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Thursday, June 1, 2006

If you’ve always wanted to live in a world populated by elves, dwarves and wizards, you don’t need to pay for a World of Warcraft subscription or buy the Special Extended DVD Trilogy Edition of The Lord of the Rings just yet. You could instead give Battle for Wesnoth a try — an open source turn-based strategy game in a fantasy setting. For the practically minded, “open-source” means that the code which the game is made of is available to anyone who wishes to use, redistribute or change it. It was created by volunteers and can be freely shared. Even the multiplayer online part of the game is free (no ads or spyware either).

But Wesnoth, as it is often abbreviated, is notable not only because it is free. While its graphics are simple by modern standards, the sheer number of units and scenarios that are available for the game is staggering. This is where the “open source” philosophy comes truly into play: anyone can contribute art or new campaigns. As of May 2006, the forum where users can share and discuss their own art contained over 25,000 messages. Most of this art is made available under the same open source terms as the game itself.

Battle for Wesnoth lets you command armies of units such as archers, swordmen, mages and gryphons during the course of a campaign consisting of multiple missions. Typically, your mission is to defeat an enemy leader, but some scenarios let you liberate a prisoner, find a lost artifact, traverse dangerous territories, and so on. Your best units can be taken from one mission to the next, “levelling up” in the process. Even units of the same type vary in their abilities, making the tactical use of the right unit at the right time very important.

The game is reminiscent of turn-based strategy classics such as Heroes of Might and Magic or Warlords. Throughout each campaign, the player is informed of the progress of the story. For instance, in the “Heir to the Throne” campaign, the player follows the story of Prince Konrad, who must reclaim the throne of Wesnoth from an evil queen.

The game was originally designed by David White, who is still the project’s lead developer. We exchanged e-mails with David about the state of open source gaming, the future of Wesnoth, and the collaborative aspects of game development.

David, thanks for taking our questions. Open source games suffer from the problem that very few people have all the abilities needed to make a good game: programming, graphics, story development, sound effects, music, and so on. When you started Battle for Wesnoth, how did you deal with this?

Not very well. 🙂

Version 0.1 of Wesnoth was developed entirely by me, and it was ugly. It had awful graphics, and no sound or music at all.

I think the best way to deal with the problem is to make an early version of the game which showcases the desired gameplay. Then, people with the appropriate skills who like the game will contribute. This worked out well with Wesnoth, anyhow, as I soon attracted a fine artist, Francisco Munoz, and once the graphics were decent, more people started wanting to help.

I noticed that the forum allows anyone to submit art for the game. How important have contributions from ordinary players been for development?

Well, as with almost any free software project, contributions from users have been very important. In the area of art, this is definitely so, though making a substantial contribution of art generally requires a reasonable amount of skill, so the number of people who can contribute art is somewhat limited.

This has meant that the number of people who contribute art is much smaller than, say, the number of people who contribute bug reports or feature requests. Still, there are plenty of good pixel artists out there, and we have had many good contributions from our community.

Also, within the game itself, it’s possible to directly download new campaigns from the Internet, many of which have been created by players. Do you think that, in essence, we are seeing the beginnings of applying “wiki” principles to game development?

On one hand, I see the ability to directly download new campaigns as a mild convenience — it wouldn’t be much more difficult for the user to, for instance, go to a web page and download campaigns.

On the other hand, it does blur the line between ‘developer created content’ and ‘user created content’ and so, like a Wiki, makes it much easier for any user to contribute to the game.

I think that for an Open Source game, making it as easy as possible for users to contribute content is a key way to help make the game succeed. We have tried hard to do this in Wesnoth. I don’t think that with something dynamic like a game, it’s quite as easy to make absolutely anyone be able to edit it or contribute as easily as they can in a Wiki, but we have tried to make it as easy as possible.

How do you moderate user-submitted content? Are there scenarios or graphics you have rejected because they crossed a line — sexual content, excessive violence, etc.?

Well, there are basically three levels of content acceptance:

1. ‘Official’: content can be accepted into the game itself — the content will reside in our SVN repository, and will be in the tarballs released by developers.
2. ‘Campaign Server’: Content can be allowed on the campaign server (the server which users can connect to in-game to download more content).
3. ‘Disallowed’: Finally, content can be disallowed on the campaign server, which means that the creator could only distribute it using their own channels (for instance, having a web site people could download it from).

Content only makes it to (1) if the developers happen to like it very much. We don’t have any firm rules as to what is allowed and disallowed, and a campaign that has short-comings from the developer’s point of view might still be allowed if it is exceptional in other areas. As an example of this, the campaign ‘Under the Burning Suns’ contained explicit references to religion. To avoid controversy, we wanted to avoid references to religion in Wesnoth. However, recognizing the exceptional quality of the campaign, we decided to accept it into the official version of Wesnoth in spite of this one aspect we didn’t like.

Artwork containing nudity has also been a controversial point in the past, as has violence (particularly explicit depiction of blood). We generally take the point of view that we will review each item as it comes, rather than making blanket rules.

With regard to whether we allow things onto the campaign server, (2), our general policy is that to be allowed onto the campaign server, the content need only be licensed under the GPL. However, we reserve the right to remove content that we consider to be distasteful in any way. Fortunately, our content submitters are generally very reasonable, and we haven’t had to exercise this right.

Our aim is to keep Wesnoth appropriate for users of any age and background — of course, it contains some level of violence, but this is not depicted very explicitly, and only parents who do not want to expose their children to animated violence of any level need be concerned. For this reason, we also do not allow expletives on our forums or IRC channels.

How do you feel about games like “Second Life”, where players trade user-generated content for money?

I’ve never understood the appeal of games like that. I don’t enjoy cheating in games, and to me buying items with real money seems like cheating — except worse, since it actually costs money.

What changes to the game or gameplay do you anticipate in the coming months and years?

Well, we’ve avoided making many gameplay changes at all, since very early on in Wesnoth’s development. Wesnoth is meant to be a simple game, with simple gameplay, and ‘changing’ gameplay will probably lead to it being more complex. We want to keep it simple.

Changes will probably focus on improving existing features, and making the engine a little more customizable. Enhancing the multiplayer component is big on the list — we’ve progressively added more and more features on the server. We also want to add more graphical enhancement. For instance, a particle system to allow various combat effects.

If you had unlimited resources at your disposal to improve the game, what would you change about it?

Wesnoth was always designed to be a simple game, with simple goals. It has exceeded all the expectations I originally had for it. There is still some ‘polishing’ work going on, but really I don’t think there is too much I would dramatically change.

Probably the largest thing I can name is a much better AI than we currently have. I’m pretty happy with the AI developed for Wesnoth — I think it’s much better than AIs for most commercial games — but it could be better. That’s the only area of Wesnoth that I think could really be very dramatically improved.

I am pretty happy with our in-game graphics. Some people compare our graphics to modern commercial games, and think our graphics are laughably poor. We often get comments that our graphics are around the same quality as those seen in SNES or Genesis games, or PC games from a decade ago. (These people should try playing a strategy game on the SNES/Genesis/PC from this long ago; Wesnoth’s graphics are much better).

I am very happy with our graphics overall. I think our artists have done an excellent job of making the game look attractive without detracting from functionality. Adding 3D graphics, or changing the style of the 2D graphics would only be wasted effort in my mind — I think we’ve achieved a great balance of making the game easy and clear, while making it look good.

With unlimited resources, I would like some more storyline/cutscene images, and a nice new title screen, but these are relatively small concerns I think.

There are some enhancements to multiplayer I would like added — multiplayer campaigns is a long-time feature request. As are more options and features on the multiplayer server.

Overall though, if I had ‘unlimited resources’, I’d much rather develop an entirely new game. We don’t have enough good Open Source games — it’s a waste to pour all the resources we have into one. 🙂

Wesnoth has dwarves with guns, World of Warcraft has gnomes and goblins with explosives and flying machines — where do you, personally, define the limits of the fantasy genre? Are there scenarios playing in a steampunk world, or ones with modern technology? Would you allow those?

Actually we have Dwarves with ‘Thundersticks’ 🙂 — mysterious weapons that make a loud sound and do lots of damage, but are clumsy and unreliable. The developers do not comment on whether or not these ‘thundersticks’ are or are not like ‘guns’ on earth. We like to keep Wesnoth slightly mysterious, and leave some things up to the player’s interpretation, rather than spell it out.

We once used to have dragoons with pistols, and other weapons like that, but we made a very intentional decision to remove them.

I don’t like categorizing things into ‘genres’. Many people debate whether Wesnoth is an ‘RPG’, or ‘strategy game’, etc. I think the debate of what genre something is in is largely irrelevant.

We do have a vision for what the world of Wesnoth is like though — and Wesnoth is a world of ancient-era weaponry, with a little magic. Of Elves and Dwarves and Orcs. Very much inspired by Tolkien. I actually originally chose this setting because my focus was on technical excellence — writing a good, solid engine — not on creating a new fantasy world. I decided to stick with a very well-known, proven theme, figuring I couldn’t go wrong with it.

We probably wouldn’t allow anything that departs dramatically from the world we’ve made into the official version of the game, but we’d be happy to have it on our campaign server. The main attempt at a ‘total modification’ of Wesnoth is a project known as Spacenoth, which has a sci-fi/futuristic theme.

At this time though, there is no release of this project. I hope they do well though.

How do you feel about turn-based games like “Heroes of Might and Magic” with their massive army-building and resource management? Do you think there’s going to be an open source equivalent of this type of game soon?

I haven’t played Heroes of Might and Magic very much. The few times I have played it, I thought it was boring to be honest. I don’t like the type of game where one marches armies around a ‘large map’ and then must ‘zoom in’ to a different ‘battle field’ every time a battle takes place. I find games like that to take far too long, and tend to become tedious.

I would prefer a civilization or perhaps colonization type game. FreeCiv is nice, though it’s close to being a clone of Civilization II. I’d like an original game that had the same sort of theme as civilization, but with new and innovative rules.

Every online game and community is also a social space. Have you met interesting people through Wesnoth whom you would not have met otherwise? Are there other stories you can tell from the community — have there been real world meetups, chat rooms, etc.?

I’ve come into contact with lots of very interesting people through Wesnoth, and have learned a great deal from them. The Wesnoth developers — many of whom are from Europe — used the LSM conference in France in 2004 as an opportunity to meet each other. Nekeme, an organization dedicated to developing and promotion Free games was kind enough to sponsor two developers to go. Unfortunately, I was not able to attend, but the developers who did had a very nice time.

We have several IRC channels on irc.freenode.net, and the most popular ones — #wesnoth and #wesnoth-dev are usually fairly busy with both discussion about Wesnoth, and friendly discussion of other topics.

Also, the developers have tried to make a habit of playing “co-operative multiplayer” games against the AI. During these games, we use the in-game chat facility to get to know each other better, and discuss improvements to the game.

Are there other open source games that have personally impressed you, or that you enjoy playing?

I’m afraid I haven’t played many. I like RPGs, and I know lots of people love NetHack and similar games, but I much prefer party-based and generally more storyline-oriented RPGs.

FreeCiv is pretty well-done, though I am happy to play commercial games, and so I think Civilization 3 and Civilization 4 are both technically superior in virtually every regard. I think that’s an inevitable problem when you make an Open Source game a straight clone of a commercial game.

Probably the most promising Open Source game I’ve seen is GalaxyMage, but it still has a long way to go.

Honestly, I don’t play that many games. I like playing commercial RPGs, usually console-based, with my wife, and I occasionally like playing the commercial Civilization series. To play an Open Source game, it’d have to be very good, and appeal to my tastes, and I haven’t found any Open Source games like that, sadly.

Saturday, September 27, 2008

The plan to incinerate over 200 years’ worth of archived newspapers at the University of Oslo was paused this week, following an article by the Norwegian newspaper Aftenposten publicising the intended destruction.

The unwanted archives take up 3 kilometres of shelf space, and neither the University nor the National Library are interested in retaining and storing the years of history any more.

The collection consists of both Nordic and non-Nordic newspapers, including Manchester Guardian, New York Times, Frankfurter Allgemeine Zeitung and Le Figaro.

A planned incineration of them in 2002 was avoided by moving them into a warehouse owned by Nils Christian Bang at Follum Grend, near Ringerike. Edgar Learn Borg, retired supervisor of the collection, continues to be involved in the preservation of the collection which hasn’t been accessed by researchers since its move.

The order came again to clean up the store. Frode Meinich, technical director of the University, says that the collection is not unique, and indicated that the University needs temporary storage for some antiquarian furniture during renovation of a music facility of the University.

In 2007, Frode Meinich told Aftenposten that a national program of infrastructure modernization was desperately needed. “For the time being we are managing to keep the ship afloat, but if something serious isn’t done in the next few years we have a major problem”.

Thursday, September 18, 2008

According to the International Maritime Bureau (IMB), pirates have seized a Greek bulk carrier en route to Kenya with 25 crew on board in the Gulf of Aden some 370 kilometers from Mogadishu, the capital of Somalia.

Noel Choong, who represents the International Maritime Bureau, advised ships traveling through the gulf to take extra precautions. “It appears that the pirates are now attacking ships in two areas, the eastern part of Somalia and northern parts of the Horn of Africa nation,” he said. “Ships are warned to take extra measures and stay 200 nautical miles away from the coast. They must maintain a strict watch.

The Gulf of Aden is a dangerous place for ships, with many incidents of piracy occurring regularly in the Gulf.

Four hours earlier pirates had attacked another vessel, a chemical tanker from Hong Kong, which was at the time carrying 22 crew members. Following that attack, the gulf was described by the managing director of the Hong Kong Shipowners Association as an “incredibly dangerous place.”

In response to this, several large shipping organisations have called for countries to deploy forces from their Navies in the Gulf of Aden.

“The shipping industry’s plea is in response to a situation which it describes as in danger of spiralling completely and irretrievably out of control,” said the group which consisted of the International Chamber of Shipping, Intercargo, Bimco and Intertanko. “Continued inaction against these violent acts could prompt shipowners to redirect their ships via the Cape of Good Hope, with severe consequences for international trade, including increased prices for delivered goods.”

The group also said that there have been 40 hijackings in the gulf, resulting in 133 crew members being kidnapped and 10 ships being held. According to the IMB six gangs totalling approximately 1,200 people have carried out these attacks.

Tuesday, February 23, 2010

Toyota has been accused by a U.S. House of Representatives committee with misleading the public and investigators over its recent recalls.

The accusations, in a statement from the House Energy and Commerce Committee, claim that Toyota both relied on a flawed study in its assessment of the issue of sticking accelerator pedals at the heart of the recalls, and then made misleading statements about its response. According to the authors of the letter, Henry Waxman and Bart Stupak, Toyota dismissed, rather than investigated, the idea that the cars’ computers were at fault. In a statement, James Lentz, the president of Toyota’s American division, claimed that hardware issues were to blame, and that dealers were repairing the faulty part. Toyota also released a study commissioned from the research firm Exponent that said electronic systems were not to blame.

According to the House committee, however, the study involved only six vehicles, none of which had problems with their electrical systems, and was insufficient to produce an accurate result. “Our preliminary assessment is that Toyota resisted the possibility that electronic defects could cause safety concerns, relied on a flawed engineering report and made misleading public statements concerning the adequacy of recent recalls to address the risk of sudden unintended acceleration.”

The company is under a criminal investigation, and has received two subpoenas for documents from two House committees relating to the recalls, although whether they are directly related to the letter is unclear. The documents are related to accelerator issues in several models, as well as brake problems with the Prius hybrid car, and were served earlier in in February by a federal grand jury and the Securities and Exchange Commission. Toyota has released upwards of 75,000 pages of documents under the requests.

In a separate, though related, development, it has emerged that Toyota last year negotiated a limited recall for two models, the Toyota Camry and Lexus ES, that were affected by the accelerator recalls, saving the company an estimated $100 million. A confidential internal presentation in July 2009 made the claim, and a month later, a Lexus ES, one of the models under the limited recall crashed in California, killing four people. The claims apparently referenced a September, 2007 recall of floor mats that could trap gas pedals, the same problem that triggered a full recall of numerous Toyota cars to fix the same problem. In the same presentation, the company claimed to have avoided recalls of another model related to rust, as well as delaying new federal safety regulations.

Friday, October 2, 2009

Companies in the United States are shedding more jobs, pushing the country’s unemployment rate to a 26-year high of 9.8%.

The US Labor Department said on Friday that employers cut 263,000 jobs in September, with companies in the service industries — including banks, restaurants and retailers — hit especially hard. This is the 21st consecutive month of job losses in the country.

The United States has now lost 7.2 million jobs since the recession officially began in December 2007. The new data has sparked fears that unemployment could threaten an economic recovery. Top US officials have warned that any recovery would be slow and uneven, and some have predicted the unemployment rate will top 10% before the situation improves.

“Continued household deleveraging and rising unemployment may weigh more on consumption than forecast, and accelerating corporate and commercial property defaults could slow the improvement in financial conditions,” read a report by the International Monetary Fund’s World Economic Outlook, predicting that unemployment will average 10.1% by next year and not go back down to five percent until 2014.

Mark Zandi, chief economist at Moody’s Economy.com, said that “it’s a very fragile and tentative recovery. Policy makers need to do more.”

“The number came in weaker than expected. We saw a lot of artificial involvement by the government to prop up the markets, and now that that is starting to end, the private sector isn’t yet showing signs of life,” said Kevin Caron, a market strategist for Stifel, Nicolaus & Co.

Also on Thursday, the US Commerce Department said factory orders fell for the first time in five months, dropping eight-tenths of a percent in August. Orders for durable goods — items intended to last several years (including everything from appliances to airliners) — fell 2.6%, the largest drop since January of this year.

The US government has been spending billions of dollars — part of a $787 billion stimulus package — to help spark economic growth. There have been some signs the economy is improving.

The Commerce Department said on Thursday that spending on home construction jumped in August for its biggest increase in 16 years. A real estate trade group, the National Association of Realtors, said pending sales of previously owned homes rose more than 12 percent in August, compared to August 2008.

A separate Commerce Department report said that consumer spending, which accounts for more than two-thirds of US economic activity, rose at its fastest pace in nearly eight years, jumping 1.3 percent in August.

Other reports have provided cause for concern. A banking industry trade group said Thursday the number of US consumers making late payments, or failing to make payments, on loans and credit cards is on the rise. A survey by a business group, the Institute for Supply Management, Thursday showed US manufacturing grew in September, but at a slower pace than in August when manufacturing increased for the first time in a year and a half.

Stock markets reacted negatively to the reports. The Dow Jones Industrial Average fell 41 points in early trading, reaching a level of 9467. This follows a drop of 203 points on Thursday, its largest loss in a single day since July. The London FTSE index fell 55 points, or 1.1%, to reach 4993 points by 15.00 local time.

Tuesday, September 20, 2005

US doctors are to interview 12 patients with a view to performing the first ever transplant of a human face.

The Cleveland Clinic will choose between seven women and five men to find the person most suited for the experimental procedure, which is a radical and controversial solution to extreme facial scarring or disfigurement.

Having practiced the procedure on bodies donated for medical research, the Cleveland Clinic team believe they have a 50% chance of success. The procedure will not live up to science-fiction predictions and give the recipient the appearance of the donor; the underlying bone structure is the deciding factor in the final appearance. The new face will end up resembling neither the donor nor recipient.

Surgeons in several other countries have announced being ready to perform this procedure in the past. However, the risk and non life-threatening nature of disfigurement have meant that gaining approval for the groundbreaking surgery has been difficult. Like many other transplant operations, the recipient would be required to take drugs to prevent tissue rejection for the remainder of their life. These drugs can have side effects and carry their own risks involving the patient’s immune system.

Friday, August 24, 2007

Just before midnight Wednesday, four-year-old Taylor Bailey, nicknamed Bucky, was attacked by a neighbor’s dog. The Staffordshire Bull Terrier mix named Money chased the boy after he stepped out of his mother’s car, eventually knocking the boy to the ground and latching onto his leg.

The same dog had bitten the boy’s father the week before, according to the family, although this has not been confirmed by police. He recognized the dog and alerted his mother to the dogs presence just moments before the attack. She urged her son to come to her, but the one-year-old, 85-pound (~39 kg) male broke free from his restraints and attacked the screaming boy.

The struggle lasted several minutes before the boy’s mother, Melinda Walters, was able to fight off the dog, leaving her knees scraped and thigh scratched. The boy’s legs were punctured, scratched and bruised with bits of flesh missing. “It didn’t go away. It was just trying to grab me … trying to kill me,” the boy said. Walters was carrying her three-year-old son Jason on her hip during much of the fight.

The dog’s owner, Marquita Mooney, 23, was ticketed along with a relative who was watching the dog. She said that rather than register the dog as a potentially dangerous animal—which involves an insurance bond, fees, kennel requirements and more—she would have the dog put down. Police reports indicate that the dog bit two other dogs about two weeks ago. Mooney has been ticketed for both incidents.

This is the second such incident in Minneapolis this month—seven-year-old Zach King Jr. was attacked and killed in his home last week by his family’s pit bull—fueling the debate over banning pit bulls and other “dangerous breeds” in some communities. Since 1966, there have been four other deaths from dog attacks in Minnesota, all but one of which were of children seven-years-old or younger.

Friday, June 9, 2006

Someone said to be an informant within Abu Musab al-Zarqawi‘s trusted circle told Coalition forces the insurgent leader was going to have a meeting, it has emerged. This information appears to have led US F-16Cs to a safehouse in the Iraqi town of Hibhid, where the Jordanian and five others, including a child, were killed on Wednesday.

“We had absolutely no doubt whatsoever that Zarqawi was in the house. There was 100 percent confirmation,” Caldwell said.

The informer is said to want the insurgency to pursue a strategy within the Iraqi political process, which in the informer’s view was in contrast to tactics executed by al-Zarqawi’s leadership that involved ethnic killings.

It was one of the last in a long line of breadcrumbs leading the hunt for the Iraqi government’s most-wanted murderer to the doorstep of an attractive isolated house in Hibhid.

In a late-April video al-Zarqawi had been shown spraying bullets from a machine gun with a horizon in the background. This is said to have revealed the general location of al-Zarqawi, found near Diyala province, in the north east of Iraq. The ethnically mixed region had seen an upsurge in violence and over days preceding the airstrike.

Murders had included a number of decapitated heads left in fruitboxes. Al-Zarqawi had been known for kidnapping and video beheadings of westerners in Iraq.

Another al-Zarwaqi insider also had given vital clues to the investigators before the final tip-off. A former customs clearance officer in Rutba identified as Ziad Khalaf al-Karbuli had named Sheikh Abu Abdul-Rahman as al-Zarqawi’s spiritual advisor and gave-up contact details.

Ziad Khalaf al-Karbuli had appeared on Jordanian television, May 23, to confess his links to al-Zarqawi, and to his murder of a Jordanian driver and his kidnap of two Moroccan embassy employees in 2005. The vital clue about Abu Abdul-Rahman was not broadcast.

With details from the al-Karbuli interrogation the gunsights got closer to al-Zarqawi. “Through painstaking intelligence effort, they were able to start tracking him, monitoring his movements and establishing when he was doing his link-ups with Zarqawi, ” Maj. Gen. William Caldwell said of the investigators.

The US search for the Sheikh included the use of remote controlled aircraft, it was revealed.

However; it is said neither the al-Karbuli information nor the al-Zarqawi betrayer lead the Americans to press the fire button on al-Zarwaqi’s two-story home. Al-Zarqawi was hard to catch because he reportedly eschewed trackable cell-phones in favour of high-tech Thuraya-made satellite phones to communicate.

The death certificate was signed by the secret informant who said both Sheikh Abu Abdul-Rahman and al-Zarqawi would be in Hibhid, Wednesday night.

For the elusive insurgent who had previously escaped attempts to bomb him, the execution came after comparison of this source’s information with tracks of the location of satellite phone users.

The location found was beside a property with a courtyard surrounded by fields away from other buildings. It appears then the US command made the decision to strike at an address in the small town, near Baqubah.

US special forces were on the scene to photograph the dead al-Zarqawi at 6:17 p.m., two minutes after two 500lb bombs were dropped. Al-Zarqawi was said to be alive and being given medical assistance when he died of wounds sustained in the bombing.

The announcement of the killing was made Thursday by Iraqi Prime Minister Nouri Maliki. Iraqi Prime Minister Nouri al-Maliki said to viewers of Iraqi television the $25 million bounty for information leading to the death or capture of al-Zarqawi would be “honored.”

Wednesday, October 29, 2008

The Mars Reconnaissance Orbiter has found evidence of hydrated silica or opal, a form of mineral, over large areas in the Martian surface, including in the large martian canyon called Valles Marineris. The discovery was made by the Compact Reconnaissance Imaging Spectrometer (CRISM) instrument on the orbiter. The findings are published by Ralph Milliken of Jet Propulsion Laboratory and other scientists in the November issue of the journal Geology.

Opaline minerals were first found recently on Mars by Spirit rover in the Gusev crater. The present find points to more widespread occurrence of the minerals in comparatively younger strata of Mars. The find indicates that liquid water might have been present on the surface of Mars for a longer time than previously thought. The previous view was that liquid water disappeared from the Martian surface three billion years ago. Now it is estimated that water could have been present as late as two billion years ago.

The presence of opal not only indicates water, but also that it was there long enough to alter some of the rocks. CRISM, which detected the mineral measures visible and infrared reflection spectra in 544 channels and has 20 times better resolution than previously deployed instruments.

Hydrated minerals such as opal that indicate presence of water is yet another evidence of presence of liquid water on Mars. Opal found on Earth’s surface usually contain 3 – 10% water, but can be as high as 20%. Other water-bearing minerals found earlier are phyllosilicates and hydrated sulfates. Presence of liquid water is also suggested by suspected water-sculpted land forms on Mars, such as gullies and river channels. Currently water is present only as ice at both polar caps of Mars.

A number of outcrops of opaline minerals are found as thin layers over large distances, rimming the Valles Marineris canyon. It is expected that Martian explorations for past or present life will have to focus on similar younger terrains with hydrated minerals.

“This is an exciting discovery because it extends the time range for liquid water on Mars, and the places where it might have supported life,” said Scott Murchie, from Johns Hopkins University Applied Physics Laboratory in Maryland, one of the co-authors.