Has  James Hansen, head of the NASA Goddard Institute for Space Studies,  been taking bribes from George Soros and others?   I'm not an attorney so I don't know if Hansen has actually done anything illegal.  However,  as a political scientist  the situation definitely has an odor to it.  

There is no legitimate reason for any private body to spend $750,000 to "package" a government official the way  George Soros     allegedly did for James Hansen.    There is no legitimate reason for a government official to receive a grant from a private research organization  for supporting one of its causes as James Hansen allegedly received from the foundation directed by Sen. John Kerry's wife.    Hansen subsequently endorsed Kerry for President, possibly in  violation of federal law.

Bribery  primarily involves someone providing something of value  to a government  official  to  take an action  favored by the person providing the inducement.  The  term can also apply to an attempt to get someone to act  contrary to the desires  of  an employer.   Hansen's recent claim that energy company payments to non-government scientists to support some theory is a bribe is nonsense.  Payments to private individuals, including university professors, represents an employer employee relationship.
 
Hansen may be committed to the global warming nonsense, but if he is receiving anything of value from the private sector his continued commitment could be for personal financial gain.  I'm particularly  concerned about Hansen misusing his position to  present false data and  suppress  information  that challenges his theories.   These actions could  be  a response to a bribe. Those offering him inducements may want more than just his verbal support.

Hansen  suppressed  a discovery by NASA scientist Ferenc Miskolczi  that the equations used to calculate catastrophic warming contained a major flaw. The  equation  falsely assumed an atmosphere of infinite thickness. 

Steve McEntire discovered in  that  NASA's portrayal  of 1998 as being the warmest year in the U.S. was wrong and that 1934 was actually warmer.  The official explanation is that the original claim was a "mistake", but the federal government has a history of producing false data to support federal policies.  For that matter scientists have a long history of altering data to validate their theories.  Is NASA playing Enron type accounting games with data?
 
If someone at NASA was accepting a bribe, he might alter data with a plan to claim an honest mistake if someone discovered the error.  The official NASA response to discovery of the error is that the error is small, but  the change in temperature during the 20th Century was only 0.17% which is of questionable significance.  Lying about 1998 being warmer than 1934 made the claim of global warming seem more valid.  1934 being warmer than years late in the century provides a strong argument against the whole claim of global warming.     
  
NASA's claim of 2007 being the second warmest  is highly questionable and  inconsistent with the data.   NASA claims continued warming while other organizations disagree. 

NASA has been circumventing  federal regulations requiring review of federally funded research before it is distributed by having employee  Gavin Schmidt operate a privately funded website RealClimate to publish information.  Websites that question NASA's beliefs request visitors to donate money to fund the site.  RealClimate doesn't have to because it is subsidized by the same George Soros who has been aiding James Hansen.  What would be the response if the Department of Defense  used this approach to influence public opinion?

Recently NASA has been shifting research funds to scientifically worthless projects, such as computer studies about how global warming might affect tornadoes.  The studies ignore the fact that the only difference in temperatures comparing the future and now would come on the hottest days of summer when tornadoes are less frequent.  Temperatures would still pass through the normal  seasonal changes from winter to summer.

I don't know if James Hansen is guilty if is guilt of taking bribes  under the legal definition of the term.  However, he and his supporters routinely accuse those who disagree with them of doing  so because they are being "bribed".  Thus, Hansen by supporting the claims of those who pay him from the private sector is guilty of taking bribes under his definition of the term.