National Aeronautics and Space Administration Logo
Follow this link to skip to the main content NASA Banner
Solar System Exploration at 50
Exploration Stories: Favorite Historical Moments

Add New Story

Amazing Galileo
Steve Vance
Planetary Scientist/Astrobiologist, Jet Propulsion Laboratory
"The photo was released when I was in third grade (January of 1986). I remember thinking about these huge worlds that were farther from the sun than the Earth, and how they were so large that our planet could fit within them many times over." -- Steven Vance

What do you think are the most significant events that have occurred in the past fifty years of robotic planetary exploration? Why?

The missions that were the most significant for me were the twin Voyagers and the Galileo mission because these were the missions that produced the pictures that influenced me to get into planetary science. In particular, the images that stuck with me when I was a kid were the pictures of Uranus and Neptune by Voyager 2. I remember I wrote a report on Uranus, and I used this particular Voyager picture of the planet with the eerie blue color (see above). I was intrigued by the idea that it was out there, in the sky.

This full view of Europa showcases the surface geology and hints at complex tidal resurfacing and an ocean under the surface.

Galileo is a mission close to my heart: I finished my undergraduate studies just as Galileo was returning a lot of the amazing results about Jupiter and Europa. It is hard for me to imagine what our knowledge of the Jupiter system was like before we measured its magnetic field and before we saw all the various forms of volcanism on Io.

One of the most surprising discoveries of the Voyager 1 mission was the violent volcanoes of Jupiter's moon Io.

At the same time, Galileo breaks my heart too. Galileo only returned a tenth of the data it was intended to return, due to the deployment failure of an antenna. Galileo still did an amazing job, and is a testament to the ingenuity of the people who designed and operated the craft. The team was able to rework the mission after the antenna failure and the Galileo mission returned powerful science results despite all the difficulties.

I went to the Mars Science Laboratory (MSL) launch. I am super excited for the next phase of Mars exploration. I look at how the Mars Reconnaissance Orbiter (MRO) has changed our view of the surface of Mars and I think that MSL will do something very similar -- in terms of showing us things we couldn't imagine on Mars; making Mars a planet, in our minds, more like the Earth than we currently see it.

Kaiser Crater is a part of the impact basin of the Hellespontus region on Mars. Smaller dunes and ripples are visible across the much larger sand dunes. Look closely and between the dunes you will see areas with seasonal frost.

At least for me, before MRO, Mars was red and dusty everywhere. Now, we have all these images of a diverse and active planet: beautiful rock formations, dunes, flow features (possible evidence for water just below the surface), glaciers, and erupted geyser-like features -- so-called "spiders" -- in the north.

This picture by MRO shows seasonal polar caps on Mars. When springtime on Mars occurs, this dry ice evaporates and causes some erosion of the surface. This erosion gives us "araneiform" terrain (various formations on the surface, such as "spiders," "caterpillars" and "starbursts").

Each mission is part of a story that keeps evolving -- I am looking forward to a rich history of robotic exploration to come.

In your field of work, what are some examples of the great achievements and discoveries in planetary science and robotic exploration throughout the past 50 years?

I am working on a CubeSat project right now. I am hoping to be involved in the development of small low-cost satellites to be launched opportunistically along with larger ones; that way we can get a lot more science out of a much smaller investment. CubeSats can do simple things like coordinated measurements of gravity around an object. Using CubeSats for these tasks creates the possibility for dividing huge investments in monolithic projects instead into coupled multi-element missions.

Other Images of Note:

My favorite picture of Jupiter is by Cassini, taken as a "target of opportunity" as it was passing by. The details and the different cloud forms swirling around remind me of a mixture of oil and water. I understand that Jupiter's atmosphere is massive and violent compared with Earth's, and that the variations in color are linked to materials coming up from below. However, my gut impression is how physics at a length scale larger than the Earth can somehow resemble a bowl used for dipping one's bread.

This true-color simulated view of Jupiter is composed of four images taken by NASA's Cassini spacecraft.

Spirit's image of a Martian sunset seems to me like one of the most significant images. It is right up there with our view of Earth from the Moon in my opinion.

In 2005 NASA's Mars Exploration Rover Spirit captured this stunning view as the sun sank below the rim of Gusev crater on Mars.

Read More:


Missions: Planets/Moons:

Awards and Recognition   Solar System Exploration Roadmap   Contact Us   Site Map
NASA Official: Kristen Erickson
Advisory: Dr. James Green, Director of Planetary Science
Outreach Manager: Alice Wessen
Curator/Editor: Phil Davis
Science Writer: Autumn Burdick
Webmaster: David Martin
> NASA Science Mission Directorate
> Budgets, Strategic Plans and Accountability Reports
> Equal Employment Opportunity Data
   Posted Pursuant to the No Fear Act
> Information-Dissemination Policies and Inventories
> Freedom of Information Act
> Privacy Policy & Important Notices
> Inspector General Hotline
> Office of the Inspector General
> NASA Communications Policy
> NASA Advisory Council
> Open Government at NASA