1. Comments by Independent Reviewer (page limit – 1)
In the system overview diagram, voltage supply buses are missing. Moreover, it appears from the
provided diagram that each subsystem component needs to establish a communication link with
every other subsystem (Eg. Camera needs to connect to transceiver IMU, magnetorquer needs to
connect to photodiode etc.). Is this necessary for the mission? Such a design will lead to very
complex circuits involving communication links between your subsystem components. The system
overview diagram shall be revised to address the aforementioned issues.
The proposed space mission is composed of various small objectives such as measuring the effect of
GPS signals due to altitude, measuring the change in temperature and chemical composition with
altitude etc. According to the description, there are as many as 4 payloads components. This is a
considerably large number of payload components for a single unit CubeSat. Although there is no
requirement in the number of payloads for the mission, the team is advised that such a mission may
place a very significant weight and power constraints, but most importantly, an increased complexity
in the CubeSat design to accommodate the large number of payloads.
Modes of operation are sufficient although a diagram showing the how the modes transition
between each other should be included.
In the provided mass budget, a payload net weight of only 50g and 5g contingency was chosen which
is rather small considering the number of payloads the team intends to use. There is also no
justification of this estimation in the appendix. Moreover, the mass of the EPS system was omitted in
the mass budget, and this system contributes a very significant amount of mass to the satellite
(Especially the solar panels). The team shall revise the mass budget for their satellite.
The structure and calculations in the power budget is reasonable although the power consumption
of the communication subsystem (Rx and Tx) shall be revised since it does not match that mentioned
in the datasheet. However, based on the given results, the available time of usage (According to
“Battery Use (min)” row) for the de-tumble mode and the payload modes is only in the order of 4 to
12 minutes. This is a rather short time and thus causes a concern in terms of power management for
the team’s satellite. Subsequently, the team shall either revise the EPS system to provide a higher
power to the satellite or revise the subsystem components to have lower power consumption.
For the pointing budget, the ADCS sensor accuracy calculations are reasonable and sufficient.
However, there is no mention into the strength of the actuators in terms of torque and whether it
can successfully stabilize the satellite during the de-tumble mode as of R1.2.1 in the requirements
documents.
The data and link budgets calculations are reasonable and well structured.
For the project planning and schedule, the team is advised to split the tasks such as “Software
Design” and “Payload Sensors” into the design and implementation stages.No references were
included in the document which is rather disappointing. Examples of references the team could have
included are the datasheets of components, especially those where data was extracted and used in
the calculations in the document. Moreover, the equations used in the uplink and downlink budget
surely would have been based on an external reference.