
‘Mother of Pearl’ Colored Clouds form above the Countdown clock at the Kennedy Space Center Press Site about 23 minutes after the April 5, 2010 launch of Space Shuttle Discovery, as 3 excited Science Journalists point out (from left, Rob van Mackelenbergh, Jacob Kuiper and Ken Kremer). Credit: Jacob Kuiper
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(Editor’s Note: Ken Kremer is at the Kennedy Space Center for Universe Today covering the flight of Discovery)
Well I’ve never witnessed anything like the magnificently colored clouds following Monday’s (April 5) predawn launch of Shuttle Discovery. They are known as “Mother of Pearl” clouds – according to Jacob Kuiper, Senior Meteorologist with the Royal Netherlands Meteorological Institute (KNMI).
Kuiper and myself observed the launch together with journalist Rob van Mackelenbergh (Dutch Society for Spaceflight, NVR) at the Kennedy Space Center (KSC) Press Site, located across the street from the iconic Vehicle Assembly Building where Shuttle’s are prepared for launch. See our STS 131 Launch day photo mosaic below of the day’s thrilling events.
At first the wispy clouds were nearly all white and set against the still dark sky. Then the sky overhead was suddenly lit on fire with a growing multitude of these pastel colored “Mother of Pearl” clouds – also called “Nacreous” clouds.
“The Mother of Pearl Clouds began turning from white to hues of pink and yellow. Starting about 10 minutes after the launch of Space Shuttle Discovery, its exhaust plume turned into a magnificently colorful panorama. Generally, this continues until about 40 minutes or more after blast off”, Kuiper told me as we stood next to the world famous Countdown clock and gazed in awe at the colored clouds above.
STS 131 Launch Day Mosaic: Crew walkout to Astro Van and ride to launch pad; Discovery Blast off and Countdown Clock at KSC Press site at T Plus 4 Seconds; Pastel Colored ‘Mother of Pearl’ Clouds which formed above the Countdown Clock at T Plus 23 Minutes as three science journalists are in awe. Click to Enlarge. Credit: Rob van Mackelenbergh, Ken Kremer and Jacob Kuiper
“Launching northeast in the predawn sky here on the ground means as the shuttle and its exhaust plumes head to orbit they’re going to catch the rising sunlight and that’s what creates the spectacular clouds we saw on launch morning !” KSC spokesman Allard Beutel explained to me.
Mother of Pearl Clouds form above US Flag at Kennedy Space Center from STS 131 Launch Exhaust Plume. Credit: Ken KremerThe wispy clouds are transient events – constantly evolving in mere seconds as they are blown in a multitude of directions. Indeed it’s quite easy to let your imagination run wild and dream all sorts of fantastical things ranging from mythical creatures to assorted life forms and even people. Certainly someone has sighted Elvis in the rocket plumes.
“Atmospheric layers between 15 and 85 kilometers height normally contain very low quantities of water vapor. But the final exhaust product of the Shuttle’s external tank (hydrogen and oxygen) provides an enormous amount of water vapor”, Kuiper said.
“In the very cold atmosphere layers, the vapor turned into a tremendous mass of ice crystals and tiny super cooled water droplets. These crystals reflect and bend the solar rays very efficiently and create a nice spectrum of colors”.
“The lowest clouds, turned pink and orange, because at that height the sun just rises and most rays are a bit more reddish due to a certain extinction of the atmosphere. The higher portions of the exhaust plume hardly experience any extinction,” Kuiper explained.
“In layers around the Mesopause (about 85 km), clouds sometimes appear in the weeks around June 21 (northerly latitudes). These clouds are called Noctilucent clouds – or NLC. Both types can be produced due to the exhaust plumes from a Space Shuttle launch”, said Kuiper.
By far the largest and most long lasting rocket exhaust clouds derive from the Space Shuttle because it’s the most powerful rocket in the US Fleet – although not for much longer after the shuttle is retired and the US completely loses its Heavy Lift boost capability.
STS 131 Launch Contrails over the Kennedy Space Center on 5 April 2010. Credit: John O’Connor
Flock of Birds fly in front of Pastel colored clouds which formed above Kennedy Space Center from STS 131 Launch Exhaust Plume. Credit: Ken Kremer Wispy contrails from the launch of space shuttle Discovery on the STS-131 mission glow in rainbow colors in the early morning hours as the sun rises over the Vehicle Assembly Building at NASA's Kennedy Space Center in Florida. Shuttle Discovery lifted off at 6:21 a.m. EDT on April 5, 2010. Credit: NASA/Kim Shiflett
Mosaic of the area adjacent to ‘Home Plate’ where Spirit remains stuck as 4th Martain winter experienced by Spirit approaches. Spirit has entered hibernation as of March 30, 2010 due to tripping a low power fault as a result of declining sunlight. Mosiac shows smooth area, foreground, that concealed slippery water related sulfate material where rover became stuck. Will Spirit survive the extremely harsh bone chilling cold temperatures of winter ? Credit: Kenneth Kremer, Marco DiLorenzo, NASA/JPL/Cornell/Spaceflight Now
[/caption]The Mars rover Spirit has entered her long anticipated low power hibernation mode according to a statement released by NASA’s Jet Propulsion Laboratory late Wednesday (March 31). Spirit skipped her scheduled downlink on Sol 2218 (March 30, 2010) via the Ultra-High Frequency (UHF) relay through the Mars Odyssey orbiter from her location on the Martian surface at Gusev crater. No telemetry was received from Spirit and there was no evidence of a UHF signal.
“Well, we knew it was coming… in fact, I’m surprised it didn’t happen earlier”, Steve Squyres told me today, April 1. Squyres is the Chief Scientist for the Mars rover twins, Spirit and Opportunity.
Energy production from the solar arrays had dropped to only 134 watt-hours on March 22. So, the most likely explanation for the missing downlink is that Spirit did go into that low-power fault taking her batteries off-line, sometime between the last downlink on Sol 2210 (March 22, 2010), and Sol 2218 (March 30, 2010).
Mosaic of microscopic images of Spirit underbelly on Sol 1925 (June 2009) showing the predicament of being stuck at Troy with wheels buried in the sulfate-rich martian soil. The sulfate deposits formed by aqueous (water-related) processes when this area dubbed “Home Plate’ was volcanically active. This false color mosaic has been enhanced and stretched to bring out additional details about the surrounding terrain and embedded wheels and distinctly show a pointy rock perhaps in contact with the underbelly. Spirit fortuitously discovered extensive new evidence for an environment of flowing liquid water at this location on Mars adjacent to ‘Home Plate’, an eroded over volcanic feature. Credit: Marco Di Lorenzo, Ken Kremer - NASA/JPL/Cornell
In hibernation mode, Spirits master clock keeps on ticking, but communications and other activities are suspended in order to channel all available energy into powering the critical survival heaters necessary to save the rovers electronics as well as to try to recharge the batteries and attempt to wake up. When the battery charge is adequate, the rover attempts to wake up and communicate on a schedule it knows.
“Components within the rover electronic module (REM) inside the rover’s warm electronic box (WEB) are experiencing record low temperatures,” says Doug McCuistion, the director of Mars Exploration at NASA Headquarters in Washington, DC, in an interview about Spirit’s predicament. “So far, the coldest temperatures recorded within the REM by one reached a low temperature of -41.5 degrees Celsius (-42.7 degrees Fahrenheit)”. This occurred just prior to the loss in communications.
“The REM electronics rack is located inside the WEB and is about a half meter cube in size”, McCuistion told me. “The expectation is for the REM hardware to reach -55C at the coldest part of the winter. We have tested the REM down to -55C”.
“Spirit’s lowest power production during a single sol (so far) was during a dust storm in November of 2008. For that one sol, Spirit’s solar arrays produced only 89 watt-hours of energy,” McCuistion said.
“We may not hear from Spirit again for weeks or months, but we will be listening at every opportunity, and our expectation is that Spirit will resume communications when the batteries are sufficiently charged,” said John Callas of NASA’s Jet Propulsion Laboratory who is project manager for Spirit and Opportunity.
Spirit has been stuck at a place called ‘Troy’ since becoming mired in a sand trap of soft soil in April 2009. While driving on the western edge of ‘Home Plate’, she unknowingly broke through a hard surface crust (perhaps 1 cm thick) of water related sulfate materials and sank into hidden soft sand beneath. At Troy she made a great science discovery by finding evidence of the past flow of liquid water on the surface of Mars.
This mosaic assembled from Phoenix images shows the spacecraft's three landing legs and patches of water ice exposed by the landing thrusters. Splotches of Martian material on the landing leg strut at left could be liquid saline-water. Larger version on Spaceflightnow.com .Credit: Kenneth Kremer, Marco Di Lorenzo, NASA/JPL/UA/Max Planck Institute and Spaceflightnow.com.
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Well my original thought for this piece was, “Last Chance for Phoenix”, since the third and final chance for NASA to reestablish radio contact with the long silent Phoenix Mars Lander was coming up soon on April 5 to 9.
Instead I was pleasantly surprised to just learn from the director of NASA’s Mars Program that NASA is seriously entertaining the idea of extending the listening campaign for Phoenix into May 2010. NASA’s first two listening campaigns in January and February 2010 failed to detect even a hint of a radio signal from the hugely successful Phoenix lander.
“NASA is considering the possibility of adding one final campaign, right around the summer solstice for the northern hemisphere of Mars, which occurs on May 13,” says Doug McCuistion, the director of Mars Exploration at NASA Headquarters in Washington, DC. “This would offer the best possible power/thermal conditions”, McCuistion told me in an interview.
“A final decision regarding this additional campaign will be made after completion of the April 5-9 campaign”, McCuistion said.
The 2010 listening campaign was timed to coincide with the onset of springtime and disappearance of ice at her location in the martian north polar regions. Theoretically the return of plentiful sunlight impinging onto the power producing solar arrays would reawaken the long dead robotic explorer.
“NASA has completed two campaigns of listening for the Phoenix Lander with the Odyssey orbiter – the first in January and the second in February”, McCuistion explained to me.
“During the five-day period of the second campaign of Feb 22-26, Odyssey passed over the Phoenix site 60 times, configuring its UHF relay radio to listen for any transmission from the surface”.
“In the unlikely event that the lander had returned to an operational, energy-positive condition after the Martian winter, it would have been in a state where it would awaken periodically and transmit to any orbiters in view, with a very high likelihood that one of those transmissions would have occurred during one or more of the 60 Odyssey overflights,” according to McCuistion.
“A third campaign is scheduled for early April (5-9), with improved power/thermal conditions as we approach summer in the northern hemisphere of Mars. For this third campaign, the sun will be continuously above the horizon at the high-latitude Phoenix site, corresponding to the solar illumination conditions just prior to Phoenix arrival at Mars as well as around sol 64 (within the primary 90-sol mission)” said McCuistion.
Phoenix set down successfully on the northern martian polar regions on May 25, 2008. During over five months of operations on top of the martian arctic plains, she made breakthrough science discoveries by finding patches of water and nutrients that could possibly sustain past or current martian life forms, if they exist.
Mosaic of microscopic images of Spirit underbelly on Sol 1925 (June 2009) showing the predicament of being stuck at Troy with wheels buried in the sulfate-rich martian soil. The sulfate deposits formed by aqueous (water-related) processes when this area dubbed “Home Plate’ was volcanically active. This false color mosaic has been enhanced and stretched to bring out additional details about the surrounding terrain and embedded wheels and distinctly show a pointy rock perhaps in contact with the underbelly. Spirit fortuitously discovered extensive new evidence for an environment of flowing liquid water at this location on Mars adjacent to ‘Home Plate’, an eroded over volcanic feature. Credit: Marco Di Lorenzo, Ken Kremer - NASA/JPL/Cornell
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The plucky Mars rover ‘Spirit’ may yet rove again !
She’ll just have to outwit and outlast the unavoidably harsh cold and desperately low power levels of the looming winter in Mars southern hemisphere. Rather long odds to be sure – but she’s done it before. Remember – at this moment on Sol 2192, Spirit is 75 months into her 3 month mission ! That’s 25 times beyond her “warrenty” as Rover Principal Investigator Prof. Steve Squyres of Cornell University is extremely fond of saying.
Spirit has been stuck in a rut since becoming mired in a sand trap of soft soil in April 2009. While driving on the western edge of ‘Home Plate’, she unknowingly broke through a hard surface crust (perhaps 1 cm thick) and sank into hidden soft sand beneath. Her wheels churned, sinking deeply – and became embedded in the sand trap at the place called ‘Troy’.
See the underbelly mosaic above, created by Marco Di Lorenzo and Ken Kremer, to get a glimpse of the predicament Spirit lurched into with her sunken wheels. Note: we have significantly enhanced and stretched the mosaic to extract out hard to see details.
As luck would have it, “Troy is a great place to be stuck. It’s like getting stuck in front of Disneyland”, says John Callas the Mars Rover Project manager at the Jet Propulsion Laboratory.
Spirits wheels are buried in sulfate-rich Martian soil. “The sulfate deposits formed by aqueous [water-related] processes when volcanism was active at this area dubbed Home Plate”, says Roy Arvidson, the deputy Rover Principal Investigator. “Spirit has uncovered evidence for two timescales of water related processes”.
“The Troy area is one of the most scientifically interesting ones that we’ve found the whole mission, and we rarely have enough time to study something this thoroughly. So we’re putting that to good use”, Squyres told me.
Spirit Traverse close-up map shows route rover has traveled from Sol 200 to today. Spirit is located at black dot, adjacent to western edge of ‘Home Plate’ volcanic feature. Husband Hill is upper left of center. Click to enlarge. Credit: NASAAt a press briefing on 26 January 2010, NASA declared Spirit would henceforth be a “stationary lander” after exhaustive extrication efforts failed to ‘Free Spirit’. So the small remaining team of rover handlers are now busily getting Spirit ready for sleeping – and surviving – through plunging winter temperatures at her current parked position. Spirit may enter a ‘hibernation’ mode for weeks or even months at a time as she struggles to survive through the freezing winter cold of her upcoming 4th Martian winter.
Remarkably, just as Spirit was concluding her escape efforts and being put into her “stationary” winter parked position to achieve a more optimal tilt for power generation, she finally managed to move about 34 centimeters (13 inches) toward the south southeast in a series of drives beginning on Sol 2145 (Jan. 15, 2010). Her final movement was on Sol 2169 (Feb. 8, 2010). The left-rear wheel even moved out of a rut that it had dug into back in April 2009.
Spirit Traverse close-up map shows entire route rover has traveled until today. Spirit is located at black dot, adjacent to western edge of ‘Home Plate’ volcanic feature. Husband Hill is upper left of center. Click to enlarge. Credit: NASABut with the onset of winter and dropping power levels, time had just run out for further escape attempts. The team was forced to halt extrication efforts and focus instead on maximizing chances for mere survival. The goal was to adjust the tilt of the rover more towards the sun in order to increase the energy output generated from the wing like solar arrays. This strategy had been successfully implemented and saved Spirit during the last two Martian winters as she eked out just enough power to endure – and make new breakthrough (pun intended) science discoveries !
Given that Spirit did move 13 inches in the final drive attempts, I enquired whether NASA is reevaluating to try more driving IF she survives winter ?
Yes.
“The rover team does plan to try driving Spirit out of the immediate sand trap if the rover survives the winter. That was always a possibility”, Guy Webster informed me. He is the Public Affairs Officer at the Jet Propulsion Laboratory which manages the Mars rover project for NASA. Webster cautioned that, “With only four working wheels, the expectation is that even if Spirit gets out of Troy, the rover will not be able to rove significant distance, but might reposition itself to reach different targets in the immediate vicinity”.
Due to the extremely low power levels, the team is implementing plans to minimize energy usage by shutting down almost all functions except keeping a master clock running and checking its power status periodically until it has enough power to reawaken. Even communications will only be on an sporadic basis.
As of Feb. 23, the power output was down to 163 watt-hours. That compares to roughly 900 watt hours at landing. Earlier in the mission, “the line of death” was considered to be in the 200-250 watt hour range. Now, out of necessity, the team has developed ways to operate the rover on somewhat less power.
To get an idea of just how deeply Spirit was embedded and better evaluate her chances to escape, the team seized on an idea that was completely different. For the very first time, they commanded Spirit to carefully maneuver the robotic arm to peek underneath the rover and image her underbelly using the microscopic imager (MI) mounted at the end of the arm’s ‘hand’.
“We used the MI in a new way, because we have no bellycam”, explained Callas.
This action was outside the design envelope of the arm and not previously contemplated partly because the MI is a short focuser, built to focus on objects only 6 centimeter (2.4 inches) away – as well as concerns for damaging the rover and arm assembly. Nonetheless it was hoped that the expected fuzzy pictures would clarify the situation somewhat and perhaps elucidate clues about the wheels and terrain.
Indeed, the underbelly images from Sol 1925 in June 2009 revealed significant new details on how deeply the wheels had sunk and also discerned an upward pointing rock, possibly in contact with the rovers belly. See our mosaic (above) assembled from the MI images. If the rover was caught on the rock, the wheels could be spinning aimlessly if not in firm contact with the soil and thereby obstruct potential escape movements.
At the time of her embedding, Spirit was making great progress towards her next science targets, ‘Von Braun’ mound and the ‘Goddard’ depression in hopes of further elucidating the historical record of flowing liquid water in the Columbia Hills region where Spirit safely landed on Jan 3, 2004.
‘Von Braun’ is the intriguing feature some 100 meters distant at the top left of the mosaic (below) created by Ken Kremer and Marco Di Lorenzo for Spaceflight Now. ‘Troy’ is located approximately in the left of center foreground of the mosaic which was assembled from images taken by the Pancam imager just a few sols – martian days – before she became stuck. Pancam is bolted to the top of Spirits head like mast.
Mosaic of the area adjacent to Home Plate where Spirit remains stuck was made especially for Spaceflight Now, and is used by permission. It shows smooth area, foreground, that concealed slippery water related sulfate material where rover became stuck. Credit: Kenneth Kremer, Marco DiLorenzo, NASA/JPL/Cornell/Spaceflight Now
Teams had spent many months developing and testing numerous drive strategies to escape by using nearly identical replicas of the rovers at a test bed at the Jet Propulsion Lab. They solicited ideas worldwide from outside experts. No clear answers emerged, according to Project manager John Callas.
At last Spirit was commanded to move her 5 still functioning wheels. The 6th wheel had broken long ago after climbing down from Husband Hill (see our mosaic below). After a somewhat hopeful start, actual progress could only be measured in millimeters of movement. And her wheels began to sink deeper. Then another wheel broke, leaving only 4. Thus an already desperate situation became much worse with diminished wheel capacity. At last she moved that last foot, slightly improving her chances. And that’s the State of Spirit today.
Self portrait of Spirit atop Martian mountain top on Sol 618, September 2005. Spirit climbed for more than 1 year to reach the summit of Husband Hill where she made crucial discoveries related to water flowing on Mars. This mosaic was assembled by a group of mars enthusiasts at Unmannedspaceflight.com and originally published on the cover of Aviation Week & Space Technology magazine on 14 November 2005. Credit: Marco Di Lorenzo, Doug Ellison, Bernhard Braun, and Kenneth Kremer – NASA / JPL/Cornell/Aviation Week & Space Technology
The solar powered Spirit is now tilted unfavorably, about 9 degrees to the south. The team stove mightily to obtain the desired northward tilt to achieve a better attitude for generating energy from the sun in the northern Martian sky.
Only time will tell the outcome. Let’s pray for clear skies for Spirit.
Squyres has often been quoted to say, “Never bet against the rovers. Those who have bet against the rovers have been repeatedly proven wrong !”
Spirit recorded this fisheye view with its rear hazard-avoidance camera after completing a drive during the 2,169th Martian day, or sol, of Spirit's mission on Mars (Feb. 8, 2010). The drive left Spirit in the position where the rover will stay parked during the upcoming Mars southern-hemisphere winter. The top of the image shows the underside of Spirit's solar array. Credit: NASA/JPL-Caltech
Time lapse photo mosaic was assembled from Phoenix images taken of the lander deck and martian terrain. Panorama shows the robotic arm in action as it scoops up soil samples (right) and delivers the samples to the MECA and TEGA science instruments (left). Credit: Marco Di Lorenzo, Kenneth Kremer - NASA/JPL/UA/Spaceflight
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As expected, NASA’s February 2010 listening campaign for the Phoenix Mars Lander has failed to detect any signals emanating from the long silent vehicle. NASA’s attempts to reestablish contact with Phoenix were restarted in January 2010 and timed to coincide with the onset of springtime and disappearance of ice at her location in the martian north polar regions. In theory, the return of abundant sunshine striking the twin energy producing solar arrays could again power up the science lander sufficiently to revive itself and ‘phone home’ to Earth.
This just completed 2nd listening campaign consisted of 60 overflights conducted by NASA’s Mars Odyssey orbiter from Feb 22 to Feb 26. The first campaign was conducted in January and likewise yielded no signals of activity. But with each passing Sol, or martian day, the sun is now rising higher in the sky and impinging longer on the solar powered craft. A third campaign is scheduled for early April 2010 just in case the sun enables a miraculous revival. The sun will be continuously above the Martian horizon in April.
Check out the time lapse photo mosaic above, created by Marco Di Lorenzo and Ken Kremer, which shows Phoenix actively at work as she digs up Martian icy soil samples and delivers them to the MECA and TEGA science instruments on the lander deck for compositional analysis.
It’s currently mid-springtime at the landing site with about 22 hours of sunlight each Sol. That illumination is comparable to the period when Phoenix was in full swing in the middle of her mission.
“Each overflight lasts about 10 minutes”, says Doug McCuistion, the director of Mars Exploration at NASA Headquarters in Washington, DC. But no one at NASA or on the science and engineering teams is under any illusions. “We think the chances are very low that Phoenix survived winter”, McCuistion told me in an interview.
NASA is using both of its Martian orbiting assets currently circling above the red planet to ascertain the condition of Phoenix. “Odyssey is the prime communications spacecraft. The Mars Reconnaissance Orbiter (MRO) will try to image Phoenix about every 2 weeks”, McCuistion said to me. See the latest MRO images herein which show a receding ice layer.
Stages in the seasonal disappearance of surface ice from the ground around the Phoenix Mars Lander are visible in these images taken on Feb. 8, 2010, (left) and Feb. 25, 2010 by the HiRise Camera on NASA’s Mars Reconnaissance Orbiter, during springtime on northern Mars. The views cover an area about 100 meters wide. North is toward the bottom. Credit: NASA/JPL-Caltech/University of Arizona
Phoenix was pre-programmed with a Lazarus mode to reawaken itself in the unlikely event that it survived the exceedingly harsh northern Martian winter during which it endured extremely low temperatures for longer than 1 earth year already. Furthermore, the spacecraft was potentially even partially encased in up to several feet of ice during several months of continuous arctic darkness. Unlike the rovers Spirit and Opportunity, Phoenix was not designed to withstand Martian winter.
After more than 5 months of intensive and breakthrough science investigations, all contact with Phoenix was lost on 2 November 2008 as increasing storm clouds blocked the waning sun from reaching the life giving solar arrays and the vehicle could no longer function.
Phoenix lasted more than 2 months beyond her planned primary mission design of 3 months. She discovered that Mars currently possesses a habitable environment with water and nutrients that could sustain potential past or current martian life forms, IF they exist. Read my earlier Phoenix report to learn about the robust science program that could be carried out to build on the initial results, if this bird rises again.
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No, it’s not the Universe Puzzle No. 3; rather, it’s an intriguing result from recent work into the strange shapes and composition of small asteroids.
Images sent back from space missions suggest that smaller asteroids are not pristine chunks of rock, but are instead covered in rubble that ranges in size from meter-sized boulders to flour-like dust. Indeed some asteroids appear to be up to 50% empty space, suggesting that they could be collections of rubble with no solid core.
But how do these asteroids form and evolve? And if we ever have to deflect one, to avoid the fate of the dinosaurs, how to do so without breaking it up, and making the danger far greater?
Johannes Diderik van der Waals (1837-1923), with a little help from Daniel Scheeres, Michael Swift, and colleagues, to the rescue.
Rocks and dust on asteroid Eros (Credit: NASA)
Asteroids tend to spin rapidly on their axes – and gravity at the surface of smaller bodies can be one thousandth or even one millionth of that on Earth. As a result scientists are left wondering how the rubble clings on to the surface. “The few images that we have of asteroid surfaces are a challenge to understand using traditional geophysics,” University of Colorado’s Scheeres explained.
To get to the bottom of this mystery, the team – Daniel Scheeres, colleagues at the University of Colorado, and Michael Swift at the University of Nottingham – made a thorough study of the relevant forces involved in binding rubble to an asteroid. The formation of small bodies in space involves gravity and cohesion – the latter being the attraction between molecules at the surface of materials. While gravity is well understood, the nature of the cohesive forces at work in the rubble and their relative strengths is much less well known.
The team assumed that the cohesive forces between grains are similar to that found in “cohesive powders” – which include bread flour – because such powders resemble what has been seen on asteroid surfaces. To gauge the significance of these forces, the team considered their strength relative to the gravitational forces present on a small asteroid where gravity at the surface is about one millionth that on Earth. The team found that gravity is an ineffective binding force for rocks observed on smaller asteroids. Electrostatic attraction was also negligible, other than where a portion of the asteroid this is illuminated by the Sun comes into contact with a dark portion.
Fast backward to the mid-19th century, a time when the existence of molecules was controversial, and inter-molecular forces pure science fiction (except, of course, that there was no such thing then). Van der Waals’ doctoral thesis provided a powerful explanation for the transition between gaseous and liquid phases, in terms of weak forces between the constituent molecules, which he assumed have a finite size (more than half a century was to pass before these forces were understood, quantitatively, in terms of quantum mechanics and atomic theory).
Van der Waals forces – weak electrostatic attractions between adjacent atoms or molecules that arise from fluctuations in the positions of their electrons – seem to do the trick for particles that are less than about one meter in size. The size of the van der Waals force is proportional to the contact surface area of a particle – unlike gravity, which is proportional to the mass (and therefore volume) of the particle. As a result, the relative strength of van der Waals compared with gravity increases as the particle gets smaller.
This could explain, for example, recent observations by Scheeres and colleagues that small asteroids are covered in fine dust – material that some scientists thought would be driven away by solar radiation. The research can also have implications on how asteroids respond to the “YORP effect” – the increase of the angular velocity of small asteroids by the absorption of solar radiation. As the bodies spin faster, this recent work suggests that they would expel larger rocks while retaining smaller ones. If such an asteroid were a collection of rubble, the result could be an aggregate of smaller particles held together by van der Waals forces.
Asteroid expert Keith Holsapple of the University of Washington is impressed that not only has Scheeres’ team estimated the forces in play on an asteroid, it has also looked at how these vary with asteroid and particle size. “This is a very important paper that addresses a key issue in the mechanics of the small bodies of the solar system and particle mechanics at low gravity,” he said.
Scheeres noted that testing this theory requires a space mission to determine the mechanical and strength properties of an asteroid’s surface. “We are developing such a proposal now,” he said.
Source: Physics World. “Scaling forces to asteroid surfaces: The role of cohesion” is a preprint by Scheeres, et al. (arXiv:1002.2478), submitted for publication in Icarus.
Secondary electron image of the Coki section analyzed in this study showing mineral shards surrounded by compressed aerogel. Credit: Lawrence Livermore National Lab.
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One of the most surprising results from the Stardust mission – which returned comet dust samples to Earth in 2006 – is that comets don’t just consist of particles from the icy parts of the outer solar system, which was the common assumption, but also includes sooty dust from the hot, inner region close to the Sun. A new study confirms this finding, and also provides the first chronological information from the Wild 2 comet (pronounced like Vilt 2). The find paints a chaotic picture of the early solar system.
Even some of the first looks at the cometary particles returned by Stardust showed that contrary to the popular scientific notion, there was enough mixing in the early solar system to transport material from the sun’s sizzling neighborhood and deposit it in icy deep-space comets. Whether the mixing occurred as a gentle eddy in a stream or more like an artillery blast is still unknown.
“Many people imagined that comets formed in total isolation from the rest of the solar system. We have shown that’s not true,” said Donald Brownlee back in 2006, principal investigator for Stardust.
The new study, conducted by scientists from Lawrence Livermore (Calif.) National Laboratory, shows the dust from comet 81P/Wild 2 has been altered by heating and other processes, which could have only occurred if a transport of space dust took place after the solar system formed some 4.57 billion years ago.
“The mission was expected to provide a unique window into the early solar system,” the team, led by Jennifer Matzel wrote in their paper, “by returning a mix of solar system condensates, amorphous grains from the interstellar medium, and true stardust – crystalline grains originating in distant stars. Initial results, however, indicate that comet Wild 2 instead contains an abundance of high-temperature silicate and oxide minerals analogous to minerals in carbonaceous chondrites.” Corresponding false color mineral map overlaid on a montage of brightfield Transmission Electron Microscope (TEM) images.
They analyzed a particle from the comet, about five micrometers across, known as Coki. The particle does not appear to contain any of the radiogenic isotope aluminum-26, which implies that this particle crystallized 1.7 million years after the formation of the oldest solar system solids. This means that material from the inner solar system must have traveled to the outer solar system, across a period of at least two million years.
“The inner solar system material in Wild 2 underscores the importance of radial transport of material over large distances in the early solar nebula,” said Matzel. “These findings also raise key questions regarding the timescale of the formation of comets and the relationship between Wild 2 and other primitive solar nebula objects.”
The presence of CAIs in comet Wild 2 indicates that the formation of the solar system included mixing over radial distances much greater than anyone expected.
