60 Starlink satellites stacked together just after being launched on 24 May 2019.
|Country of origin||United States|
|Spacecraft type||Small satellite|
|Launch mass||227–260 kg (500–573 lb)|
|Equipment||Ku and Ka band phased array antennas|
(335.9–1,325 km, 208.7–823.3 mi)
|Maiden launch||22 February 2018|
|Last launch||18 March 2020|
Starlink is a satellite constellation being constructed by American company SpaceX to provide satellite Internet access. The constellation will consist of thousands of mass-produced small satellites in low Earth orbit (LEO), working in combination with ground transceivers. SpaceX also plans to sell some of the satellites for military, scientific, or exploratory purposes.
Concerns have been raised about the long-term danger of space junk resulting from placing thousands of satellites in orbits above 1,000 kilometres (620 mi) and a possible impact on astronomy, although SpaceX is reportedly attempting to solve the latter issue. On Starlink 2, one of the satellites has an experimental coating to make it less reflective, and thus impact ground-based astronomical observations less.
The total cost of the decade-long project to design, build, and deploy the constellation was estimated by SpaceX in May 2018 to be about US$10 billion. Product development began in 2015, with the first two prototype test-flight satellites launched in February 2018. A second set of test satellites and the first large deployment of a piece of the constellation occurred on 24 May 2019 UTC when the first 60 operational satellites were launched. The SpaceX satellite development facility in Redmond, Washington, houses the Starlink research, development, manufacturing, and on-orbit control operations.
As of March 2020, SpaceX is targeting service in the Northern U.S. and Canada in 2020, rapidly expanding to near-global coverage of the populated world by late 2021 or 2022. However, these are only internal projections and not set dates.
The communication satellite network SpaceX envisions was publicly announced in January 2015, with the projected design capability to support sufficient bandwidth to carry up to 50% of all backhaul communications traffic, and up to 10% of local Internet traffic, in high-density cities. CEO Elon Musk said that there is significant unmet demand for low-cost global broadband capabilities.
The opening of the SpaceX satellite development facility in Redmond was announced by SpaceX in January 2015 with partners, to develop and build out the new communication network. At the time, the Seattle-area office planned to initially hire approximately 60 engineers, and potentially 1,000 people by 2018. The company operated in 2,800 square meters (30,000 sq ft) of leased space by late 2016, and by January 2017 had taken on a 3,800 square meters (40,625 sq ft) second facility, both in Redmond. In August 2018, SpaceX consolidated all their Seattle-area operations with a move to a larger three-building facility at Redmond Ridge Corporate Center to support satellite manufacturing in addition to R&D.
In July 2016, SpaceX acquired a 740 square meters (8,000 sq ft) creative space in Irvine, California (Orange County). SpaceX job listings indicated the Irvine office would include signal processing, RFIC, and ASIC development for the satellite program.
By January 2016, the company had publicly disclosed plans to have two prototype satellites flying in 2016, and to have the initial satellite constellation in orbit and operational by approximately 2020. By October 2016, SpaceX had developed the initial satellites that they hoped to launch and test in 2017, but the satellite division was focusing on a significant business challenge of achieving a sufficiently low-cost design for the user equipment, aiming for something that ostensibly can be installed easily at end-user premises for approximately US$200. Overall, SpaceX President Gwynne Shotwell said then that the project remained in the "design phase as the company seeks to tackle issues related to user-terminal cost." Deployment, if carried out, would not be until "late in this decade or early in the next". The two original test satellites were not flown and were used only in ground testing. The planned launch of two revised satellites was moved to 2018.
In November 2016, SpaceX filed an application with the Federal Communications Commission (FCC) for a "non-geostationary orbit (NGSO) satellite system in the Fixed-Satellite Service using the Ku and Ka frequency bands".
By March 2017, SpaceX filed plans with the FCC to field a second orbital shell of more than 7,500 "V-band satellites in non-geosynchronous orbits to provide communications services" in an electromagnetic spectrum that has not previously been heavily employed for commercial communications services. Called the "Very-Low Earth Orbit (VLEO) constellation", it would comprise 7,518 satellites and would orbit at just 340 kilometres (210 mi) altitude, while the smaller, originally-planned group of 4,425 satellites would operate in the Ka- and Ku-bands and orbit at 1,200 kilometres (750 mi) altitude. SpaceX's plans were unusual in two areas: the company intended to utilize the little-used V-band of the communications spectrum, and they intended to use a new orbital regime, the very-low Earth orbit regime of ~340 km altitude, where atmospheric drag is quite high, which normally results in short orbital lifetimes. The March 2017 plan called for SpaceX to launch test satellites of the initial Ka/Ku type in both 2017 and 2018, and begin launching the operational constellation in 2019. Full build-out of the approximately 1,200 kilometres (750 mi) constellation of around 4,440 satellites was not then expected to be completed until 2024.
Some controversy arose in 2015–2017 with regulatory authorities on licensing of the communications spectrum for these large constellations of satellites. The traditional and historical regulatory rule for the licensing spectrum has been that satellite operators could "launch a single spacecraft to meet their in-service deadline [from the regulator], a policy is seen as allowing an operator to block the use of valuable radio spectrum for years without deploying its fleet". By 2017, the FCC had set a six-year deadline to have an entire large constellation deployed to comply with licensing terms. The international regulator, International Telecommunication Union (ITU), proposed in mid-2017 a guideline that would be considerably less restrictive. In September 2017, both Boeing and SpaceX petitioned the US FCC for a waiver of the six-year rule, but they were denied. By 2019, the FCC had ruled that half of the constellation must be in orbit in six years, with the full system in orbit nine years from the date of the license.
SpaceX filed documents in late 2017 with the FCC to clarify their space debris mitigation plan. The company will "implement an operations plan for the orderly de-orbit of satellites nearing the end of their useful lives (roughly five to seven years) at a rate far faster than is required under international standards. [Satellites] will de-orbit by propulsively moving to a disposal orbit from which they will reenter the Earth's atmosphere within approximately one year after completion of their mission". In March 2018, the FCC issued SpaceX approval, with some conditions. SpaceX would need to obtain a separate approval from the International Telecommunication Union. The FCC supported a NASA request to ask SpaceX to achieve an even higher level of de-orbiting reliability than the standard that NASA had previously used for itself: reliably de-orbiting 90% of the satellites after their missions are complete.
In May 2018, SpaceX expected the total cost of development and buildout of the constellation to approach US$10 billion. In mid-2018, SpaceX reorganized the satellite development division in Redmond, and terminated several members of senior management.
In November 2018, SpaceX received US regulatory approval to deploy 7,518 broadband satellites, in addition to the 4,425 approved earlier. SpaceX's initial 4,425 satellites had been requested in the 2016 regulatory filings to orbit at altitudes of 1,110-kilometer (690 mi) to 1,325-kilometer (823 mi), well above the International Space Station. The new approval was for the addition of a very-low Earth orbit non-geostationary satellite orbit constellation, consisting of 7,518 satellites operating at altitudes from 335-kilometer (208 mi) to 346-kilometer (215 mi), below the ISS. Also in November, SpaceX made new regulatory filings with the US Federal Communications Commission (FCC) to request the ability to alter its previously granted license in order to operate approximately 1,600 of the 4,425 Ka-/ Ku-band satellites approved for operation at 1,150 km (710 mi) in a "new lower shell of the constellation" at only 550 km (340 mi) orbital altitude. These satellites would effectively operate in a third orbital shell, a 550-kilometer (340 mi) orbit, while the higher and lower orbits at approximately 1,200-kilometer (750 mi) and approximately 340-kilometer (210 mi) would be used only later, once a considerably larger deployment of satellites becomes possible in the later years of the deployment process. The FCC approved the request in April 2019, giving approval to place nearly 12,000 satellites in three orbital shells: initially approximately 1,600 in a 550-kilometer (340 mi)-altitude shell, and subsequently placing approximately 2,800 Ku- and Ka-band spectrum satellites at 1,150 km (710 mi) and approximately 7,500 V-band satellites at 340 km (210 mi).
With plans by several providers to build commercial space-Internet mega-constellations of thousands of satellites increasingly likely to become a reality, the US military began to perform test studies in 2018 to evaluate how the networks might be used. In December, the US Air Force issued a US$28 million contract for specific test services on Starlink.
In February 2019, a sister company of SpaceX, SpaceX Services, Inc., filed a request with the FCC to request a license for the operation of up to a million fixed satellite earth stations that would communicate with its non-geostationary orbit satellite (NGSO) Starlink system.
By April 2019, SpaceX was transitioning their satellite efforts from research and development to manufacturing, with the planned first launch of a large batch of satellites to orbit, and the clear need to achieve an average launch rate of "44 high-performance, low-cost spacecraft built and launched every month for the next 60 months" to get the 2,200 satellites launched to support their FCC spectrum allocation license assignment. SpaceX said they will meet the deadline of having half the constellation "in orbit within six years of authorization… and the full system in nine years".
By the end of June 2019, SpaceX had communicated with all 60 satellites but lost contact with three; the remaining 57 were working as intended. Forty-five satellites had reached their final orbital altitude of 550 km (340 mi), five were still raising their orbits, and another five were undergoing systems checks before they raise their orbits. The remaining two satellites were intended to be quickly removed from orbit and reenter the atmosphere in order to test the satellite de-orbiting process; the three that lost contact were also expected to reenter, but will do so passively from atmospheric drag as SpaceX was no longer able to actively control them.
In June 2019, SpaceX applied to the FCC for a license to test up to 270 ground terminals — 70 nationwide across the United States and 200 in Washington state at SpaceX employee homes — and aircraft-borne antenna operation from four distributed US airfields; as well as five ground-to-ground test locations.
By September 2019, SpaceX had gone back to the FCC to apply for more changes to the orbital constellation. SpaceX asked to triple the number of orbital planes in the 550 km orbital shell, from 24 to 72, arguing that they could then place satellites into multiple planes from a single launch. SpaceX argued that this change could bring coverage to the southern US in time for the 2020 hurricane season. The change was approved in December 2019, and will now see only 22 satellites in each plane rather than the 66 that had been a part of the original design. The total number of satellites in the 550 km shell would remain the same, at 1,584.
As of 18 March 2020[update], SpaceX has launched 362 Starlink satellites. They plan to launch 60 more per Falcon 9 flight, with launches as often as every two weeks in 2020. In total, nearly 12,000 satellites are planned to be deployed, with a possible later extension to 42,000. The initial 12,000 satellites are planned to orbit in three orbital shells: first placing approximately 1,600 in a 550-kilometer-altitude (340 mi) shell, then approximately 2,800 Ku- and Ka-band spectrum satellites at 1,150 km (710 mi), and approximately 7,500 V-band satellites at 340 km (210 mi).
The deployment of the first 1,584 satellites will be into 72 orbital planes of 22 satellites each, with a requested lower minimum elevation angle of beams to improve reception: 25° rather than the 40° of the other two orbital shells.:17 SpaceX launched the first 60 satellites of the constellation in May 2019 into a 450 km orbit and expected up to six launches in 2019 at that time, with 720 satellites (12 × 60) for continuous coverage in 2020.
|Flight No.||Mission||Date and time (UTC)||Launch site||Launch vehicle[a]||Orbit altitude||Inclination||Number deployed||Version||Outcome|
|1||Tintin||22 February 2018, 14:17||Vandenberg, SLC-4E||F9 FT ♺ B1038.2||514 km (319 mi)||97.5°||2||–||Success|
|Two test satellites known as Tintin A and B (MicroSat-2a and 2b) that were deployed as co-payloads to the Paz satellite.|
|2||Starlink 0||24 May 2019, 02:30 ||CCAFS, SLC-40||F9 B5 ♺ B1049.3||440–550 km (270–340 mi)||53°||60||v0.9||Success|
|Second launch of test satellites for SpaceX's Starlink constellation. Said to be "production design", these are used to test various aspects of the network, including deorbiting. They do not yet have the planned satellite interlink capabilities and they only communicate with antennas on Earth. A day after launch an amateur astronomer in the Netherlands was one of the first to publish a video showing the satellites flying across the sky as a "train" of bright lights. By five weeks post launch, 57 of the 60 satellites were "healthy" while 3 had become non-operational and were derelict, but will deorbit due to atmospheric drag. As of 31 October 2019[update], 49 satellites were in the target 550 km orbit while the others were still raising their orbits.|
|3||Starlink 1||11 November 2019, 14:56 ||CCAFS, SLC-40||F9 B5 ♺ B1048.4||550 km (340 mi) (target)||53˚||60||v1.0||Success|
|Second large batch of satellites, first batch of v1.0 v1.0 does not have laser links yet.|
|4||Starlink 2||7 January 2020, 02:19 ||CCAFS, SLC-40||F9 B5 ♺ B1049.4||550 km (340 mi)||53˚||60||v1.0||Success|
|Third large batch of satellites. One of the satellites has an experimental coating to make it less reflective, and thus impact ground-based astronomical observations less.|
|5||Starlink 3||29 January 2020, 14:06 ||CCAFS, SLC-40||F9 B5 ♺ B1051.3||550 km (340 mi)||53°||60||v1.0||Success|
|Fourth large batch of satellites.|
|6||Starlink 4||17 February 2020, 15:05 ||CCAFS, SLC-40||F9 B5 ♺ B1056.4||550 km (340 mi)||53°||60||v1.0||Success|
|Fifth large batch of satellites.|
|7||Starlink 5||18 March 2020, 12:16:39 ||KSC, LC-39A||F9 B5 ♺ B1048.5||550 km (340 mi)||53°||60||v1.0||Success|
|The sixth Starlink launch overall and the fifth operational batch of Starlink satellites.|
|8||Starlink 6||April 2020 ||CCAFS, SLC-40||F9 B5 ♺||550 km (340 mi)||53°||60||v1.0||Planned|
|The seventh Starlink launch overall and the sixth operational batch of Starlink satellites.|
SpaceX intends to provide broadband internet connectivity to underserved areas of the planet, as well as provide competitively priced service to urban areas. The company has stated that the positive cash flow from selling satellite internet services would be necessary to fund their Mars plans.
In early 2015, two space entrepreneurs announced Internet satellite ventures in the same week. In addition to SpaceX CEO Elon Musk announcing the project that would later be named Starlink, serial-entrepreneur Richard Branson announced an investment in OneWeb, a similar constellation with approximately 700 planned satellites that had already procured communication frequency licenses for their broadcast spectrum.
After the failures of previous satellite-to-consumer space ventures, satellite industry consultant Roger Rusch said in 2015 "It's highly unlikely that you can make a successful business out of this". Musk publicly acknowledged that business reality, and indicated in mid-2015 that while endeavoring to develop this technically complicated space-based communication system he wanted to avoid overextending the company, and stated that they are being measured in their pace of development. Nevertheless, internal documents leaked in February 2017 indicated that SpaceX expected more than US$30 billion in revenue by 2025 from its satellite constellation, while revenues from its launch business were expected to reach US$5 billion in the same year.
In February 2015, financial analysts questioned established geosynchronous orbit communications satellite fleet operators as to how they intend to respond to the competitive threat of SpaceX and OneWeb LEO communication satellites.[needs update] In October, SpaceX President Gwynne Shotwell indicated that while development continues, the business case for the long-term rollout of an operational satellite network was still in an early phase.
In 2015, court documents indicate that SpaceX had engaged in collaboration with wireless chip-maker Broadcom. Five key engineers subsequently left to join SpaceX, leading to a lawsuit filed by Broadcom alleging that "SpaceX stole our best minds". In March, an Orange County judge denied Broadcom's multiple restraining order requests.[needs update]
With the initial launch of the first 60 satellites of the operational constellation in 2019, SpaceX indicated that it would require 420 satellites in the constellation to achieve minor broadband coverage of Earth, and 780 of the first ~1,600 to provide moderate coverage.
|Half size contractual
|Full size contractual
(18 March 2020)
preparing to de-orbit
(11 November 2019)
(11 November 2019)
|550||1,584||53||March 2024||March 2027||360||2||3|
|335.9||2,493||42||November 2024||November 2027||0|
The Internet communication satellites were expected to be in the smallsat-class of 100-to-500 kg (220-to-1,100 lb)-mass, and were intended to be in Low Earth Orbit (LEO) at an altitude of approximately 1,100 kilometers (680 mi), according to early public releases of information in 2015. In the event, the first large deployment of 60 satellites in May 2019 were 227 kilograms (500 lb) and SpaceX decided to place the satellites at a relatively low 550 kilometers (340 mi), due to concerns about the space environment. Initial plans as of January 2015[update] were for the constellation to be made up of approximately 4,000 cross-linked satellites, more than twice as many operational satellites as were in orbit in January 2015.
The satellites will employ optical inter-satellite links and phased array beam-forming and digital processing technologies in the Ku and Ka bands, according to documents filed with the U.S. Federal Communications Commission (FCC). While specifics of the phased array technologies have been disclosed as part of the frequency application, SpaceX enforced confidentiality regarding details of the optical inter-satellite links. Early satellites are launched without laser links, in October 2019 SpaceX expected satellites with these links to be ready by the end of 2020.
The satellites will be mass-produced, at a much lower cost per unit of capability than existing satellites. Musk said, "We're going to try and do for satellites what we've done for rockets". "In order to revolutionize space, we have to address both satellites and rockets". "Smaller satellites are crucial to lowering the cost of space-based Internet and communications".
In February 2015, SpaceX asked the FCC to consider future innovative uses of the Ka band spectrum before the FCC commits to 5G communications regulations that would create barriers to entry, since SpaceX is a new entrant to the satellite communications market. The SpaceX non-geostationary orbit communications satellite constellation will operate in the high-frequency bands above 24 GHz, "where steerable earth station transmit antennas would have a wider geographic impact, and significantly lower satellite altitudes magnify the impact of aggregate interference from terrestrial transmissions".
Internet traffic via a geostationary satellite has a minimum theoretical round-trip latency of at least 477 ms (between user and ground gateway), but in practice, current satellites have latencies of 600 ms or more. Starlink satellites would orbit at 1⁄30 to 1⁄105 of the height of geostationary orbits, and thus offer more practical Earth-to-sat latencies of around 25 to 35 ms, comparable to existing cable and fiber networks. The system will use a peer-to-peer protocol claimed to be "simpler than IPv6", it will also incorporate end-to-end encryption natively. However, no details on this have been released as of yet.
Starlink satellites use Hall-effect thrusters with krypton gas as the reaction mass for orbit raising and station keeping. Krypton Hall thrusters tend to exhibit significantly higher erosion of the flow channel compared to a similar electric propulsion system operated with xenon, but at a lower propellant cost.
The system will not directly connect from its satellites to handsets (unlike the constellations from Iridium, Globalstar, Thuraya and Inmarsat). Instead, it will be linked to flat user terminals the size of a pizza box, which will have phased array antennas and track the satellites. The terminals can be mounted anywhere, as long as they can see the sky.
At the time of the June 2015 announcement, SpaceX had stated plans to launch the first two demonstration satellites in 2016, but the target date was subsequently moved out to 2018. SpaceX began flight testing their satellite technologies in 2018 with the launch of two test satellites. The two identical satellites were called "MicroSat-2a" and "MicroSat-2b" during development but were renamed "Tintin A" and "Tintin B" upon orbital deployment in February 2018. Two previously manufactured satellites, "MicroSat-1a" and "MicroSat-1b" were meant to be launched together as secondary payloads on one of the Iridium-NEXT flights, but they were instead used for ground-based tests.
MicroSat-1a and MicroSat-1b were originally slated to be launched into 625 kilometres (388 mi) circular orbits at approximately 86.4° inclination, and to include panchromatic video imager cameras to film images of Earth and the satellite.
Tintin A and B were inserted into a 514 kilometres (319 mi) orbit. Per FCC filings they were intended to raise themselves to an 1,125 kilometres (699 mi) orbit, the operational altitude for Starlink LEO satellites per the earliest regulatory filings, but stayed close to their original orbits. SpaceX announced in November 2018 that they would like to operate an initial shell of about 1,600 satellites in the constellation at about 550 kilometres (340 mi) orbital altitude, at an altitude similar to the orbits Tintin A and B stayed in.
The satellites currently orbit in a circular low Earth orbit at about 500 kilometers (310 mi) altitude in a high-inclination orbit for a planned six to twelve-month duration. The satellites will communicate with three testing ground stations in Washington and California for short-term experiments of less than ten minutes duration, roughly daily.
The 60 Starlink v0.9 satellites, launched May 2019, have the following characteristics:
The 60 Starlink v1.0 satellites, launched November 2019, have the additional following characteristics:
In addition to the OneWeb constellation, announced nearly concurrently with the SpaceX constellation, a 2015 proposal from Samsung outlined a 4,600-satellite constellation orbiting at 1,400 kilometers (900 miles) that could provide a zettabyte per month capacity worldwide, an equivalent of 200 gigabytes per month for 5 billion users of Internet data, but by 2020, no more public information had been released about the Samsung constellation. Telesat announced a smaller 117 satellite constellation in 2015 with plans to deliver initial service in 2021. Amazon announced a large broadband internet satellite constellation in April 2019, planning to launch 3,236 satellites in the next decade in what the company calls "Project Kuiper", a satellite constellation that will work in concert with Amazon's previously announced large network of twelve satellite ground station facilities (the "AWS Ground Station unit") announced in November 2018.
By October 2017, the expectation for large increases in satellite network capacity from emerging lower-altitude broadband constellations caused market players to cancel some planned investments in new geosynchronous orbit broadband communications satellites.
A large number of planned satellites has been met with criticism from the astronomical community. Astronomers claim that the number of visible satellites will outnumber visible stars, and that their brightness in both optical and radio wavelengths will severely impact scientific observations. Because the Starlink satellites can autonomously change their orbits, observations cannot be scheduled to avoid them. The International Astronomical Union (IAU) and National Radio Astronomy Observatory (NRAO) have released official statements expressing concern on the matter.
SpaceX representatives and Musk have claimed that the satellites will have minimal impact. Many professional astronomers have disputed these claims based on initial observation of the Starlink v0.9 satellites on the first launch, shortly after their deployment from the launch vehicle. In later statements on Twitter, Musk stated that SpaceX will work on reducing the albedo of the satellites and will provide on-demand orientation adjustments for astronomical experiments, if necessary.
SpaceX has mitigated concerns about the long term danger of space junk resulting from placing thousands of satellites in orbit in part by lowering the planned orbit of the satellites. Failed satellites are expected to deorbit within a few years.
The system is designed to improve global internet access by utilizing thousands of satellites in Low Earth orbit. SpaceX President Gwynne Shotwell stated in a TED Talk last month that she expects the constellation to cost at least $10 billion. Therefore, reducing launch costs will be vital.
lower the orbit of nearly 1,600 of its proposed broadband satellites. The Federal Communications Commission said April 26 it was OK with SpaceX changing its plans to orbit those satellites at 550-kilometer (340 mi) kilometers instead of 1,150-kilometer (710 mi) kilometers. SpaceX says the adjustment, requested six months ago, will make a safer space environment, since any defunct satellites at the lower altitude would reenter the Earth's atmosphere in five years even without propulsion. The lower orbit also means more distance between Starlink and competing internet constellations proposed by OneWeb and Telesat. FCC approval allows satellite companies to provide communications services in the United States. The agency granted SpaceX market access in March 2018 for 4,425 satellites using Ku- and Ka-band spectrum, and authorized 7,518 V-band satellites in November. SpaceX’s modified plans apply to the smaller of the two constellations.
Space Exploration Holdings, LLC seeks to modify its Ku/Ka-band NGSO license to relocate satellites previously authorized to operate at an altitude of 1,150-kilometer (710 mi) to an altitude of 550-kilometer (340 mi), and to make related changes to the operations of the satellites in this new lower shell of the constellation.
SpaceX seeks experimental authority for two types of testing: (1) a total of 70 user terminals (mixed between the two types of antennas) so that it can test multiple devices at a number of geographically dispersed locations throughout the United States; and (2) up to 200 phased array user terminals to be deployed within the state of Washington at the homes of SpaceX employees for ongoing testing. Such authority would enable SpaceX to obtain critical data regarding the operational performance of these user terminals and the SpaceX NGSO system.
SpaceX seeks an experimental authorization to test activities… tests are designed to demonstrate the ability to transmit and receive information (1) between five ground sites ("Ground-to-Ground") and (2) between four ground sites and an airborne aircraft ("Ground-to-Air"). … This application seeks only to use an earth station to transmit signals to the SpaceX satellites first from the ground and later from a moving aircraft.
Construction of the first prototype spaceship is in progress. "We're actually building that ship right now", he said. "I think we'll probably be able to do short flights, short sort of up-and-down flights, probably sometime in the first half of next year".
SpaceX pointed out that it recently announced plans to build a network of 4,000 non-geostationary orbit (NGSO) communications satellites, which it will manufacture, launch and operate.
The overall outcome is that propellant different from xenon can provide significant economic benefits in the long term for commercial telecom applications. In particular, krypton would allow for a major reduction of qualification and operation costs with minor performance drawbacks.