In my last Space Sunday article, I covered the arrival of the BEAM inflatable module at the International Space Station, and the concerns for NASA’s Kepler “planet hunter” space observatory. As there’s been further news on both of these, I thought I’d start this Space Sunday with a quick round-up on them, starting with Kepler.
The Kepler observatory, located some 121 million kilometres (75 million miles) “behind” Earth as both orbit the Sun, has been engaged in a 7-year mission to try to locate planets – particularly possible Earth-type planets – orbiting other stars. As I reported last time around, despite one major setback which called a halt to the observatory’s primary mission in 2012, Kepler has been a remarkably successful mission, catalogue some 4,000 potential planets orbiting other suns, with over 1,000 subsequently confirmed as planets.
However, on April 7th, Kepler reported to mission managers that it has entered Emergency Mode – a status indicating a critical problem has occurred, causing the observatory to shut down all science operations and other systems, and was utilising its supplies of valuable propellant to maintain its orientation so it could communicate with Earth, rather than using its electric reaction wheels, powered by sunlight.
Over the next several days, mission engineers were able to upload instructions to Kepler so that it could position itself in a “point rest state” where communications could be maintained without eating into further propellant reserves. Following this, a long, slow data download commenced, which allowed engineers to fully understand the extent of the problem – but not the cause. However, this has been enough for a path to recovery to be determined.
Since April 12th, commands have been sent to the observatory instructing it to bring it non-critical systems back on-line one at a time, monitoring responses as it did so. With each system successfully restored, Kepler has been gradually coming to life whilst eliminating potential causes of the original problem. There is still a way to go, but mission managers are now reasonably confident Kepler can be restored to a fully operational status.
“The recovery started slowly and carefully, as we initially merely tried to understand the situation and recover the systems least likely to have been the cause,” said Kepler programme manager Charlie Sobeck on April 14th. “Over the last day and a half, we’ve begun to turn the corner, by powering on more suspect components. With just one more to go, I expect that we will soon be on the home stretch and picking up speed towards returning to normal science operations.”
Meanwhile, BEAM – the Bigelow Expandable Activity Module – an inflatable prototype habitat module which arrived at the International Space Station on April 10th – was extracted from its ferry vehicle, the uncrewed Dragon resupply vehicle, on Saturday April 16th, and successfully secured against the airlock node of one of the station’s modules.
the extraction and relocation were undertaken remotely, using the space station’s robot arm commanded from Earth to lift the BEAM unit, still in its compact “flight” configuration just 2.4 metres (8ft) in length and 2.1 metres (7ft) diameter, from the unpressurised section of the Dragon cargo vehicle and then position it against the US Tranquillity Module of the space station, where it was secured by astronauts Tim Kopra and Jeff Williams.
The module is not due to be inflated until early May, when it will increase in size to some 4m x 3.5m (13ft x 10.5ft) and provide some 16 cubic metres (565 cubic ft) of working space. It will be equipped with monitoring equipment to investigate how well it protects against solar radiation, space debris and contamination over a 12-18 month period. During this time, ISS crew members will enter the unit 3 or 4 times a year to collect deployment dynamics sensor data, perform microbial surface sampling, conduct periodic change-out of the radiation area monitors, and inspect the general condition of the module.
As I noted in my last update, Bigelow Aerospace, the developers of BEAM, have been working on plans to launch a commercial space station using a much larger inflatable unit – called the B330 – possibly as early as 2018/19.
However, on April 13th, Bigelow Aerospace announced that they have partnered with United Launch Alliance, the organisation which provides Delta and Atlas rocket launch services to the US Government, to build and launch the first B330 unit in 2020, with the intention of having it mated with the International Space Station. If this goes ahead, the B330 will increase the volume of working space at the station by a huge 30%, presenting a significant increase in the orbiting outposts ability to support research and development operations and manufacturing processes for NASA and commercial users.
Bigelow and ULA see this as the logical first step to developing free-flying orbital facilities based on the B330 which could be used for a variety of commercial activities, including space tourism, as well as demonstrating the viability of inflated units in missions to the Moon and Mars.
Europa’s Hot Ice
Europa, one of the four Galilean moons of Jupiter, is a fascinating place. Slightly smaller than our own Moon, it is covered by shell of water ice, much of it discoloured by mineral deposits and by deep cracks. This icy surface might only be relative thin, on the order of a handful of kilometres in extent, or it might be tens of kilometres thick, and sits over an ocean which is mostly likely liquid water (although some argue it might actually be an icy slush), perhaps extending to 100 km (60 miles) in depth.
The ocean is made possible by tidal flexing enacted by the massive gravity of Jupiter as well as from the other large Galilean moons. This generates heat within Europa, and this heat stops the water from freezing solid.
Exactly how much heat is generated as a result of this flexing isn’t known, but it has been suggested that the ocean floor could be home to volcanic activity: hydrothermal vents and fumeroles, which are responsible for pumping huge amounts of minerals into the water, as well as supplying energy, potentially marking Europa’s ocean as a place where basic microbial life has arisen.
As such, gaining a greater insight into just how much heat is being generated within Europa, what physical and chemical activities it is driving what the sources for this heat are, and so on, are all critical in determining the exact state of the moon’s ocean and, its chemistry and its potential for it to support life.
Now research carried out by a team at Brown University, Rhode Island suggests that as well as heat radiating outwards from deep inside Europa’s core, a surprising amount is also being generated within the surface ice itself, directly affecting the chemistry and thickness of the ice, and influencing the ocean beneath it.
That heat is generated in the ice is a given; the tidal flexing within the planet, as noted above, means the icy crust is cracked and broken into “plates”, and these are constantly rubbing against one another, causing frictional heat. However, the models used by the Brown University researchers indicate that the amount of heat being generated in the ice is significantly greater than previously imagined – and this could have significant repercussions in our understanding of Europa’s dynamics.
“The physics in the ice are first order in understanding the thickness of Europa’s shell,” Reid Cooper, and Earth science professor and one of the researchers said. “In turn, the thickness of the shell relative to the bulk chemistry of the moon is important in understanding the chemistry of that ocean. And if you’re looking for life, then the chemistry of the ocean is a big deal.”
As NASA plans what instrumentation its future “Europa Clipper” mission should carry to study one of the most fascinating worlds in the solar system, it is fundamental research like this that could be used to better understand the habitable potential of Europa’s mysterious ocean.
Wow! Was It Just a Comet?
Human kind has always been fascinated with the idea of intelligent life elsewhere in the galaxy. With the birth of the radio, a possible way to identify if those Little Green Men (or Lizard People or however you picture them) were really out there was found: we could listen for their signals. Thus was born SETI – the Search for Extraterrestrial Intelligence – a series of assorted attempts, gradually growing ever more sophisticated over the decades, to try to identify alien signals, initially from the other planets in the solar system, and then from other stars.
One such research programme was operated by the Ohio State University, which, between 1973 and 1995, utilised their own radio telescope (now no longer in existence) called Big Ear to listen out for possible alien radio signals.
In particular, Big Ear was listening for possible signals around the emission wavelength of hydrogen, the theory being that as this is the most abundant element in the universe, alien civilisation might mimic it to communicate with one another across vast interstellar distances. Most of the time, the telescope picked-up weak and expected background emissions, symbolised in print-outs by 1s and 2s. Occasionally slightly stronger signals, 3s and 4s might be detected, but not anything sufficiently high enough to warrant interest.
Until August 15th, 1977, when researcher Jerry R. Ehman was reviewing the numeric data printed-out by the telescope and came across a signal so strong, it not only went up into relatively high numbers, it went so high as to exceed single-digit numeric notation and used letters, generating the sequence “6EQUJ5″. What’s more, the signal – which lasted 72 seconds – appeared to originate near the binary star system Chi Sagittarii, about 1200 light years from Earth. So intense was the signal that Ehman circled it with his pen and annotated the sequence with the word which would come to denote it: “Wow!”
Had the first signal of extra terrestrial origin been found? Well, no. While assiduous work was put into following-up on the signal, eliminating possible human sources or anything else which might reasonably account for the signal, nothing like it was ever heard again, either from the direction of Chi Sagittarii or anywhere else, leaving the signed as one of few signals from space which has defied explanation in the almost 40 years since it was first detected.
But now Professor Antonio Paris from St. Petersburg College, Florida, thinks he’s found a possible answer. Fascinated by the Wow! signal, he’s been looking a possible causes, and thing he has found two possible culprits: two short period comets only identified in the last decade. Tracking the orbits of this two small comets, he’s discovered they would have been in the right part of the sky – between Big Ear and Chi Sagittarii in August 1977.
What’s interesting here is that as comets approach the Sun and are heated, the water ice they contain vaporises, and the water molecules are broken down into hydrogen and oxygen by ultraviolet radiation, the hydrogen forming a huge halo, sometimes big than the Sun, around the comet. Thus, Paris’ theory is that What Big Ear actually detected the hydrogen cloud from one of these (then) undiscovered comets.
Problem is the data also show that in 1977, both comets were each around Jupiter’s distance from the Sun. It’s therefore questionable if they’d even be active enough so far away to create hydrogen clouds which might by so powerfully detected a radio telescope – and if they were, why haven’t other comets had a similar impact?
By happenstance, each of the comets will be back in the same part of the sky in January 2017 and January 2018 respectively, and Paris is hoping to put his theory to the test by observing them with a radio telescope to see if he picks up any emissions on the same frequency as the Wow! signal.