At peak acceleration Laika's respiration increased to between three and four times the pre-launch rate. The sensors showed her heart rate was 103 beats/min before launch and increased to 240 beats/min during the early acceleration. After reaching orbit, Sputnik 2's nose cone was jettisoned successfully; however the "Block A" core did not separate as planned, preventing the thermal control system from operating correctly. Some of the thermal insulation tore loose, raising the cabin temperature to . After three hours of weightlessness, Laika's pulse rate had settled back to 102 beats/min, three times longer than it had taken during earlier ground tests, an indication of the stress she was under. The early telemetry indicated that Laika was agitated but eating her food. After approximately five to seven hours into the flight, no further signs of life were received from the spacecraft.