Planet Scanning

Scanning is a new system in Mass Effect 2 that replaces the driving with the Mako and searching for the minerals inland, from the first game. Scanning becomes available when the Normandy SR-2 enters the orbit of any planet not involved in a main storyline mission, at which point you'll be prompted to start the scan. Once begun the planet will be overlaid with a rectangular grid. You may then press and hold another button to begin a mineral scanner which is slower than the main scanner, though its speed can be upgraded slightly. A data column will appear on the side of the screen and you then move the scanner around until the data column spikes, indicating the presence of minerals at the scanner's current location. You may then fire a probe at the deposit which will in turn add the minerals to your stores.

Abundance Indicators
There are several levels of mineral abundance for a planet. Each planet will start out at a certain abundance, which will decrease as minerals are successfully harvested.

Resources are required to complete equipment and ship upgrades. Resources are found by scanning, probing and mining planets in the galaxy. There are four kinds of mineral resources in Mass Effect 2.

Anomalies and Assignments
Scanning can also be used to discover loyalty missions and N7 assignments on certain planets. Upon entering orbit, EDI will tell you she has detected an anomaly. Then, once you start scanning the planet, there will be a white line pointing at the direction of the mission. When you find a white blip, you then launch a probe at it. At this point you can go onto the planet to do the mission. For planets with speech-based radio transmissions, the repeated speech fragment will become clearer (less muffled) the closer the scanner is to the location of the blip.

Upgrades
Two upgrades may be purchased that directly affect the planet scanning process. One upgrade doubles probe capacity from 30 to 60; the other upgrade allows the scanner to move more quickly, speeding up the process.
 * Recruit Mordin first. You need him to unlock the tech lab (and all subsequent research options).
 * Ask Miranda about upgrades to Normandy. Advanced Mineral Scanner will be unlocked which allows you to scroll faster while scanning.
 * Recruit Thane and ask him about upgrades. Modular Probe Bay will be available. You'll gain more probes.
 * (Optional) Recruit Samara and ask about upgrades. Extended Fuel Cells allow Normandy to gain an additional 50% fuel cell capacity, for a total of 150% fuel capacity.

Scanning Tips

 * The bigger the spike on the graph, the bigger the reward. The "seismograph" will consistently peak at a certain height at a given location; the closer the center of your scanner is to the center of the spike, the higher the graph will peak. If the peak is at the third horizontal line, a probe may yield only 200 of the resource. If the graph peaks at the eighth line, a probe could yield as much as 2500. In other words, the progression is logarithmic; one probe at an eighth line peak is worth much more than five probes at lines 2-5. If you want to maximize your resources, you would probe all areas, including low peaks; however, probes cost credits, and it is much easier to find sufficient resources to get all desired research upgrades than it is to find sufficient credits to buy all desired upgrades from stores. (You can get virtually unlimited credits by betting on Urz in the varren fights on Tuchanka, but this can grow tedious.)
 * The scanner does not have to be at the exact center of a spike to yield the full reward. To test this, find a large spike of something (palladium is common), and move the scanner to the edge until the graph peaks at only line 2, then launch a probe. If that were the true peak, you would expect only about 200-300 units; however, you will still get 1000-2500. If the graph is showing even a little of multiple resources, a probe will yield all the spikes in that area.
 * Planet surfaces never change. If a scan shows no resource at a given spot, it will never have anything for the rest of the game. You can methodically scan the entire surface, probe all large spikes, and then leave that planet forever.
 * The overall resource level shows how much resource is still unsurveyed. Very generally, the higher the overall level, the more large spikes you can expect to find.
 * Even depleted planets may have large spikes. If you have reason to believe a depleted planet still has a resource you need badly (for example, it's only depleted because you've launched twenty probes all over it, and you still have a fourth of the surface left to scan), it may be well worth it to stay there until you've scanned the whole surface. Any planet which started out as 'Rich' is nearly guaranteed to have at least one more large deposit even after the planet has been 'Depleted'.
 * Eezo is rare. Palladium is common. Iridium and platinum are in between. Many planets may have abundant amounts of palladium, iridium, and platinum, and absolutely no eezo. If they do have eezo, chances are high that they will have more. If you have no eezo, it may be worth it to scan a planet's entire surface meticulously if you found even a single eezo spike. (On later playthroughs, you typically start with enough bonus eezo to research every upgrade you could possibly want, other than Advanced Training.)
 * Resources are not random. Resources tend to be found on areas that are visually similar. If you find a big resource deposit look where you found it and try scanning areas that are visually similar. You can find resources faster that way then simply "scanning everything".
 * Upgrade your scanner. Your scanner will move twice as fast while your scan button is held down, if you upgrade it. You can upgrade it as soon as your research lab opens, and you've asked Miranda about upgrades.
 * You can scan fast without upgrading, if you must. The scanner reticle moves much faster when the right mouse button isn't held down. With practice, you can scan almost as thoroughly by tapping the right mouse button repeatedly as you move around the surface. The only downside is a higher chance that you might "skip" a spike by accident. Alternately, you can temporarily increase the mouse sensitivity (either in the game options or on the mouse if it has variable DPI settings) to make the reticle move faster.
 * Only scan as required. Don't probe every planet unless there's a side quest available. You'll end up with tons of minerals and nothing to upgrade in the end.
 * Always seek anomalies. If EDI does not report an anomaly as soon as you zoom in on a planet, there won't be one. If she does, then the scanning reticule will show a white line in the direction of the anomaly. Scan toward it; anomalies are always additional assignments, awarding experience, credits, possible additional resources, and even followup assignments. Even if you do not intend to play the assignment immediately, finding the anomaly lets Shepard begin the assignment immediately at his or her leisure the next time the planet is visited.
 * Know how much you need. More doesn't necessarily mean better. Know that it only takes 195,000 Palladium, 275,000 Platinum, 220,000 Iridium, and 31,000 Element Zero (+5000 for every Bonus training and +2500 for every retraining of powers and skills) to purchase EVERY research project in the game. What that means is, if you have already collected the aforementioned resources in the above numbers, buying more probes to scan for more resources is a waste of credits, especially since between rare resources and credits, the latter is much more difficult to come by.

Planet Types
You may find Element Zero on planets where it is listed as None, as each planet has a random number of low value deposits. While there are general rules and assumption for mineral distribution, do not assume that every planet of the same type will give up the same minerals.

Resource Rich Planets by Type
A rich resource is one above 10,000 of that resource gathered. The following list shows the Planets with a specific 'rich' resource and other resources. (Element Zero is so rare that no planet is 'rich', however the list of all the planets with element zero can be found here.) If you need many resources of one type for upgrades, try these planets:


 * Iridium: Aigela, Alingon, Antictra, Atahil, Beach Thunder, Bres, Capek, Corang, Crick, Durak, Ekuna, Elatha, Farlas, Fitful Current, Franklin, Gregas, Imaen, Israfil, Kakabel, Kopis, Laban, Maitrum, Makhaira, Mantun, Maskawa, Nepyma, Pahhur, Parnassus, Quarem, Sakata, Saleas, Sehtor, Siano, Talaria, Tosal Nym, Uwan Oche, Vatar, Vecchio


 * Palladium: Aequitas, Alchera, Alingon, Bannik, Beregale, Canalus, Canctra, Epho, Euntanta, Flett, Gei Hinnom, Gotha, Karumto, Ker, Klendagon, Kruban, Laena, Moros, Murky Water, Neith, Pietas, Ponolus, Sakata, Sarapai, Surtur, Synalus, Taitus, Tamahera, Thegan, Tunfigel, Venture, Wenrum, Wrill, Zeona, Zesmeni


 * Platinum: 2175 Aeia, Acaeria, Anedia, Anhur, Bindur, Bothros, Eingana, Etamis, Invictus, Keimowitz, Kopis, Lorek, Makhaira, Odasst, Rough Tide, Tamahera, Tarith, Theonax, Trident, Utha, Viantel, Zirnitra

Xbox 360 Tips

 * Scan intermittently. Your scanner moves 5x as fast when you're not scanning (holding LT). Try pulsing Left Trigger instead.
 * Rotate the planet for additional speed. - You move your scanner with the Left Thumbstick. You rotate the planet with the Right Thumbstick. You can combine these movements by moving your scanner to the left or right edge of the planet, and then pushing both thumbsticks in that direction.
 * As of May 17, 2010 a patch was added to the 360 version increasing the size of the scanner and the rate at which it moves.

Trivia

 * The planet Uranus is depleted of resources, so many people won't notice that, if probed, EDI will give a unique dialogue. Upon launching the first probe, she will say "Really, Commander?", and upon the second she will add in an unamused voice "Probing Uranus...". After this is done it follows the normal speech for the rest of the game.