The Boeing Starliner ‘Calypso’, the much-delayed addition to NASA’s Space Station supply fleet, was rolled out on 16th April and mated to its Atlas V booster for a planned launch on May 6th (Fig. 1). It has previously been flown, failing to dock with the ISS the first time, and another one subsequently flew uncrewed, when docking was achieved. In an amazing revelation, it turns out that one of last year’s delays was the realisation that most of the internal wiring was flammable – in view of the 1967 Apollo 1 fire tragedy, one has to wonder how such a mistake could possibly be made, let alone not noticed for so long. (Elizabeth Howell, ‘Boeing Starliner spacecraft rolls out to Atlas V rocket ahead of 1st astronaut launch’, Space.com, 16th April 2024.)
Another embarrassing event for NASA was the impact of a piece of space debris on a house in Naples, Florida, on March 8th (Fig. 2). It has been identified as a bracing strut from a pallet-load of expired batteries, massing over a ton, launched from the ISS in 2021 (Fig. 3). The problem is that it should have burned up in the atmosphere right away, and apart from how come it didn’t, there’s the question as to why it wasn’t monitored in orbit meantime. (Mike Wall, ‘Object that slammed into Florida home was indeed space junk from ISS, NASA confirms’, Space.com, 15th April 2024.)
There’s also potential embarrassment for China, because it turns out that EVA repairs to the Tiangong-2 space station in December and March were to power cables between the solar panels and the space station (Fig. 4), made necessary by a space debris strike (Frank Landymore, ‘China Repairs Space Station Damaged by Debris Strike’, Yahoo News, 24th April 2024). The Chinese space agency has promised measures to prevent a recurrence, and without hesitation a slew of critics have replied, ‘Don’t do any more space weapon tests like the Anti-Satellite one of 2007’, which added more than 3000 pieces of wreckage to the space debris hazard. I’m giving references for these stories because when I point out problems, I’m sometimes accused by space enthusiasts of making them up, or getting them from unreliable sources. At the time of the 2007 test there were still advocates of space militarisation in the Scottish spaceflight society ASTRA, and when I wrote that incident up for ‘Space Notes’ in Jeff Hawke’s Cosmos, one of them accused me of having taken my data on space debris from scare stories in the tabloid newspapers. Unfortunately they were actually from two papers in ESA Journal by Prof. Colin McInnes, an honorary member of the society (full references available on request). If the Tiangong damage was caused by debris from the 2007 test, we’re unlikely to hear about it, but it should make the point to the Chinese authorities that all the supposedly harmless debris in higher orbits will descend through lower levels as time goes on.
Meanwhile, on the Moon, the Japanese SLIM lander has survived a third lunar night and renewed contact with Earth on April 24th. It wasn’t designed to survive lunar night at all, and doing so three times is all the more remarkable because it’s still nose-down (Fig. 5), able to power up and send images and data only during the latter part of the lunar day. My guess is that because the heat loss during the night is due to radiation into space, the nose-down configuration may be preserving enough warmth to keep the lander alive. But that’s only a guess, and Japan’s engineers are working hard to find a full explanation, which no doubt we shall hear in due course. At the moment of writing, China’s Chang’e-6 mission to retrieve samples from the lunar Farside was due for launch on May 3rd (see ‘Space Notes, March 2024’, ON, 3rd March 2024) – and see below.
The last transmission from the Ingenuity helicopter on Mars was received on April 16th. Ingenuity has been sending to Earth via the Perseverance rover, and now that the helicopter is grounded with two broken rotor blades, the rover has now moved out of range. Such moments have a chequered history: the USA’s first solar-powered satellite, Vanguard 1, made a nuisance of itself in 1958 because when its job was done, it was using frequencies that were needed for its successors, and there was no way to turn it off. It was expected to remain in orbit for 2000 years, but fluctuations in upper atmosphere density reduced that to 240 years, and it finally fell silent after 6 years, to general relief.
Off-switches were routinely fitted to satellites later, but not always used as intended. The Phobus-1 probe was accidentally switched off on its way to Mars in 1988; Robert Farquhar ‘forgot’ to switch off International Comet Explorer at the end of its mission in 1986, so citizen scientists were able to reactivate it when it passed Earth again in 2014. ESA had to switch off the International Ultraviolet Explorer space telescope in 1996, for lack of funds to operate it, although it was still in full working order and to this day there’s no full substitute for it. A similar controversy now surrounds the Chandra x-ray space telescope, launched in 1999 as one of the four ‘Great Observatories’ including the Hubble Space Telescope, and the last still to be operating along with the HST. It too is working perfectly well, but the cost of processing the data is rising steadily, and NASA has not been allowed funds to continue beyond the current financial year.
ESA orchestrated the final descent of the Rosetta probe on to the surface of Comet 67-P in 2016, with the help of artist Carlo Palazzari, who had produced animations of the mission throughout. I said at the time that the result ‘would bring a tear to a gless e’e’; but when Cassini made its fatal plunge into the atmosphere of Saturn the following year, NASA just prosaically recorded ‘Loss of Signal’. Before losing Ingenuity’s signal, the Jet Propulsion Laboratory pre-recorded an emotional farewell message to the controlling team.
Although Ingenuity is now out of contact, its fate is different again. Because its signal is too weak to reach Earth, NASA has left it on, it has enough memory to store weather and other data for the next 20 years, and it will wake up for a while, each Martian day, to do so. Whether anyone will get to Mars in time to collect the data remains to be seen. At least it won’t be left sadly transmitting in hopes of a reply, as a cartoonist imagined for the Spirit rover when it got stuck in sand and couldn’t maintain solar power through the winter (Fig. 6).
There’s good news from Voyager 1, which has been sending garbled messages from interstellar space for over five months (Fig. 7).
The problem is made worse because at its great distance (currently 24 billion km), an exchange of signals with the spacecraft takes 45 hours. However, by repeatedly ‘poking’ it with commands, engineers succeeded in getting a full engineering download from the spacecraft and identifying the problem, which lies with a single chip in the Flight Data System, at the point where signals are packaged for transmission to Earth. Whether it has suffered a cosmic ray strike or simply died of old age is uncertain. Engineering data has been redirected to bypass the chip, and the ground team are now in touch with Voyager in real time, as nearly as the time-lag will allow. The spacecraft has proved to be in good shape in all other respects, except that the backup for the FDS stopped working after the Saturn flyby in 1980, so outgoing transmissions can’t simply be switched to it, and there isn’t enough memory in the onboard computer to repackage the science data the same way. But six or more years of data before Voyager’s power finally gives out are worth fighting for, and the search for other solutions is on. As I’ve previously pointed out, the scientific instruments are being switched off one by one to conserve power as the end draws nearer, and there may be some hard decisions ahead, as to whether some will switch off early to provide more memory for the rest.
One intriguing feature of the success so far is the photograph of the Voyager team celebrating their success to date on April 20th (Fig. 8). When I visited the Jet Propulsion Laboratory in Pasadena in 1986, my friend Mike Urban (Fig. 9) was in charge of one of the two teams controlling Voyager 2, after its Uranus flyby that year, and there were only three people on each shift (Fig.10). Presumably more were called back for the demanding task of programming the spacecraft for its Neptune encounter in 1989. But as I remarked last month, Voyager 1 has been in cruise mode since 1980, apart from its last photo assignment in 1990 when it imaged all the planets including Earth as the ‘pale blue dot’. Looking at the people on the far side of the table in Fig. 8, I suspect many of the ‘science and engineering teams’ quoted (Carolyn Collins Petersen, ‘NASA Restores Communications with Voyager 1’, Universe Today, April 22nd 2024), are volunteers, possibly called back from retirement. But whether or not that’s true, the best of luck to them all.
Speaking of which, last-minute news is that China’s Chang’e-6 mission lifted off successfully for the Moon on the morning of Friday, May 3rd. For details of its missions, see ‘Space Notes’, ON 3rd March 2024. Live transmission from the Space Centre finished at 11.40 a.m., our time, by which the orbiter had separated from the booster and was on trans-lunar trajectory, with its solar panels unfurled. The Long March 5 lift off was in mist, into cloud, and the solar panel deployment was within the Earth’s shadow, so there are no images and just one short video to see thus far. The three-stage combination of orbiter, lander and sample return vehicle will take three days to reach the Moon, so as this goes to press, once again the best of luck to all.
