The present invention discloses a novel active insulation device and method for thermally shielding an external body from temperature fluctuations of a contained body. The method comprising providing an active thermal insulation envelope between the contained body and the external body; regulating the heat transfer from the active thermal insulation envelope to the external body; and regulating the heat transfer from the contained body to the active thermal insulation envelope, thus maintaining the temperature of the external body at a constant temperature or within a narrow temperature range.