TORONTO – This week, the European Space Agency made history after landing a probe on a comet.
The mission cost 1.4 billion euros and was a challenging one at best: landing a probe on a comet moving at 60,000 km/h is a difficult job to say the least. There was much that could go wrong — and it did.
First, engineers realized that jets designed to keep Philae — the mission’s lander — from flying off into space when it deployed its anchors into Comet 67P/Churyumov-Geramisenko’s surface (it has extremely low gravity) had failed. Still pushing ahead with the mission, the lander reached the surface only to bounce three times — up to a kilometre high at one point. And the anchors didn’t deploy.
Then, to make things just that much more complicated, when Philae did finally come to rest on the comet, part of it landed in shadow, which meant it wasn’t receiving enough sunlight to power its solar panels. It is believed that it may not last more than a few days into its mission.
Still, Philae is being touted as a success, and understandably so. It is, after all, the first time a probe landed on a comet’s surface, even if it did so rather ungracefully.
This isn’t the only mission slated to probe a comet or asteroid.
In 2006, the Stardust mission returned a sample of comet debris after flying through a comet’s tail.
Just last month, Comet Siding Spring flew extremely close to Mars, and, though space agencies didn’t send spacecraft to specifically visit the comet, it did turn several spacecraft to it in an effort to study it.
Later this year the Japanese Aerospace Exploration Agency will launch its Hayabusa-2 mission which will collect samples of asteroid 1999JU3 in 2018, returning it to Earth the same year.
In 2016, NASA will launch the Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer, more commonly referred to as OSIRIS-Rex (thankfully). Aboard it will be some Canadian instruments that will rendezvous with asteroid 1999 RQ3, also known as Bennu, in 2019 (interestingly, the comet has a small chance of impacting Earth in the future). The mission will collect samples of the asteroid and return them to Earth in 2023.
So why do we do it? Why do we spend billions of dollars to probe asteroids and comets?
The answer is simple: knowledge.
We are, as far as we know, the only life in our 4.5 billion-year-old solar system. And the question of how we came to be — how Earth came to possess so much water and such diverse life — is one that many scientists seek to answer.
“Rosetta is trying to answer the very big questions about the history of our Solar System.” said Matt Taylor, ESA Rosetta project scientist shortly after landing. “What were the conditions like at its infancy and how did it evolve? What role did comets play in this evolution? How do comets work?”
Comets and asteroids are leftover pieces of our solar system. They are the bits of rock and debris that didn’t coalesce to form planets or moons.
Comprised of hydrogen, oxygen and nitrogen, they have many elements found in nucleic and amino acids, the building blocks of life.
A leading theory on how life came to be on Earth is that a comet or comets, rich with these minerals and possibly water, impacted Earth, seeding our planet with the necessary ingredients for life.
Then there’s the possibility of redirecting a potentially hazardous asteroid.
NASA’s Asteroid Redirect Mission (ARM) that is targeted for some time in the 2020s will attempt to send robotic missions to attempt to capture and redirect an asteroid that could impact Earth. These missions are paving the way to make this possible.
While the life of Philae may be very much shortened, the Rosetta mission will continue.
“The data collected by Rosetta will provide the scientific community, and the world, with a treasure-trove of data,” said John Grunsfield, NASA’s Science Mission Directorate associate administrator. “Small bodies in our solar system like comets and asteroids help us understand how the solar system formed and provide opportunities to advance exploration.”
There will certainly be some who question the return on investment for these types of missions, but to scientists, answering the age-old question “How did we get here” is very much worth it.