<P> Observers outside the vehicle see an implosion of plasma as the vehicle disappears, while occupants within the vehicle see a quick flash of light and instantaneously arrive at the target time in the same spatial location (relative to the Earth) as when it departed . In the destination time, immediately before the car's arrival, three large and loud flashes occur at the point from which the car emerges from its time travel . After the trip, the exterior of the DeLorean is extremely cold, and frost forms from atmospheric moisture all over the car's body . </P> <P> A few technical glitches with the DeLorean hinder time travel for its users . In the first film, the car has starter problems and has a hard time restarting once stopped, much to Marty's repeated frustration . In the second movie, the destination time display malfunctions and shows random dates (mostly January 1, 1885), which partially cause Doc to be sent to 1885 . In the third movie, the flying circuits (added by Doc in 2015), fuel line, and fuel injection manifold are damaged, preventing the car from moving under its own power . </P> <P> The time machine is electric and requires a power input of 1.21 gigawatts (pronounced "jigowatts") to operate, originally provided by a plutonium - fueled nuclear reactor . In the first movie, Doc has no access to plutonium in 1955, so he outfits the car with a large pole and hook in order to channel the power of a lightning bolt into the flux capacitor and send Marty back to 1985 . During Doc's first visit to 2015, he has the machine refitted to hover above ground in addition to standard road driving, and he replaces the nuclear reactor with a Mr. Fusion generator that uses garbage as fuel . </P> <P> Although the Mr. Fusion unit provides the required power for the time machine, the DeLorean is still powered by an internal combustion engine for propulsion . The fuel line is damaged during Marty's trip to 1885 in Back to the Future Part III; after he and Doc patch it, they attempt to use whiskey as a replacement fuel since commercial gasoline is not yet available . The test fails, destroying the car's fuel injection manifold and leaving it unable to travel under its own power . </P>

What material does the machine need to travel back to the future
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