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56-554: Riding atop the launcher's final stage, SHERPA's release follows deployment of the primary mission payload for the dispensing of minisatellites, microsatellites, or nanosatellites such as CubeSats . SHERPA builds upon the capabilities of the Spaceflight Secondary Payload System (SSPS) by incorporating propulsion and power generation subsystems, which creates a propulsive tug dedicated to maneuvering to an optimal orbit to place secondary and hosted payloads. SHERPA

112-404: A = 7200 km , i.e., for an altitude a − R E ≈ 800 km of the spacecraft over Earth's surface, this formula gives a Sun-synchronous inclination of 98.7°. Note that according to this approximation cos i equals −1 when the semi-major axis equals 12 352  km , which means that only lower orbits can be Sun-synchronous. The period can be in the range from 88 minutes for

168-399: A SpaceX Falcon 9 Block 5 is an optional third stage for delivery of deployable and hosted payloads in low earth orbit (LEO) and polar orbit (SSO). SHERPA-AC Augmented version of the free-flying SHERPA-FX equipped with attitude knowledge & control capabilities and a flight computer, optimized for hosted payloads. SHERPA-LTC SHERPA LTC is an optional third stage that utilizes

224-435: A formation . The generic term "small satellite" or "smallsat" is also sometimes used, as is "satlet". Examples: Astrid-1 and Astrid-2, as well as the set of satellites currently announced for LauncherOne (below) In 2018, the two Mars Cube One microsats—massing just 13.5 kg (30 lb) each—became the first CubeSats to leave Earth orbit for use in interplanetary space. They flew on their way to Mars alongside

280-518: A heliosynchronous orbit , is a nearly polar orbit around a planet, in which the satellite passes over any given point of the planet's surface at the same local mean solar time . More technically, it is an orbit arranged so that it precesses through one complete revolution each year, so it always maintains the same relationship with the Sun. A Sun-synchronous orbit is useful for imaging , reconnaissance , and weather satellites , because every time that

336-464: A 10 kg (22 lb) payload into a 250 km (160 mi) orbit to an even-more-capable clustered "20/450 Nano/Micro Satellite Launch Vehicle" (NMSLV) capable of delivering 20 kg (44 lb) payloads into 450 km (280 mi) circular orbits . The Boeing Small Launch Vehicle is an air-launched three-stage-to-orbit launch vehicle concept aimed to launch small payloads of 45 kg (100 lb) into low Earth orbit. The program

392-542: A Sun-synchronous orbit. The angular precession per orbit for an Earth orbiting satellite is approximately given by where An orbit will be Sun-synchronous when the precession rate ρ = ⁠ d Ω / d t ⁠ equals the mean motion of the Earth about the Sun n E , which is 360° per sidereal year ( 1.990 968 71 × 10   rad /s ), so we must set n E = ⁠ Δ Ω E / T E ⁠ = ρ = ⁠ Δ Ω / T ⁠ , where T E

448-520: A bi-propellant propulsion system to deliver satellites and hosted payloads to low earth orbit (LEO) and polar orbit (SSO). Propulsion system by Benchmark Space Systems uses high test peroxide and isopropanol as propellants, with four pressure-fed 22 N thrusters. SHERPA-LTE SHERPA LTE is an optional third stage that utilizes a Xenon propulsion system to deliver satellites and hosted payloads to Geostationary orbit (GEO), Cislunar, or Earth-escape orbits. SHERPA-ES SHERPA-ES (SHERPA EScape)

504-562: A dragsail to lower its orbit before payload deployment. The 400 variant is used for low Earth orbit deployments, and it features two tanks with mono-propellant. SHERPA 400 has a fueled mass of 1,000 kilograms and it has a maximum capacity of 1,500 kg (3,300 lb) to low Earth orbit. It is capable of accompanying a primary payload to 800 km and then lower its orbit to a more favorable altitude to drop off secondaries. Most small satellites are required to orbit at about 450 kilometers to deorbit or move to an unused orbit within 25 years of

560-435: A larger "mother" satellite for communication with ground controllers or for launching and docking with picosatellites. Picosatellites are emerging as a new alternative for do-it-yourself kitbuilders. Picosatellites are currently commercially available across the full range of 0.1–1 kg (0.22–2.2 lb). Launch opportunities are now available for $ 12,000 to $ 18,000 for sub-1 kg picosat payloads that are approximately

616-425: A market value estimated at US$ 7.4 billion . By mid-2015, many more launch options had become available for smallsats, and rides as secondary payloads had become both greater in quantity and easier to schedule on shorter notice. In a surprising turn of events, the U.S. Department of Defense , which had for decades procured heavy satellites on decade-long procurement cycles, is making a transition to smallsats in

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672-433: A mass of no more than 1.33 kilograms (2.9 lb) per unit. The CubeSat concept was first developed in 1999 by a collaborative team of California Polytechnic State University and Stanford University , and the specifications, for use by anyone planning to launch a CubeSat-style nanosatellite, are maintained by this group. With continued advances in the miniaturization and capability increase of electronic technology and

728-474: A number of companies began development of launch vehicles specifically targeted at the smallsat market. In particular, with larger numbers of smallsats flying, the secondary payload paradigm does not provide the specificity required for many small satellites that have unique orbital and launch-timing requirements. Some USA-based private companies that at some point in time have launched smallsat launch vehicles commercially: The term "microsatellite" or "microsat"

784-463: A satellite in Sun-synchronous orbit might ascend across the equator twelve times a day, each time at approximately 15:00 mean local time. Special cases of the Sun-synchronous orbit are the noon/midnight orbit , where the local mean solar time of passage for equatorial latitudes is around noon or midnight, and the dawn/dusk orbit , where the local mean solar time of passage for equatorial latitudes

840-525: A spot on the Earth at the same local time each time, this refers to mean solar time , not to apparent solar time . The Sun will not be in exactly the same position in the sky during the course of the year (see Equation of time and Analemma ). Sun-synchronous orbits are mostly selected for Earth observation satellites , with an altitude typically between 600 and 1000 km over the Earth surface. Even if an orbit remains Sun-synchronous, however, other orbital parameters such as argument of periapsis and

896-412: A very low orbit ( a = 6554 km , i = 96°) to 3.8 hours ( a = 12 352  km , but this orbit would be equatorial, with i = 180°). A period longer than 3.8 hours may be possible by using an eccentric orbit with p < 12 352  km but a > 12 352  km . If one wants a satellite to fly over some given spot on Earth every day at the same hour, the satellite must complete

952-402: A whole number of orbits per day. Assuming a circular orbit, this comes down to between 7 and 16 orbits per day, as doing less than 7 orbits would require an altitude above the maximum for a Sun-synchronous orbit, and doing more than 16 would require an orbit inside the Earth's atmosphere or surface. The resulting valid orbits are shown in the following table. (The table has been calculated assuming

1008-544: Is a satellite of low mass and size, usually under 1,200 kg (2,600 lb). While all such satellites can be referred to as "small", different classifications are used to categorize them based on mass . Satellites can be built small to reduce the large economic cost of launch vehicles and the costs associated with construction. Miniature satellites, especially in large numbers, may be more useful than fewer, larger ones for some purposes – for example, gathering of scientific data and radio relay . Technical challenges in

1064-776: Is a commercial derivative of the ESPA Grande ring , and it was developed and manufactured by Andrews Space , a subsidiary of Spaceflight Industries since 2010 and was unveiled in May 2012. Spaceflight Industries fabricates SHERPA, and the SSPS, at its facility in Tukwila, Washington. Riding atop the launcher's final stage, SHERPA is to be separated from the launch vehicle prior to any deployments or dispensing of minisatellites, microsatellites, nanosatellites and CubeSats . SHERPA features an optional propulsion system to place its payloads in an orbit other than

1120-530: Is a high-energy SHERPA-NG variant that will utilize the same bi-propellant propulsion system as SHERPA-LTC with 6 times more propellant to deliver satellites and hosted payloads to geostationary and cislunar orbits. The first flight of this variant, designated "GEO Pathfinder", is planned for early 2025 as a rideshare on the IM-2 mission. 18:34:05 B1046.3 15:00 19:31 18:35 02:09 Nanosatellite A small satellite , miniaturized satellite , or smallsat

1176-506: Is a three-axis stabilized platform capable of on-orbit maneuvering meant to deploy small satellites carried as secondary payloads on rideshare orbital launches. SHERPA is integrated to the rocket as a standard adapter that is designed to fit on the SpaceX Falcon 9 , Orbital Sciences Corp.'s Antares , and United Launch Alliance's Atlas V and Delta rockets . SHERPA is to be separated from the launch vehicle prior to any deployments. SHERPA

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1232-407: Is around sunrise or sunset, so that the satellite rides the terminator between day and night. Riding the terminator is useful for active radar satellites, as the satellites' solar panels can always see the Sun, without being shadowed by the Earth. It is also useful for some satellites with passive instruments that need to limit the Sun's influence on the measurements, as it is possible to always point

1288-681: Is designed to form a quantum communication network as well as communicate with Earth through an optical ground station. The term "small satellite", or sometimes "minisatellite", often refers to an artificial satellite with a wet mass (including fuel) between 100 and 500 kg (220 and 1,100 lb), but in other usage has come to mean any satellite under 500 kg (1,100 lb). Small satellite examples include Demeter , Essaim , Parasol , Picard , MICROSCOPE , TARANIS , ELISA , SSOT , SMART-1 , Spirale-A and -B , and Starlink satellites. Although smallsats have traditionally been launched as secondary payloads on larger launch vehicles,

1344-517: Is proposed to drive down launch costs for U.S. military small satellites to as low as US$ 300,000 per launch ($ 7,000/kg) and, if the development program was funded, as of 2012 could be operational by 2020. The Swiss company Swiss Space Systems (S3) has announced plans in 2013 to develop a suborbital spaceplane named SOAR that would launch a microsat launch vehicle capable of putting a payload of up to 250 kg (550 lb) into low Earth orbit. The Spanish company PLD Space born in 2011 with

1400-411: Is the earth orbital period while T is the period of the spacecraft around the earth. As the orbital period of a spacecraft is where a is the semi-major axis of the orbit, and μ is the standard gravitational parameter of the planet ( 398 600 .440 km /s for Earth); as p ≈ a for a circular or almost circular orbit, it follows that or when ρ is 360° per year, As an example, with

1456-695: Is the opportunity to enable missions that a larger satellite could not accomplish, such as: The nanosatellite and microsatellite segments of the satellite launch industry have been growing rapidly in the 2010s. Development activity in the 1–50 kg (2.2–110.2 lb) range has been significantly exceeding that in the 50–100 kg (110–220 lb) range. In the 1–50 kg range alone, fewer than 15 satellites were launched annually in 2000 to 2005, 34 in 2006, then fewer than 30 launches annually during 2007 to 2011. This rose to 34 launched in 2012 and 92 launched in 2013. European analyst Euroconsult projects more than 500 smallsats being launched in 2015–2019 with

1512-422: Is usually applied to the name of an artificial satellite with a wet mass between 10 and 100 kg (22 and 220 lb). However, this is not an official convention and sometimes those terms can refer to satellites larger than that, or smaller than that (e.g., 1–50 kg (2.2–110.2 lb)). Sometimes, designs or proposed designs from some satellites of these types have microsatellites working together or in

1568-481: The PicoSAT series of microsatellites) is usually applied to artificial satellites with a wet mass between 0.1 and 1 kg (0.22 and 2.2 lb), although it is sometimes used to refer to any satellite that is under 1 kg in launch mass. Again, designs and proposed designs of these types usually have multiple picosatellites working together or in formation (sometimes the term "swarm" is applied). Some designs require

1624-418: The orbital eccentricity evolve, due to higher-order perturbations in the Earth's gravitational field, the pressure of sunlight, and other causes. Earth observation satellites, in particular, prefer orbits with constant altitude when passing over the same spot. Careful selection of eccentricity and location of perigee reveals specific combinations where the rate of change of perturbations are minimized, and hence

1680-595: The 2020s. The office of space acquisition and integration said in January 2023 that "the era of massive satellites needs to be in the rear view mirror for the Department of Defense" with small satellites being procured for DoD needs in all orbital regimes, regardless of "whether it's LEO MEO or GEO " while aiming for procurements in under three years. The smaller satellites are deemed to be harder for an enemy to target, as well as providing more resilience through redundancy in

1736-399: The 96–100- minute range, and inclinations of around 98°. This is slightly retrograde compared to the direction of Earth's rotation: 0° represents an equatorial orbit, and 90° represents a polar orbit. Sun-synchronous orbits are possible around other oblate planets, such as Mars . A satellite orbiting a planet such as Venus that is almost spherical will need an outside push to maintain

SHERPA (space tug) - Misplaced Pages Continue

1792-517: The DARPA SeeMe program that intended to release a " constellation of 24 micro-satellites (~20 kg (44 lb) range) each with 1-m imaging resolution ." The program was cancelled in December 2015. In April 2013, Garvey Spacecraft was awarded a US$ 200,000 contract to evolve their Prospector 18 suborbital launch vehicle technology into an orbital nanosat launch vehicle capable of delivering

1848-578: The Earth's movement around the Sun . This precession is achieved by tuning the inclination to the altitude of the orbit (see Technical details ) such that Earth's equatorial bulge , which perturbs inclined orbits, causes the orbital plane of the spacecraft to precess with the desired rate. The plane of the orbit is not fixed in space relative to the distant stars, but rotates slowly about the Earth's axis. Typical Sun-synchronous orbits around Earth are about 600–800 km (370–500 mi) in altitude, with periods in

1904-454: The ISS external platform Materials International Space Station Experiment (MISSE-8) for testing. In April 2014, the nanosatellite KickSat was launched aboard a Falcon 9 rocket with the intention of releasing 104 femtosatellite-sized chipsats, or "Sprites". In the event, they were unable to complete the deployment on time due to a failure of an onboard clock and the deployment mechanism reentered

1960-924: The atmosphere and burned up. Small satellites usually require innovative propulsion, attitude control , communication and computation systems. Larger satellites usually use monopropellants or bipropellant combustion systems for propulsion and attitude control; these systems are complex and require a minimal amount of volume to surface area to dissipate heat. These systems may be used on larger small satellites, while other micro/nanosats have to use electric propulsion, compressed gas, vaporizable liquids such as butane or carbon dioxide or other innovative propulsion systems that are simple, cheap and scalable. Small satellites can use conventional radio systems in UHF, VHF, S-band and X-band, although often miniaturized using more up-to-date technology as compared to larger satellites. Tiny satellites such as nanosats and small microsats may lack

2016-595: The atmosphere on 14 May 2014, without having deployed any of the 5-gram femtosats. ThumbSat is another project intending to launch femtosatellites in the late 2010s. ThumbSat announced a launch agreement with CubeCat in 2017 to launch up to 1000 of the very small satellites. In March 2019, the CubeSat KickSat-2 deployed 105 femtosats called "ChipSats" into Earth orbit. Each of the ChipSats weighed 4 grams. The satellites were tested for 3 days, and they then reentered

2072-649: The construction of small satellites may include the lack of sufficient power storage or of room for a propulsion system . One rationale for miniaturizing satellites is to reduce the cost; heavier satellites require larger rockets with greater thrust that also have greater cost to finance. In contrast, smaller and lighter satellites require smaller and cheaper launch vehicles and can sometimes be launched in multiples. They can also be launched 'piggyback', using excess capacity on larger launch vehicles. Miniaturized satellites allow for cheaper designs and ease of mass production. Another major reason for developing small satellites

2128-655: The design of LauncherOne". Virgin Orbit has been working on the LauncherOne concept since late 2008, and as of 2015 , is making it a larger part of Virgin's core business plan as the Virgin human spaceflight program has experienced multiple delays and a fatal accident in 2014. In December 2012, DARPA announced that the Airborne Launch Assist Space Access program would provide the microsatellite rocket booster for

2184-645: The design of a large distributed network of satellite assets . In 2021, the first autonomous nanosatellites , part of the Adelis-SAMSON mission, designed and developed by the Technion and Rafael in Israel were launched into space. In 2023, SpaceX launched a 20cm quantum communication nano satellite developed by the Tel Aviv University , it is the world's first quantum communication satellite. TAU's nanosatellite

2240-428: The emergence of the technological advances of miniaturization and increased capital to support private spaceflight initiatives in the 2010s, several startups have been formed to pursue opportunities with developing a variety of small-payload Nanosatellite Launch Vehicle (NLV) technologies. NLVs proposed or under development include: Actual NS launches: The term "picosatellite" or "picosat" (not to be confused with

2296-421: The instruments towards the night side of the Earth. The dawn/dusk orbit has been used for solar-observing scientific satellites such as TRACE , Hinode and PROBA-2 , affording them a nearly continuous view of the Sun. A Sun-synchronous orbit is achieved by having the osculating orbital plane precess (rotate) approximately one degree eastward each day with respect to the celestial sphere to keep pace with

SHERPA (space tug) - Misplaced Pages Continue

2352-453: The last launch on 25 May 2022. There are at least five SHERPA variants: SHERPA (non-propelled), SHERPA 400, 1000, 2200 and FX. Each SHERPA is able to be launched in a stacked configuration with other SHERPA modules for later separation and independent free-flying. The basic SHERPA is based on a commonly-used secondary payload adapter known as an ESPA ring and it is not propelled. It is used for low Earth orbit deployments, and can unfurl

2408-483: The mission's completion. This variant features additional monopropellant volume stored in 4 tanks. The 2200 variant has a fueled mass of 2,000 kg and it features a more powerful bi-propellant fuel (stored in 4 tanks) for the delivery of small payloads to geostationary transfer orbit (GTO) as well as the lunar environs. GTO is a highly elliptical Earth orbit with an apogee of 42,164 km (26,199 mi). SHERPA-FX The FX variant, intended to be flown on board

2464-482: The objective of developing low cost launch vehicles called Miura 1 and Miura 5 with the capacity to place up to 150 kg (330 lb) into orbit. The term "nanosatellite" or "nanosat" is applied to an artificial satellite with a wet mass between 1 and 10 kg (2.2 and 22.0 lb). Designs and proposed designs of these types may be launched individually, or they may have multiple nanosatellites working together or in formation, in which case, sometimes

2520-705: The opportunity to test new hardware with reduced expense in testing. Furthermore, since the overall cost risk in the mission is much lower, more up-to-date but less space-proven technology can be incorporated into micro and nanosats than can be used in much larger, more expensive missions with less appetite for risk. Small satellites are difficult to track with ground-based radar, so it is difficult to predict if they will collide with other satellites or human-occupied spacecraft. The U.S. Federal Communications Commission has rejected at least one small satellite launch request on these safety grounds. Sun-synchronous orbit A Sun-synchronous orbit ( SSO ), also called

2576-403: The periods given. The orbital period that should be used is actually slightly longer. For instance, a retrograde equatorial orbit that passes over the same spot after 24 hours has a true period about ⁠ 365 / 364 ⁠ ≈ 1.0027 times longer than the time between overpasses. For non-equatorial orbits the factor is closer to 1.) When one says that a Sun-synchronous orbit goes over

2632-514: The power supply or mass for large conventional radio transponders , and various miniaturized or innovative communications systems have been proposed, such as laser receivers, antenna arrays and satellite-to-satellite communication networks. Few of these have been demonstrated in practice. Electronics need to be rigorously tested and modified to be "space hardened" or resistant to the outer space environment (vacuum, microgravity, thermal extremes, and radiation exposure). Miniaturized satellites allow for

2688-460: The primary payload's orbit. The powered variants are capable of large orbit change. SHERPA's first mission was to deploy 90 small payloads, during a 2015 launch on a Falcon 9 rocket, then it was rescheduled for 2017, but delays caused in part by a Falcon 9 rocket explosion on a launch pad in 2016, prompted Spaceflight to cancel the mission. SpaceX appears to have severed ties with Spaceflight Inc., but has continued to fly manifested missions with

2744-929: The same mission cost, with significantly increased revisit times: every area of the globe can be imaged every 3.5 hours rather than the once per 24 hours with the RapidEye constellation. More rapid revisit times are a significant improvement for nations performing disaster response, which was the purpose of the RapidEye constellation. Additionally, the nanosat option would allow more nations to own their own satellite for off-peak (non-disaster) imaging data collection. As costs lower and production times shorten, nanosatellites are becoming increasingly feasible ventures for companies. Example nanosatellites: ExoCube (CP-10) , ArduSat , SPROUT Nanosatellite developers and manufacturers include EnduroSat , GomSpace , NanoAvionics , NanoSpace, Spire , Surrey Satellite Technology , NovaWurks , Dauria Aerospace , Planet Labs and Reaktor . In

2800-430: The satellite is overhead, the surface illumination angle on the planet underneath it is nearly the same. This consistent lighting is a useful characteristic for satellites that image the Earth's surface in visible or infrared wavelengths, such as weather and spy satellites, and for other remote-sensing satellites, such as those carrying ocean and atmospheric remote-sensing instruments that require sunlight. For example,

2856-690: The secondary payload paradigm does not provide the specificity required for many increasingly sophisticated small satellites that have unique orbital and launch-timing requirements. In July 2012, Virgin Orbit announced LauncherOne , an orbital launch vehicle designed to launch "smallsat" primary payloads of 100 kg (220 lb) into low Earth orbit , with launches projected to begin in 2016. Several commercial customers have already contracted for launches, including GeoOptics , Skybox Imaging , Spaceflight Industries , and Planetary Resources . Both Surrey Satellite Technology and Sierra Nevada Space Systems are developing satellite buses "optimized to

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2912-479: The size of a soda can. The term "femtosatellite" or "femtosat" is usually applied to artificial satellites with a wet mass below 100 g (3.5 oz). Like picosatellites, some designs require a larger "mother" satellite for communication with ground controllers. Three prototype "chip satellites" were launched to the ISS on Space Shuttle Endeavour on its final mission in May 2011. They were attached to

2968-608: The successful Mars InSight lander mission. The two microsats accomplished a flyby of Mars in November 2018, and both continued communicating with ground stations on Earth through late December. Both went silent by early January 2019. A number of commercial and military-contractor companies are currently developing microsatellite launch vehicles to perform the increasingly targeted launch requirements of microsatellites. While microsatellites have been carried to space for many years as secondary payloads aboard larger launchers ,

3024-564: The ten years of nanosat launches prior to 2014, only 75 nanosats were launched. Launch rates picked up substantially when in the three-month period from November 2013–January 2014 94 nanosats were launched. One challenge of using nanosats has been the economic delivery of such small satellites to anywhere beyond low Earth orbit . By late 2014, proposals were being developed for larger spacecraft specifically designed to deliver swarms of nanosats to trajectories that are beyond Earth orbit for applications such as exploring distant asteroids. With

3080-417: The term "satellite swarm" or " fractionated spacecraft " may be applied. Some designs require a larger "mother" satellite for communication with ground controllers or for launching and docking with nanosatellites. Over 2300 nanosatellites have been launched as of December 2023. A CubeSat is a common type of nanosatellite, built in cube form based on multiples of 10 cm × 10 cm × 10 cm, with

3136-414: The use of satellite constellations , nanosatellites are increasingly capable of performing commercial missions that previously required microsatellites. For example, a 6U CubeSat standard has been proposed to enable a satellite constellation of thirty five 8 kg (18 lb) Earth-imaging satellites to replace a constellation of five 156 kg (344 lb) RapidEye Earth-imaging satellites, at

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