The Near Earth Object Surveillance Satellite (NEOSSat) is a Canadian

microsatellite A microsatellite is a tract of repetitive DNA in which certain DNA motifs (ranging in length from one to six or more base pairs) are repeated, typically 5–50 times. Microsatellites occur at thousands of locations within an organism's genome. ...

using a 15-cm aperture f/5.88 Maksutov

telescope A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observe ...

(similar to that on the

MOST Most or Möst or ''variation'', may refer to: Places * Most, Kardzhali Province, a village in Bulgaria * Most (city), a city in the Czech Republic ** Most District, a district surrounding the city ** Most Basin, a lowland named after the city ** A ...

spacecraft), with 3-axis stabilisation giving a pointing stability of ~2

arcsecond A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...

s in a ~100 second exposure. It is funded by the

Canadian Space Agency The Canadian Space Agency (CSA; french: Agence spatiale canadienne, ASC) is the national space agency of Canada, established in 1990 by the ''Canadian Space Agency Act''. The president is Lisa Campbell, who took the position on September 3, 2020 ...

(CSA) and

Defence Research and Development Canada Defence Research and Development Canada (DRDC; french: Recherche et développement pour la défense Canada, ''RDDC'') is a special operating agency of the Department of National Defence (DND), whose purpose is to provide the Canadian Armed Forces ...

(DRDC), and searches for interior-to-Earth-orbit (IEO)

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

s, at between 45 and 55 degree solar elongation and +40 to -40 degrees

ecliptic latitude The ecliptic coordinate system is a celestial coordinate system commonly used for representing the apparent positions, orbits, and pole orientations of Solar System objects. Because most planets (except Mercury) and many small Solar System bod ...

Spacecraft

NEOSSat is a suitcase-sized

measuring , including telescope baffle, and weighing . It is powered by

gallium arsenide Gallium arsenide (GaAs) is a III-V direct band gap semiconductor with a Zincblende (crystal structure), zinc blende crystal structure. Gallium arsenide is used in the manufacture of devices such as microwave frequency integrated circuits, monoli ...

(GaAs)

solar cells A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physics, physical and Chemical substance, chemical phenomenon. the entire spacecraft uses around 80 watts of power, with the

bus A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for cha ...

core systems consuming an average of 45 watts. The spacecraft uses miniature

reaction wheel A reaction wheel (RW) is used primarily by spacecraft for three-axis attitude control, and does not require rockets or external applicators of torque. They provide a high pointing accuracy, and are particularly useful when the spacecraft must be ...

s for stabilization and attitude control, and magnetic torque rods to dump excess momentum by pushing against Earth's magnetic field, so no on-board fuel is required for operation. NEOSSat is a descendant of Canada's earlier

satellite. It was built on the Multi-Mission Microsatellite Bus, which was created using data from the development of MOST. Its science payload includes a telescope of the same design as that on MOST, and uses spare CCD detectors from the MOST mission. The sole instrument is a Rumak-Maksutov telescope with a 0.86

degree Degree may refer to: As a unit of measurement * Degree (angle), a unit of angle measurement ** Degree of geographical latitude ** Degree of geographical longitude * Degree symbol (°), a notation used in science, engineering, and mathematics ...

field of view The field of view (FoV) is the extent of the observable world that is seen at any given moment. In the case of optical instruments or sensors it is a solid angle through which a detector is sensitive to electromagnetic radiation. Humans a ...

and a 5.88

focal ratio In optics, the f-number of an optical system such as a camera lens is the ratio of the system's focal length to the diameter of the entrance pupil ("clear aperture").Smith, Warren ''Modern Optical Engineering'', 4th Ed., 2007 McGraw-Hill P ...

. Incoming light is split and focused on two passively cooled 1024×1024 pixel CCDs, one used by the NESS and HEOSS projects and the other by the spacecraft's

star tracker A star tracker is an optical device that measures the positions of stars using photocells or a camera. As the positions of many stars have been measured by astronomers to a high degree of accuracy, a star tracker on a satellite or spacecraft may ...

. Since the telescope is aimed relatively close to the Sun, it contains a baffle to shield its detectors from intense sunlight. The science camera takes 100-second-long exposures, allowing it to detect celestial objects down to

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

20. NEOSSat's attitude control allows it to maintain pointing stability of less than one

during the entire 100 second exposure period. It takes up to 288 images per day, downloading multiple images to its Canadian ground station with each pass.

Launch

NEOSSat was originally scheduled for launch in 2007, but delays set it back until 2013. Alongside another Canadian spacecraft,

Sapphire Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide () with trace amounts of elements such as iron, titanium, chromium, vanadium, or magnesium. The name sapphire is derived via the Latin "sapphir ...

(a military surveillance satellite), and five other satellites, NEOSSat launched on February 25, 2013, from the

Satish Dhawan Space Centre Satish Dhawan Space Centre - SDSC (formerly Sriharikota Range - SHAR) is a rocket launch centre (spaceport) operated by Indian Space Research Organisation (ISRO). It is located in Sriharikota, Tirupati district of Andhra Pradesh. Sriharikota R ...

Sriharikota Sriharikota is a Barrier island off the Bay of Bengal coast located in the Shar Project settlement of Tirupati district in Andhra Pradesh, India. It houses the Satish Dhawan Space Centre, one of the two satellite launch centres in India (the o ...

, India, at 12:31 UTC aboard an Indian PSLV-C20 rocket.

Missions

The NEOSSat satellite carries out three missions. The spacecraft is a demonstrator of the utility of the ''Multi-Mission Microsatellite Bus'' (MMMB) as part of the CSA's efforts to develop an affordable multi-mission bus. ''Near Earth Space Surveillance'' (NESS), led by Principal Investigator Alan Hildebrand of the University of Calgary, uses NEOSSat to search for and track near-Earth asteroids inside Earth's orbit around the Sun, including asteroids in the

Aten Aten also Aton, Atonu, or Itn ( egy, jtn, ''reconstructed'' ) was the focus of Atenism, the religious system established in ancient Egypt by the Eighteenth Dynasty pharaoh Akhenaten. The Aten was the disc of the sun and originally an aspect of ...

and Atira classes. These asteroids are particularly difficult to detect from the surface of the Earth, as they are usually positioned in the daylit or twilit sky, when background light from the Sun makes such faint objects invisible. This form of stray light is not an issue for a telescope in orbit, making even a small-aperture telescope such as that on NEOSSat capable of detecting faint asteroids. The NESS science team expects to be able to detect many such asteroids as faint as visual magnitude 19. The NESS mission is funded by the CSA. ''High Earth Orbit Space Surveillance'' (HEOSS), led by Principal Investigator Brad Wallace of DRDC, uses NEOSSat to conduct experimental satellite tracking activities. It focuses principally on satellites in the range, such as geostationary communications satellites, which are difficult to track via ground-based radar. These experiments include submitting tracking data to the

Space Surveillance Network The United States Space Surveillance Network (SSN) detects, tracks, catalogs and identifies artificial objects orbiting Earth, e.g. active/inactive satellites, spent rocket bodies, or fragmentation debris. The system is the responsibility of Uni ...

, as part of Canada's role in

NORAD North American Aerospace Defense Command (NORAD ), known until March 1981 as the North American Air Defense Command, is a combined organization of the United States and Canada that provides aerospace warning, air sovereignty, and protection ...

. The HEOSS activities support planning for follow-on missions to the Canadian Department of National Defence's operational satellite-tracking satellite,

, which was launched with NEOSSat. The HEOSS mission is funded by DRDC.

Development

NEOSSat, originally conceived under the name NESS ("Near Earth Space Surveillance"), was proposed by Dynacon in 2000 to DRDC and CSA as a follow-on to the

microsatellite mission which was then halfway through its development. As conceived during an initial Phase A study for DRDC, it would have re-used almost all of the equipment designs from MOST, the main addition being a large external baffle to reduce the stray light impinging on the instrument's focal plane, necessary in order to achieve its asteroid detection sensitivity target of magnitude 19. DRDC's Technology Demonstration Program (TDP) approved CDN$6.5M of funding for NEOSSat in 2003. By mid-2004 CSA had approved the remaining funding needed to initiate the NEOSSat procurement, and with DRDC formed a Joint Program Office to manage the mission development. At this point the spacecraft's name was changed from NESS to NEOSSat. A final Phase A study was carried out under CSA supervision in 2005, and a Phase B/C/D procurement was carried out in 2006/07, with a total development price cap of CDN$9.8M (not including launch cost). Dynacon was selected as prime contractor in 2007, at which point the total development cost was reported as CDN$11.5M, with a target launch date of late 2009. Shortly after that, Dynacon sold its Space division to Microsat Systems Canada Inc. (MSCI), which completed development of NEOSSat. As development proceeded, while the basic design concept was kept, much of the equipment in the satellite was replaced by new designs in order to meet requirements imposed by the CSA's Multi-Mission Microsatellite Bus program. The basic instrument design was kept, as was the basic structure design, and the attitude control subsystem sensors and actuators; the on-board computers and radios were replaced, the instrument readout electronics was redesigned, and the external instrument "door" was replaced by an internal shutter. By 2012, the CSA's contribution to program funding had risen by CDN$3.4M to CDN$8.8M, implying a total program contracted-out cost to end of satellite commissioning of CDN$15.4M. However, according to a Canadian Space Agency audit, the total program cost by the end of 2013 was CDN$25M, including both CSA and DRDC costs, with CSA's portion of the cost reported at just under CDN$13M.

Audit of the NEOSSat program

In February 2014, the CSA released a report detailing the results of an audit of the NEOSSat program, commissioned by CSA and conducted by external companies. This audit, carried out as "a requirement of the CSA five-year evaluation plan", covers only the period beginning with the signing of the CSA's NEOSSat contracts in 2005 through the end of 2013. Reports highlighted several negative findings of the audit, including delays in the program, and problems experienced by the satellite on-orbit that have kept it from achieving operational status. This includes the Electrical Power Subsystem interfering with the imager CCD, and delays in the development of flight software needed for operating the camera and maintaining spacecraft pointing stability. These problems were mainly attributed to poor performance by the contractor, MSCI, as well as to a perception that the project had been "under-funded by as much as 50 per cent" from the outset. However, MSCI has disputed criticism against the company, saying that program requirements were poorly written and that CSA staff interfered with the satellite's construction.

References

External links

*
CSA NEOSSat website
{{Canadian Space Agency Satellites orbiting Earth Near-Earth object tracking Optical telescopes Satellites of Canada Space telescopes Spacecraft launched in 2013