One of the important factors to plan for in a mission such as this is the mission operations support. Operations support consists of several tasks, e.g.
For a 'traditional' space mission the prolonged development and, in many cases, flight phase allows plenty of time for mission planning and operations training. Even if the target encounter phase is short as compared with the development and flight time there is still plenty of opportunity to run training simulations. The actual target encounter will be planned well in advance - certainly long before the launch date - and so there will be abundant time to analyse it, optimize the encounter and prepare for any contingencies.
A rapid-response mission, by contrast, may need to be planned in a very short time period. From target detection to launch to encounter will be a few months at most, and in extreme cases may be a matter of weeks. It is clearly impractical to do detailed mission planning from scratch in this time. Instead a much more flexible approach must be adopted. In the introductory section on low-cost rapid-response space probes a 'standard' space mission was contrasted with the flight of a missile. To recap, a missile is not optimized for any one particular engagement but instead is designed to be capable of carrying out a wide range of possible intercepts. We refer to it as having an engagement envelope within which it can carry out its mission; the missile designers specify this envelope and then plan how to ensure that the missile can hit any target inside it.
We can adopt a similar approach with planning this mission. Rather than plan one mission years in advance we can specify a target engagement envelope within which NEOs can be intercepted. As specified in this design study, this is a sphere of radius 0.05 AU centred on the Earth, subject to the constraint that the velocity of the probe relative to the target is less than 20 km/s. If the probe is designed to cope in principle with any encounter in this envelope then mission planning can to a great extent be simplified to predicting the required launch date and trajectory to carry out the intercept. As discussed in Section 8 the intercept can then be optimized to give the best flyby conditions for data return.
Operations training and mission control are potentially more difficult. A mission intended to respond to newly-identified targets cannot be carried out on a set timetable. Once operations staff have been trained there is no set timetable for them to carry out their task. Whilst there are many areas of research where investigators must be prepared to wait for unpredictable events (e.g. earthquake and volcano studies) the amount of specialist training required to gain and retain currency in spacecraft mission control makes this a rather different case. One promising way forward would be to develop automated mission planning and management tools (e.g. expert systems) to handle as much of the mission control load as possible. A pool of operations personnel could then be trained for call-out when a suitable mission operation is identified. As mentioned earlier, an indefinite wait could be avoided by specifying a fallback target from the list of predicted NEO encounters and planning a mission to that if no suitable target of opportunity arrives beforehand.
| Previous | Contents | Next |