Dat is fijnquote:Op woensdag 23 mei 2007 19:53 schreef Quyxz_ het volgende:
Ik las laatst ook een heel stukje over mars in de Quest
Ik wilde ermee zeggen dat als iemand dat ook wil lezen dat hij weet dat het erin stata in de Quest van juni.quote:
quote:Op donderdag 24 mei 2007 03:14 schreef star_gazer het volgende:
Hmmmm.. Niet-kristallijne silicium-dioxide. Dat riekt naar (overblijfselen van) een zeer snel gestold lava (silicaglas, obsidiaan) als je het mij vraagt. Volgens mij hoeft het echt geen water te zijn. Het merkwaardige is dat het op Aarde in de natuur niet veelvuldig voorkomt, maar we er toch wilde conclusies aan verbinden.
Ja zeker. Het simpele feit is dat we nog steeds geen ondubbelzinning bewijs hebben voor water op Mars. Tot die tijd moeten we dit soort bevindingen vind ik wel met de nodige argwaan bekijken. Het begint er wat mij betreft een beetje op te lijken dat men wanhopig op zoek is naar bewijs voor water, omdat zowat 80% van de wetenschap m.b.t Mars als een kaartenhuis in elkaar dondert als het tegendeel bewezen wordt. Er worden hele studies gedaan waarin de aanwezigheid van water ergens in de geschiedenis gewoonweg wordt aangenomen, terwijl dit fundament nog helemaal niet goed verankerd is. Ik weet het, de morfologische bedvormen (zowel kwalitatief als kwantitatief, droge stromen worden door stromingsleer bijna zeker uitgesloten: het verplaatsen van het materiaal dat ooit deel uitmaakte van Ares Vallis zou bijvoorbeeld volgens een eenvoudig model secondenwerk zijn) schreeuwen bijna 'rivier' en 'oceaan', maar totdat er definitief ondubbelzinnig bewijs geleverd wordt, blijft het linke soep om zomaar 'water' te roepen. Mijn hoop is gevestigd op phoenix en exomars, die hopelijk voor het eerst direct water zullen aantonen. Daarnaast zal er met het binnenkort vrijkomen van een berg MARSIS-data hopelijk ook wat meer onderzoek gedaan kunnen worden naar de subsurface.quote:
http://www.nos.nl/nosjournaal/artikelen/2007/7/2/020707_nasa.htmlquote:Mars Rover gaat op zelfmoordmissie 2-07-07
Na drieėneenhalf jaar trouwe dienst staat NASA op het punt de Mars Rover Opportunity op een mogelijke zelfmoordmissie te sturen: over de rand van de enorme Victoria-krater.
"We weten niet zeker of Opportunity straks weer uit de krater zal kunnen klimmen, maar vanwege de mogelijke waarde van onderzoek heb ik toestemming gegeven," zegt de baas van het project. "We willen het risico nemen."
Opportunity rijdt al een tijdje langs de rand van de krater om het juiste plekje vinden om aan de afdaling te beginnen. NASA verwacht op de weg naar beneden een geologische kaart van Mars te kunnen maken.
Klimaatgeschiedenis
"Deze krater is een venster op de klimaatgeschiedenis van Mars," legt NASA uit. Hoe verder naar beneden Opportunity komt, hoe ouder de rotslagen zullen zijn.
De krater (750 meter doorsnee, 60 meter diep) ontstond bij de inslag van een meteoriet. Hoe lang dat precies geleden is, is niet bekend. Astronomen houden rekening met "miljarden jaren". NASA hoopt er onder meer sporen van water aan te treffen.
Wielen
Als het onderzoek is afgerond, wil NASA Opportunity weer terug omhoog laveren. Als alles blijft werken, moet dat geen probleem zijn. Maar NASA is bang dat een of meerdere wielen het begeven.
Bij Opportunity’s broertje Spirit, die aan de andere kant van Mars onderzoek doet, viel vorig jaar een wiel uit. Spirit kan sindsdien alleen maar achteruit rijden. Geen probleem op vlakke grond, maar fataal in de krater.
Garantie
Overigens is de garantie op Opportunity al lang verlopen. Toen het voertuig in januari 2004 op Mars landde, verwachtte NASA er 30 tot 90 dagen plezier van te hebben. De rovers rijden nu al twaalf keer zo lang rond.
"We willen niet dat dit een enkele reis wordt. Er zijn nog genoeg wetenschappelijk interessante dingen te vinden. Maar als Opportunity vast komt te zitten, is het de kennis die gewonnen is waard."
http://www.knack.be/nieuw(...)n45-article5762.htmlquote:Ruimtesonde Dawn maakt reis in de tijd
05/07/2007 16:00
De Amerikaanse ruimtesonde Dawn vertrekt deze maand voor een heel bijzondere missie naar de planetoļden Ceres en Vesta.
Op de eerste dag van de negentiende eeuw nam de Italiaanse astronoom Giuseppe Piazzi vanuit Palermo een merkwaardig object waar. Het leek eerst op een nieuwe planeet, maar algauw bleek de op 1 januari 1801 ontdekte Ceres het grootste exemplaar te zijn van de zogenaamde planetoļdengordel: een reeks van duizenden kleine hemellichamen die tussen de planeten Mars en Jupiter rond de zon draaien.
Naar schatting zijn er tussen 1,1 en 1,9 miljoen planetoļden - ook aangeduid als asteroļden of kleine planeten - die een diameter hebben van meer dan één kilometer. Er zijn er meer dan 375.000 waargenomen. 160.000 kregen een officieel nummer en bijna 14.000 een naam.
De bolvormige Ceres kreeg vorig jaar van de Internationale Astronomische Unie (IAU) een opwaardering tot 'dwergplaneet', een titel die het hemellichaam deelt met ex-planeet Pluto en het object Eris in de verre regionen van het zonnestelsel.
Planetoļden kunnen ons heel veel vertellen over het ontstaan van het zonnestelsel uit een roterende wolk van gas en stof 4,6 miljard jaar geleden. Ze zijn in feite primitief kosmisch puin, dat als gevolg van de gravitationele invloed van de reuzenplaneet Jupiter niet tot een volwaardige planeet kon samenklonteren.
Onbemande ruimtesondes fotografeerden al verschillende van deze bouwstenen van het zonnestelsel. De sonde NEAR Shoemaker maakte in 2001 zelfs een gedurfde landing op de planetoļde Eros. Japan probeert ondertussen zijn door problemen geplaagde sonde Hayabusa in juni 2010 terug op de aarde te krijgen met aan boord stofdeeltjes van de planetoļde Itokawa.
En nu maakt de NASA zich op voor de lancering van de sonde Dawn. Die heeft een lange en heel bijzondere trip van acht jaar door het zonnestelsel voor de boeg. Hij zal rond twee verschillende hemellichamen draaien en dat is een primeur: eerst rond de planetoļde Vesta tussen oktober 2011 en april 2012, daarna tussen februari en juli 2015 rond Ceres. Zowel Vesta als Ceres is sinds zijn ontstaan intact gebleven en dat maakt ze heel bijzonder.
De twee hemellichamen zijn wel behoorlijk verschillend. Vesta is met een gemiddelde diameter van 520 kilometer waarschijnlijk een droge rotsachtige wereld met een diepe krater nabij de zuidpool. De 960 kilometer grote Ceres is vermoedelijk een 'nat' hemellichaam, dat misschien poolkappen van ijs heeft.
De Amerikaanse ruimtevaartorganisatie NASA ziet Dawn als een reis in de tijd. En zoals dat vaker het geval is met missies in het zonnestelsel komen we door andere hemellichamen te bestuderen meteen ook weer wat meer te weten over onze eigen blauwe planeet.
Benny Audenaert
quote:Dust Delays Mars Crater Entry
A giant dust storm brewing for more than a week on Mars has become worse and is affecting surface operations of the Mars Exploration Rovers, Spirit and Opportunity. Because the rovers depend on solar energy for survival, and the dust is partially blocking the sun, the storm is being watched closely by the rover scientists and engineers. Opportunity's entry into Victoria Crater is delayed for at least several days.
The storm, the most severe storm yet to hit the rovers, is expected to continue for at least another week. Opportunity is perched near "Duck Bay" as it readies to descend into Victoria Crater, but operations were scaled back on Saturday, June 30, to conserve power.
"The storm is affecting both rovers and reducing the power levels on Opportunity," said John Callas, Mars Exploration Rover project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We are keeping an eye on this as we go forward, but our entry into Victoria Crater will be delayed until no sooner than July 13."
"We have some data that show the atmospheric opacity is decreasing, so the storm might have peaked and we may have passed the worst of this. The situation could improve quickly from here, but we will have to wait and see," said Callas.
Weather reports from NASA's Mars Reconnaissance Orbiter Mars Color Imager camera are helping track the storm and plan rover operations.
Pictures from the orbiter's Mars Color Imager show the storm is regional in extent, and includes several local areas of especially high dust activity. The storm has been moving eastward and toward mid-latitudes, and is now also causing an increase in atmospheric dust at Spirit's location, on the opposite side of the planet at Gusev Crater. Dust levels at Gusev remain much lower than at the Opportunity site, however.
Both rovers take daily measurements estimating the amount of dust in the atmosphere. The less dust the better, because it means more sunlight reaches the rover's solar panels, which power the vehicles. In the last week, Opportunity has broken its dust record, with the opacity level rising from 1.0 to 3.3. Solar array energy on Opportunity dropped from 765 watt-hours to 402 watt-hours over the same period of time.
"While this only represents enough dust to coat the planet to about the thickness of a human hair, it is enough to decrease the brightness of the noon sun by 96 percent compared to a completely clear atmosphere," said Steve Squyres, principal investigator, Cornell University, Ithaca, N.Y. "Of course, the solar arrays also receive light that is scattered from the dust, so the decrease in power is not nearly that great."
"We have not seen dust measurements this high on either rover before. If the dust levels were to increase further and stay elevated for several days, there is a risk to how well Opportunity could continue to work in this darkened environment," said Callas.
credit: NASA/JPL/Cornell/University of Arizona/Ohio State University
quote:Evidence of A Wet Martian Past
A shallow trench made by Spirit's dragging right front wheel uncovered some of the best evidence Spirit has found for ancient water-rich environments in Gusev Crater -- bright patches of almost pure, fine-grained silica (SiO2). On ancient Earth, warm, evaporating coastal waters deposited fine silica in shallow sediments. In Yellowstone National Park, hot, mineral-laden waters deposit fine-grained silica around geysers and hot springs. The discovery of silica-rich deposits on Mars adds compelling new evidence of ancient environments that might have been favorable for life.
Spirit acquired this false-color view of the remarkable, light-colored soil patch with the panoramic camera on the rover's 1,198th sol, or Martian day of exploration (May 17, 2007), more than three years after landing on Mars.
credit: NASA/JPL-Caltech/Cornell
http://www.theregister.co.uk/2007/07/10/nasa_mars_water/quote:NASA packs bucket and spade for new Mars mission
Going digging for ice
By Lucy Sherriff → More by this author
Published Tuesday 10th July 2007 09:40 GMT
NASA is packing its things and getting ready for an ice-hunting trip to Mars. The space agency says it is preparing for the August 3 launch of the Phoenix lander, the first NASA mission specifically designed to touch and analyse water on the dwarf planet. The aim is to discover whether or not there are areas on the Martian surface that could, even now, harbour Martian microbes.
The plan is for Phoenix to land on a region of Mars with plenty surface ice: the northern, arctic plains. Once there it will dig down into the icy soil and look for signs that liquid water once flowed. The other main objectives of the mission are to determine if arctic soil could support life and to study the weather at a Martian pole.
"Phoenix has been designed to examine the history of the ice by measuring how liquid water has modified the chemistry and mineralogy of the soil," said Peter Smith, the Phoenix principal investigator at the University of Arizona.
"In addition, our instruments can assess whether this polar environment is a habitable zone for primitive microbes. To complete the scientific characterisation of the site, Phoenix will monitor polar weather and the interaction of the atmosphere with the surface."
NASA says it expects the ice layer to begin just inches below the soil. Once Phoenix has unfurled its 18 foot wide solar panels, it will start to dig down using its robotic arm. The arms is tipped with a camera and a conductivity probe to examine the surface before samples are collected and lifted to the lander's two analysis instruments.
At least one sample will be heated to check for volatiles such as water and organic molecules. The second instrument will examine the chemistry of the soil.
"Our 'follow the water' strategy for exploring Mars has yielded a string of dramatic discoveries in recent years about the history of water on a planet where similarities with Earth were much greater in the past than they are today," said Doug McCuistion, director of the Mars Exploration Program at NASA's HQ in Washington.
"Phoenix will complement our exploration of Mars by being our first attempt to actually touch and analyse Martian water water in the form of buried ice."
The timing of the launch is critical, because it determines the landing zone on Mars, and the best route to the planet. NASA has a three week launch window, opening on August 3, in which to get the lander into space on a trajectory that will hit the target. Each day of the two weeks has two possible launch times, separated by between 36 and 42 minutes.
Earth has a tighter orbit than Mars, and so once every 26 months or so it "laps" the smaller planet, passing a point of closest approach known as opposition. The best time to launch a mission to the Red Planet is a few months ahead of opposition, NASA explains, so that the amount of fuel required is minimised, and journey time is kept manageably short. The next opposition is of December 18 2007.
If Phoenix makes its launch window it will travel to Mars via the most direct route possible, and make its landing between May 25 and June 5 2008. ®
quote:July 20, 2007
Dwayne Brown/Tabatha Thompson
Headquarters, Washington
202-358-1726/3895
dwayne.c.brown@nasa.gov, tabatha.thompson-1@nasa.gov
Guy Webster/Gay Yee Hill
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6278/5011
guy.w.webster@nasa.gov, gay.y.hill@nasa.gov
RELEASE: 07-162
NASA MARS ROVERS BRAVING SEVERE DUST STORMS
PASADENA, Calif. - Having explored Mars for three-and-a-half years in
what were missions originally designed for three months, NASA's Mars
rovers are facing perhaps their biggest challenge.
For nearly a month, a series of severe Martian summer dust storms has
affected the rover Opportunity and, to a lesser extent, its
companion, Spirit. The dust in the Martian atmosphere over
Opportunity has blocked 99 percent of direct sunlight to the rover,
leaving only the limited diffuse sky light to power it. Scientists
fear the storms might continue for several days, if not weeks. "We're
rooting for our rovers to survive these storms, but they were never
designed for conditions this intense," said Alan Stern, associate
administrator of NASA's Science Mission Directorate, Washington.
If the sunlight is further cut back for an extended period, the
rovers
will not be able to generate enough power to keep themselves warm and
operate at all, even in a near-dormant state. The rovers use electric
heaters to keep some of their vital core electronics from becoming
too cold.
Before the dust storms began blocking sunlight last month,
Opportunity's solar panels had been producing about 700 watt hours of
electricity per day, enough to light a 100-watt bulb for seven hours.
When dust in the air reduced the panels' daily output to less than
400 watt hours, the rover team suspended driving and most
observations, including use of the robotic arm, cameras and
spectrometers to study the site where Opportunity is located.
On Tuesday, July 17, the output from Opportunity's solar panels
dropped to 148 watt hours, the lowest point for either rover. On
Wednesday, Opportunity's solar-panel output dropped even lower, to
128 watt hours.
NASA engineers are taking proactive measures to protect the rovers,
especially Opportunity, which is experiencing the brunt of the dust
storm. The rovers are showing robust survival characteristics.
Spirit, in a location where the storm is currently less severe, has
been instructed to conserve battery power by limiting its activities.
"We are taking more aggressive action with both rovers than we needed
before," said John Callas, project manager for the twin rovers at the
Jet Propulsion Laboratory, Pasadena, Calif.
By Opportunity's 1,236th Martian day, which ended Tuesday, driving
and
all science observations had already been suspended. The rover still
used more energy than its solar panels could generate on that day,
drawing down its battery. "The only thing left to cut were some of
the communication sessions," Callas said.
To minimize further the amount of energy Opportunity is using,
mission
controllers sent commands on Wednesday, July 18, instructing the
rover to refrain from communicating with Earth on Thursday and
Friday. This is the first time either of the rovers has been told to
skip communications for a day or more in order to conserve energy.
Engineers calculate that skipping communications sessions should
lower daily energy use to less than 130 watt hours.
A possible outcome of this storm is that one or both rovers could be
damaged permanently or even disabled. Engineers will assess the
capability of each rover after the storm clears.
NASA will provide mission updates as events warrant. The Jet
Propulsion Laboratory manages the rover project for the Science
Mission Directorate.
For more information about the rovers, visit:
http://marsrovers.jpl.nasa.gov
En gezien vanuit Mars Reconnaissance Orbiterquote:For nearly a month, a series of severe Martian summer dust storms has affected the rover Opportunity and, to a lesser extent, its companion, Spirit. The dust in the Martian atmosphere over Opportunity has blocked 99 percent of direct sunlight to the rover, leaving only the limited diffuse sky light to power it. Scientists fear the storms might continue for several days, if not weeks.
"We're rooting for our rovers to survive these storms, but they were never designed for conditions this intense," said Alan Stern, associate administrator of NASA's Science Mission Directorate, Washington.
If the sunlight is further cut back for an extended period, the rovers will not be able to generate enough power to keep themselves warm and operate at all, even in a near-dormant state. The rovers use electric heaters to keep some of their vital core electronics from becoming too cold.
Before the dust storms began blocking sunlight last month, Opportunity's solar panels had been producing about 700 watt hours of electricity per day, enough to light a 100-watt bulb for seven hours. When dust in the air reduced the panels' daily output to less than 400 watt hours, the rover team suspended driving and most observations, including use of the robotic arm, cameras and spectrometers to study the site where Opportunity is located.
On Tuesday, July 17, the output from Opportunity's solar panels dropped to 148 watt hours, the lowest point for either rover. On Wednesday, Opportunity's solar-panel output dropped even lower, to 128 watt hours.
NASA engineers are taking proactive measures to protect the rovers, especially Opportunity, which is experiencing the brunt of the dust storm. The rovers are showing robust survival characteristics. Spirit, in a location where the storm is currently less severe, has been instructed to conserve battery power by limiting its activities.
"We are taking more aggressive action with both rovers than we needed before," said John Callas, project manager for the twin rovers at NASA’s Jet Propulsion Laboratory, Pasadena, Calif.
By Opportunity's 1,236th Martian day, which ended Tuesday, driving and all science observations had already been suspended. The rover still used more energy than its solar panels could generate on that day, drawing down its battery. "The only thing left to cut were some of the communication sessions," Callas said.
To minimize further the amount of energy Opportunity is using, mission controllers sent commands on Wednesday, July 18, instructing the rover to refrain from communicating with Earth on Thursday and Friday. This is the first time either of the rovers has been told to skip communications for a day or more in order to conserve energy. Engineers calculate that skipping communications sessions should lower daily energy use to less than 130 watt hours.
A possible outcome of this storm is that one or both rovers could be damaged permanently or even disabled. Engineers will assess the capability of each rover after the storm clears.
NASA will provide mission updates as events warrant. The Jet Propulsion Laboratory manages the rover project for the Science Mission Directorate.
###
Guy Webster/Gay Yee Hill 818-354-6278/5011
Jet Propulsion Laboratory, Pasadena, California
Dwayne Brown/Tabatha Thompson 202-358-1726/3895
NASA Headquarters, Washington, D.C.
NEWS RELEASE: 2007-080
http://marsrovers.jpl.nas(...)eases/20070720a.html
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