Voyager changes to running in gray mode, with the power cut to Decks 4 to 9, replicators, holodecks, and all other non-essentials are put offline. The remaining systems are left operating at 20 percent capacity. With the deuterium supply this low, even at one-quarter impulse, Voyager will be out of power inside a week. Gray mode is a Federation Starship emergency low-power status implemented to conserve dwindling power supplies. Gray mode is introduced to Star Trek in this episode. Eventually life support is shut down on all but Decks 1 and 5 to give the crew an extra hour of breathable air. It was first mentioned in the Season 2 story [#38 Innocence] that the warp core is designed to operate for up to three years before refuelling, which accounts for Voyager's desperate need for fuel at this time.

a corridor in grey mode

sickbay in grey mode

Chakotay notes that 20 kilos of deuterium should be enough to get the main systems back online. The crew work on ways to synthesise deuterium in geophysics. Seven attempts to beam deuterium from beneath the planet's surface, which leads to an overload in the pattern buffers and an explosion. If a probe were to be sent to collect the deuterium, it would incinerate within seconds of entering the upper atmosphere. Adaptations are made to the shields to repel the thermionic discharges from the planet.

Deuterium is an isotope of hydrogen consisting of one proton and one neutron in the nucleus, around which circles a single electron. Cryogenic (extremely cold) deuterium is the primary fuel source for the fusion impulse-engine reactors in Federation starships. Deuterium is also used as one of the reactants in the matter/antimatter reaction system in Federation Starship warp drive. The deuterium is the matter, and anti-hydrogen served as the antimatter. This is established in [TNG: Relics]. Deuterium is also used as fuel in the fusion reactors of the impulse drive as well as the reaction-control thrusters of Federation starships, noted in [#6 The Cloud]. In 2373, in [#55 Fair Trade], Neelix is assigned to deuterium maintenance, the technical support repair crew aboard a Federation starship responsible for the ship's supply of slush deuterium fuel; Janeway ordered Neelix to serve two weeks scrubbing the exhaust manifolds. The deuterium control conduit is an integral part of a Starship's warp propulsion system, [TNG: The Dauphin].

The backup systems on the environmental suits are what allow Paris and Kim to stay alive after a sustained period of time without oxygen.

Nadion bursts from the photon emitters damage the metallic compound.

It is not stated how much deuterium the crew is able to mine after reaching an agreement with the planet's lifeforms.

Kim and Paris take a shuttlecraft down to the demon planet. Seven and Chakotay take a second one to search for them.

There is an explosion in the transporter room that knocks the transporters offline. Following the ship's landing on the demon planet, Tuvok says he could give a litany of damaged systems, but now that they are down they are not getting back up again soon. Thrusters go offline as the result of the attempt to break free of the planet.

The planet is listed as class-Y and referred to as a 'demon' planet due to its toxic atmosphere filled with thermionic radiation. Just entering a standard orbit would be considered suicide, and there is no known environment less hospitable to humanoid life. The planetary classification used is that of Federation Starfleet.