Manned spacecraft will require a much improved ability to forecast particle events. The lead required will depend on the use to which the forecast is put. lere we discuss problems of forecasting with the lead times of hours to weeks. Such forecasts arc needed for scheduling and carrying out activities. Our present capabilities with these lead times is extremely limited. our capability we must develop an ability to predict fast coronal mass ejections It is not sufficient to observe that a has already taken place since that time it is already too late to make predictions with these lead times. Both learn how predict and to carry out forecasts on time scales of several days weeks, observations of the other side of the Sun are required. describe a low cost spacecraft, class), that has been proposed for launch in 2001 that will further the development of an hours-to-weeks forecast capability. introduction expected return human beings space brings new requirements for our ability to predic..