MOST (spacecraft)
Canada's first space telescope and smallest in orbit for nearly a decade.
MOST (Microvariability and Oscillations of Stars/Microvariabilité et Oscillations STellaire) was Canada's first space telescope. For nearly a decade after its launch, it held the title of the smallest space telescope in orbit, earning it the nickname "Humble Space Telescope" from its builders—a nod to the much larger Hubble. It pioneered the field of asteroseismology as the first spacecraft dedicated to that science, later followed by the now-finished CoRoT and Kepler missions. It also marked Canada's first science satellite since ISIS II, launched 32 years earlier.
The telescope's main job, as its name suggests, was to track variations in starlight by staring at a single target for up to 60 days. Larger space telescopes typically can't spare that much time on one object because of competing demands. Weighing 53 kg (117 lb) and measuring 60 cm (24 in) on each side and 24 cm (9 in) deep, MOST was about the size and weight of a small chest or an oversized suitcase packed with electronics, placing it in the microsatellite class.
MOST was a joint project of the Canadian Space Agency, Dynacon Enterprises Limited (now Microsatellite Systems Canada Inc), the Space Flight Laboratory (SFL) at the University of Toronto Institute for Aerospace Studies, and the University of British Columbia. Led by Principal Investigator Jaymie Matthews, the science team planned to use asteroseismology to help date the age of the universe and to search for visible-light signs of extrasolar planets. The original SFL proposal to the CSA is available online.
Its instrument was a visible-light dual-CCD camera fed by a 15-cm aperture Maksutov telescope. One CCD captured science images; the other fed star-tracking software that, along with four reaction wheels (computer-controlled motorized flywheels similar to gyroscopes), kept pointing accurate to less than 1 arc-second—far better than any other microsatellite at the time. The rest of MOST's design was inspired by microsatellite bus designs pioneered by AMSAT and first commercialized by SSTL at the University of Surrey in the UK. During early development, the core AMSAT microsatellite team advised and mentored MOST's designers through a know-how transfer with UTIAS.
Quick Facts
- Names List
- MOST
- Mission Type
- Astronomy
- Operator
- CSA
- Cospar Id
- 2003-031D
- Satcat
- 27843
- Launch Mass
- 53 kg
- Dimensions
- 60 x
- Power
- 35 W
- Launch Date
- 30 June 2003, 14:15 UTC
- Launch Rocket
- Rockot/Briz-KM
- Launch Site
- Plesetsk 133/3
- Launch Contractor
- Eurockot
Facts from the source article.
Lore & Background
MOST was developed as a joint effort of the Canadian Space Agency, Dynacon Enterprises Limited (now Microsatellite Systems Canada Inc), the Space Flight Laboratory (SFL) at the University of Toronto Institute for Aerospace Studies, and the University of British Columbia, led by Principal Investigator Jaymie Matthews. Its design was inspired by and based on microsatellite bus designs pioneered by AMSAT, and first brought to commercial viability by the microsatellite company SSTL. During early development, the core group of AMSAT microsatellite designers advised and mentored the MOST team via a know-how transfer arrangement with UTIAS. This approach made use of commercial-grade electronics and a "small team," "early prototyping" engineering development approach, achieving relatively very low costs.
As of ten years after launch, despite failures of two components (one of four reaction wheels and one of two CCD driver boards), the satellite was still operating well due to on-going on-board software upgrades and built-in hardware redundancy. In 2008, the MOST Satellite Project Team won the Canadian Aeronautics and Space Institute's Alouette Award. On 30 April 2014, the Canadian Space Agency announced funding to continue operating MOST would be withdrawn as of 9 September 2014, apparently due to funding cuts by the Harper government, despite the satellite being fully operational. P.I. Jaymie Matthews responded that he would consider all options, including a direct appeal to the public. In October 2014, MOST was acquired by MSCI, which commenced commercial operation. MOST was finally decommissioned in March 2019 after an apparent failure of its power subsystem.
Reader's Guide
MOST's significance lies in its pioneering role as the first space telescope dedicated to asteroseismology, a field it helped establish before the later CoRoT and Kepler missions. Its small size and low cost—less than $10 million Canadian—demonstrated that a microsatellite could achieve high-precision science, including pointing accuracy better than 1 arc-second, surpassing any other microsatellite to date. The mission's discoveries include the disputed finding that Procyon does not oscillate as expected, the identification of a new class of variable stars (slowly pulsating B supergiants) in 2006, and the detection of transits by exoplanet 55 Cancri e in 2011, which confirmed earlier detections and allowed studies of the planet's composition. In 2019, MOST photometry disproved claims of permanent starspots on HD 189733 A. Its operational longevity—over a decade despite component failures—and its transition to commercial operations after CSA funding ended illustrate the resilience and adaptability of its design. The mission's legacy includes proving that a small, low-cost satellite can contribute meaningfully to astrophysics and exoplanet research.
Did You Know?
- MOST was nicknamed the 'Humble Space Telescope' in reference to the Hubble Space Telescope.
- It was the first Canadian science satellite launched since ISIS II, 32 years earlier.
- MOST's life-cycle cost was less than $10 million Canadian (about 7 million Euros or 6 million USD at launch).
- In 2006, MOST observations revealed a previously unknown class of variable stars called slowly pulsating B supergiants (SPBsg).
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