Identity authentication is currently an effective method to ensure the security of satellite communications. However, existing authentication schemes incur excessive overhead, rendering them impractical for resource-constrained satellite system. Thus, we propose Time-Controllable Satellite-Space-Ground Authentication(TCAu), a lightweight authentication scheme enabling direct user-satellite identity verification. TCAu uniquely supports active configuration of authentication credential validity periods, significantly improving satellite authentication efficiency. We formally prove the security of the scheme, demonstrating its resistance to man-in-the-middle attacks. Experimental results further validate its superior performance in both computational and storage overheads compared to existing solutions.