Joseph Shoer is a Ph.D. candidate in aerospace engineering, studying how modular spacecraft could be assembled, and hoping that they will be the telescopes and human exploration vehicles of the future, and not for crushing the dreams of Martian colonists.

I had a discussion recently with friends about the various depictions of space combat in science fiction movies, TV shows, and books. We have the fighter-plane engagements of Star Wars, the subdued, two-dimensional naval combat in Star Trek, the Newtonian planes of Battlestar Galactica, the staggeringly furious energy exchanges of the combat wasps in Peter Hamilton’s books, and the use of antimatter rocket engines themselves as weapons in other sci-fi. But suppose we get out there, go terraform Mars, and the Martian colonists actually revolt. Or suppose we encounter hostile aliens. How would space combat actually go?

First, let me point out something that Ender’s Game got right and something it got wrong. What it got right is the essentially three-dimensional nature of space combat, and how that would be fundamentally different from land, sea, and air combat. In principle, yes, your enemy could come at you from any direction at all. In practice, though, the Buggers are going to do no such thing. At least, not until someone invents an FTL drive, and we can actually pop our battle fleets into existence anywhere near our enemies. The marauding space fleets are going to be governed by orbit dynamics – not just of their own ships in orbit around planets and suns, but those planets’ orbits. For the same reason that we have Space Shuttle launch delays, we’ll be able to tell exactly what trajectories our enemies could take between planets: the launch window. At any given point in time, there are only so many routes from here to Mars that will leave our imperialist forces enough fuel and energy to put down the colonists’ revolt. So, it would actually make sense to build space defense platforms in certain orbits, to point high-power radar-reflection surveillance satellites at certain empty reaches of space, or even to mine parts of the void. It also means that strategy is not as hopeless when we finally get to the Bugger homeworld: the enemy ships will be concentrated into certain orbits, leaving some avenues of attack guarded and some open. (Of course, once our ships maneuver towards those unguarded orbits, they will be easily observed – and potentially countered.)

Now, Let’s Talk Technology

First, pending a major development in propulsion technology, combat spacecraft would likely get around the same way the Apollo spacecraft went to the Moon and back: with orbit changes effected by discrete main-engine burns. The only other major option is a propulsion system like ion engines or solar sails, which produce a very low amount of thrust over a very long time. However, the greater speed from burning a chemical, nuclear, or antimatter rocket in a single maneuver is likely a better tactical option. One implication of rocket propulsion is that there will be relatively long periods during which Newtonian physics govern the motions of dogfighting spacecraft, punctuated by relatively short periods of maneuvering. Another is that combat in orbit would be very different from combat in “deep space,” which is what you probably think of as how space combat should be – where a spacecraft thrusts one way, and then keeps going that way forever. No, around a planet, the tactical advantage in a battle would be determined by orbit dynamics: which ship is in a lower (and faster) orbit than which; who has a circular orbit and who has gone for an ellipse; relative rendezvous trajectories that look like winding spirals rather than straight lines.

Second, there are only a few ways to maneuver the attitude of a spacecraft around – to point it in a new direction. The fast ways to do that are to fire an off-center thruster or to tilt a gyroscope around to generate a torque. Attitude maneuvers would be critical to point the main engine of a space fighter to set up for a burn, or to point the weapons systems at an enemy. Either way, concealing the attitude maneuvers of the space fighter would be important to gain a tactical advantage. So I think gyroscopes (“CMGs,” in the spacecraft lingo) would be a better way to go – they could invisibly live entirely within the space fighter hull, and wouldn’t need to be mounted on any long booms (which would increase the radar, visible, and physical cross-section of the fighter) to get the most torque on the craft. With some big CMGs, a spacecraft could flip end-for-end in a matter of seconds or less. If you come upon a starfighter with some big, spherical bulbs near the midsection, they are probably whopping big CMGs and the thing will be able to point its guns at you wherever you go. To mitigate some of the directionality of things like weapons fire and thruster burns, space fighters would probably have weapons and engines mounted at various points around their hull; but a culture interested in efficiently mass-producing space warships would probably be concerned about manufacturing so many precision parts for a relatively fragile vessel, and the craft would likely only have one main engine rather than, say, four equal tetrahedral engines.

How About Weapons?

We have to consider just how you might damage a spacecraft to put it out of action.

Explosions are basically a waste of energy in space. On the ground, these are devastating because of the shock wave that goes along with them. But in the vacuum of space, an explosion just creates some tenuous, expanding gases that would be easily dissipated by a hull. No, to damage spacecraft systems, you can’t hit them with gas unless it’s really, really concentrated and energetic. So unless you want to just wait till your enemy is close enough that you can point your engines at him, the best bets for ranged weapons are kinetic impactors and radiation.

A kinetic impactor is basically just a slug that goes really fast and hits the enemy fighter, tearing through the hull, damaging delicate systems with vibrations, throwing gyroscopes out of alignment so that they spin into their enclosures and explode into shards, puncturing tanks of fuel and other consumables, or directly killing the pilot and crew. You know…bullets. But it sounds much more technical and science-fictiony to say “mass driver” or “kinetic lance” or something of the sort. Of course, the simplest way to implement this sort of weapon in space is just as some kind of machine gun or cannon. Those will work in space (ask the Soviets, they tested a cannon on their first Salyut space station), and the shells will do plenty of damage if they hit anything. However, space is filled mostly with empty space, and hitting the enemy ships might be a challenge. Furthermore, if the impactors are too large, the enemy could counter them by firing their own point-defense slugs and knocking the shells out of line. Therefore, I contend that the most effective kinetic space weapons would be either flak shells or actively thrusting, guided missiles. The flak shells would explode into a hail of fragmented shards, able to tear through un-armored systems of many craft at once without the shell directly hitting its target, or able to strike a target even after it tries to evade with a last-minute engine burn. The missiles would be a bit different from the missiles we are used to on Earth, which must continuously thrust to sustain flight. In space, such a weapon would rapidly exhaust its fuel and simply become a dummy shell. No, a space missile would either be fired as an unguided projectile and power up its engine after drifting most of the way to its target, or it would fire its engine in sporadic, short bursts. A definite downside to kinetic weapons on a starfighter is that they would impart momentum to the fighter or change its mass properties. Very large cannons or missiles might therefore be impractical, unless the fighter can quickly compensate for what is essentially a large rocket firing. Even that compensation might give the enemy just the window he needs…

Radiation-based weapons that burn out the electronics of a spacecraft sound exotic, but are still potentially achievable. This would be the attraction of nuclear weapons in space: not the explosion, which would affect just about nothing, but the burst of energetic particles and the ensuing electromagnetic storm. Still, such a burst would have to be either pretty close to the target vessel to scramble its systems, or it would have to be made directional in some way, to focus the gamma-ray and zinging-proton blast. But while we’re talking about focused energy weapons, lets just go with a tool that we already use to cut sheet metal on Earth: lasers. In space, laser light will travel almost forever without dissipating from diffraction. Given a large enough power supply, lasers could be used at range to slice up enemy warships. The key phrase there, though, is “given a large enough power supply.” Power is hard to come by in the space business. So, expect space laser weapons to take one of three forms: small lasers designed not to destroy, but to blind and confuse enemy sensors; medium-sized lasers that would be fired infrequently and aimed to melt specific vulnerable points on enemy space fighters, like antennae, gimbals, and maneuvering thrusters; and large lasers pumped by the discharge from a large capacitor or similar energy storage device to cut a physical slice into the enemy craft wherever they hit. Such a large weapon would likely only be fired at the very beginning of a battle, because the commander of a ship with such a weapon would not want to keep his capacitor charged when it might unexpectedly blow its energy all at once once he’s in the thick of things.

Deflector shields like those in fiction are not possible at present, but it would still make sense to armor combat spacecraft to a limited extent. The spaceframes of the fighters would likely be designed solely for the space environment; the actual ships would be launched within the payload fairings of a rocket or assembled in space. If launched from the ground, armor must be minimized to reduce the launch weight of the spacecraft. But if built and launched in space, it would make sense to plate over vital systems of the vehicle. Thick armor would prevent flak or small lasers from piercing delicate components, and might mitigate a direct strike from a kinetic impactor or heavy cutting laser. However, the more heavily armored and massive a space fighter is, the more thrust it will take to maneuver in orbit and the more energy it will take to spin in place. (Here’s where computer games get space combat all wrong: the mass of a huge space cruiser would not place an upper limit on the speed of a vehicle, but it would reduce the acceleration a given engine could produce compared to the same engine on a less massive vehicle.)

I’m assuming that we’d have some intrepid members of the United Earth Space Force crewing these combat vessels. Or, at least, crewing some of them – robotic drone fighters would be a tremendous boon to space soldiers, but the communication lag between planets and vessels in orbit would make the split-second judgments of humans necessary at times. (Until we perfect AIs… but if we’re giving them the space fighters from the beginning, we deserve the robot uprising we’ll get.) The crews will hardly be sitting around nice conference-room command bridges with no seat belts; nor will they be standing upright in slate-gray console pits with glowing glass displays all over. It’s not even a good idea for them to have windows, which would be vulnerable to flak and could give the crew an intense sense of disorientation as the spacecraft maneuvers, and could give them tremendous trouble adapting to rapid changes in light levels as the ship rotates near a planet or star. No, they should be strapped into secure couches and centrally located in the most protected part of the spacecraft. They should also be in full pressure suits, and the interior cabin of the spacecraft should already be evacuated – to prevent fires, or any secondary damage if all the atmosphere rushes out a hull breach. This also reduces the need for escape pods. Camera views from the exterior of the ship and graphical representations of the tactical situation would then be projected directly onto helmet faceplates.

Now, for the final word, let’s say the United Earth Space Force defeats the Martian rebels in orbit. What do we do to hit them on the ground? Well, strategic weapons from space are easy: kinetic impactors again. You chuck big ol’ spears, aerodynamically shaped so they stay on target and don’t burn up in the atmosphere, onto ground targets and watch gravitational potential energy turn into kinetic energy and excavate you a brand-new crater. At some point, though, the imperialist Earthlings probably want to take over the existing infrastructure on Mars. Time to get out the Space Marines!

It’s not terribly expensive or difficult, comparatively speaking, to get people from orbit down to a planet surface. You fall. This is the purpose of a space capsule. What’s really, really, prohibitively difficult is getting them back up again. So, the victorious orbital forces would have to bring in a transport ship chock full of Space Marines and drop them all at once in little capsules (little because they can only be so big for the atmosphere to effectively brake them, and because you don’t want all your Marines perishing in some unfortunate incident). Some orbital forces would remain in place to threaten the ground with bombardment and give the Marines a bit more muscle, but really, the ground-pounders are going to have to be pretty self-sufficient. If they ever want to come back up, they would have to build and/or fuel their own ascent vehicle. (This is the problem facing any NASA Mars efforts, too: getting back up through the Martian atmosphere is much harder than any of the lunar ascents were.)

What Would Combat Spacecraft End Up Looking Like?

There are good arguments to have both large and small spacecraft in the Earth forces. A big spacecraft could have a lot more armor to keep its systems and crew safe, more room for large fuel tanks and electrical power supplies, and larger mass to resist impulses from cannon recoil. However, a smaller craft would be less visible to radar, more maneuverable, and could achieve higher accelerations for constant engine thrust. As with just about any military force, the role of the craft would be tailored to the tactical operations required, so the Space Force would probably include several sizes of craft.

Enemies could come at your ship from any direction in space, which means that you would want to react, strike, and counterattack in any direction. So, you would either have to mount weaponry all around your starfighter, put the weapons on gimbals so that they could rapidly point in any direction, or make the fighter maneuverable enough that it could rapidly point in any direction. Gimbals would be a bad option, because they would introduce points of increased vulnerability, unless they could be very well-armored. I conclude that the big ships would have many weapons, pointed in many directions; the small ships would have a few weapons, with the main weapon systems pointed in one direction.

Maneuverability (angular acceleration) you could achieve with gyroscopes, or by mounting engines or thrusters away from your fighter’s center of mass. For the highest levels of maneuverability, the spacecraft should be close to spherical and these engines should be as off-center as possible, which might mean putting thrusters on long booms or struts. The problem with this kind of Firefly-like engine layout is that it becomes very vulnerable. If a fighter can achieve high maneuverability with gyros, those are probably the best option.

So, I think the small fighter craft would be nearly spherical, with a single main engine and a few guns or missiles facing generally forward. They would have gyroscopes and fuel tanks in their shielded centers. It would make sense to build their outer hulls in a faceted manner, to reduce their radar cross-section. Basically, picture a bigger, armored version of the lunar module. The larger warships would also probably be nearly spherical, with a small cluster of main engines facing generally backward and a few smaller engines facing forward or sideways for maneuvering. Cannons, lasers, and missile ports would face outward in many directions. On a large enough space cruiser, it would even be a good idea to put docking ports for the small fighters, so that the fighters don’t have to carry as many consumables on board.

I think it’s time to sketch some pictures and write some stories!

Space-Wide Peace

I certainly hope we don’t get into any space wars. Human nature being what it is, though, and given how scarce a lot of resources really are on the scale of a solar system or a galaxy, I don’t think it’s out of the question. I would like to think that when we start colonizing other worlds, we will be sufficiently enlightened to do so from on board the Ship of the Imagination, and not as futuristic conquistadores. Still, the part of me that loves science fiction has fun with these thought experiments.

Reprinted with permission from Joseph Shoer. Photo by TG Daily

When technologists of the future look back in time, they’ll remember 2009 as the year Google got serious about an internet operating system, speeding up the web, and indexing EVERYTHING in sight. Take a look at the year 2009 in Google.

Google’s Three Biggest Launches of 2009

Two of the three most significant Google releases of 2009 are not yet available to the public in a final release build, but all three are open source. In no particular order:

Chromium OS: In July, Google got Microsoft and Apple shaking in their boots when they announced they were building an operating system. The source code for Chrome OS (in its development phase it’s called Chromium OS) became available in November; early adopters can run virtual machine images and bootable USB drive versions of the OS.

Google Wave: In May, Google demonstrated their new, real-time collaboration webapp, Google Wave, to a crowd of incredulous developers who couldn’t stop applauding. In September, they invited 100,000 users to try the Wave Preview. By now, over one million users have joined the Wave Preview. We wrote a book about Wave; and you can give and get Wave invitations on our dedicated forum page.

Android 2.0/Droid: While Android-based handsets were already available when the year started, the Motorola Droid debuted in November running Android 2.0 (with turn-by-turn GPS capabilities) and took on the iPhone in its “Droid Does” ad campaign. Google also released a flurry of Android-only applications and updates to existing ones in 2009 to boost their mobile platform, including the Google Voice app (which Apple rejected on the iPhone), the amazing Google Goggles app, Google Maps enhancements, and Google Listen.

Google’s Most Updated Apps of 2009

While a few Google products did get shut down, “sunsetted,” or just didn’t change much, several marquee apps grew up a whole lot this year with serious feature additions and upgrades.

Search Engine Upgrades: Remember when Google was just a search engine? Googlers do, because they’re still busy bees improving search results and rolling out new ways to get to them. This year saw the rollout of Google web search’s Caffeine update, as well as music, social, and real-time search, along with several new Google Image search options, and updates to the Google Suggest drop-down.

Gmail: Thanks to Gmail Labs, our favorite web-based email client got a slew of new features for power users, from automatic translations to offline attachments to time zone notifiers to exportable mail filters. If you haven’t recently, cruise through your Gmail account’s Labs area to pick and choose from over 60 experimental features. Gmail’s mobile web application for the iPhone and on Android also saw an overhaul and vast improvement this year.

Chrome web browser: Google’s own browser, Chrome, saw a whole lot of movement in 2009, especially late in the year with the release of bookmark sync, official beta builds for Mac and Linux (finally!), and Chrome extensions.

Google News also saw a couple of interesting experiments like Fast Flip and the News Timeline.

Google’s Mission to Speed Up the Web

If there’s any one thing Google did this year, it was launch a concerted effort on all fronts to make the web faster. From developer tools (like Speed Tracer and the Google Web Toolkit) to consumer products (like Chrome and Google Public DNS), it’s kind of astounding the sheer amount of stuff Google put out there this year under the speed umbrella. They’re even going so far as attempt to reinvent the two pillar protocols of email and the web with Wave and SPDY (a faster replacement for HTTP).

And the rest….

2009 was also the year of a few legal skirmishes (like the Google Books settlement, the Cyanogen C&D, the Google Voice/FCC dust-up), a few acquisitions (like reCAPTCHA, Gizmo5, and AppJet), and data control initiatives (the Google Dashboard and the Data Liberation Front).

You could say it was a pretty busy year at the Googleplex.

Google’s 2009 Product Release Calendar

Take a chronological ride through the last four seasons at Google in this list of 2009 product releases and updates, listed month by month.

January

• Offline Gmail gets released with Google Gears
• Picasa for Mac released

February

• Google Latitude and search by voice for Android launch
• Google Sync for your mobile phone launches

March

• Google Calendar goes offline with Google Gears

April

• Google Profiles show up at the bottom of search results
• Updated mobile Gmail and Google Calendar webapps for iPhone and Android launch
• Google Maps mashup tracks swine flu
• GV Mobile makes Google Voice the default for your iPhone (later, Apple pulled this app from the iTunes Store for reasons that are still unclear)

May

• Engineers demo Google Wave at the Google I/O conference, give developers access to the Wave “sandbox”

June

• Google Apps Sync syncs Microsoft Outlook with Gmail, Google Contacts, and Calendars (updates with push Gmail in September)
• Google Squared puts your search results into a spreadsheet
• Gmail, Google Calendar, Docs, and Talk leave beta

July

• FeedDemon, NetNewsWire sync exclusively with Google Reader
• Google announces Chromium OS (but doesn’t release any code, doctored screenshots and fan-made versions start popping up)
• Apple rejects all Google Voice applications from the iTunes Store
• Gmail Tasks graduates from Google Labs (where it first appeared in December of 2008)

August

• Gmail makes importing mail and contacts from old email accounts easy
• PubSubHubbub gets baked into Google Reader

September

• Google Wave Preview opens to 100,000 users
• GrandCentral closes its doors, transitions entirely to Google Voice
• Google Sidewiki launches

October

• Google offers voicemail storage and transcriptions for your existing phone number (part of Google Voice)
• Google Maps Navigation adds turn-by-turn GPS to Android
• Google Voice gives existing users invitations to send to their friends

November

• Chrome OS announced, Chromium build demo’ed and source code released (here’s how you can try out a Chromium build yourself)
• Google Chrome adds bookmark sync
• Google releases Go, a new programming language

December

• Chrome browser hits Mac/Linux with extensions enabled (Chrome for Windows left beta in December of 2008)
• Google’s new real-Time search includes Twitter streams
• Google Public DNS launches
• Google “lets the sun set” on Gears, moving to HTML5
• Google Goggles for Android searches the web by photo
• Google Favorite Places puts a barcode on restaurants and shops you can scan with your mobile phone

Now you tell us:

What was the best Google launch of the year? The biggest flop? The product that made the biggest difference in your daily life? Let us know in the comments.

Gina Trapani, Lifehacker’s founding editor, looks forward to what the GOOG will come up with in 2010. Find her at Smarterware and on Twitter.

They call themselves the Worldwide Loyalty Team. Among some employees, they are known as the Apple Gestapo, a group of moles always spying in headquarters and stores, reporting directly to Jobs and Oppenheimer. Here’s how they hunt people down.

“You may want to know about their Worldwide Loyalty Team,” Tom told me recently in an email. I read what he had to say. It felt like a description of the Gestapo, without the torture and killing part.

Tom never lived in Nazi Germany, back in the time when the Geheime Staatspolize had the power to get into any house or any office, at any time of the day or night, without any warrant or reason, to seize whatever or whoever they wanted in their never ending search to find enemies of the state. A place in which you had no right to privacy whatsoever. A place in which you were guilty until proven otherwise.

No, Tom never lived in Nazi Germany, nor in East Germany, nor in the Soviet Union, nor in Communist China. He lives in the United States. For sure, he has never been scared of losing his life nor the ones he loves, like thousands of millions in those countries. But he knows how it feels to be watched, to always be considered guilty of crimes against another kind of state. He knew how it felt to have no privacy whatsoever when he was working right here, in a little Californian town called Cupertino, in a legendary place located in One Infinite Loop.

Tom knew about all that pretty well, back when he was working at Apple Inc.

Operation Lockdown

Of course, if Tom had never sent any sensitive information to media outlets, he would have never had the fear of being caught, only to get fired and sued into oblivion by Apple Legal. But the lack of any privacy whatsoever is something that he shared with all his fellow employees.

“Apple has these moles working everywhere, especially in departments where leaks are suspected. Management is not aware of them,” he told me, “once they suspect a leak, the special forces—as we call them—will walk in the office at any hour, especially in the mornings. They will contact whoever was the most senior manager in the building, and ask them to coordinate the operation.”

The operation, as Tom calls it, is not anything special. It is not one of a kind event. It’s just a normal practice, and the process is pretty simple: The manager will instruct all employees to stay at their desks, telling them what to do and what to expect at any given time. The Apple Gestapo never handles the communication. They are there, present, supervising the supervisors, making sure everything goes as planned.

All cellphones are then taken. Usually, they collect them all at the same time, which means that the process could take a long time. If you need to contact the exterior during the time your cellphone is under examination, you will have to ask for permission, and your call will be monitored.

They don’t ask for cameras because there are no cameras at Apple: Employees are not allowed to get into the campus with them. If the cellphone is an iPhone, it gets backed up onto a laptop. “In fact, at the beginning they used to say that the iPhones were really their property, since Apple gave every employee a free iPhone,” he points out. All the employees are asked to unlock and disable any locking features in their cellphones, and then the special forces will proceed to check them for recent activity.

They back up everything and go through all the other phones’ text messages and pictures. If you have porn in your phone, they will see it. If you have text messages to your spouse, lover, or Tiger Woods, they will see them, too. Just like that. No privacy, no limits.

While all this is happening, the employees are ordered to activate the screensaver on their computers, so the special forces are sure there are no chats happening between employees or with the exterior. They are told not to speak, text or call one other when the lockdown is happening: “It is like a gag order, and if the employee does not want to participate, they are basically asked to leave and never come back.”

2009 Is Like “1984”

Of course, all this is voluntary. Management recommends that you relinquish your phones. If you don’t do it they will fire you, or they will investigate why you didn’t want to give them your cellphone. Simultaneously, everyone is asked to sign NDA’s during the investigations, even though they already signed Apple NDAs to work there.

“I was at several events. When they find what they are looking for—which they usually do—the person is asked to stay until the end of the business day. Then he is asked to leave the premises quietly, escorted by security,” Tom says. While he’s there, the special forces hang around, watching. “There is a lot that goes behind doors that I don’t really know about. I do know, however, that they really interrogate people that are serious suspects, intimidating them by threatening to sue.”

There is no way to know how often this happens, however, as everything is handled very quietly. The same Worldwide Loyalty Team does many other things to keep everyone in check, from searching out the email history of every employee—which is also a normal practice in other corporations and government agencies—to seeding fake images to catch potential leaks and diffuse the hype about some product introductions.

As Tom was describing all this, my mind was getting back to all I’ve read about Steve Jobs and Apple, back when he was El Capitán of the brave group of free pirates who created the Macintosh. The Mac was a secret project too, but there was no secret police making sure there were no leaks. After a hard day of work, all the Mac team sometimes played on the beaches of California, careless and happy, confident that this new revolutionary computer would change the world, one desktop at a time. All of them shared information, there were no seeeecrets, and that’s why they came up with an “insanely great” computer, as Steve Jobs himself used to refer to it.

And while I understand that secrecy is paramount to success in today’s extremely competitive market—hello, dear marketdrones—now I look at this story on the Worldwide Loyalty Team, and it makes me realize how much Apple has changed. From a happy hippie company, to a company that does KGB-style lockdowns and Gestapo interrogations that end in suicides.

I wonder if the special forces have ever chased anyone through the Infinite Loop campus, dressed in their full regalia:

I wouldn’t be surprised.

It’s amazing what one letter will do. The Segway becomes the Kegway, Nikon becomes Nixon and Gatorade becomes, uh, Gatorape. I know that last one isn’t gadgety, but I let it slide.

First Place — JPS

Second Place — Jeff Forde

Third Place — Harm Veenstra

We’ve featured hundreds of free Windows applications over the course of 2009 that we hoped might bolster your productivity, workflow, or your PC usefulness in one form or another. Here’s a look back at the most popular Windows downloads of the year.

As with 2008’s most popular free Windows downloads, keep in mind that the apps featured here are chosen by the popularity of the associated post we published in 2009. Many were new, some were improvements to already loved apps, and others were simply new-to-us. Here’s a quick look back at the 19 or so most popular Windows downloads of 2009:

Windows 7—from Beta to Release Candidate and So On

2009 was a big year for Windows, and Windows 7 was the most important ingredient in Windows’ solid year. (In fact, you’ll notice that several of this year’s most popular downloads are related to Windows 7 in one way or another.) Sure it’s not exactly an application but rather a full-blown operating system, but it only makes sense that a new version of Windows would top the list of Windows downloads for the year. It started with the Windows 7 beta download in January, which had a ton of hiccups. It was released, then pulled, then released again, then extended because of the trouble Microsoft had handling the demand. (Actually, we just think they underestimated the web.) Later, in May, Microsoft released the Windows 7 release candidate. You even jumped on the chance to try Windows 7’s beautiful new themes.

Folks who were still using Vista also flocked to Vista’s Service Pack 2 (32-bit; 64-bit) to keep their PCs secure and up to date.

Enigma Desktop 2.0 Released, Adds Installer, Widget Manager, and Templates

One of our very own readers released his popular desktop configuration as a installable utility that brings a handful of great customization and productivity tools to your desktop. It’s called Enigma 2.0. Then Rainmeter, another very popular desktop customization tool, set Enigma as its default desktop. Fancy pants.

Portable Ubuntu Runs Ubuntu Inside Windows

Ever wish you could enjoy some of the finer tools available to Linux but stay comfortably in your Windows desktop? Sure you could run a virtual machine, but Portable Ubuntu for Windows runs an entire Linux OS as a Windows application. Better yet, it’s portable.

Seven Remix XP Makes Windows XP Look Like Windows 7

The release of Windows 7 left a lot of XP users wishing they could get in on some of that snazzy new eye candy. Seven Remix XP is a free utility that does its best to bring Windows 7’s comely looks to XP.

Ninite Bulk-Installs Great Free Windows Apps

Another result of the Windows 7 launch: A whole lot of us were rebuilding systems from the ground up, which often means a lot of tedious downloading and installing one app at a time. Ninite makes it easy, streamlining the download and installation processes for tons of the most popular free Windows apps, including most of our 2009 Lifehacker Pack.

Windows 7 Shortcuts Enables the Best Win7 Shortcuts in XP or Vista

Apart from all the new eye candy, Windows 7 really tickled our fancy with tons of incredible new keyboard shortcuts. For folks still chilling out with XP or Vista, we released Windows 7 Shortcuts, a lightweight utility written to bring some of the best new shortcuts of Windows 7 to previous versions of Windows.

Computer Repair Kit Packs Dozens of Tools in One Portable Package

By virtue of reading Lifehacker, you’re more likely than not the most schooled person among your friends and family when it comes to fixing a bum PC. It’s a dubious honor, because it also means you generally are the person who gets called when something goes wrong. Computer Repair Utility Kit puts a handful of useful PC repair utilities in one handy, portable suite. Update: It appears the surge of readers looking to download this one brought down the server; luckily helpful reader Richard offers a mirror of the download on his own server here.

Fences is a Seriously Awesome Desktop Icon Organizer

Like to keep items you want to access frequently easily accessible on your desktop but don’t want to deal with the added clutter? Fences arranges your cluttered desktop icons into containers so you can clean up the mess into useful groups of shortcuts—or optionally hide them altogether.

AVG 9 Free Antivirus

We’re of the mind that Microsoft’s security tools are good enough—including the new and impressive Microsoft Security Essentials antivirus app—but that doesn’t mean many of you don’t get excited when the AVG 9 Free update is available. It’s still the favorite antivirus app of Lifehacker readers (who doesn’t love free), though we’re sensing a slow but steady sea of change on this one.

Google Chrome—Stable, Beta, and Dev Releases

Google Chrome is just over a year old, but it’s made huge strides among early adopters. Chrome came out with its stable 2.0 release in May, then followed up with a Chrome 3.0 release in September. Early adopters willing to try their luck in the beta and dev channels get more features, which we detailed in our power user’s guide to Google Chrome. Whichever version of Chrome interests you most, it’s clear that it was a pretty good year for Chrome.

Hulu Video Downloader Saves Your Favorite Shows for Offline Enjoyment

Hulu Video Downloader was a fun little app that lasted about as long as you could say Hu… that is, it doesn’t work anymore. But when it did, it grabbed videos from the popular video service for your offline viewing pleasure, and you were eager to try it out.

Safari 4 Tempts with Good Looks

Safari‘s 4.0 beta release for Windows came with a lot of bugs and some serious eye candy, but despite the interest at release, we can’t imagine many people still stick with Safari on Windows over, say, Firefox, Chrome, Opera, etc.

Namebench Helps You Find the Fastest DNS Server for Your Computer

Google very recently announced a free DNS service they boasted as fast, but rather than take their word for it, we pointed you toward namebench (and several readers also pointed toward the excellent DNS Name Server Benchmark). It tests various popular DNS servers to find what’s really going to be the fastest choice for your system.

Google Earth 5.0 Beta Released, Looks Incredible

We’re sort of junkies for maps and 3D, so when Google Earth 5 was released, we were pleased as punch. The update featured historical imagery, ocean maps, and improved world touring capabilities. Maybe we just like saving ourselves some dough in these tough economic times with a little Google Earth sightseeing.

And Then There Was Firefox

The notorious Firefox memory slow-downs may have some of us down on the reliable old ‘fox, but that doesn’t mean we aren’t all still eager to grab the latest and greatest releases and stick with it as our default browser—whether it’s the big Firefox 3.5 release or the Firefox 3.6 beta (1, 2, 3, or 4). We’re looking forward to more great Firefox’ing in 2010.

Motion Detection Is an Effective, Dead Simple Security Camera App

If your webcam is sitting around collecting dust, try out Motion Detection, a free, motion-detecting security camera application. It’ll snap pics and video when it detects movement, can upload the results via FTP, and more fun at-home security stuffs.

Thunderbird 3 Officially Released with New Features, Improved Look

Sure it was two years since Thunderbird‘s 2.0 release, but at least they didn’t disappoint. Thunderbird 3.0 comes with solid new search and filtering tools, better looks, and a great new tabbed interface.

HandBrake Updates to 0.9.4 with Over 1,000 Changes, 64-Bit Support

Free, open-source DVD ripping and encoding tool HandBrake released a pretty saucy update last month with a ton of fixes and improvements. It’s no coincidence that it’s always been our reader’s favorite video encoder, and this year’s big-ish (but still not 1.0) update should only help keep it there.

DeskHedron Adds 3D Virtual Desktop Eye-Candy to Windows

Linux users have a killer desktop management tool called Compiz Fusion that puts multiple desktop management on a 3D cube that we’ve always been jealous of on Windows. Open-source application DeskHedron brings a similar three-dimensional desktop management tool to Windows users.

Now, for fun:

Got a favorite Windows download from 2009 that you’d add to your list of favorites? Let’s hear about it in the comments. If you’re craving still more popular Windows downloads, you can also take a look back at the most popular free Windows downloads of 2008.