Phase II Final Report - NASA's Institute for Advanced Concepts

Planetary Exploration Using Biomimetics
An Entomopter for Flight on Mars
Both the rover information updates and the Entomopter ID and status replies are low bandwidth
data and can be exchanged in bursts even with error-correcting code overhead. A refresh rate of
10 Hz for these two-way data bursts even means that not all parameters need to be exchanged
upon each radar painting. The highest priority information will be that necessary for obstacle
avoidance (the Entomopters themselves being obstacles to each other). Information about fuel
remaining is low priority and could be downloaded once every hundred scans (every 10 seconds).
The transmission of high bandwidth data over the navigation link is ill-advised for several reasons.
First, the bandwidth and revisit time for this method of information exchange does not support
the high bandwidth requirements of video, still-frame pictures, or real-time streaming data.
Transmission of color video can consume as much as 75 MHz of bandwidth depending upon the
resolution. This is also costly from an energy standpoint, as any onboard emitters carried by the
Entomopter will either increase its mission payload weight or reduce mission endurance.
Finally, because the projected Entomopter flights will be brief (minutes as opposed to hours),
any high bandwidth data can be stored onboard for downloading later during the refueling process.
The need for real-time streaming data is not warranted during early missions prior to manned
exploration, because there is no one present to take advantage of the real-time data, and the
latency for transmission back to Earth diminishes the timeliness of the data. Data gathered during
a 10-minute flight would not be received for 11 minutes, were it able to be transmitted
directly back to Earth from the Entomopter. Any reaction to the data received would require a
further delay of 11 minutes to be received by the Entomopter due to the 190 million km distance
between Earth and Mars--long after the Entomopter would have landed for refueling.
It is assumed that most of the Entomopter science data will be uploaded to the refueling rover
when the Entomopter returns for refueling. Continual linking of high bandwidth data is
extremely costly from an energy standpoint, and since it is essentially only being archived (as
opposed to being used for flight control or real-time viewing), quick-look updates are assumed
to be adequate. In the event of a failure or crash, a large amount of data would not be lost since
the Entomopter excursions are assumed to be fairly brief (missions of several minutes each,
unless the vehicle lands to take data from a stationary location for an extended period). Therefore,
only several minutes of stored data would be at risk before it was uploaded to the refueling
rover upon return of the Entomopter. Also, because of the low mass of the Entomopter, crashes
will not likely disable any of the onboard electronics. Thus, if an Entomopter failed, it might still
be able to transmit its data cache back to the rover from its crash site.
The major implication for the use of a rover-centric navigation system is that the Entomopters
must remain within the line of sight of the rover to get rapid situational updates. This implies
that as range from the rover is increased, due to terrain irregularities, the Entomopters will have
to fly at higher altitudes. Because the Entomopters are fully autonomous, however, there is no
need for the navigation information to maintain stability of flight.
Therefore, it is entirely reasonable that an Entomopter can consciously break its navigation link
and fly below the radar horizon to more closely investigate an item of interest, with the intent of
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Phase II Final Report