Planet Detective | National Air and Space Museum

Over the past 30 years, Bruce Campbell has patiently sought to solve the mysteries of Venus.

Bruce Campbell is a senior scientist at the Center for Earth and Planetary Studies of the National Air and Space Museum, where he has worked since 1992. He holds a BA in geophysics from Texas A&M University and a Ph.D. in Geology and Geophysics from the University of Hawaii. Using radar observations from orbiting space probes and ground-based telescopes, Campbell studies the surface and subsurface geology of the Moon, Mars, Venus, and the icy moons of the exoplanets. His research has been published in more than 100 scientific publications. Campbell is a member of the science team for the Mars Reconnaissance Orbiter Radar, Jupiter Ice Moons Explorer, and Europa Clipper missions. recently spoke with Air & Space Quarterly Senior Editor Diane Tedeschi.

When did you first become interested in space?

Well, when I was a kid, I always liked things about space exploration. I remember them bringing a TV to the school cafeteria so we could watch some Apollo moon landings later. And I watched the Apollo Soyuz mission. But when I did my undergraduate work at Texas A&M University, my studies centered on a program that was primarily oil drilling.

Campbell’s early interest in radar would prove essential to his career in planetary exploration. As a university student, he built his first radar: the transceiver is located in the long box (top right) and antenna feed horns are on the left. (Courtesy of Bruce Campbell)

How did you start your career in planetary science?

My interest in planetary science emerged after I left Texas A&M University. As an undergraduate, I didn’t really understand that you could get a job in planetary science – and that you could get a job in it. I was fortunate that just after my final year of college ended, I took an internship at the astronomy branch of the USGS in Flagstaff, Arizona. At the time, they were working on Soviet radar images of Venus – part of the first batch of images collected by Venera 15 and 16. And I had just been sold. Learning how to analyze those images of Venus was a great experience for the apprentice. After that, she transferred to the Graduate School of Planetary Sciences.

Why is radar an important technology in the study of planets?

The radar signal travels much further into the ground than a normal photogram would allow you to see. If we go to long enough wavelengths, we can see three kilometers below the polar peaks of Mars. As for the Moon, we can see up to about 30 meters below the surface. But the really neat part for me, and the part that I saw that summer in Flagstaff, is that radar is the only way to make a detailed map of the surface of Venus – because the atmosphere is just solid clouds. So this was a way for the satellite to make an image of the Earth that was completely invisible by other means. There was a large black and white print. At the time of my training with the USGS, satellite data was mostly displayed on printed images. And it was absolutely amazing to me that she could do that.

Venus has been the subject of many of Campbell’s investigations. In this composite radar image – based on data from Magellan – the different colors indicate changes in elevation.

What is the most unexpected thing you have discovered about Venus?

We’re getting more and more evidence from some of my work and the work of a lot of others that point to relatively recent – and possibly ongoing – volcanic activity at the surface. With each new Venus mission popping up, one of its primary goals is to determine what’s happening today on the surface. Where can volcanoes erupt? How did that happen recently?

If you could travel safely anywhere in the solar system, where would you go?

Oh, without a doubt – it would be Venus. I mean, it was the first thing I saw when I discovered planetary science during my internship in Flagstaff. And for Venus, there are only four images of the surface. Thats all about it. Four photos peeking out from the side of a landing craft. This is for a planet the size of the Earth. So yeah, it would be nice to see what the rooftop looks like. Some of the terrain on Venus is different from anything we see anywhere else in the solar system. We do not understand how they were formed.

Some of Campbell’s research relies on ground-based observatories. Using the radio telescope in Arecibo, Puerto Rico, Campbell and his team made this radar image of Venus, which shows a network of mosaics — unusual terrain shapes — in the Alpha Reggio region. (Bruce Campbell/CEPS)

What is this strange terrain?

They are called tesserae, and they are high plateaus with very dense tectonic folds, ridges, and valleys. Valleys and ridges veer in multiple directions, and it is difficult even to understand what the surface looked like before it deformed. The plot covers only about seven percent of Venus, but it’s the places where we’re most likely to find ancient rocks that could hold clues to past waters.

If funding is not an issue, then what is your dream planet exploration mission?

Staying with the same theme, it will be a lander or several landers that can go to the mountainous regions of Venus. Because these are places where there may be geological evidence of a period when the water was at the surface. That’s a big question these days: Was there a period of time when Venus had an ocean? And if there is an ocean, is there something behind it? Is there any geological evidence that we can use to say, yes, there was an ocean at some point?

How did you contribute to the Europa Clipper mission?

Are there water columns in Europe rising from its surface? Campbell is part of the radar sounder team for the Europa Clipper, scheduled to launch in October 2024 to determine if the moon has the geological requirements to support life.

My primary role in Europa Clipper is to be part of the Radar Influencer team, which is called REASON [Radar for Europa Assessment and Sounding: Ocean to Near-surface]. Most of the work I’ve done up to this point is trying to understand what REASON will see by looking at radar probe data from the Mars Reconnaissance Orbiter, where we can look at Mars’ polar peaks. We’ve been doing this for 15 years or so. We have a long-running database of Mars to draw from, which will help us understand what REASON may eventually see when it begins searching Europe’s ice. And of course, it is hoped that the main discovery will be to see the ice base and its interaction with the ocean of Europe. Equally important, though, will be seeing the surging bodies of water rising through the ice – these would be great places to land.

Which object in our solar system do you think might have life?

It must be Europe. This is the only place you get this combination of water, minerals, and heat. Hopefully we’ll get a landing craft to take a look at this article on the road.

Campbell studied the geology of Mars (seen in this mosaic of images taken by Viking Orbiter 1).

How to make peace with the slow pace of planetary research?

Campbell’s Mars research includes a place on the science team of the Mars Reconnaissance Orbiter, which has a radar probe that can peer more than half a mile below the surface (shown in this artwork). (NASA/JPL)

Using the radar instrument I worked on for the Mars Reconnaissance Orbiter, for example, it was a few years since our team was brought in to work with the engineering group until the time the instrument was finally launched and put into orbit around Mars. Now pre-launch teamwork continues with REASON, and VERITAS’ mission to Venus is at that point in time to begin building the hardware. For me, this is a satisfying thing to work on – just to enjoy the engineering part of it. But, yes, these planetary exploration projects have very long lead times — especially missions to Jupiter and Saturn, looking for five to seven years of post-launch travel time. I’ve found that the best thing is to have enough projects so that all the tasks mature at different times. Surely, for Venus, we waited a very long time between Magellan and now. She attended school when Magellan was beginning her mission to Venus, and now VERITAS, DAVINCI, and EnVision come 35 years later.

Have you ever been wrong? Is planetary science sometimes modest?

Many of our findings from Mars have surprised us. Using very long-wavelength radar to look below the surface of Mars, we expected to find ice early in specific places — and we didn’t. On the contrary, we began to believe that there were fairly good sized ice deposits in places that weren’t high on the list.

Are there any modern technologies that could facilitate exploration of the outer solar system?

I think at this point we are still very limited in pushing. And the data rate is limited – by the fact that we are using the radio downlink. There are demonstrations of technologies like laser communications that may one day increase the amount of data you can get from the outer solar system. And solar-electric propulsion—at least for cruising the inner solar system—has a lot of hope.

Does your job require field research?

The Robert C. Bird Green Bank Telescope in West Virginia – with its huge 100-meter dish – enabled Campbell to collect data for radar maps of the Moon, Mars and Venus. (Bruce Campbell/CEPS)

Over the years, our team at CEPS [Center for Earth and Planetary Studies] The radio telescope in Green Bank, West Virginia, and the Arecibo telescope in Puerto Rico have been used. Most of the time, there will be a CEPS person in one telescope and another CEPS person in the other. Because for radar experiments, it can still be very practical. You are actually connecting the cables to go from one part of the device to the other. You follow the radio signal until it travels from where it comes from the antenna to where it goes for computer sampling. For me, being in telescopes during an experiment is an exciting part of the job. You walk outside at three in the morning, looking up. You see the telescope pointed at the Moon or Mars as it makes its observations. The radar is on – sending and receiving – and you’re standing there looking at the sky above the telescope. Yes, this does not age.

Venus has at least 1,600 volcanoes, and Campbell thinks it’s possible that some of them are still active. Three upcoming missions to Venus – VERITAS, DAVINCI and EnVision – could finally solve one of the solar system’s biggest mysteries.