What Missions Have Been Cancelled? The Alternative History of Space Exploration

What Missions Have Been Cancelled? The Alternative History of Space Exploration

Over the past decades, many missions have been canceled. What alternative history could we have had if these projects had gone through?

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Team: Fraser Cain – @fcain / frasercain@gmail.com
Karla Thompson – @karlaii /
Chad Weber – weber.chad@gmail.com
Chloe Cain – Instagram: @chloegwen2001

People love to imagine alternative history, what could have happened if a certain battle or political event went the other way. Would the Nazis have won World War II? Would there been a nuclear war over the Cuban Missile Crisis?

It’s a fascinating concept, and I really enjoy this kind of speculation. In fact, there’s a great channel you should check out if you haven’t already called Alternate History Hub. Lots of great space related alternate history as well as other topics.

Anyway, because I’ve been doing space journalism for so long, I’ve seen the creation and then cancellation of many space-related projects and missions. Some make sense, there was too much technological risk, the project was over budget, while others seem a little short sighted.

In this episode, I wanted to take a look back at some projects and missions that were developed to various stages and then cancelled. What science could we have gotten from the mission? What did we ultimately get?

It’s the alternative history of astronomy and space exploration. I’m going to present the three missions that I was most excited about, and the saddest to lose.

If you listen to Astronomy Cast, you know, that podcast about space and astronomy that I’ve been doing for 10 years with the astronomer Dr. Pamela Gay, where we cover topics in space and astronomy, you’ll know that my greatest sadness is the loss of the Terrestrial Planet Finder.

The Kepler Space Telescope, which has already given us a treasure trove of planetary discoveries was actually supposed to be the first part of a trilogy of space-based planetary observatories.

The second spacecraft in the series was called the Space Interferometry Mission, or SIM. Unlike Kepler, which uses a single mirror, SIM was going to test the idea of interferometry, where you combine the light from multiple mirrors into a single observation. This idea is used successfully here on Earth, but it had never been tried in space (and still hasn’t).

You would think that by having two mirrors, your telescope would act like the combined surface area of both. But what actually happens is you get a resolution equal to the separation of the mirrors. There are downsides, you can only see brighter objects, but the boost in resolution is very useful.

In fact, this is why people talk about the powerful kinds of telescopes that could be built if you put equal telescopes on opposite sides of the Solar System, for example. It’s as if you had a telescope with the resolution of the size of the Solar System.

Once launched, SIM would be the most powerful extrasolar planet ever launched, and it would have have been capable of turning up Earth-sized worlds orbiting nearby Sun-like stars in the habitable zone. In other words, it would have found Earth 2.0.

But the third part of the trilogy is the one I miss the most: The Terrestrial Planet Finder, cancelled in 2011. This mission would have been built on the success of SIM to fly a formation of space telescopes to act as a single large telescope.

It’s job would be to help us discover planets, and more importantly, help us find out if they have life on them.

The instrument would have used a coronagraph to block the light from stars to see the fainter planets orbiting them in infrared light. With hundreds of times the observing power of Hubble, the TPF would be able to measure the composition of exoplanet atmospheres. Find an atmosphere with ozone and it’s a clear indication there’s life present. And if it could detect the air pollution from an advanced civilization, then we’d know we’re not alone in the Universe.

Although I’m sad to lose SIM and the Terrestrial Planet Finder, there’s hope. Astronomers are planning and building several new ground and space-based telescopes that will have the same capability or even greater. And if it ever gets built, the LUVOIR mission will put a 16-meter telescope into space. That will change everything. We’ll talk more about the upcoming super telescopes in future episodes.

Now, it’s time to go to Europa and look for life.

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