A lighter than air vehicle comprising: an envelope containing a lighter than air gas, at least part of the envelope admitting the passage of light therethrough; a plurality of devices (44, 50) for receiving the light; means for selectively redirecting the light which passes through the at least part of the envelope onto at least one of the devices (44, 50) of the plurality of devices, the lighter than air vehicle being characterised in that: the means for selectively redirecting the light is configured to operate in either a first mode of operation or a second mode of operation; the means for selectively redirecting the light is configured to be changed from operating in its first mode of operation to operating in its second mode of operation; the means for selectively redirecting the light is configured to, when operating in its first mode of operation, direct the light onto a first device of the plurality of devices (44, 50) and not onto a second device of the plurality of devices (44, 50), the second device being a different device to the first device; and the means for selectively redirecting the light is configured to, when operating in its second mode of operation, direct the light onto the second device and not onto the first device. an envelope containing a lighter than air gas, at least part of the envelope admitting the passage of light therethrough; a plurality of devices (44, 50) for receiving the light; means for selectively redirecting the light which passes through the at least part of the envelope onto at least one of the devices (44, 50) of the plurality of devices, the lighter than air vehicle being characterised in that: the means for selectively redirecting the light is configured to operate in either a first mode of operation or a second mode of operation; the means for selectively redirecting the light is configured to be changed from operating in its first mode of operation to operating in its second mode of operation; the means for selectively redirecting the light is configured to, when operating in its first mode of operation, direct the light onto a first device of the plurality of devices (44, 50) and not onto a second device of the plurality of devices (44, 50), the second device being a different device to the first device; and the means for selectively redirecting the light is configured to, when operating in its second mode of operation, direct the light onto the second device and not onto the first device. the means for selectively redirecting the light is configured to operate in either a first mode of operation or a second mode of operation; the means for selectively redirecting the light is configured to be changed from operating in its first mode of operation to operating in its second mode of operation; the means for selectively redirecting the light is configured to, when operating in its first mode of operation, direct the light onto a first device of the plurality of devices (44, 50) and not onto a second device of the plurality of devices (44, 50), the second device being a different device to the first device; and the means for selectively redirecting the light is configured to, when operating in its second mode of operation, direct the light onto the second device and not onto the first device.