View source for Tech Tree

The '''Tech Tree''' is used to unlock new parts for building vessels. The tech tree has a branching structure made up of nodes, each containing a collection of one or more parts. Nodes are unlocked by spending [[Science]] points to research their listed technologies. These nodes are spread out across multiple tiers which generally divide the parts by their ability to facilitate further exploration and build more complex crafts. The tree starts with the initial [[Starting Rocketry]] node already unlocked. Subsequent nodes all have a prerequisite node which must be unlocked before itself. The entire tech tree requires 152,080 Science points to unlock. 

The tech tree is accessible via the [[Kerbal Space Center|KSC]] [[R&D Center]] and is therefore only available in [[Exploration Mode]].
== Use ==
The tech tree is displayed a horizontal branching structure going from left to right. The player can use Science points earned by completing [[Missions]] and conducting experiments to unlock the nodes on the tech tree. Green nodes are already unlocked, bright gray nodes with a blue Science points icon are available to be researched, and dark gray nodes are not yet accessible. Once a node is unlocked, it's subsequent node or nodes become available to unlock. Clicking on any node provides a description of it's technology, list of parts included, cost in Science points, and the option to research the node if not already researched.

Nodes are arranged into rows and columns which indicate their cost in Science points. Nodes in any particular column generally cost the same amount of Science points, with some exceptions, and the cost increases as you move from left to right along a row. Branches along the tree broadly follow certain themes, such as propulsion, utility, construction, or aerodynamics. Each tier following Tier 1 is made accessible by unlocking all of the top level nodes. For example, once [[Power Launchers]] is unlocked in Tier 1, Tier 2 becomes available starting with [[Medium Orbital Rockets]].
== Tier 1 ==
The first tier of the tech tree requires 1,010 Science points to fully unlock. This tier is generally aimed at navigating [[Kerbin]] and its moons.
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== Tier 2 ==
The second tier of the tech tree requires 11,170 Science points to fully unlock. This tier introduces parts typically used for initial interplanetary travel, particularly [[Nuclear Propulsion]].
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== Tier 3 ==
The third tier of the tech tree requires 42,900 Science points to fully unlock. This tier introduces parts typically used for deep space interplanetary travel.
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== Tier 4 ==
The fourth tier of the tech tree requires 97,000 Science points to fully unlock. This tier introduces parts for {{Size|Size=XL|Add Category=0}} sized crafts. Colony parts are expected to first become available in this tier once released. The large yellow star seen in the background of Tier 4 is thought to potentially be [[Deb Deb]], hinting at interstellar travel.
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== Tier 5 ==
{{Unimplemented Content}}
The fifth tier of the tech tree was expected to be made available with the release of the Colonies milestone update and was said to contain colony parts.

== Tier 6 & Beyond ==
{{Unimplemented Content}}
The sixth tier of the tech tree was "planned". Considering the number of colony parts alleged to be introduced as well as parts necessary for interstellar travel, tiers could have continued past 6 depending on the number of nodes to be added to Tiers 4 - 6 and the number parts per node.