On March 2, 2004, in a marvellous feat of technology and engineering, scientists sent a spacecraft (Rosetta) and its lander (Philae) on a 6.4-billion kilometre, 10-year mission to meet and land on the comet 67P/Churyumov-Gerasienko. On November 12 this year, after circling the comet for six weeks, Philae was sent down to 67P and landed successfully on its surface: bull’s eye! The comet is so far away that radio signals from the spacecraft sometimes took 50 minutes to get back to earth. Upon landing, Philae bounced twice and ended up leaning against a cliff, getting very little sunlight to recharge its batteries. Its primary batteries would last only 64 hours before Philae would shut down, much shorter than it would be with the recharged batteries.
This ambitious mission raised two questions for me: why would we be interested in landing a robot spacecraft on a comet, aside from the human sense of achievement; and was 64 hours enough to get meaningful data? Apparently, there are good answers to the first question, and some scientists say that 64 hours was enough to accomplish 90 percent of the mission’s aims.
This visit to 67P was designed to provide insight for several research areas. First, because comets are composed of debris from the very early days of our solar system, and are believed to be largely unchanged since their formation billions of years ago, an examination of 67P’s materials can tell us something about long-ago conditions. Second, it is thought that the ice and water in comets are responsible for much of the water found on earth. By looking at the isotopes of water (the levels of deuterium hydrogen) found on 67P and comparing them to the water found on earth, we can tell if they come from a common source.
Additionally, some simple organic molecules have been found to exist on comets, and it has been suggested that these molecules combining carbon, oxygen and hydrogen may have arrived on earth if it was hit many times by comets earlier in its history. In this case, these amino acids may have been part of God’s method to create life on earth. Philae was designed to gather data about these molecules.
Finally, amino acids on earth are molecules that, like our hands, can have a right and left version. The vast majority of amino acids that occur in biological systems are “left-handed,” meaning the proteins in our bodies are all left-handed. From a chemical point of view, these molecules could just as easily be “right-handed”; why they are all left-handed and not 50/50 is a bit of a mystery. One suggestion is that if these molecules come from comets, the conditions in comets would have promoted the left-handed version because of the destructive effects of solar radiation on the right-handed version. Philae has tools to determine whether 67P’s amino acids were left-handed like those on earth, potentially solving this mystery of earth biology.
Beautiful and complex
But having only 64 hours – less than three days – to collect data and transmit it to Rosetta and on to earth is not very long. Some experiments did not happen, such as digging into the comet to look at molecules below the surface. Many experiments were possible, however. By “sniffing” the molecules on 67P’s surface, Philae detected organic molecules. Philae’s physical measurements of 67P revealed that the ice of which it is composed is harder than expected; scientists were expecting a softer layer of something like compact snow.
Much of Philae’s data has yet to be analyzed. The data it collected had to be digitized then sent to Rosetta during twice-a-day, three- to four-hour windows. It is highly compacted, and mission scientists will require considerable time to analyze its exact meaning.
There is also the possibility that as 67P comes closer to the Sun (its closest point will occur on August 13, 2015), there will be enough light to re-power the instruments and collect more data. Between now and August, the main spaceship Rosetta will be collecting data from around 67P. As the Sun heats the comet and a tail is formed, there will potentially be considerably more data coming to earth for several months from this very successful space mission revealing the complexity and beauty of our Lord’s creation.