This bubble, known as the heliosphere<\/a>, is enormous. It encompasses the entire Solar System<\/a>, spanning such a vast distance that only two spacecraft have ever managed to leave it.<\/p>\n Launched in 1977, NASA\u2019s Voyager 1 and 2<\/a> passed beyond the heliosphere into interstellar space \u2013 the region between stars \u2013 in 2012 and 2018 respectively.<\/p>\n They\u2019re the first man-made objects to ever travel beyond the Sun\u2019s protective bubble, and are still transmitting data about the charged particles and plasma waves that can be found there.<\/p>\n But astronomers want to learn more about the heliosphere and what lies beyond it.<\/p>\n What\u2019s its exact size and shape? How do solar particles emitted by the Sun interact with interstellar space once they pass through it? And how effective is it at protecting us from the high-energy cosmic rays coming in from outside?<\/p>\n \u201cWe\u2019re still putting together a lot of pieces about how the local interstellar medium really interacts with the heliosphere,\u201d says Dr Ralph McNutt<\/a>, a physicist at Johns Hopkins University Applied Physics Laboratory (JHUAPL) in Maryland, in the US.<\/p>\n It\u2019s hoped a new $782 million (\u00a3580 million) NASA mission will help put more of those pieces together.<\/p>\n The Interstellar Mapping and Acceleration Probe (IMAP<\/a>) spacecraft was launched on 24 September 2025.<\/p>\n And instead of spending decades travelling to the edge of the heliosphere, over the next few months it\u2019ll travel to a position about 1.5 million kilometres (one million miles) from Earth called Lagrange Point 1 (L1).<\/p>\n Once there, unhindered by interference from Earth, IMAP can carry out its purpose: study the heliosphere, from afar.<\/p>\n Mission objective<\/p>\n IMAP is a hexagonal, solar-powered spacecraft that\u2019s 2m (6.5ft) wide and looks a bit like a lollipop.<\/p>\n It\u2019s equipped with 10 instruments designed to study the heliosphere, the Sun and incoming particles from interstellar space. It spins about four times a minute, letting its detectors scan the entire sky.<\/p>\n Over the course of two years, it\u2019ll conduct its primary missions, continuously sending data back to Earth for scientists to pore over.<\/p>\n \u201cFebruary 2026 is the official start of the science phase of the mission,\u201d says Prof Dave McComas<\/a>, mission lead at Princeton University in New Jersey, US.<\/p>\n \u201cThe mission is nominally two years, although we have propulsion and gas to last for at least five years and probably many decades.\u201d<\/p>\n The purpose of the IMAP mission is to map the heliosphere around the Sun.<\/p>\n We know from Voyager 1 and 2<\/a> that the boundary of the heliosphere and interstellar space, called the heliopause<\/a>, is about 120 astronomical units (AU) away (120 times the Earth-Sun distance), or about 18 billion kilometres (11 billion miles).<\/p>\n But we don\u2019t know if this is the same distance in all directions.<\/p>\n If it isn\u2019t, the heliosphere may not actually be a sphere. It might be more of an egg shape with a long tail. Some scientists even think it could be a croissant shape<\/a>, with the Sun in the middle and two tails on either side.<\/p>\n \u201cWe believe it\u2019ll be possible to resolve [the heliosphere\u2019s shape] with IMAP,\u201d says Dr Matina Gkioulidou<\/a>, the project scientist for IMAP at JHUAPL.<\/p>\n To do that, instruments onboard IMAP will look at neutral atoms, tiny particles with no electric charge, coming from the heliopause. These are created when outgoing charged particles from the Sun\u2019s solar wind \u2013 a steady outflow of plasma from the Sun’s outer atmosphere \u2013 crash into interstellar gas. <\/p>\n Because neutral atoms have no charge, they travel in straight lines. Hotter neutral atoms travel towards us faster and come from more energetic regions of interstellar space, while colder atoms originate from calmer areas.<\/p>\n By measuring their energies and angle of arrival, scientists can model how long the atoms took to reach us.<\/p>\n With this information, they can map the heliopause in different directions and reveal its true shape to a distance of about 300\u2013400 AU, says McComas.<\/p>\n \u201cWe should be able to get the shape\u201d in most directions, he says.<\/p>\n In regions where the heliopause stretches beyond 400 AU, however, such as at the end furthest from the Sun, \u201cwe just won\u2019t know what that looks like,\u201d says McComas, but we should get at least an idea of the rough shape in that direction.<\/p>\n Read more:<\/p>\n Life on the outside<\/p>\n The nature of the heliosphere is crucial to our understanding of how we came to exist on Earth.<\/p>\n \u201cI\u2019m trying to understand the properties of today\u2019s heliosphere to say if the shape has changed,\u201d says Prof Merav Opher<\/a>, an astronomer and heliosphere expert at Boston University.<\/p>\n Her research suggests Earth might have found itself beyond the heliopause in the past, during periods when the Sun was less active.<\/p>\n \u201cIf we were, at times, outside of the heliosphere, how did life evolve on Earth?\u201d she asks. \u201cIt\u2019s really critical for us to understand which type of radiation Earth would have encountered.\u201d <\/p>\n A prior mission has already explored the shape of the heliosphere. NASA\u2019s Interstellar Boundary Explorer (IBEX<\/a>) launched in 2008 and is still operational today.<\/p>\n It gave us our first hint that the heliosphere wasn\u2019t a perfect sphere and looked slightly lopsided, but its instruments are low resolution, giving us only a blurry image of the heliosphere. IMAP should give us a much clearer picture.<\/p>\n \u201cIMAP is a big step up over IBEX,\u201d says McComas. \u201c[IBEX is] a very small mission. But you need a big, strong mission with the resolution and sensitivity to put together the full picture.\u201d <\/p>\n IBEX also revealed something unusual: there seems to be a band of neutral atoms surrounding the heliosphere, called the IBEX ribbon, possibly caused by the interstellar magnetic field.<\/p>\n \u201cSome of these energetic neutral [atoms] are in the shape of a ring in the sky,\u201d says McNutt. IMAP should give us a better understanding of this ribbon and exactly how it\u2019s produced.<\/p>\n Dust in the wind<\/p>\n It\u2019s not just the heliopause that IMAP will study, however. One of its other instruments, the Interstellar Dust Experiment (IDEX<\/a>), will be trying to collect dust grains arriving from interstellar space.<\/p>\n We know that there are tiny grains of dust drifting between the stars because we\u2019ve seen their infrared glow \u2013 some spacecraft have even captured interstellar dust before \u2013 but we only have a small number of detections. <\/p>\n It\u2019s hoped IMAP will collect hundreds of incoming grains of dust, both from interstellar space and from the interplanetary space between the planets of the Solar System. That\u2019s possible thanks to the size of IDEX, which has a collection area comparable to an A4 sheet of paper.<\/p>\n \u201cWe have this huge dust collector,\u201d says McComas. \u201cWe should get about 100 [interstellar] dust grains in the first year alone. That would be more dust grains than all of humanity has collected in the space age.\u201d<\/p>\n IDEX will measure the size, velocity and energy of the incoming dust, telling us more about its formation and journey to us.<\/p>\n Each grain will be broken up inside the instrument, striking an ultra-pure gold surface where they become vaporised, breaking down into atoms with either a positive or negative electrical charge.<\/p>\n A detector will then identify the elements present in the dust fragments, helping scientists deduce where they likely came from \u2013 exploding stars, for example, or other cosmic explosions.<\/p>\n The last key goal of IMAP is to measure the solar wind at L1, including how it interacts with Earth\u2019s magnetic field<\/a>, and give us a better understanding of so-called space weather.<\/p>\n Several of its instruments are designed to track energetic particles from the Sun that could damage satellites or cause geomagnetic storms and threaten our way of life here on Earth.<\/p>\n \u201cThe solar wind flies everywhere in space,\u201d says Gkioulidou. \u201cIMAP will measure all these particles as they\u2019re coming out of the Sun.\u201d <\/p>\n Those measurements could be useful not just for tracking space weather on Earth, but for future human missions to the Moon and Mars<\/a> (both China and the US have plans to land humans on the lunar surface by 2030).<\/p>\n Astronauts travelling that far will spend prolonged amounts of time outside Earth\u2019s protective magnetic field and will be subjected to more solar radiation.<\/p>\n \u201cIf there\u2019s an event that could be dangerous to astronauts on the surface of the Moon, [IMAP\u2019s data] will feed into that forecast,\u201d says Jamie Favors<\/a>, director of NASA\u2019s Space Weather Program in Washington, DC.<\/p>\n For humans going further afield, \u201con that journey to Mars, there may be months in deep space [with] no protection,\u201d he says. \u201cThere are things about the [space] environment we don\u2019t know.\u201d <\/p>\n Interstellar exploration<\/p>\n It\u2019s the observations of the heliosphere, however, that are perhaps the most enticing aspect of IMAP\u2019s mission. \u201cIt\u2019s extremely exciting,\u201d says Opher. \u201cIt\u2019s a state-of-the-art mission to study the heliosphere.\u201d <\/p>\n Aside from the Voyager 1 and 2 spacecraft, only one other active spacecraft is set to cross the boundary into interstellar space.<\/p>\n NASA\u2019s New Horizons<\/a> spacecraft, which famously provided the first high-resolution images of the dwarf planet Pluto in 2015, is expected to cross the heliopause in the 2040s.<\/p>\n It wasn\u2019t designed to study this region, however, so while it\u2019ll teach us a lot about it, scientists are hopeful of one day sending new, dedicated missions into interstellar space.<\/p>\n One such proposal led by McNutt is called Interstellar Probe<\/a>. It\u2019s an idea to send a long-lived spacecraft into interstellar space, designed to operate for generations and travel an incredible 1,000 astronomical units in about 50 years.<\/p>\n That’s roughly ten times farther than the Voyager probes have currently reached.<\/p>\n The mission would harness a gravity<\/a> assist from Jupiter to fling itself out of the Solar System, carrying a suite of advanced instruments to study interstellar dust, neutral atoms, magnetic fields and more beyond the heliopause.<\/p>\n \u201cI\u2019ve been convinced this is a good idea for a long time,\u201d says McNutt. \u201cIt\u2019s just a question of getting other people convinced.\u201d <\/p>\n In 2024, the National Academies of Sciences, Engineering and Medicine in the US \u2013 a public body that advises the US government on science, engineering and health \u2013 announced its proposal for the next decade of NASA\u2019s research into the Sun and its surrounding environment, known as the Heliophysics Decadal Survey<\/a>.<\/p>\n The survey didn\u2019t directly recommend building Interstellar Probe, but it did say it was a compelling future mission that should be considered in the next decadal survey in the 2030s.<\/p>\n Having such a mission to collect in-situ data (data directly from the source) would be invaluable, says Opher. \u201cWe still want a new Voyager,\u201d she says. \u201cThere\u2019s nothing like in-situ data.\u201d<\/p>\n![\"The](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/01\/heliosphere-IMAP-thermal-vacuum-chamber.jpg\")
The IMAP was tested in NASA\u2019s thermal vacuum chamber to simulate the harsh conditions of space – Image credit: NASA\/John Hopkins APL\/Princeton\/Ed Whitman<\/p>\n![\"The](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/01\/heliosphere-IMAP-deploys-into-orbit.jpg\")
The IMAP deploying in orbit – Image credit: BAE Systems\/Benjamin Fry<\/p>\n![\"A](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/01\/heliosphere-IMAP-KSC.jpg\")
The IMAP was loaded into a SpaceX Falcon 9 payload container at the Astrotech Space Operations Facility in Florida, US – Image credit: NASA\/KSC<\/p>\n![\"Illustration](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/01\/heliosphere-info-illo.jpg\")
Illustration of the Solar System, detailing each section of space moving from the Sun on the left all the way to the heliopause and beyond on the right – Image credit: Magic Torch<\/p>\n
![\"Illustration](\"https:\/\/www.newsbeep.com\/uk\/wp-content\/uploads\/2026\/01\/heliosphere-Quaoar.jpg\")
An illustration of the dwarf planet Quaoar with its orbiting moon, Weywot. Both are located in the Kuiper belt, a doughnut-shaped region of icy objects and dwarf planets that orbit the Sun beyond Neptune – Image credit: Shutterstock<\/p>\n