For more coverage from TheStreet.com Ratings team, check out TheStreet.com Ratings section.In my mind, any company involved with the production of the SR-71 Blackbird spy plane should carry a permanent buy rating. But for those stock investors looking for a better argument than that, TheStreet.com Ratings team has combed through the fundamentals of Lockheed Martin ( LMT) to determine if its shares hold investment value in the current recessionary-depressionary environment. Our models rate Lockheed an A, a grade that equates to a buy rating. The company is a world leader in aerospace and defense, second only to Boeing ( BA) in revenue -- $41 billion vs. $66 billion. However that's where the comparisons end, as Boeing's dependence on the commercial aviation market, i.e. the airline industry, has driven its shares down 46% year to date. Lockheed has fallen only 14% year to date. The market is pricing Lockheed more favorably due to its role in national defense and the government contracts that flow from that position. Lockheed may have more in common with smaller rivals Northrop Grumman ( NOC) and General Dynamics ( GD); however, the shares of both these companies are down significantly this year. Northrop sports has tumbled 43% YTD, and General Dynamics has declined 31%. The market is clearly favoring Lockheed in this space. The basic premise for getting behind Lockheed's stock rests with the long-term government contracts that the company can rely on over the coming years for revenue. Unlike commercial creditors, the accounts receivable from the U.S. government of $3.6 billion are going to be paid. Add in a another $1.3 billion in receivables from commercial and foreign governments, and receivables total $4.9 billion. Foreign governments are also unlikely to default on their payments to Lockheed. So the certainty of receivables collection is a strength.