[Submitted on 15 Jul 2020 (v1), last revised 16 Jul 2020 (this version, v2)]
Authors:N. H. Crisp, P. C. E. Roberts, S. Livadiotti, V. T. A. Oiko, S. Edmondson, S. J. Haigh, C. Huyton, L. Sinpetru, K. L. Smith, S. D. Worrall, J. Becedas, R. M. Domínguez, D. González, V. Hanessian, A. Mølgaard, J. Nielsen, M. Bisgaard, Y. -A. Chan, S. Fasoulas, G. H. Herdrich, F. Romano, C. Traub, D. García-Almiñana, S. Rodríguez-Donaire, M. Sureda, D. Kataria, R. Outlaw, B. Belkouchi, A. Conte, J. S. Perez, R. Villain, B. Heißerer, A. Schwalber
Download PDF
Abstract:Very low Earth orbits (VLEO), typically classified as orbits below approximately 450 km in altitude, have the potential to provide significant benefits to spacecraft over those that operate in higher altitude orbits. This paper provides a comprehensive review and analysis of these benefits to spacecraft operations in VLEO, with parametric investigation of those which apply specifically to Earth observation missions. The most significant benefit for optical imaging systems is that a reduction in orbital altitude improves spatial resolution for a similar payload specification. Alternatively mass and volume savings can be made whilst maintaining a given performance. Similarly, for radar and lidar systems, the signal-to-noise ratio can be improved. Additional benefits include improved geospatial position accuracy, improvements in communications link-budgets, and greater launch vehicle insertion capability. The collision risk with orbital debris and radiation environment can be shown to be improved in lower altitude orbits, whilst compliance with IADC guidelines for spacecraft post-mission lifetime and deorbit is also assisted. Finally, VLEO offers opportunities to exploit novel atmosphere-breathing electric propulsion systems and aerodynamic attitude and orbit control methods.
However, key challenges associated with our understanding of the lower thermosphere, aerodynamic drag, the requirement to provide a meaningful orbital lifetime whilst minimising spacecraft mass and complexity, and atomic oxygen erosion still require further research. Given the scope for significant commercial, societal, and environmental impact which can be realised with higher performing Earth observation platforms, renewed research efforts to address the challenges associated with VLEO operations are required.
Submission history
From: Nicholas Crisp [view email]
[v1] Wed, 15 Jul 2020 14:16:34 UTC (6,556 KB)
[v2] Thu, 16 Jul 2020 10:10:11 UTC (5,745 KB)
FAQs
As the orbital altitude is reduced the aperture diameter can be made smaller whilst broadly maintaining the same radiometric performance and spatial resolution. Alternatively, if the same aperture diameter is maintained the radiometric performance and spatial resolution will be improved with reducing altitude.
What are the benefits of Earth observation satellites? ›
They provide essential information on a vast number of areas, including; ocean salinity, ice thickness, crop health, and air quality.
What are the pros and cons of low Earth orbit? ›
Disadvantages: susceptibility to electromagnetic interference and link failures. Advantages: high coverage, low latency, ability to overcome geographic conditions. Disadvantages: susceptibility to electromagnetic interference and link failures. Advantages of LEO satellites include low-latency and global coverage.
What is the best orbit for Earth observation? ›
Geosynchronous Orbit (GSO) & Geostationary Orbit (GEO)
It matches the planet's rotation, but GEO objects only orbit Earth's equator, and from the ground perspective, they appear in a fixed position in the sky. GSO and GEO are used for telecommunications and Earth observation.
What are the benefits of orbit? ›
Chewing on Orbit (sugar free) is much better than the ones with sugar as constant Chewing will stimulate the salivary glands which in turn produce more saliva helping in rinsing of the oral cavity. But excess Chewing on any gum can lead to wearing out of the teeth.
What are at least two of the benefits of human exploration beyond low Earth orbit? ›
Human exploration drives innovation and economic expansion, addresses space and terrestrial challenges to improve life on Earth, and inspires people around the world. Integral to these benefits are scientific investigation and discovery.
What is the purpose of Earth observation? ›
Monitoring natural resources such as land, soils and oceans and environmental sinks, including air and water pollution. Earth observation data can offer a wealth of information on water quality, soil carbon and soil moisture, and the oceans.
What are the benefits of monitoring the Earth's climate with satellites? ›
Satellites are ideal for monitoring climate change because they can monitor the concentration of greenhouse gases in the atmosphere, such as aerosols, water vapor, carbon monoxide (CO), carbon-dioxide (CO2) and methane.
What are some benefits that satellites provide to society? ›
Satellites that circle the globe provide the most accurate weather reports and warn us of impending storms; they monitor our climate every day, helping to track increasing rates of climate change and its effects, such as rising seas and changing moisture levels, wildfires and atmospheric changes; they connect millions ...
What is the low Earth orbit theory? ›
A low Earth Sun-synchronous orbit (SSO) is an orbit in which a satellite has the same position relative to the Sun and thus passes over the same region of Earth at the same time every day. This allows for the study of changes to a specific area of Earth over time.
Table Comparison Between LEO and GEO
| Low-Earth (LEO) | Geostationary (GEO) |
|---|
| Total energy | Lower (gravitational potential energy is more negative) | Higher |
| Orbital period | Shorter | Longer. Orbital period is approximately 24 hours. |
| Orbital velocity | Faster | Slower |
4 more rowsVery Low Earth Orbit (VLEO), situated at an altitude between 100 and approximately 450 km (most commonly 250-350 km) is becoming increasingly attractive for both commercial and scientific endeavours. "It is easier to get to, requires fewer resources for communications, and allows for smaller payloads.
What are the disadvantages of low Earth orbit? ›
Like running against a strong wind, atmospheric drag can decrease satellite speed. As a result, satellites in LEO must burn fuel frequently versus other orbits to maintain their position or risk burning up as their orbit decays and they reenter Earth's atmosphere.
What is special about Earth's orbit? ›
In Earth's case, its orbit is nearly circular, so that the difference between Earth's farthest point from the Sun and its closest point is very small. Earth's orbit defines a two-dimensional plane which we call the ecliptic. It takes roughly 365 days for the Earth to go around the Sun once.
Which observation provides the best evidence that Earth revolves? ›
One of the best pieces of evidence that the Earth spins on its axis is the apparent motion of the stars in the sky. As the Earth rotates on its axis, the stars appear to move in a circular path around the celestial poles, which are located directly above the Earth's North and South poles.
What is a disadvantage of low Earth orbit is a short dwell time? ›
The primary disadvantages of being deployed in LEO include experiencing some atmospheric drag leading to loss of orbit, and shorter life spans of the satellites. Also, due to their high apparent angular velocity, LEO satellites have a smaller “dwell” time (in which the object is visible to one part of the Earth).
What is very low earth orbit? ›
Very Low Earth Orbit (VLEO), situated at an altitude between 100 and approximately 450 km (most commonly 250-350 km) is becoming increasingly attractive for both commercial and scientific endeavours. "It is easier to get to, requires fewer resources for communications, and allows for smaller payloads.
Is low Earth orbit stable? ›
It's only that in low-Earth orbit, the atmospheric drag is such a large effect that the decays happen on timescales of less than a human lifespan! All the orbits are unstable after all, but some are more unstable than others.
