40 Years Since Viking 1 Landed on Mars: What We've Learned

Jun 20, 2016

On June 19, 1976, the Viking 1 spacecraft went into orbit around Mars. A month later, on July 20, a lander descended from the mother ship and made history as the first spacecraft to land safely on another planet. The Viking mission searched for alien life, and to this day there is controversy about the results.

Planetary science expert Ross Irwin will discuss the advances made by the spacecraft and its influence on subsequent missions.

Read more about the historic Viking mission: NASA’s 1976 Viking mission to Mars did all that was hoped for it — except find Martians

When will Curiosity start examining Mount Sharp's stratigraphy. Seems to me that will possibly tell us a lot about The history of life on Mars.

Curiosity is currently examining some of the lowest rock layers that are exposed at the base of Mount Sharp.  These lake and stream deposits date back more than 3 billion years, when Mars had a thicker atmosphere and a wetter climate.  As the rover climbs the mountain, it will examine somewhat younger layers that are richer in sulfate and hematite.  Higher, the mountain transitions into younger deposits that appear to reflect a dry climate.  In this way, the rover will examine the transition from wet to dry conditions on Mars.

Why haven't we done this? NASA needs to embrace Mars Direct or some similar plan that utilizes Martian resources, and doesn't necessitate a prohibitively large large vehicle full of fuel for a return trip, that could be easily produced on Mars, with technology that's been thoroughly spelled out and demonstrated as absolutely doable. NASA continues to site the ISS and it's zero-g studies as having some kind of relevance to a Mars mission, which it DOESN'T. With the simple use of easily achievable artificial gravity, via a little thing called centrifugal force. This can negate or eliminate the prospect of preztel bones for our brave astronauts, and can be created via any number of methods. We need to encourage NASA to be mission driven. ISS is boring. We don't care, and it's gonna put them at a risk of being shutdown in the longterm. We need to salvage put all those genius minds to work for a cause and not just a paycheck. What are your thoughts on that? Thank you.

Exploring Mars with astronauts is a key goal for NASA and supported by most of us in the planetary science community.  The agency has a fairly broad and diverse mandate, however, and it can't undertake human Mars missions on its current budget.  At present, NASA is developing some of the infrastructure that will be needed to land people on Mars, including a heavy-lift rocket and a new spacecraft that will carry the crew to and from orbit, as well as complete a high-velocity re-entry to Earth.  Development of the interplanetary spacecraft and the lander are major (and costly) next steps.  Once the political will and the finding are in place, NASA seems ready to move ahead.  Producing fuel on-site is an important cost-saving measure.

I teach students space science and geology. I'd like to know what is a relevant question for teens embarking on a Mars related design challenge?

They might consider how the astronauts would work on the surface.  If you have a heavy rover that is pressurized with its own life support systems, then you can cover some distance from the lander.  If not, then you can't drive farther than the astronauts can walk back using the limited resources in their backpacks.  This was a limitation during the Apollo landings on the Moon.  What are you able to accomplish each day?  What kinds of landing sites have diverse rocks to sample within a short traverse distance?

is finding life still a priority for us?

NASA remains focused on finding evidence of past or present life on Mars and within some of the icy moons in the outer Solar System.  The Martian soil won't support life, due to high levels of ultraviolet radiation (Mars has no ozone layer to protect it), a thin atmosphere that won't support water in the liquid state, and some highly oxidizing chemicals.  The climate was much more favorable in the planet's early history, however, and we don't know if bacteria may live deep underground today.  Preservation of organic material from billions of years ago is also very challenging.  For these reasons, NASA has focused on determining whether the planet was habitable at one time (it was) and is starting more focused investigations with better instruments. 

Will Curiosity be on the lookout for fossils?

If there was life on Mars, it was probably bacteria, not something large enough to leave the kind of fossils that we find on Earth.  The Curiosity rover team is looking for habitable environments and the kind of organic chemistry that life would have left behind.

Let's say theoretically we sent humans to Mars. What would be their mission? Aside from the achievement of setting foot on another planet, what can we learn by having humans there that we can't by other means, like robots?

Robots can do many things more cheaply than a person can, and with less risk, but there is no substitute for a human crew.  The Opportunity rover took a decade to cover the same distance that the Apollo 17 crew drove in three days.  Astronauts can make real-time decisions about what to study and what to sample, without waiting for instructions from Earth.  You would always have multiple astronauts on a crew, doing multiple tasks at once.  Perhaps most importantly, we always plan to bring the astronauts home, and they bring samples for more detailed study in labs on Earth.  None of the spacecraft that we have sent to Mars so far has had the ability to return samples.  When we do launch a sample return mission, it will only bring back a small number and weight of samples.  Taking all of these things into account, robots don't have quite as much advantage as it seems.

If Curiosity was on the lookout it might find cyanobacterial fossils like stromatolites.

Stromatolites form where bacterial mats trap suspended sediment and then grow above it to trap another layer.  If those kinds of structures formed on Mars, then the rover cameras would see them in fractured rocks, but we haven't seen anything like them so far.

In my interactions with various NASA work centers, the prevailing theme seems to be failure-prevention and "risk mitigation". I understand the impulse, given several high profile accidents, and that their funding is dependent on fickle politicians and a generally uneducated public. However, when doing cutting-edge exploration, eliminating risk is physically impossible. What is the balance between ensuring astronaut safety and moving forward with an inherent set of risks?

Managing risk is important on rover missions as well.  At landing site selection meetings, we often hear that if you don't land safely, then you don't get any science.  On top of the work designing and testing the spacecraft components, JPL and supporting organizations spend a lot of time determining whether a rover can land safely, traverse, and complete its mission in particular locations.  Those issues are even more important with a human crew, but the risk to life and the mission will never be zero.  We will have to take the risk in stride and press on.

Is this in development right now? Beyond the conceptual phase?

A Mars sample return mission is a priority for NASA and was cited as such in the last Planetary Science Decadal Survey, but it has not been funded beyond concept.

If gold comes from space, is it correct to infer that we can find it on Mars?

Gold is found mainly in high-temperature veins of quartz in extrusive rocks, and it can be concentrated in stream (placer) deposits.  The second condition is found on Mars, but the first one is unlikely.  You wouldn't expect to find a concentration of gold like you do in some places on Earth.

It likely is project specific, but overall how is the morale at NASA?

NASA is often named the best place to work in the Federal government, and overall the morale is high.  NASA employees work on a variety of different projects, and they are all pushing the envelope in some way.

Thank you everyone for participating and for sending great questions!

In This Chat
Ross Irwin
Dr. Ross Irwin is a geologist in the Center for Earth and Planetary Studies at the Smithsonian’s National Air and Space Museum. He received his bachelor of science in geological sciences from Virginia Tech in 1997 and a PhD in environmental sciences from the University of Virginia in 2005. He completed a post-doctoral appointment at the Center for Earth and Planetary Studies in 2010. For two years he worked for the Planetary Science Institute as a visiting scientist at NASA Goddard Space Flight Center. In 2012, he returned to CEPS as a staff scientist. Dr. Irwin's research focuses on relationships between the environment, geologic processes, and landforms.
Recent Chats
  • Next: