Nov 28, 2016: A journey to Mars presents many challenges, not the least of which will be how to feed the astronauts during what is expected to be a six-month journey to the Red Planet.

To that end, the U.S. space agency NASA is working to create lightweight food bars that provide calories without adding a lot of extra weight to the Orion spacecraft and the massive booster needed to get to Mars.

Unlike the International Space Station, where astronauts can choose from more than 200 food items, that's simply not feasible on a mission to Mars, primarily because the amount of fuel needed to get to Mars means finding ways to save weight in other areas, like food. Also, the ISS is regularly resupplied with various consumables.

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The food bars, for now at least, are being developed for breakfast, NASA said.

"When you have 700 to 900 calories of something, it's going to have some mass regardless of what shape it's in, so we've taken a look at how to get some mass savings by reducing how we're packaging and stowing what the crew would eat for breakfast for early Orion flights with crew," said Jessica Vos, deputy health and medical technical authority for Orion. "When you think about multi-week missions in Orion, having just one package for breakfast items for crew will help us limit the space we need to store them."

While many Americans eat a protein bar in place of a meal from time to time, NASA said those are not good enough for the Mars mission.

"There's no commercially-available bar right now that meets our needs, so we've had to go design something that will work for the crew, while trying to achieve a multi-year shelf-life," said Takiyah Sirmons, a food scientist with the Advanced Food Technology team at NASA's Johnson Space Center in Houston.

Some of the flavors being worked on include orange cranberry and barbecue nut.

NASA notes that for other meals, astronauts on their way to and from Mars will have food selection similar to the ISS.

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One potential problem with food bars is that they may lower crew morale, as food choice, taste and quality are important on long missions.

So, NASA is also working on other ways to provide food to astronauts, including a vegetable production system like the one on the space station as well as other types of packaged foods.

The first manned launch of the Orion is expected as early as 2021, with manned missions to Mars coming sometime later. (VOA)