How long does it take to send a signal to Mars?

Talking to Mars

Radio to Mars takes 3 to 22 minutes each way. Why rovers drive themselves, how the relay network works, and why commanding stops every 26 months.

TL;DR· 22 min read

A radio signal takes about three minutes to reach Mars when the two planets are closest and about twenty-two when they are farthest, and nothing shortens it. That is why rovers are briefed rather than driven, why landings fly themselves, and why 99.9 per cent of Perseverance's science data goes home through a passing orbiter. It all arrives at one of three Deep Space Network sites, oversubscribed by up to 40 per cent, and roughly every twenty-six months Mars passes behind the Sun and commanding stops.

We talk to Mars by radio, and the answer to the question people actually ask is that a signal takes somewhere between about three and about twenty-two minutes to get there, one way, depending on where the two planets happen to be. Nothing shortens it. It is the speed of light crossing a gap that swings between roughly 55 and 401 million kilometres, and no bigger dish, hotter transmitter or laser changes that number by a second. Everything else follows from it. Rovers have to drive themselves because nobody can steer one. Landings have to fly themselves because the news arrives after they are over. Almost all surface data goes home through an orbiter rather than straight to Earth. And for a couple of weeks roughly every twenty-six months, when Mars passes behind the Sun, nobody sends it anything at all.

one-way light time to Mars, depending where the two planets are in their orbits: 3 to 22 minone-way light time to Mars, depending where the two planets are in their orbits
of Perseverance's surface science data that goes home through an orbiter instead of straight to Earth: 99.9%of Perseverance's surface science data that goes home through an orbiter instead of straight to Earth
the most recent solar conjunction moratorium, when NASA stopped commanding every Mars mission: 29 Dec to 16 Janthe most recent solar conjunction moratorium, when NASA stopped commanding every Mars mission

One-way light time from Earth to Mars, computed every ten days from real orbital geometry rather than sketched. The swing is why a rover cannot be driven from Earth: at its worst a question and its answer are forty minutes apart.

Radio waves travel at the speed of light and nothing carries information faster, so the delay between Earth and Mars is a distance problem with no engineering solution. The two planets orbit the Sun on different ellipses at different speeds, so the gap between them swings enormously: about 54.6 million kilometres at its narrowest, about 401.4 million at its widest. Divide by 299,792.458 kilometres per second and the one-way light time runs from a little over three minutes to a little over twenty-two. Queried across 2000 to 2040, JPL's Horizons ephemeris service puts the real extremes at 3 minutes 6 seconds on 27 August 2003, the closest the two planets came in that whole forty-year span, and 22 minutes 15 seconds on 29 August 2019. Round trips are double: roughly six minutes at best and forty-five at worst. Published ranges differ a little and it helps to know why. ESA's own Mars Express blog says roughly four to twenty-four minutes, which is a looser rounding rather than a rival measurement, since twenty-four minutes would put Mars 431 million kilometres away and it never gets that far. On 3 September 2026 Horizons places Mars at 1.839 astronomical units, 275.1 million kilometres, which is 15 minutes 18 seconds each way and 30 minutes 35 seconds there and back. By the close approach of 20 February 2027 that will have dropped to 5 minutes 38 seconds. A bigger dish, a hotter transmitter or a laser buys more bits per second. None of them buys a faster second. The number has not moved since Mariner 4 flew past in July 1965, when the one-way delay was 12 minutes and a single picture, trickling in at 8 1/3 bits per second, took more than eight hours to arrive.

The most important consequence is that nobody has ever driven a rover on Mars. JPL states it flatly: "Because of the radio signal delay between Earth and Mars, they can't simply move the rover forward with a joystick." Picture what steering would actually mean today. The image showing your rover approaching a sand trap left Mars fifteen minutes ago. Your command to stop takes another fifteen to arrive. The rover has been in the sand for half an hour before your instruction lands. So rovers are not driven, they are briefed. Once or twice a Martian day a plan goes up, and the rover executes it alone, using onboard autonomy to fill the gaps a human would otherwise fill. The AutoNav system on Perseverance builds three-dimensional maps of the ground ahead, spots hazards and picks its own route while its wheels are still turning, a capability its engineers call thinking while driving, at up to 120 metres an hour against about 20 for Curiosity. In Science Robotics in 2023, Vandi Verma, Mark Maimone and colleagues reported that AutoNav had evaluated 88 per cent of the 17.7 kilometres Perseverance covered in its first Mars year, with a longest unsupervised drive of 699.9 metres, against a previous record of 2.4 kilometres evaluated autonomously by Opportunity in fourteen years. The same logic governs landing. When Perseverance entered the atmosphere on 18 February 2021, the one-way delay was 11 minutes 22 seconds, so every milestone announced on Earth had already happened. The seven minutes of terror are terrifying precisely because they are unattended.

Everything reaching Earth from Mars arrives at one of three places. NASA's Deep Space Network is three complexes spaced roughly 120 degrees apart in longitude, at Goldstone in the Mojave Desert of California, at Robledo de Chavela west of Madrid, and at a site near Canberra in Australia. The spacing is the whole design: as the Earth turns, a spacecraft setting below the horizon at one site is already rising at the next, so nothing in deep space is ever out of reach for want of a dish. As of early September 2026 the network has fifteen antennas, one 70 metre dish at each site plus twelve of 34 metres, the newest of which, DSS-23 at Goldstone, entered service on 3 August 2026. It is not enough. NASA's Inspector General found in July 2023 that the DSN is oversubscribed, with demand exceeding supply by about 40 per cent at times across nearly sixty missions, heading for roughly 50 per cent excess by the 2030s, and that over five years missions had received between 8,500 and 15,000 fewer tracking hours than they requested. The Mars consequence is specific: the managers of Perseverance told the auditors the mission was hit at least seven times in twenty-one months, unable to get the data it needed to decide where to drive next and forced to wait for the following slot. The network is also physically vulnerable. DSS-14 at Goldstone was damaged by over-rotation while tracking Juno in September 2025, and the Madrid site was evacuated ahead of wildfires on 24 July 2026.

Three other agencies run deep space ground stations, and they are all much smaller. ESA's ESTRACK has three 35 metre deep space antennas, at New Norcia in Western Australia, Cebreros in Spain and Malargüe in Argentina, though they are not spread as evenly as the DSN's, with Cebreros and Malargüe only about 65 degrees apart in longitude; Mars Express downlinks to New Norcia at up to 230 kilobits per second and returns 1 to 5 gigabits of science a day, with cross-support from NASA's Spanish and Californian complexes. China's network has a 66 metre antenna at Jiamusi in Heilongjiang from 2012, four 35 metre antennas arrayed at Kashi in Xinjiang since November 2020 with the collecting power of a single 66 metre dish, and a 35 metre antenna at Espacio Lejano in Neuquén province, Argentina, since 2017; a separate 70 metre dish at Wuqing in Tianjin was built to receive the science data from Tianwen-1. The published Chinese figures are not consistent across sources, with English Wikipedia giving 64 metres for Jiamusi and 50 for Argentina where Chinese sources give 66 and 35. India's IDSN at Byalalu near Bengaluru has a 32 metre antenna from 2008, an 18 metre from 2021 and an 11 metre, and it tracked Mangalyaan. What none of them has is three sites. A single-station network goes deaf every time the Earth turns, which is why cross-support agreements exist and why almost every Mars mission of any nationality has at some point leaned on somebody else's dishes.

The rovers themselves barely talk to Earth. A rover carries a small antenna and a strict power budget, and the distance is punishing: the direct X-band link on Curiosity manages between about 500 bits per second and 32 kilobits per second, which is dial-up modem territory at best. Its UHF link to an orbiter a few hundred kilometres overhead reaches up to 2 megabits per second for a fraction of the energy. A pass lasts about eight minutes and moves 100 to 250 megabits, which straight to Earth might take twenty hours. NASA's Mars 2020 press kit puts the outcome in one line: during surface operations, 99.9 per cent of the science data from Perseverance goes out through its UHF antenna to a passing orbiter. So the working architecture is a chain. Rover to orbiter on UHF, orbiter to Earth on X-band, Earth to scientist. The orbiters carrying that traffic were all funded to do something else: Mars Odyssey went to map chemistry, Mars Reconnaissance Orbiter to take pictures, ExoMars Trace Gas Orbiter to hunt methane. Averaged over February to May 2026, the Trace Gas Orbiter carried 2,228 megabits a day, Mars Reconnaissance Orbiter 851 and Mars Odyssey 107, with Mars Express held in reserve. MAVEN, which had averaged 898, went silent on 6 December 2025 and the mission ended on 3 June 2026. The other three add up to about 3.2 gigabits a day, roughly 400 megabytes, on spacecraft launched in 2001, 2005 and 2016: the entire daily scientific take of the planet Mars would fit on one CD-ROM. That ageing fleet is the argument behind the Mars Telecommunications Network, the relay orbiter Congress ordered NASA to buy in 2025, and the belated answer to the Mars Telecommunications Orbiter, the dedicated relay spacecraft cancelled in 2005. NASA selected Blue Origin to build it on 1 September 2026, a firm-fixed-price contract worth up to about $700 million, with the orbiter to be delivered no later than 31 December 2028 and the network expected to be operational at Mars by 2030.

Then, roughly every twenty-six months, everything stops. Mars passes behind the Sun as seen from Earth, and although the planet usually misses the solar disk itself, the signal has to cross the corona, a turbulent shell of ionised gas that scatters radio waves. The measure is the Sun-Earth-Probe angle, the angular gap in the sky between the Sun and the spacecraft. Where the cutoff sits is not agreed: NASA's 2007 technical memorandum works to 2 degrees at X-band and 1 degree at Ka-band, while ESA puts serious disruption at 3 to 4 degrees. Below whichever figure applies, telemetry lock becomes unreliable and bits get corrupted, and a corrupted command is far more dangerous than a lost one. So flight projects impose a command moratorium and simply stop transmitting. As Chad Edwards of JPL's Mars Relay Network Office put it in 2017, "we don't want to take a chance that one of our spacecraft would act on a corrupted command." The most recent moratorium ran from 29 December 2025 to 16 January 2026, about two and a half weeks with no contact of any kind; Horizons puts Mars inside 2 degrees of the Sun from 3 to 16 January, with the minimum of 0.95 degrees on 9 January; the moratorium was wider than that at both ends and lopsided, opening with Mars 3.0 degrees out and closing at 1.9. Rovers stop driving and sit still. Orbiters keep collecting, some keep transmitting, and corrupted data is retransmitted later. ESA uploads three or four weeks of commands beforehand instead of the usual one and cuts the Mars Express uplink from 2,000 bits per second to 250. The intervals are not exactly 26 months either: successive conjunctions between 2000 and 2038 fall 767 to 803 days apart. The next is around 21 March 2028.

Commonly wrong. Several confident beliefs about talking to Mars are wrong. (1) The delay is not a signal-strength or computing problem and it is not something better technology will fix. It is the speed of light across a distance, and the only thing that changes it is the distance. The Deep Space Optical Communications demonstration on Psyche streamed video at 267 megabits per second from 31 million kilometres in December 2023 and downlinked from 494 million kilometres a year later; lasers raise the data rate by an order of magnitude and leave the delay exactly where it was. (2) People routinely conflate one-way and round-trip figures. The commonly quoted 3 to 22 minutes is one way. A question asked and answered takes twice that, up to about 45 minutes, and published ranges vary: ESA's own Mars Express blog says roughly 4 to 24 minutes where the distances give 3 to 22. (3) During solar conjunction the Sun does not usually block the signal. The visible solar disk is about 0.26 degrees in radius as seen from Earth, and at most conjunctions Mars never crosses it; the January 2026 minimum was 0.95 degrees. What stops work is the corona's turbulent plasma corrupting bits, and specifically the risk that a spacecraft acts on a garbled command. That is also why the moratorium is one-directional: NASA stops commanding, but orbiters keep collecting and some keep sending, with damaged data retransmitted afterwards. NASA's own blog said the agency would "not have contact with any Mars missions" until 16 January, which is the agency's shorthand for the moratorium rather than a literal silence in both directions. (4) Conjunction is not exactly every two years or exactly every 26 months. Successive superior conjunctions from 2000 to 2038 fall between 767 and 803 days apart, a mean of about 778 days. (5) Rovers are not steered. There is no joystick, no live video and no possibility of one; a rover receives a plan once or twice a sol and executes it alone, and by 2023 AutoNav was evaluating 88 per cent of Perseverance's driving. Landings are the same case at higher stakes: on 18 February 2021 every reported milestone of Perseverance's descent had happened 11 minutes 22 seconds earlier. (6) Rovers do not mostly phone home. NASA's own press kit says 99.9 per cent of Perseverance's surface science goes through an orbiter, because the short UHF hop runs at up to 2 megabits per second against a direct link of 500 bits to 32 kilobits per second, and costs less power. (7) There is no chain of relay satellites between Earth and Mars, and nothing is bounced off anything. It is one direct radio path from a dish on Earth to a spacecraft at Mars. (8) The Deep Space Network is not a global scattering of dishes. It is three sites, fifteen antennas, and by NASA's own audit it is oversubscribed by up to 40 per cent. (9) MAVEN is still widely listed as a relay orbiter. It went silent on 6 December 2025 and the mission was declared over on 3 June 2026. (10) None of it is live. There is no live video from Mars and there never has been. Even the first successful landing, Mars 3 in December 1971, was not heard as it happened: the lander spoke to its own orbiter, which recorded the signal and replayed it to Earth at quarter speed over the following days.

What we know

The speed limit, and the range

Radio waves travel at exactly 299,792.458 kilometres per second, the speed of light, and nothing carries information faster. Earth and Mars orbit the Sun on different-sized ellipses at different speeds, so the gap between them is never the same twice: the commonly published extremes are about 54.6 million kilometres at the narrowest and about 401.4 million at the widest, giving one-way delays of about 3 minutes 2 seconds and about 22 minutes 19 seconds. Round trip, double it, so roughly 6 minutes at best and 45 at worst. Queried across 2000 to 2040 at one-day steps, JPL's Horizons ephemeris service puts the extremes actually reached at 3 minutes 6 seconds on 27 August 2003, at 0.3727 astronomical units or 55.76 million km, the closest the two planets came in that whole 40-year span, and 22 minutes 15 seconds on 29 August 2019, at 2.6753 au or 400.2 million km.↗

The delay today, and next year

On 3 September 2026 Horizons gives an Earth to Mars range of 1.83905584 au, which is 275.1 million kilometres, a one-way light time of 15 minutes 18 seconds and a round trip of 30 minutes 35 seconds. Mars reaches opposition in February 2027; at its closest, on 20 February 2027, the range falls to 0.6779 au (101.4 million km) and the one-way delay to 5 minutes 38 seconds. That is a factor of nearly three in less than six months, and every data rate at Mars moves with it.↗

Published ranges disagree, mildly

Sources round the delay differently and it is worth knowing which is which. ESA's own Mars Express blog gives "the minimum delay of around 4 minutes and the maximum of around 24 minutes". The 3 to 22 minute figures used here come from dividing the published minimum and maximum Earth to Mars distances by the speed of light, and they match Horizons. Twenty-four minutes would require Mars to be about 431 million kilometres away, which never happens. Treat the ESA figures as a loose rounding rather than a competing measurement.↗

Which radios, and at what frequencies

Three separate links. Direct to Earth uses X-band, about 7.1 to 7.2 GHz up and 8.4 GHz down; some orbiters add Ka-band near 32 GHz for high rates. The short hop between a surface craft and a passing orbiter uses UHF near 400 MHz under the CCSDS Proximity-1 protocol: 437.1 MHz on the forward link from orbiter to surface and 401.585625 MHz on the return, with Electra radios covering roughly 390 to 405 MHz and 435 to 450 MHz. Proximity-1 is the reason a European orbiter can pick up an American rover.↗

The Deep Space Network

Three complexes, placed roughly 120 degrees apart in longitude so that a spacecraft is always above someone's horizon as Earth turns: Goldstone in the Mojave Desert of California, Robledo de Chavela about 60 km west of Madrid, and a site near Canberra. NASA's Office of Inspector General describes the placement as strategic siting equally distant across the Earth that permits constant communication, with forward sites picking up spacecraft that have sunk below the horizon at the previous one. As of early September 2026 the network fields 15 antennas: one 70 m dish at each site plus twelve 34 m dishes, of which eleven are beam-waveguide designs and one, DSS-65 at Madrid, is the older high-efficiency type. No published inventory states that total in one place: it follows from JPL counting DSS-23 as the fifth antenna at Goldstone, and it leaves out the research antenna DSS-13.↗

It is oversubscribed

The Inspector General's audit of 12 July 2023 states that DSN antennas "are currently operating at capacity and are oversubscribed", meaning more time is requested by missions than the network can provide, with "demand exceeding supply by about 40 percent at times". The network supports nearly 60 NASA and international space missions. NASA's own loading studies put excess demand at about 50 per cent by the 2030s. Over the preceding five years, missions including Mars Odyssey, Voyager 2 and New Horizons received between 8,500 and 15,000 fewer tracking hours than they asked for.↗

What that costs a rover

The same audit records the concrete consequence at Mars. Perseverance's managers said the mission was affected by DSN oversubscription at least seven times in a 21-month period. During those events the mission could not retrieve the data it needed to decide where the rover should go next, so it had to wait for the next opening to receive location data, work out the route and send the commands. The auditors summarise it as missed opportunities to send commands that delayed the rover's progress. The audit also warns of a coming contention period in which Mars missions, the James Webb Space Telescope and Artemis are in the same part of the sky competing for the same dishes every two years.↗

The network is physically fragile

Two incidents inside a year. On 16 September 2025 DSS-14, the 70 m dish at Goldstone, was damaged by over-rotation while tracking Juno, classified as a Type A mishap with damage estimated at $4.1 to $4.6 million. On 24 July 2026 the Madrid complex was evacuated as wildfires swept the area; 90 staff were moved out and NASA said it had "seamlessly transitioned support for mission operations to the Goldstone Deep Space Communications Complex". NASA said it would assess the damage when it was safe to do so. Losing one of three sites for a day is survivable. It is not comfortable.↗

The newest dish

DSS-23, a 34 m multifrequency beam-waveguide antenna at Goldstone, entered service on 3 August 2026 after testing from May to July. It is the fifth antenna at Goldstone and the fifth delivered by the Deep Space Network Aperture Enhancement Project, which began in 2009. A sixth, DSS-33 at Canberra, is expected in 2029 and will bring the network to thirteen 34 m dishes. Several 34 m antennas can be arrayed, combined and operated together, to stand in for an ageing 70 m one.↗

ESA's network

ESTRACK has three 35 m deep space antennas: New Norcia in Western Australia (DSA 1), Cebreros in Spain (DSA 2) and Malargüe in Argentina (DSA 3). The three sites are on three continents but they are not spread the way the DSN's are: Cebreros and Malargüe lie only about 65 degrees apart in longitude against the DSN's 120. Mars Express is served by all three plus cross-support from NASA's complexes in Spain and California, downlinking to New Norcia at up to 230 kbit/s and returning between 1 and 5 gigabits of science a day.↗

China's deep space stations

Three tracking stations plus a dedicated science-data dish, and the published figures do not all agree. Chinese sources give Jiamusi in Heilongjiang a 66 m antenna completed in 2012, Kashi in Xinjiang four 35 m antennas arrayed from November 2020 with the receiving power of a single 66 m dish, and the Espacio Lejano station in Neuquén province, Argentina, a 35 m antenna operating since 2017. English Wikipedia instead gives 64 m for Jiamusi and 50 m for Argentina. Separately, a 70 m dish 72 m tall was built at Wuqing in Tianjin specifically for Tianwen-1, described in Chinese sources as Asia's largest single-aperture fully steerable antenna and able to array with existing dishes for an effective 103 m aperture.↗

India's network

The Indian Deep Space Network sits at Byalalu, about 60 km from Bengaluru: a 32 m S-band and X-band beam-waveguide antenna commissioned in 2008, an 18 m antenna added in November 2021, and an 11 m dish. It tracked Chandrayaan-1, the Mars Orbiter Mission and Chandrayaan-3, the last of these with supplementary support from the NASA and ESA networks. A single-site network cannot see a spacecraft when the Earth has turned, which is why cross-support agreements exist at all.↗

The relay link, and why it exists

A rover's own transmitter is small and its power is scarce. Curiosity's direct-to-Earth X-band rate runs between about 500 bits per second and 32 kilobits per second. Its UHF link to a passing orbiter reaches up to 2 megabits per second, sixty times the rover's best direct rate and four thousand times its worst, for a fraction of the energy, because the orbiter is a few hundred kilometres overhead rather than a few hundred million away. A pass lasts about eight minutes and moves 100 to 250 megabits; sending the same 250 megabits straight to Earth could take up to twenty hours. NASA's Mars 2020 press kit states the result plainly: during surface operations 99.9 per cent of Perseverance's science data goes through the rover's UHF antenna to a passing orbiter.↗

What the relay actually carries now

NASA's Mars Relay Network page, last updated 5 June 2026, tabulates five orbiters, four of them still flying. Averaged over February to May 2026, ESA's Trace Gas Orbiter carried 2,228.1 megabits a day, Mars Reconnaissance Orbiter 850.6 and Mars Odyssey 107.3, while Mars Express is held as backup and used no relay passes. MAVEN, which averaged 897.5 megabits a day through 2025, went silent on 6 December 2025 and the mission was declared over on 3 June 2026, so its figure is now zero. Rover data reaches scientists on Earth about a dozen times a week. Added up, the working relay fleet moves roughly 3.2 gigabits a day, which is about 400 megabytes: the entire daily scientific take of the planet Mars would fit on a single CD-ROM with room to spare.↗

Solar conjunction, the geometry

Every synodic period Mars passes behind the Sun as seen from Earth. Successive superior conjunctions from 2000 to 2038 fall 767 to 803 days apart on Horizons, a mean of about 778 days, which is where the shorthand of 26 months comes from. The relevant number is the Sun-Earth-Probe angle, the angular gap in the sky between the Sun and the spacecraft. Where the cutoff sits is not agreed. NASA's 2007 technical memorandum tabulates outages below 2 degrees at X-band and below 1 degree at Ka-band; ESA says the link is badly disrupted once the angle is inside 3 to 4 degrees. Below whichever figure applies, turbulent ionised gas in the solar corona scatters the signal enough to break telemetry lock and corrupt bits. No source consulted reconciles the two into a single figure. The Sun's visible disk is only about 0.26 degrees in radius, so at most conjunctions Mars never actually goes behind it. The 9 January 2026 conjunction bottomed out at 0.95 degrees.↗

Solar conjunction, the operations

Flight projects impose a command moratorium: they stop sending. NASA's most recent ran from 29 December 2025 to 16 January 2026, about two and a half weeks, during which the agency stated it would have no contact with any Mars mission. Horizons puts Mars inside 2 degrees of the Sun from 3 to 16 January 2026, so NASA's window is wider than the 2 degree criterion on both sides and is not symmetric about the geometric minimum: it opened with Mars 3.0 degrees from the Sun and closed with Mars at 1.9. The opening angle is close to ESA's 3 to 4 degree figure, but no source consulted explains the asymmetry. The 2007 NASA technical memorandum's table gives 14.29 days under 2 degrees for that conjunction and 17.05 for the next, centred on 21 March 2028; Horizons independently gives 14 and 17 days. Rovers stop driving. Orbiters keep collecting and some keep transmitting, with corrupted data retransmitted afterwards. ESA uplinks three or four weeks of commands in advance instead of the usual one and drops the Mars Express uplink rate from 2,000 bits per second to 250.↗

What happened, and when

15 Jul 1965Mariner 4 flies 9,846 km above Mars, 216 million km from Earth, where the one-way light time is 12 minutes. Its link runs at 8 1/3 bits per second and each picture holds about 250,000 bits, so JPL's own release warns that a single frame will take more than eight hours to arrive. The two constraints that still define Mars communications, the delay and the trickle, are both present on day one.
2 Dec 1971Mars 3 becomes the first spacecraft to land on Mars and survive, and nobody hears it live. The lander talks to its own orbiter, which records the transmission and replays it to Earth at quarter speed over the following days. The relay architecture that carries almost everything today is already there in outline.
24 Oct 20012001 Mars Odyssey reaches Mars carrying a UHF relay payload. For the next two decades it is the default switchboard for almost everything NASA puts on the Martian surface, and by its 100,000th orbit it has relayed about 1.3 terabits from the ground.
2004ESA's Mars Express relays data from NASA's Spirit rover, in what ESA calls "the first-ever demonstration of an interagency communications network around another planet". The shared CCSDS Proximity-1 protocol is what makes it possible, and it is why an American rover can be heard by a European orbiter today.
10 Mar 2006Mars Reconnaissance Orbiter enters Mars orbit carrying Electra, a software-defined UHF radio that can change its data rate on the fly as the orbiter crosses a rover's sky. It becomes the high-rate backbone of the relay network and, twenty years later, still is.
18 Feb 2021Perseverance lands with a one-way light time of 11 minutes 22 seconds, so every milestone reported on Earth happened 11 minutes 22 seconds earlier. Nobody could have intervened. MRO relays telemetry throughout the descent in five-second packets with about 16 seconds of latency, using a newly added mode called pseudo bent pipe, while Green Bank in West Virginia and Effelsberg in Germany listen for the rover's bare UHF carrier tone directly.
12 Sep 2021On its 200th sol Perseverance drives 175.15 metres in a single day, 167 of them under AutoNav, which JPL's chief engineer for robotic operations calls the farthest any Mars rover had then driven autonomously in one sol.
12 Jul 2023NASA's Office of Inspector General publishes its audit of the Deep Space Network: oversubscribed by as much as 40 per cent, supporting nearly 60 missions, with excess demand heading for 50 per cent in the 2030s and Perseverance already losing commanding opportunities to the shortage.
26 Jul 2023Verma, Maimone, Gaines and colleagues report in Science Robotics that AutoNav evaluated 88 per cent of the 17.7 kilometres Perseverance drove in its first Mars year, against a previous record of 2.4 kilometres evaluated autonomously by Opportunity across fourteen years, with a longest drive without human review of 699.9 metres.
11 Dec 2023NASA's Deep Space Optical Communications experiment, riding on the Psyche spacecraft, streams ultra-high-definition video at 267 megabits per second from about 31 million kilometres. In December 2024 it downlinks from 494 million kilometres, farther than Mars ever gets. The demonstration ends on 2 September 2025 having delivered 13.6 terabits. Lasers raise the data rate. They do not touch the delay.
29 Dec 2025 to 16 Jan 2026The Mars solar conjunction moratorium. NASA states it will have no contact with any Mars mission across that stretch. The geometric minimum falls on 9 January 2026 with Mars 0.95 degrees from the Sun. MAVEN, silent since 6 December, cannot be worked on until it is over.
3 Aug 2026DSS-23, a 34 m beam-waveguide antenna, enters service at Goldstone, the fifth delivered by an aperture enhancement project that started in 2009. Ten days earlier the Madrid complex had been evacuated ahead of wildfires and its traffic shifted to California.