small satellite constellations

small satellite constellations插图

Examples of satelliteconstellationsinclude the Global Positioning SystemGlobal Positioning SystemThe Global Positioning System (GPS) is a space-based navigation system that provides location and time information in all weather conditions, anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. The system provides critical capabilitie…, Galileo and GLONASS constellationsfor navigation and geodesy, RASAT, the Disaster Monitoring Constellation(DMC), RapidEyeRapidEyeRapidEye AG was a German geospatial information provider focused on assisting in management decision-making through services based on their own Earth observation imagery. The company operated a five-satellite constellation producing 5-meter resolution imagery that was d…, COSMO-SkyMed (COnstellation of smallSatellitesfor the Mediterranean basin Observation), and Huanjing constellation (the SmallSatelliteConstellationfor Environment Protection and Disaster Monitoring) for remote sensing (table 2)….

Why are geo constellations so expensive to launch?

At present, the relative efficiency of medium and heavy launch vehicles, which are used to place large, costly satellites into GEO, helps make such constellations more cost-effective for many missions than large constellations made up of small satellites. Individually, the cost of lifting large satellites into GEO is very expensive.

What is the difference between a constellation and a satellite mission?

Many, if not most, satellite missions can, in theory, be performed by either type of constellation. But the former approach requires small numbers of complex and costly satellites, while the latter approach requires large numbers of less complex and costly satellites.

Can a large constellation of small satellites work in Leo?

It is also a mission for which a large constellation of small satellites in LEO might prove especially effective because of the satellites’ relatively low altitude and high revisit rates—assuming cross-link and constellation management challenges can be overcome.

Can small satellite constellations improve resiliency of communications links?

MOUNTAIN VIEW, Calif. – Small satellite constellations promise to improve the resiliency of communications links, according to speakers at the SmallSat Symposium here.

What is the rest of the industry doing?

One other interesting feature of the current space industry is that smallsat constellations are becoming popular in the communication sector too: Iridium is currently launching its 2nd-generation constellation, SpaceX is thinking about launching several thousands of LEO communication satellites, and OneWeb is securing funds for a similar constellation. The OneWeb project is the most interesting because it has attracted several billions in financing, and a partnership with Airbus to build a new factory to mass-produce small satellites. This factory is set to produce 700 satellites, weighing 150kg each, for half a million dollar a piece. After the OneWeb production run, Airbus is even considering using the same low-cost platform for Earth observation, and sees the US government as a potential customer.

Why are constellations of small satellites the best way forward to get high revisit rates?

Overall, constellations of small satellites are the best way forward to get high revisit rates: they have no technical risk, are relatively cheap, and can still provide submetric resolution. The combination of a global coverage, medium-resolution component with a higher-resolution system also gives them the ability to act as a highly responsive, uncued search system. Along with lower launch costs, this ensures they will play a big role in the future of Earth observation.

What are the limitations of satellite constellations?

However, one of the main limitations of small satellite constellations is that since the satellites have limited agility, if there are many areas to image, and if these areas are in the same region and close to each other, each satellite cannot take pictures of all of them. That means that some satellites have to be tasked to some of the areas of interest, and others the the rest of the areas. This cuts down the revisit rate in the region. Consequently, such constellations can provide an almost persistent surveillance of places spread out all over the world, but when there is a crisis in a region, they cannot perform as well: they cannot provide persistent coverage over all the region at the same time. So they cannot fully replace a fleet of surveillance drones focused on one region in particular, but they can help maintain an up-to-date global picture.

How many spacecraft are in the constellation?

An example of such a constellation is the one planned by BlackSky Global. The full constellation is to include 60 spacecraft on low-inclination orbits, in order to provide high revisit over the most populated areas of the globe:

What is medium resolution satellite imagery?

In some sense, the medium resolution imagery provides peripheral vision to the high-resolution satellites, much in the same way human vision works: only a tiny part of the eye is capable of high resolution, but since that part is pointed at the interesting details, it gives the illusion of high resolution in all the field of view. This idea of combining a medium and a high resolution constellation is not specific to Planet alone: it is also what Digital Globe wants to do with the Scout constellation. BlackSky, on the other hand, is looking into integrating news feed and social media with satellite imagery, and could deploy an algorithm tasking a satellite based on these in the near future.

Can satellites take snapshots?

Such a constellation gives a high revisit: while with a limited number of satellites, it may not be able to provide an uninterrupted video stream of a place, it can take snapshots of it every few minutes. With more satellites, a truly persistent stream might be achievable.

How long are NOAA weather satellites in orbit?

Traditional NOAA weather satellites designed to operate in orbit for at least seven years were expensive, often requiring a decade and several hundred million dollars to move from proposal to orbit.

What is an ESPA ring?

Originally developed to carry secondary payloads on Pentagon-funded Atlas 5 and Delta 4 launches, ESPA rings have become a standard for accommodating small satellites on government and commercial launches of EELV-class rockets, namely Unit ed Launch Alliance’ s vehicles and SpaceX’s Falcon 9.

Why does NOAA need new cost models?

NOAA also needs new cost models because the ones created by NASA and the Defense Department tend to be based on missions involving large government satellites with multiple sensors.

How many kilograms are there in a BAE satellite?

BAE Systems sees promise in constellations of 60- or 70-kilogram satellites following one another in low Earth orbit to reveal changing atmospheric conditions over time, said Kevin Maschhoff, BAE Systems engineering fellow.

What is the European Space Agency?

The European Space Agency is developing a prototype for a constellation of small Arctic Weather Satellite spacecraft. Government agencies are eager to profit from the steady stream of commercial innovation. Companies are relaying communications and gathering weather-related information and imagery with growing fleets of cubesats …

What determines the size of a satellite?

In spite of company preferences, though, everyone noted that government requirements often determine satellite size for a particular program. “The mission drives the capability required onboard: the avionics, propulsion, pointing accuracies, sensors and power requirements for all of those,” said Nick Bucci, vice president for missile defense and space systems at General Atomics Electromagnetic Systems.

Where is the NOAA satellite dish located?

Data from NOAA polar-orbiting satellites is relayed through this satellite dish at McMurdo Station, Antarctica, part of NASA’s Near Earth Network. Credit: Joshua Swanson, National Science Foundation. It’s a good thing the National Oceanic and Atmospheric Administration has plenty …

Why are small satellites important?

Another argument for developing a more robust small-satellite capability is that small satellites represent the most cost-effective approach to acquiring a wartime replenishment reserve. This path is attractive in the case of dispersed constellations of small satellites, not only because of the relatively low cost per satellite but also because—due to the shorter designed service lives of individual satellites—routine replenishment is inherent to the operation of such constellations. Rather than a reserve of dedicated satellites held in long-term storage, this warfighting “reserve” might involve increasing the number of satellites maintained in the replenishment pool, with the pool continually refreshed and upgraded with new technology. However, in the event of an attack, this pool would also constitute an effective reserve.

What are the factors that make constellations more cost effective?

Movement in this direction, which is already clearly visible in commercial space, is the result of a variety of factors, including continued improvements in the miniaturization of computers, sensors, and other technologies and , even more importantly, reductions in space launch costs.

Why is the dispersion of space assets among large constellations of small satellites important?

The dispersion of space assets among large constellations of small satellites also offers an important means of complicating a potential adversary’s task of attacking space-based assets. However, this advantage is by no means a panacea, given the variety of anti-satellite capabilities being developed and potential countermeasures available. More compelling is the opportunity small-satellite capabilities offer as a means of constituting a substantial wartime reserve.

How many AeHF satellites are in orbit?

AEHF: This system is intended to provide secure, jam-resistant communication globally, replacing the legacy Milstar satellite system. So far, four AEHF satellites have been placed in orbit. Another three are scheduled for deployment over the next three years, resulting in a six-satellite constellation by 2020.

Why are satellites smaller than GEO?

By comparison, because the distances involved are so much shorter, satellites operating in LEO can be equipped with less powerful communications equipment and smaller, less complex sensors—resulting in satellites that are generally smaller, less complex, and less costly than satellites operating in GEO.

How many satellites are in the medium class?

A total of 45 of those satellites fall into the large, heavy, and extra-heavy classes. Combined, these three classes account for 72 percent of the total mass for all U.S. military satellites in orbit. Of the remainder, 47 satellites fall into the medium or intermediate classes, and only 12 are classified as small.

What are the potential shifts in satellites?

The potential for such a shift is driven by historical and projected trends in a number of areas, including the miniaturization of electronics, computing, and other technologies related to satellite design and reductions in launch costs (especially costs associated with small launch vehicles). According to some observers, because of these factors and the natural advantages of dispersed satellite constellations for some missions, the time is fast approaching when large constellations made up of small satellites will in many instances prove more cost-effective than the small constellations of large, costly, and complex satellites that currently dominate most national security missions. 2 Trends in the commercial satellite market also suggest a growing role for small satellites deployed in large constellations

How much weight can CubeSat support?

support payloads up to 600 kg each. Furthermore, industry is also developing accommodations for ESPA to support CubeSat deployment.

How much does a 1U CubeSat weigh?

The design specification introduced in 1999 by Bob Twiggs (formerly at Stanford) and Jordi Puig-Suari (Cal Poly San Luis Obispo), defines a 1U CubeSat structure as 10 cm on a side with a mass of no more than 1.33 kg.

What is the second workshop on satellites?

The second three-day workshop focused on identifying technology gaps and future needs for the broad class of science missions identified from the first workshop. This included plenary discussions on the state-of-the-art in small satellite technology as well as a facilitated mission concept design and concurrent engineering session based on the Team-X mission formulation design approach applied at the Jet Propulsion Laboratory. The L5 Sentinel heliophysics concept was used a reference mission for this activity and served as a baseline for additional work performed during the study period. The second workshop also included a public lecture for the community given by Professor Jordi Puig-Suari from California Polytechnic State University at San Luis Obispo on “CubeSat: An Unlikely Success Story”.

What are the three potential concepts?

The set of potential concepts, three per focus area, are listed in the following table. The astrophysics concepts are RELIC , SoftX, and UVIP-UV Reionizaton Probe. These mission concepts were selected to span most of the spectrum where important scientific discoveries could be made. The heliophysics concepts are IMCC, Solar Polar Constellation, and Fractionated L5 Space Weather Sentinel Constellation. They emphasized large-scale first-of-a-kind multipoint physics measurements that take advantage of distributed and fractionated small satellite observation capabilities. The planetary concepts are ExCSITE, C/entinel, and Lunar Cube Vibrations. These were largely multi-scale spacecraft systems using a few host spacecraft with hundreds to thousands of observers. These nine concepts represent the final set proposed within focus groups during the first workshop, but there were many other ideas generated during discussions, like the CHAMPAGNE planetary ring explorer concept, that is briefly introduced as well.

What is a limsat?

LIMSAT is a proposed low mass and low cost small satellite constellation mission of eight telescopes designed to carry out a wide-field UV transient survey. It is aimed at studying shock breakouts of supernovae producing important science at low risk. With an instantaneous field of view of 1,200 square degrees (covered by eight telescopes) LIMSat expects to detect a shock breakout every month. When compared to a mission like GALEX, LIMSat has a sensitivity goal approximately ten times less with a field of view goal that is approximately 1,000 times larger. If these requirements were met, LIMSat would have a detection rate 30 times higher than GALEX based on a small satellite design.

How did the universe become ionized?

Following the Big Bang, and prior to recombination, the Universe was fully ionized when the protons and electrons combined to form hydrogen and the Universe became neutral and dark. Eventually, the first stars and galaxies formed and the Dark Age ended. UV light from these first bright objects disassociated the Hydrogen atoms to recognize the universe. This is the state of most of the Universe today, fully ionized and very low density making it essentially transparent to electromagnetic radiation and thus enabling us to see very distant objects. The process by which the early universe became re-ionized is not very well understood yet a leading candidate is the UV light from young star-forming galaxies that escapes (or leaks) from these galaxies and disassociates the local hydrogen atoms in an ever-expanding volume around these galaxies until eventually most of the Universe is recognized.

What is the purpose of the satellite report?

It is also meant to serve as a public document to inform the larger community of the role small satellites can have to initiate a new program of exploration and discovery in space science. As such, it includes recommendations that could inform programmatic