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SpaceX "DARKSAT" results: can Starlink and astronomy happily coexist?
Astronomers have begun to gather and analyze detailed observations of a SpaceX Starlink satellite prototype officially labeled DARKSAT and the initial results hint that the satellite constellation should be able to happily coexist with ground-based astronomy in the future.
Since SpaceX began launching batches of 60 Starlink satellites in May 2019, the company has raised the ire of parts of the astronomy community and simultaneously awed and inspired many less technical observers with clusters of shooting star-like satellites that are easily visible after launches. While the mid-sized spacecraft do become much dimmer as they raise their orbits from ~300 km (185 mi) to 550 km (340 mi), they are far from invisible even at that operational altitude. It’s safe to say that the current impact on ground-based astronomy is still just shy of negligible even with 360 satellites in orbit, but that impact is assuredly greater than zero and the relatively bright spacecraft have already interrupted telescope observations at many sites around the world.
Given that the 360 satellites already in orbit are just a tiny fraction of the ~4400, ~12,000, or even ~40,000 that SpaceX could one day launch, it would be irresponsible to argue that the constellation’s impact – and the impact of others like it – will continue to be minor as the number of satellites grows. Thankfully, while it doesn’t appear that prospective low Earth orbit (LEO) constellation architects anticipated the potential astronomy impact, SpaceX’s Starlink team has rapidly responded and already launched a satellite featuring tweaks designed to dim its appearance from the ground. For several reasons, the initial results from “DARKSAT” are extremely promising – now visible below in some of the first photos offering a useful comparison.
Launched on January 7th, 2020, a set of 20 spacecraft including DARKSAT – representing a single “plane” of the broader Starlink constellation – all arrived at their operational ~550 km (340 mi) orbits by February 23rd. As previously discussed on Teslarati, initial results first published on March 18th revealed that the Starlink DARKSAT prototype – essentially an early alpha test for darkening techniques – was already 55% darker than unmodified spacecraft. While making satellites less reflective makes thermal management a much greater challenge, DARKSAT has managed to raise its orbit and begin operations without issue, although it’s unknown whether the satellite’s antennas and avionics are also functioning nominally.
For darker spacecraft, perhaps the most important test will be long-term reliability, as constantly absorbing more heat than a reflective satellite is likely to put their structure, avionics, and radiators through significantly more thermal stress. As such, SpaceX may launch a limited number of additional darkened prototypes over the coming months but is much less likely to darken all satellites on any given launch until DARKSATs have successfully operated in orbit for months or even years.
On the ground, SpaceX may try to perform sped-up stress testing, but proving that darker satellites are a viable solution will almost invariably take time. Earlier this month, CEO Elon Musk revealed that SpaceX may attempt to design deployable solar shades for Starlink satellites if darkening their bodies is not enough to fully mitigate major impacts to astronomy. Knowing SpaceX, the first in-orbit solar shade test(s) could happen during any of several upcoming Starlink launches.
Adding reliable, deployable solar shades without appreciably raising Starlink’s production costs could be a major challenge, given the fundamental complexity of large, deployable mechanisms in space, but SpaceX – if anyone – is likely up to the challenge. More importantly, the fact that SpaceX’s very first attempt at reducing Starlink albedo (reflectivity) has produced a satellite 55% darker than its peers suggests that much more can probably be done along those lines, given additional time for extra experiments and deeper optimization.
As a result, it may be the case that SpaceX ends up launching 750-1000+ reflective Starlink satellites before an affordable, mass-producible DARKSAT variant is ready to take over. In that event, Starlink could plausibly have a small to moderate negative impact on ground-based astronomy for several years. However, comments made by SpaceX executives over the years suggest that no single Starlink satellite is likely to operate for more than five or so years before being replaced, meaning that the entire constellation would be continuously refreshed (as long as it’s generating revenue). Even if a thousand bright(er) Starlink satellites make life a bit harder for some astronomers, the fact remains that the consequences of any single Starlink satellite variant – assuming SpaceX remains serious about fully mitigating the constellation’s impact – are inherently temporary.
If SpaceX continues to make progress darkening satellites and developing cheap solar shades, it seems all but guaranteed that even a constellation of tens of thousands of Starlink satellites will be able happily coexist with the astronomy community, all the while delivering cheap, fast internet to millions of people – especially those lacking access – around the world.
Elon Musk
Tesla reveals Optimus Academy, where robots teach themselves
Tesla has begun building production quality Optimus robots in Fremont and revealed its training plan.
Tesla has started building Optimus on the high volume line it set up inside its Fremont factory, and the company says the robots coming off it are the first that meet the bar for a real product. “The bots coming off this line are the first production-quality bots that we have manufactured,” Tesla wrote in its third quarter shareholder letter, adding that it has “proven that the current manufacturing process for Optimus is suitable for a commercial product.”
The line sits in space that built the Model S and Model X until this spring. Tesla cleared the old vehicle line in 46 days, as Teslarati reported in July, to make room for robot production sized for one million units a year. On Wednesday’s earnings call, Elon Musk said most of the equipment for that capacity is already in Fremont, with output set to climb toward roughly 20,000 robots a week as the line ramps.
Musk described the ramp as a classic S curve. “The growth of Optimus is an S curve, but the initial curve is a shallow slope,” he said. The team is now refining the robot’s AI, electromechanical design, reliability and service life, and Musk expects that work to be finished by the end of next year, when Tesla plans to start delivering Optimus to outside companies for dangerous, repetitive and around the clock jobs.
The most interesting part of the call was how Tesla plans to teach the robots. Its cars send real driving data back to the AI team from millions of vehicles, but Optimus has no fleet like that yet. “A big difference with Optimus versus the cars is we don’t have this vast fleet of cars from which we can gather training data,” Musk said. Tesla’s answer is an Optimus Academy, where 10,000 to 20,000 robots will practice a wide range of tasks and feed what they learn into the next version of the model. Every unit off the Fremont line becomes a source of that training data.
Smarter hardware is on the way too. Tesla plans to put its AI5 chip into Optimus next year, and Musk said a new Optimus video should arrive within one or two months showing the robot completing tasks driven by AI rather than preprogrammed motions. He took aim at rival humanoid demos that only run scripted routines, saying those would not hold up in the real world.
The supply chain is lining up behind the program. In September, Tesla certified Tuopu, Joyson and Sanhua as mass production partners for Optimus components. A far larger Optimus factory is also rising at Giga Texas, where drone footage from Joe Tegtmeyer showed the steel frame nearing completion, and Musk has pegged that plant’s long term target at 10 million robots a year.
Tesla executives also said Optimus production costs are trending toward the expected manufacturing cost of Cybercab, a sign the robot is being engineered for volume from the start. The hands remain the toughest piece of the design, a point Musk also made at the X Takeover event earlier this month, as Teslarati covered at the time, and that is where much of the current engineering effort is focused.
Elon Musk
The Starship moon landing number NASA and Elon Musk can’t agree on
Musk disputes NASA estimate of 22 Starship launches for Moon landing, predicting 6 to 8.
Elon Musk is disputing a new NASA safety panel estimate of how many Starship launches it will take to put astronauts on the Moon, saying the real number will be less than half the panel’s figure.
On Thursday, NASA’s Aerospace Safety Advisory Panel held its quarterly public meeting. Panel member Charlie Precourt, a former NASA astronaut, flagged the fueling process for SpaceX’s lunar lander as a major risk for Artemis IV, the mission planned to land a crew on the Moon in 2028. “We need to keep our eyes on numerous required fuelings for the lander,” Precourt said, according to Ars Technica. “I think the last estimate is around 22 flights.”
Ars Technica’s Eric Berger posted the comment on X, and Musk replied. “That’s way too high,” Musk wrote. “Actual number will be more like 6 to 8.”
The disagreement comes down to a basic problem with sending a ship as large as Starship to the Moon. Starship burns nearly all of its propellant just reaching Earth orbit, so it cannot continue on to the Moon without stopping for a refill. SpaceX’s answer is a gas station in space. First, a Starship that works as a storage tank, called a depot, is launched into orbit. Then a series of tanker Starships launch one at a time, dock with the depot and pump their leftover propellant into it. Once the depot is full, the lunar lander version of Starship launches, docks, fills up and heads for the Moon.
Every tanker trip is its own full rocket launch, which is why the count matters. More launches mean more time, more cost and more chances for something to go wrong before astronauts ever leave Earth. Berger estimated that even if SpaceX reaches twice weekly Starship launches by the end of 2027, filling a depot at the panel’s number would still take roughly three months.
How many tankers are needed depends mostly on how much propellant each one can carry to orbit and how much is lost along the way. Starship’s fuel and oxygen are stored at extremely cold temperatures, and some of it slowly boils off while waiting in orbit. More is lost in each transfer. NASA appears to be working from what Starship can lift today, while Musk’s range assumes a more capable rocket.
Musk has pushed back on higher counts before. In 2021, after a government document suggested 16 launches, he called that “extremely unlikely” and said eight tankers would be the most required.
Much of the answer depends on hardware SpaceX has not finished flying. As Teslarati noted earlier this year, the company plans to carry out the refueling process with its upgraded V3 Starship, and Precourt described Artemis IV as carrying “a large number of firsts.” He also praised NASA Administrator Jared Isaacman’s team for working to clear obstacles for both SpaceX and Blue Origin, whose Blue Moon lander does not rely on orbital refueling for its first mission.
Elon Musk
Tesla’s secretive “Project Crystal Sun” gets a big green light in Texas
Fort Bend County approved four incentive agreements Thursday for Tesla’s proposed $10.1 billion solar factory.
Fort Bend County commissioners on Thursday approved a package of tax incentives for Tesla’s proposed $10.1 billion solar cell factory near Needville, Texas, giving the company one of the last local approvals it needs before it decides where to build. All four Tesla agreements passed 4 to 0.
The votes covered a property tax abatement inside Reinvestment Zone No. 34, a Chapter 381 economic development agreement, a foreign trade zone non-objection paired with payments in lieu of certain taxes, and a separate payment in lieu of taxes “true up” agreement, according to agenda notes from the Fort Bend Commissioners Court meeting.
The project, known internally as “Project Crystal Sun,” would make solar cells and finished modules on roughly 3,000 acres near FM 762 and FM 1994, south of the Brazos River. As Teslarati reported when the filing first surfaced in August, Tesla’s application under the state’s JETI Act splits the investment into $1.5 billion in real property and $8.6 billion in equipment, with 9,712 permanent jobs projected by 2033 and commercial operations targeted for the first quarter of 2029. The plant would handle the full chain from ingot and wafer production through cell testing.
Inside Tesla’s secretive $10 Billion “Project Crystal Sun” filing
Thursday’s approval does not lock in the site. Tesla has told the Texas Comptroller it is still weighing other locations, and site selection adviser David Dennison told Lamar Consolidated ISD trustees in September that the race had narrowed to Fort Bend and one out of state rival with a “very compelling package,” according to the Houston Chronicle. Tesla hopes to decide before the end of 2026, and the incentives still need sign off from the Comptroller and the Governor’s office.
Local officials have now done nearly everything within their control. Commissioners created the reinvestment zone in an August 24 special meeting, with Interim County Judge Daniel Wong formally withdrawing himself over his engineering firm’s past work with Tesla. Lamar CISD trustees voted 7 to 0 on September 15 to advance a JETI agreement that would tax Tesla’s qualifying property at 50 percent of its value for maintenance and operations from 2029 through 2038.
The plant lines up with a target Elon Musk set on Tesla’s Q4 2025 earnings call in January, when he said the company would “work toward getting 100 GW a year of solar cell production, integrating across the entire supply chain from raw materials all the way to finished solar panels.” In March, Tesla was reported to be negotiating a $2.9 billion purchase of Chinese solar manufacturing equipment bound for Texas. The Houston area already hosts Tesla’s Megafactory in Brookshire, where Megapack 3 production has started. Tesla said on its Q3 call that Megapack supply for 2027 is nearly sold out, and Musk wrote on X Thursday that the company is “increasing production of Megapacks as much as possible,” as demand from data centers climbs.
Tesla reveals Optimus Academy, where robots teach themselves
The Starship moon landing number NASA and Elon Musk can’t agree on
