NASA is starting the planning process for its scaled-back robotic Mars exploration program immediately and will use 2012 funds previously earmarked for outer planets missions to shore up the effort. NASA will spend about $30 million in 2012 on its retooled Mars exploration program. In total, NASA plans to spend about $700 million on the mission. It is tentatively planned for launch in either 2018 or 2020.
Of the $30 million NASA is spending on Mars Mission planning this year, $20 million will come from money the agency expects to have left after paying to close out its ExoMars work and fund ongoing missions. The other $10 million is being taken from the Planetary Science Division's outer planets program, which is being downsized as NASA tables plans for a large-scale mission to a planetary destination beyond Mars. Another $24 million was diverted from outer planets for "foundational technology work on critical sensor development in support of the revised future Mars mission as well as other future planetary missions, as recommended by the recent decadal survey," according to the operating plan.
ExoMars is a European led robotic mission to Mars, which due to budget cuts, NASA had to pull out of. NASA found itself with massive budget cuts after Obama released his 2012 Budget. The budget cuts were approximately 21% of the Mars mission budget