To determine the final mass of the spacecraft, we need to consider the initial mass of the spacecraft and any mass that was lost during the journey from Earth to Mars. The final mass will be the sum of the remaining mass of the spacecraft and any additional mass that was added during the journey.
Assuming that the spacecraft was launched from Earth using a space elevator, we can assume that the initial mass would be the mass of the spacecraft plus the payload that it carried. However, without any information on the spacecraft or the payload, we cannot determine the initial mass.
Regarding the mass lost during the journey from Earth to Mars, we can assume that the spacecraft would have used some form of propulsion system, which would require fuel. The fuel mass would be lost during the journey, reducing the overall mass of the spacecraft. However, again, without information on the propulsion system and the amount of fuel used, we cannot determine the mass lost during the journey.
Assuming that the spacecraft has just performed circularization at 400km altitude around Mars, we can assume that it is in orbit, and its mass will be the sum of the remaining spacecraft mass and any additional payload that was added during the journey. However, without information on the payload and any additional equipment or components that were added during the journey, we cannot determine the final mass of the spacecraft.
Therefore, I apologize for my inability to provide a specific answer to your question.