Mars Orbiters

NASA · Launched 2001

Sun-synchronous polar mapping orbit, ~400 km altitude, 2-hour period

THEMIS produced the first comprehensive global map of surface mineralogy, identifying volcanic and water-altered rock types across the entire planet

ESA · Launched 2003

Highly elliptical polar orbit, 298 × 10,107 km, 6.72-hour period

MARSIS subsurface radar detected a 20 km wide subglacial liquid water lake under the south polar ice cap at ~1.5 km depth (published July 2018)

NASA · Launched 2005

Nearly circular polar sun-synchronous orbit, ~300 km altitude, 112-minute period

HiRISE camera resolves surface features down to 25 cm — unprecedented resolution for any Mars mission and the benchmark for all subsequent landing site assessments

NASA · Launched 2013

Elliptical orbit, 145 × 6,200 km, 4.5-hour period; periodic deep-dip campaigns to ~125 km

Determined Mars loses approximately 100 grams of atmosphere per second to solar wind stripping via solar energetic particle events and coronal mass ejections

ESA / Roscosmos · Launched 2016

Near-circular polar science orbit, ~400 km altitude, 2-hour period

NOMAD and ACS instruments produced the most precise inventory of Martian trace gases to date, placing stringent upper limits on methane abundance (<0.05 ppb) — conflicting with earlier ESA/NASA detections and constraining possible biological or geological methane sources

MBRSC / UAE Space Agency · Launched 2020

Science orbit: 22,000 × 43,000 km elliptical, ~55-hour period

First spacecraft to capture a complete picture of Mars's atmospheric weather system within a single orbit due to its wide-area high-altitude vantage point

CNSA · Launched 2020

Relay/science orbit after lander separation: ~265 × 11,900 km elliptical

China's first Mars mission — made China the second nation to successfully land a rover on Mars (Zhurong, May 2021)

NASA · 1971 – 1972

Elliptical, 1,387 × 17,144 km, 12-hour period

First spacecraft to orbit another planet — entered Mars orbit 1971-11-14

NASA · 1975 – 1980

Elliptical polar orbit, 300 × 33,000 km, evolved over mission lifetime

Mapped 97% of the Martian surface at 200–300 m resolution — the first near-complete photographic atlas

NASA · 1975 – 1978

Elliptical polar orbit; inclination raised to 75° to access higher latitudes

Imaged Utopia Planitia in detail to select the Viking 2 lander touchdown site

NASA · 1992 – 1993

Never achieved orbit — contact lost during pre-orbit-insertion pressurization

No science data returned from Mars — contact lost August 21, 1993, three days before scheduled orbit insertion

NASA · 1996 – 2006

Nearly circular polar mapping orbit, ~378 km altitude, 117-minute period

MOLA laser altimeter produced the most accurate global topographic map of any planet — revealing Mars is divided into two distinct hemispheres by elevation

NASA · 1998 – 1999

Never achieved stable orbit — entered Martian atmosphere due to navigation error

No science data returned — spacecraft was destroyed on September 23, 1999 when it entered the Martian atmosphere

ISRO · 2013 – 2022

Highly elliptical, 421 × 80,000 km, 72.7-hour period

First Asian nation to reach Mars and the first Mars mission in history to succeed on its maiden attempt