The Week in Space and Physics
On exoplanet discoveries, Artemis delayed, the end of the ISS and a growing threat to satellites
NASA’s first attempt to launch the new Space Launch System - SLS - rocket ended in failure on Monday. That is perhaps not too surprising: launching a new rocket is hard, and given what is at stake with this mission, NASA is bound to tread cautiously.
Several problems emerged during the early morning preparations for the launch. In one, engineers detected a leak as they pumped hydrogen fuel into the rocket’s enormous tanks. Though the issue was resolved, they then spotted what appeared to be a crack in a section of the rocket. That was serious enough for engineers to undertake a more detailed inspection. Ultimately, however, they concluded the crack was in the insulation, rather than the more critical layers underneath.
In the end it was an issue with the rocket’s engines that proved fatal to the launch attempt. To prepare these engines for the thermal shock of liftoff, they are cooled to just a few degrees above absolute zero. This, sensors reported, successfully happened in three of the four engines. Yet, no matter what engineers tried, the fourth engine stubbornly remained too warm.
This, it seems, was a step that NASA skipped during the launch rehearsals held earlier this year. At the time engineers seemed confident that they had enough data from other tests to confirm it would work in practice. Unfortunately, reality proved them wrong.
Exactly what went wrong has not yet been announced. One possibility, according to NASA, is that the temperature sensor itself was faulty. The engine, they suspect, may actually have cooled to close to the required temperature. If so that may be good news. Though the sensor itself cannot easily be replaced, controllers could use other sensors to judge if the engine has reached a safe temperature.
NASA will now proceed with a second launch attempt. Though two more dates were originally given – Friday 2nd and Monday 5th – NASA has since said that launch is also possible on Saturday and Sunday this week. An attempt has thus been scheduled for Saturday afternoon. Weather forecasts currently give a sixty percent chance of conditions good enough to fly.
Exoplanets: Worlds of Oceans and Carbon Dioxide
So many exoplanets have been found – more than five thousand at the last count – that it now takes something really special to grab attention. Yet the last week saw two such announcements. In the first, astronomers spotted a world that might, they think, be covered in an endless ocean. The other, examined by the James Webb Telescope, is the first proven to hold carbon dioxide in its atmosphere.
Ocean worlds - that’s to say, planets covered in a deep layer of water – are probably scattered across the galaxy. Yet discovering them is tricky, as astronomers can rarely pick out a planet in enough detail to say what it is made of. This planet, TOI-1452b, lies roughly one hundred light years away. It is close to its star, so it is likely to be warm - but probably not too hot for liquid water to exist on its surface.
Though we often think of Earth as a blue planet, it actually contains fairly little water by mass: less than one percent of our planet is water. Models of TOI-1452b, by contrast, suggest that close to a third of the planet is composed of water. If true that would mean a vast ocean, thousands of kilometres deep, covers the entire world.
Researchers now want to point the James Webb Space Telescope towards it to confirm this theory. In principle the telescope’s powerful gaze should be able to pick out details of TOI-1452b’s atmosphere, data that could back up the ocean theory. Yet for now the James Webb has been working elsewhere, scanning a distant world for signs of carbon dioxide.
Its target was WASP-39b, a giant and superhot planet locked in a close orbit around its star. The world is odd – though it has the mass of Saturn, it has “puffed up” so it appears bigger than Jupiter. The James Webb scanned the atmosphere of this planet, and found – for the first time – clear signs of carbon dioxide present within it.
The data also suggests another chemical is floating around the atmosphere, one researchers had not expected to find. For now they are unsure exactly what this chemical is, but it may form some kind of cloud of haze around the planet.
The discovery is an interesting early demonstration of the power of the James Webb’s eye. Future work will shift to smaller planets, with fainter and harder to measure atmospheres. Though the James Webb is unlikely to pick out signs of life, it will allow us to narrow down the possibilities, and identify – with a bit more certainty – the worlds that might be alive.
De-Orbiting the ISS
The International Space Station is by far the largest thing ever built in space. It was constructed piece by piece, with each module laboriously lofted into orbit over more than a decade. Yet when the time comes to destroy the station, it will all come crashing down as one.
The obvious question is how to do this safely. The station is big and sturdy enough that large chunks of it will survive falling through the atmosphere and then smash into the Earth at high speeds. NASA will therefore direct the station to re-enter over the Pacific Ocean, targeting one of the most remote areas on Earth.
Current plans call for the station to be slowly lowered over several months, until a Russian Progress spacecraft delivers a final push back to Earth. Yet, perhaps due to the apparent Russian reluctance to stick with the space station program, NASA is now looking for alternatives.
While one option is to use the existing Cygnus spacecraft, NASA also seems to be thinking about commissioning a specially built vehicle for the task. In a recent request for information, NASA asked companies to assess the feasibility of developing such a spacecraft.
For now NASA is simply listing their needs. The craft would need to be powerful enough to nudge the space station back to Earth but also, they say, available at short notice in case of a sudden failure of the station. Interestingly the document hints at a possible extended future of the space station: NASA note the spacecraft may not be needed until well after 2030, the current retirement date of the station.
Rising Solar Cycle Threatens Satellites
Intelsat, an American satellite communications company, reported losing control of one of its satellites, Galaxy 15, earlier this month. The likely cause of the failure was a solar storm which, Intelsat says, knocked out the radio systems used to control the satellite.
The number of such events is likely to increase over the next few years. The Solar Cycle – an eleven year pattern of rising and falling solar activity – is now ramping up, heading towards a peak in 2025 or 2026. The strength of each solar cycle is unpredictable but this one, so far at least, appears to be stronger than the last.
That may be a particular threat to the constellations of small satellites launched over the last decade. None of these satellites will have faced such conditions before, and many have been launched without good radiation protection. Expect to hear of many more satellites running into trouble over the next few years.
WATER PLANETS LIKE IN STAR WARS OH MY GOD!!!