[HamSat] SSETI Express Power Problems

[Tim Pickett]

The SSETI Express student microsatellite mission has been a remarkable 
success, achieving its two first mission objectives and a number of 
important milestones. Due to a failure in the electrical power system on 
board the spacecraft is inoperable and mission control is on "standby". 
There is a small but significant possibility of recovery, the likelihood of 
which is being ascertained by ongoing testing. The educational goals of the 
project continue to be met by the student teams who are still working hard 
to analyse and understand all available data, such that the lessons learned 
can be applied to future missions.



Detailed statement:

Despite the brevity of the initial mission a number of important milestones 
were achieved:

1) Objective 1 is fulfilled: Reaching the launch pad after progressing 
through the challenging and rigorous acceptance process is a major milestone 
demonstrating the capability and applicability of the SSETI Programme itself 
and all of the student teams involved.

2) Objective 2 is fulfilled: All evidence suggests that the three Cubesat 
passengers were successfully deployed into orbit by SSETI Express, and were 
hence able to begin their own independent missions. The Cubesats Xi-V and 
UWE-1 are alive and well, the status of NCube-2 has yet to be confirmed.

3) SSETI Express booted up in orbit and transmitted its first data back to 
earth precisely on schedule. This data was received and decoded by the 
primary groundstation and several others. This confirmed that SSETI Express 
survived its journey into space and was successfully separated from the 
launcher.

4) The primary groundstation established reliable two-way communication with 
SSETI Express. This was a remarkable achievement further demonstrating the 
capability of the SSETI Programme and all the students involved.

5) A significant amount of house-keeping data was downloaded from the 
spacecraft, allowing for a detailed analysis of the situation on board. This 
also involved the global network of radio amateurs, who have given us 
invaluable support and additional data during this mission.



The problem:

6) In order to ensure the safety of the other spacecraft on the same launch 
vehicle, SSETI Express remained inactive and coasted for 65 minutes before 
deploying the three Cubesat passengers.

7) During this time all the energy gathered by the solar panels was to be 
dissipated within the spacecraft. Evidence strongly suggests that this 
dissipation system failed by fusing on, therefore not allowing any energy to 
charge the spacecraft batteries.

8) The battery charge steadily declined during the mission, causing the 
spacecraft to enter safe mode after approximately 6.5 hours, and eventually 
shutting it down altogether.



The outlook:

9) Careful analysis of the data received, coupled with ground-based computer 
simulations and hardware tests, strongly support the proposed theory of a 
specific component failure in the excess power dissipation system.

10) Ground-based hardware tests confirm the possibility of a further failure 
mode of the specific component, which would allow the batteries to charge 
and the spacecraft to operate once again.

11) Testing is ongoing to ascertain the specific likelihood of (10), and to 
investigate other possible alternative explanations.

12) Given that the spacecraft is currently inoperable, the mission cannot 
continue as planned. It is therefore on indefinite "standby", pending the 
technical possibility of re-activation of the spacecraft, as in (10).

13) The team remain hopeful and vigilant. The primary groundstation and 
mission control centre are being configured for autonomous monitoring of the 
spacecraft, such that if it reactivates the team will be immediately alerted 
and ready to resume the mission.

14) The educational goals of the mission continue to be met daily as we try 
to analyse and understand the events since the launch.



Neil Melville - Project Manager