Merkaba, also spelled Merkabah, is the divine light vehicle allegedly used by ascended masters to connect with and reach those in tune with the higher realms. "Mer" means Light. "Ka" means Spirit. "Ba" means Body. Mer-Ka-Ba means the spirit/body surrounded by counter-rotating fields of light, (wheels within wheels), spirals of energy as in DNA, which transports spirit/body from one dimension to another.
In modern esoteric teachings, it is taught that the MerKaBa is an interdimensional vehicle consisting of two equally sized, interlocked tetrahedra of light with a common center, where one tetrahedron points up and the other down. This point symmetric form is called a stella octangula or stellated octahedron which can also be obtained by extending the faces of a regular octahedron until they intersect again.

In his books, researcher and physicist Drunvalo Melchizedek describes this figure as a "Star Tetrahedron", since it can be viewed as a three dimensional Star of David. By imagining two superimposed "Star Tetrahedrons" as counterrotating, along with specific "prana" breathing techniques, certain eye movements and mudras, it is taught that one can activate a non-visible 'saucer' shaped energy field around the human body that is anchored at the base of the spine.
Depending on the height of the person doing the exercise, this field is about 55 feet across. Once activated, this 'saucer' shaped field is capable of carrying ones consciousness directly to higher dimensions.