Space travel is becoming more accessible due to the low-cost spaceflight. One way to maintain the communication between the space station and the ground station is to use several relay satellites. However, those relay links suffer from high loss rate, limited bandwidth, and long round trip time (RTT). Meanwhile applications running over these links, such as real-time communication, usually have deadline requirements for their data transfer. Recently, QUIC version 1 is released as RFC9000 (by Iyengar and Thomson in 2021), which provides great opportunity to improve transport services. Based on QUIC, we develop multipath deadline-aware transport proxy (MPDTP) to provide the deadline-aware transmission service for those applications. To avoid the loss caused by congestion control of each application, the proxy aggregates the data transmission of applications and transmits them along multiple paths. MPDTP uses deadline-aware scheduling and adaptive redundancy to deal with the link fluctuation and packet loss. Based on our implementation experience, we give some guidance on how to standardize MPDTP.