We know why Mars, geologically, is a dead planet — it’s only 10% of the mass of Earth. Venus is 90% of Earth’s mass and an active geological planet, very Earth-like, and yet, it’s environmentally totally different. It’s got surface pressure 90 times that on Earth — why is Venus so hostile to life when Earth isn’t?
Because it’s environmentally the easiest to operate in, ghail explained, ‘The main interest in space exploration has been Mars. When TE spoke with Richard Ghail, the scientist was in his office, a white bookshelf above his head, lined with texts, under which Ghail described his research, ‘My real interest is in Venus and its relationship to Earth. I study Venus by developing radar tools and techniques, also applied to Earth science. Why Venus though? He then emphasises, ‘Venus is very, very different. What does that say about Earth-sized planets we’re finding dozens of now? Will they be Earth-like, Venuslike or something else? And will future missions show whether Venus once had life and then sterilised itself?’
NO, WOMEN AREN’T FROM VENUS: Once, Venus was thought to have an Earth-like climate and water vapour — scientists have later found its composition makes life impossible
Because when it transited in front of the sun, there was a ring of light around the planet — that indicates an atmosphere refracting light, it was one of the earliest telescopic discoveries that Venus has an atmosphere. Because it’s easiest to get to Venus of all the planets — but when it became obvious how hostile it was, interest waned, missions went there. You can observe Venus with your bare eye. It’s the brightest object in the sky after the sun and moon. You can see it in daytime at certain times of the year. Only later did we discover Venus’ true surface temperature, atmospheric composition, etc. It was a favoured target of both America and Russia in the space race of the 1960s. In the 1970s, a drive began in the United States to send an imaging radar to Venus — that spawned Magellan. Venus remains the planet we know least about within the inner solar system — and there’s a whole generation of younger scientists keen to work on it.’
Ghail smiles, ‘Earlier, there was this fancy idea that it might have been like an early Earth, a hot, tropical world with lots of water vapour and clouds.
When NASA’s Magellan mission went to Venus in the 1990s, it had the most advanced imaging radar then — but that got 100-meter resolution images and no real information on seismicity, etc. There are almost eight billion people now, projected to reach 11 billion soon. Because of the temperatures, oceans, etc., water vapour by far dominates over sulfur dioxide, on Earth,.
‘Of course,’ the scientist says. The choice, Ghail says, is entirely ours. What technologies are used to study Venus? Ghail replies, ‘As Venus has an atmosphere completely covered in clouds at quite a high elevation, the only thing we can utilise is imaging radar. What future missions will do’ — here, Ghail’s voice warms with the enthusiasm of a scientist, ‘is use advances in radar technology to learn how the surface is behaving. One of the most powerful radar applications we do on Earth is interferometric SAR or InSAR. This uses repeated images of the surface to look for very, very small-scale changes. We want to do that on Venus. That would tell us about the mobility of the Venus surface and how much this is changing. It’ll also be sensitive to volcanoes. In the future, high-temperature seismometers and other equipment would allow landers to undertake direct seismic measurements — that would be the holy grail in this field. In describing Venus, Ghail mentioned clouds. Usually, when we think ‘clouds’, we also think ‘water’. Is there such a link on Venus? Ghail responds, ‘Yes — and no. There has to be water vapour on Venus to make clouds — but the clouds themselves are sulfuric acid. Like Earth, volcanoes spew water vapour and sulfur dioxide. We get some acid rain but mostly, our clouds are water. On Venus, it’s the other way around. Sulfur dioxide dominates over water vapour — instead of water forming clouds, sulfuric acid droplets do, so they’re really harsh acidic clouds. He adds, ‘One of the things Envision, a mission I proposed to the European Space Agency, will do is study the relationship between volcanism and tectonic processes on Venus and its atmosphere. With high-resolution infrared, ultraviolet spectrometers and an infrared imaging system, we’ll study the ground surface and lower atmosphere and look for plumes of water vapour and sulfur dioxide from volcanoes. Alongside, Ghail also works on ISRO data. He comments, ‘We’re developing new techniques for processing Chandrayaan data, mostly from the South Polar region. This radar data has two different wavelengths and can tell you a lot more about surface materials. There’s probably ice at the lunar South Pole. The longer wavelength radar is sensitive to that. We’re trying to learn where the ice is and its conditions. In studying other planets, does Ghail ponder climate change on his own homebase? ‘On the one hand, I can see we’ve actually gone past points of no return. The climate will change inevitably now. We must stop burning fossil fuels and use clean energy. Another environmental impact on Earth is the huge human population. How can we sustain that? We need to use the space environment better, which scientific cooperation can help with. As a scientist, I think Earth isn’t endangered — we are endangered. Humans have exploded across the planet, we’re close to annihilating ourselves and wrecking our environment. We’re at a crossroads now. Will the only planet known to sustain life remain so?