A big difference between Hayabusa and the probes before it is that its orbit had to actually be controlled every day. Those probes, including Sakigake and Suisei, which were bound for Halley's Comet, as well as Nozomi, which was bound for Mars, basically flew according to the laws of motion, and the engines were only used to correct the orbit a few times before they reached their destinations.
So, as long as no problems occurred, the work involved in operating older probes before they reached their destinations was relatively simple. All that was required was light work, such as receiving radio waves, receiving telemetry data indicating the state of the probes, making sure no problems were occurring, and performing required device checks before the probes reached their destinations.
However, Hayabusa's ion engines were continuously used to supply propulsive force starting at the launch in 2003, well before the probe reached its destination, Itokawa. Firing the engines continuously changed the orbit. So, Hayabusa involved way more work than past probes, such as constantly paying attention to the condition of the ion engines, measuring whether the probe was on the planned orbit, calculating the output of the ion engines and thrust direction based on the measurement results, and sending commands to Hayabusa.
And that was just the beginning. When Hayabusa touched down on the unexplored Itokawa, commands had to be created in a timely manner and rapidly sent to Hayabusa to respond to constantly changing conditions. In addition, when communication was lost at the end of 2005, the software used for operations had to be quickly modified. Finally, during the operations to return the probe to Earth, because Hayabusa had sustained extensive critical damage, new method after new method had to be considered.
NEC engineers thoroughly assisted in the Hayabusa operations, which spanned seven years. Hayabusa's dramatic return to Earth on June 13th was the result of their tireless daily operations that started with the launch on May 9th, 2003.
In the following interview, four engineers look back on the operations during Hayabusa's seven-year journey, from devising the orbit plan to the return to Earth: Masatoshi Matsuoka, who was in charge of orbit operations, Masanori Sugiura, who was in charge of the operation-supporting facilities at Usuda station, and Sunao Kawada and Yosuke Nakamura, who were at the forefront of the daily operations.
Re-entry of the Hayabusa probe and capsule
