The Gardeners

An Unnatural Pattern At twenty past four, Padma Bhandari was trying to work out whether someone had left the calibration transmitter switched on. If that was the explanation, she could be on the road by five and still get to Neha's school before the curtains opened. She had promised to sit where her daughter could see her. The arrangement had been discussed at breakfast with the seriousness of an international treaty. The receiver display was less cooperative. A thin bright line had appeared in the afternoon's spectral sweep, vanishing at regular intervals and returning a little higher in frequency. Most interference announced itself with a mess of companions: machinery, a passing aircraft, an irritated transmitter somewhere over the horizon. This had arrived alone. It occupied a narrow strip of the screen and repeated a sequence that was almost, though not quite, the same each time. Sipho Dlamini was consulting the receiver-status log at the adjoining terminal, with a pencil tucked behind one ear. "Which dish?" he asked. "All the ones still taking data." He leaned over the back of her chair without touching it. Sipho Dlamini ran the receiving systems and had developed a dislike of anyone who said a telescope had discovered something before asking what the telescope had been doing that morning. "Then it's probably us." "That's what I'm hoping." "Don't sound so disappointed. I've been trying to get the calibration people to replace that board for nine months. If it's finally failed, I want witnesses." Padma enlarged the previous sweep. The line had begun seventeen minutes earlier, between two ordinary maintenance checks. Its timing was wrong for the calibration transmitter, which used a fixed test pattern, but she had been wrong about calibration faults before. She asked for the raw voltages, opened the receiver logs and checked the local interference monitor. Sipho moved to the spare terminal to retrieve the transmitter schedule. Outside the control-room window, a maintenance vehicle was making slow progress along the gravel road between the low service buildings. The dish field lay beyond a fold in the dry country, hidden from this room by the same ridge that sheltered the staff quarters from the worst of the wind. Padma had once told Neha that radio astronomers spent much of their lives looking at numbers inside buildings, a description her daughter found suspiciously similar to accountancy. Her telephone vibrated under a notebook. She turned it over. A photograph from Jo showed the school hall in a state of energetic preparation: folded chairs, strips of painted scenery, a child carrying something made from cardboard. Beneath it Jo had written, Parking is already ridiculous. I'll save you a seat. Padma typed, Leaving soon, and stopped before sending it. Sipho came back with the maintenance record. "Transmitter was off. I can walk down there and pull the feed if you like." "Do that. Check the door log as well." He glanced at the clock. "You have somewhere to be." "I know." He waited just long enough to make clear that he did not believe she was going. Then he took his jacket from the hook by the door and went out. The array had been watching a patch of sky selected for its relative emptiness. No bright source had been scheduled. The team were collecting long-duration background measurements, the kind of work nobody put in a public lecture because the plots needed too much explaining. Padma compared the signal with recordings made on earlier days. Nothing. She checked the monitoring service for aircraft and satellites, then ran the time stamps through a separate clock reference. The pulses obeyed the observatory clock, but the pattern within them did not resemble a fault she recognised. There were seventeen identifiable intervals before the sequence began again. Their lengths made a peculiar progression. She plotted them against one another and felt an unwelcome excitement at how readily they resolved into groups. It was exactly the sensation she distrusted in herself. A person could persuade a plot to show almost anything with the right choice of axes. Ruth Menon called from the adjoining analysis room. "Is it still there?" "For the moment." "I've got two people asking whether to stop their reduction run." "Tell them to keep their own data untouched. The analysis can wait." Ruth appeared at the door, still wearing the badge from a visiting workshop that had ended three days earlier. "Padma, the repeat period is regular to the millisecond." Padma tapped the filename displayed above the reduction log. "On the same software that found it." "I know that. I'm telling you what the data say." "And I'm asking what the data would say if we took away the software." Ruth looked at the clock, then at Padma's bag on the floor. "You can go. I'll stay." It was an offer made without ceremony. Ruth had a paper due and a difficult relationship with the project's director, but she was good at waiting for unhelpful results. Padma could have handed over the anomaly and walked out. She had already done the sensible part: made copies of the raw stream and recorded what she knew. "I want to check one more thing," she said. Ruth went back to the second terminal without comment. Padma brought up the independent clock feed and asked a small, old-fashioned question: whether a distant source should drift across the receiver in the way the line had. She found a displacement. It was slight, and she did not immediately trust it. She checked again using the timestamps from a neighbouring antenna group that ran on a separate ingest process. The displacement was there too. Her phone showed another message from Jo. Neha's looking for you. I've said you're coming. Padma rang. It took three attempts before Jo could hear her over the children and the hall's amplified music. "I'm at work," Padma said, keeping the telephone close to her mouth as a group of children shouted something in the background. "Yes, I worked that bit out. Where are you?" A door banged at Jo's end of the call and she said, "Sorry, go on," although Padma had not managed to answer yet. "Still at the site. Something's come up." "Can you get here by six?" Padma considered the forty-minute road, the early-evening traffic around town and the line creeping across her screen. She knew what a useful answer would be. "I don't think so." Jo did not scold her. "All right. Do you want to speak to Neha?" A moment later her daughter came on, sounding distant and occupied. "Mum?" "Hello, sweetheart. I might be late." "I'm in the second half." Someone nearby asked Neha to move away from the door, and Padma heard her daughter say, "I am," before turning back to the call. "I know." "Jo says the first half's really short." "I'll do my best." "You said you wouldn't have a meeting." "It's not a meeting." There was a rustle, a shout in the background and Neha saying something to someone beside her. "Okay," she said into the phone. "I've got to go." Padma remained with the telephone at her ear for a second after the call ended. She put it face down and wrote the exact time of the unexplained drift in her notebook. She had learnt to do that years earlier, whenever she thought a result might change after someone else looked at it. Sipho returned with a scrape on one hand and a photograph of the transmitter's disconnected power lead. He had also checked the road-side monitor and the site's auxiliary antenna. The narrow line was absent from the monitor, which largely ruled out a nearby vehicle transmitter, but the auxiliary had been pointing elsewhere. "The board didn't fail," he said. "I'm devastated." Padma showed him the drift. He studied the plot, then reached across and changed its scale. "Could be the processing clock." "I used two." "Two systems that share a reference." She stared at the little note at the bottom of the screen. He was right. Both had taken their timing correction from the same upstream service. "We should shut that down and recompute," she said. "Tomorrow?" She picked up her bag, then put it down again. The practical way to test the possibility was to preserve the uncorrected data and have somebody far away take measurements using a different instrument and a different clock. The signal was weak but visible. If it remained above their horizon for another hour, a second observatory farther east might still catch it. She called the duty office at the Australian array. The first voice was recorded. The second belonged to a technician who seemed mildly offended by the words urgent independent observation. "Do you have a target?" "Yes. I can give you coordinates and a frequency range. I don't want you to run our detection code." "We wouldn't. We haven't got it." "Good." "That was a joke, Dr Bhandari." She supplied the coordinates and asked for unprocessed samples. He could request a gap in the next block of scheduled observations, he said, but the duty scientist would have to authorise it. "What should I tell the duty scientist to look for?" "An intermittent narrowband source that we're having trouble explaining." "Satellite?" "Possibly. That's why we need the observation." He promised to ring back. She thanked him and opened an incident record, entering the obvious sources of contamination first. It gave her something useful to do while waiting. Ruth returned carrying two paper cups of coffee. "I've seen your request to Australia." "They haven't agreed yet." Padma pulled the message back onto her screen, in case she had overlooked a reply. "The director will want to know." Ruth set one of the cups beside the notebook and kept the other in her hand. "The director can know that we have an unidentified signal. Nothing more." "People are going to notice if we divert another array." Padma took the cup. The coffee had been made with milk from the communal fridge and had the stale taste of the end of a working day. "Then the notice should say we're testing a receiver anomaly." "You really think it might be that?" "I think we haven't earned anything else." Ruth sat on the edge of the desk. She did not argue. Instead, she opened the receiver's raw stream on her tablet and began checking its periodic gaps by hand, reading out the intervals as though calling numbers at a bingo game. Padma followed on paper. Twice they disagreed and went back to the recordings. On the third pass they obtained the same sequence. It was a little after seven when the Australian duty scientist called. Her name was Alina Wu, and she sounded as tired as Padma felt. "We've got forty-six minutes on your coordinates," Alina said. "Before you ask, I've instructed my team to treat this as ordinary interference work. We haven't downloaded any of your processed products." "Thank you." "Your contact put the frequency range in the title line of the ticket. I've had that removed from the general queue. It wasn't restricted." Padma checked her copy of the request and found the frequency exactly where Alina had said. "I'm sorry." "It happens. I'm not promising you anything. We have a filtering fault of our own this week." "I'd prefer an ordinary fault, at this stage." "So would I. I'm meant to be on leave tomorrow." Alina said she would send raw data once her team had checked the receiver state, and rang off without asking what Padma hoped to find. By then the school performance had finished. Jo sent a photograph of Neha standing beside a painted postbox in an oversized blue coat, her mouth caught halfway through a smile. Underneath: She remembered all her lines. She was upset, but she's having chips and hasn't mentioned it for ten minutes. Padma read the message twice and asked Jo whether she could bring Neha home. Jo replied, Of course. We'll be back after eight. Padma typed a thank-you and left the phone beside the notebook. She knew she ought to call her daughter again, but Neha would be in Jo's car and the apology would have to compete with the radio and the packet of chips on her lap. While they waited, Sipho came back with sandwiches from the service station at the junction and a list of things that could still explain the signal. One item was a receiver fault; another was a piece of equipment at the Australian site that might imitate the same pattern by chance. Padma added a third, a source closer to Earth than the direction suggested. It was a reasonable list and she was relieved to see it. They took turns checking it, including faults they had already ruled out locally. Sipho wanted to change the pointing of one dish to a nearby empty coordinate while leaving the others where they were. Padma authorised the short interruption and recorded it in the observation log, despite Ruth's worry that they would lose the line while it lasted. The source disappeared on the diverted dish and remained where the others were looking. When the antenna returned, the line came back after the expected settling delay. "That helps," Sipho said, eating the corner of his sandwich over a bin. "It doesn't get us off the hook for the rest." Padma appreciated that he still spoke as though a discovery were something one might be charged for. He gave Ruth the second sandwich, which she had forgotten to ask for, and went to fetch a replacement cable for the clock monitor. The Australian data arrived shortly before nine. Sipho had gone to find food. Ruth was at a second desk, trying to reconcile discrepancies between their two independent receiver logs. Padma opened Alina's transfer folder and checked the accompanying observations: dish status, clock reference, pointing history, weather flags and the technician's initials. Then she made a new plot without importing any of the local analysis settings. The same narrow line appeared. Its frequency had shifted by the amount expected from the two observatories' different motion and observing times. The timing sequence reproduced, including a slight irregularity in the eleventh interval that Padma had initially assumed came from a faulty sample. She made Ruth repeat the reduction from the raw Australian file on a different workstation. Ruth did so, first grumbling about the documentation and then growing very quiet as the pattern took shape. Their displays were not identical; the Australian receivers had a different response, and one interval was partly obscured by local noise. The long sequence underneath was unmistakably the same. "We should call Alina," Ruth said. Padma had already dialled. Alina answered at once, though she made Padma wait while she closed another conversation. "We see the line," Alina said. "And the modulation. Our hardware group hasn't found a local source. I want another pass before anybody puts the word artificial in a report." "So do I." "But you know what's awkward about it?" Padma looked at the packet intervals. The pattern repeated with deliberate changes, as though the source were counting through parts of a much longer arrangement. It behaved like information, although information about what was beyond them. "Yes," she said. Neither woman named the awkwardness. Alina asked for permission to share the raw samples with a third, unconnected analysis team. Padma agreed and insisted that the supporting logs travel with them. They spent another twenty minutes discussing a test that might still make the anomaly disappear. When she eventually drove through the low hills towards town, the sky above the road had gone completely dark. Her phone was connected to the car but she did not call home while she was driving. She wanted to choose her words instead of speaking simply because the device made it possible. Neha was awake when Padma reached the house. Jo had left a plate of food in the fridge and a note about the play, written in the hurried slant she used for shopping lists. Padma put her bag down in the hall and found her daughter sitting cross-legged on the sofa, still in the blue costume coat. The heavy fabric had bunched around her knees, and the yellow paper envelope from the performance lay on the cushion beside her. "I've got a picture," Neha said. She held up Jo's phone, which she had apparently been allowed to borrow. "I was meant to be the postmistress but they lost the hat." "You look wonderful." "I wore the wrong shoes." Padma sat beside her. The picture showed a group of children under the school hall lights, several looking in different directions. Neha was near the edge, holding an envelope made from folded yellow paper. "Did they laugh at the bit you wanted?" Padma asked. Neha shrugged and brought up another photograph. "I didn't see you," she said after a while. "I know. I'm sorry." "Were there people from space?" The question startled her. She had told Neha only that something unexpected had happened at work, through a bad connection and with twenty schoolchildren shouting nearby. "Nobody knows what it is yet." "Jo said it might be exciting." "Jo's allowed to hope." Neha considered this, then gave the phone back to Jo's bag and asked for her own pyjamas. Padma helped untangle the heavy costume coat without saying anything more about telescopes. There were two safety pins inside the collar, presumably from the missing hat; she took them out and put them where Neha would not step on them. Later, when the house was quiet, she opened the incident record once on her laptop. She read the two observatories' separately signed findings and closed it again. An artificial origin was the most defensible explanation they had. Nothing in the data told her who had sent the pattern, whether anybody had meant Earth to receive it, or what it contained. She left the fields blank.