The office of Senator Mikulski has posted a copy of the letter from Admiral Gehman to Mikulski offering his review of NASA’s decision to cancel the SM4 Hubble servicing mission. (Although O’Keefe said he had requested Gehman carry out the review, the report was actually delivered directly to Mikulski, and not to NASA.) The gist of the report, dated March 5 and about four and a half pages long, is that non-ISS shuttle missions like SM4 “may be slightly more risky” than those to ISS. However, he adds that “only a deep and rich study of the entire gain/risk equation can answer the question of whether an extension of the life of the wonderful Hubble telescope is worth the risks involved”. Mikulski has also issued a press release with her take on Thursday’s hearing, along with the letter that she and Sen. Bond sent to O’Keefe asking him to request the National Academy of Sciences undertake its own comprehensive review of the risk of the SM4 mission.
You should also post a link to NASA’s White Paper on the issue. This is the first time that the agency has explained its decision in writing (all previous explanations have been verbal).