NASA: Asteroid Apophis Will Pass Closer to Earth Than Many Satellites in 2029

On Friday, April 13, 2029, an asteroid roughly the height of the Eiffel Tower will thread the gap between Earth and its highest-orbiting satellites. Apophis — named after the Egyptian god of chaos — will pass approximately 31,600 kilometers above Earth's surface, close enough to be visible to the naked eye for up to two billion people in the Eastern Hemisphere [1][2]. No asteroid this large has come this close to Earth in recorded history.

The flyby poses no danger. NASA has ruled out any chance of impact for at least the next century [3]. But the event has mobilized two space agencies, spawned more than 235 peer-reviewed research papers, and reignited a debate over whether humanity is genuinely prepared to deflect a threatening asteroid — or merely confident it can study one as it passes by.

How Close Is Close?

Apophis will pass at an altitude of roughly 31,600 km — below the 35,786-km ring where geostationary communications and weather satellites orbit, but above the GPS constellation at approximately 20,200 km and far above the International Space Station at around 400 km [1][4].

Source: NASA/JPL

Data as of Apr 14, 2026CSV

To put this in human terms: the Moon orbits at about 384,400 km. Apophis will pass more than ten times closer. The asteroid will spend approximately 34.3 hours inside the Moon's orbital radius, with its perigee (closest approach point) estimated between 29,500 and 33,800 km above Earth's surface [4].

NASA has stated explicitly that the asteroid poses no risk to satellites, despite passing through the same altitude band [1]. The geostationary belt is vast — roughly 265,000 km in circumference at the equator — and its approximately 573 active satellites [5] are spread thinly enough that a collision with Apophis would require an extraordinary coincidence of timing and geometry. The U.S. Space Surveillance Network tracks over 40,000 artificial objects in orbit as of April 2025 [6], but the overwhelming majority are in low Earth orbit, far below Apophis's closest approach altitude.

From Existential Threat to Cosmic Spectacle

Apophis was discovered on June 19, 2004, by astronomers Roy Tucker, David Tholen, and Fabrizio Bernardi at Kitt Peak National Observatory in Arizona [4]. Within six months, it became the most alarming object in the sky.

In December 2004, initial observations indicated a 2.7% probability that Apophis would strike Earth on April 13, 2029 — enough to earn it a rating of 4 on the Torino Scale, a ten-point system for communicating asteroid impact hazards [4][7]. No other object has ever been rated that high. A Torino 4 rating signals a "close encounter, meriting attention by astronomers" with a 1% or greater chance of a collision capable of regional devastation.

The alarm lasted hours. On December 27, 2004, astronomers located precovery images — earlier photographs of the asteroid taken before its formal discovery — that extended its known orbital arc back to March 2004. The additional data reduced the 2029 impact probability to effectively zero [4][7].

Subsequent observations continued to tighten the orbital solution. High-precision radar measurements from the Goldstone Deep Space Communications Complex and the Arecibo Observatory (before its collapse in 2020) reduced the uncertainty in Apophis's predicted 2029 position by 98% [4]. A key factor in these refinements was accounting for the Yarkovsky effect — a subtle force produced when an asteroid absorbs sunlight and re-emits it as heat, creating a tiny thrust. For Apophis, this effect can shift its predicted position by 20 to 740 km over 22 years [4].

By August 2006, the danger of a 2036 impact was lowered to Torino 0 [4]. In March 2021, radar observations from Goldstone allowed JPL to announce definitively that Apophis posed no impact threat for at least 100 years, and the asteroid was removed from the Sentry Risk Table [3][8].

The Keyhole Problem — and Why It's Been Closed

The most persistent concern about Apophis was not a direct hit in 2029 but what astronomers call a "gravitational keyhole" — a narrow region of space through which the asteroid's trajectory could be bent by Earth's gravity onto a collision course during a future return [8][9].

A gravitational keyhole is a specific, very small window in space. If an asteroid passes through it during a close encounter, gravitational perturbation shifts its orbit just enough to set up an impact on a subsequent pass. For Apophis, the keyhole of concern was a corridor approximately 600 meters wide, 212.14 km below the asteroid's nominal closest-approach point, that would have redirected it toward Earth in 2068 [4][9].

Simulations in 2013 showed that the Yarkovsky effect could, in theory, nudge Apophis through this keyhole during the 2029 flyby, leading to a close approach in 2051 and a possible impact in 2068. The estimated probability was roughly two in a million [4].

The 2021 Goldstone radar campaign resolved the question. Apophis's orbit is now known precisely enough to confirm it will not pass through any keyhole leading to impacts in 2036 or 2068 [3][8]. Preliminary Goldstone radar data in 2013 had already dropped the 2036 impact probability below one in a million [4].

Two Spacecraft, One Asteroid

The 2029 flyby has attracted two dedicated missions — a scale of attention rarely given to a single asteroid.

OSIRIS-APEX (Origins, Spectral Interpretation, Resource Identification, and Security — Apophis Explorer) is a NASA mission repurposed from the OSIRIS-REx spacecraft that successfully returned samples from asteroid Bennu in September 2023. The renamed spacecraft will arrive at Apophis roughly one month after the April 2029 flyby and study the asteroid for 18 months [10][11]. Its instruments will measure how Earth's gravitational tides physically altered Apophis during the encounter — reshaping its surface, triggering landslides, or changing its spin. The mission will also fire its engines near the surface to expose subsurface material for analysis [10].

Ramses (Rapid Apophis Mission for Space Safety) is the European Space Agency's contribution. Unlike OSIRIS-APEX, Ramses is designed to arrive before the flyby — launching in April 2028 and reaching Apophis by February 2029, two months ahead of closest approach [12][13]. This will allow Ramses to observe the asteroid's "before" state and then document changes in real time as Earth's gravity exerts tidal forces during the encounter. ESA's Ministerial Council committed to the mission in full at its November 2025 meeting, and JAXA (the Japan Aerospace Exploration Agency) has formalized a partnership to contribute technical components and launch the probe on its H3 rocket [13].

Funding remains precarious for the U.S. mission. The House FY 2026 appropriations bill included $20 million for OSIRIS-APEX [14]. Mission leadership has warned that recent budget cuts threaten to force the science team to stand down — a funding level that, as the mission's principal investigator Daniella DellaGiustina has noted, is "far less than the cost of one fighter jet" [15].

Source: OpenAlex

Data as of Jan 1, 2026CSV

What If It Did Hit?

Apophis is not going to hit Earth. But the hypothetical matters — because Apophis-sized asteroids do hit Earth, on average once every 80,000 years, and understanding their destructive potential is the reason planetary defense exists.

At roughly 340 meters wide and traveling at more than 10,000 miles per hour, Apophis would strike with the kinetic energy of approximately 1,200 megatons of TNT [4][16]. For comparison, the Tunguska event of 1908 — which flattened 2,150 square kilometers of Siberian forest — released an estimated 3 to 30 megatons, from an object only about 50–60 meters across [17][18]. Apophis carries roughly 80 to 400 times that energy.

Source: NASA/Wikipedia

Data as of Jan 1, 2026CSV

A land impact would create a crater approximately 5.1 km across. Severe destruction would extend 10 to 30 km from the impact point, with heavy structural damage and widespread fires reaching 30 to 60 km, and window-shattering force extending 100 to 200 km [16][19]. An ocean impact would generate significant tsunami waves.

The event would be devastating regionally but would not cause a global extinction. The Chicxulub impactor that killed the non-avian dinosaurs 66 million years ago was approximately 10 km across and released energy on the order of 100 million megatons — roughly 83,000 times more than Apophis's estimated yield [20]. Chicxulub triggered global firestorms, an impact winter, and the extinction of 75% of all species. An Apophis-scale impact would destroy an area of thousands of square kilometers but would be "unlikely to have long-lasting global effects, such as the initiation of an impact winter" [4].

Could We Deflect It?

In September 2022, NASA's DART (Double Asteroid Redirection Test) mission proved that a kinetic impactor — a spacecraft deliberately crashed into an asteroid — can measurably change an asteroid's orbit. DART shortened the 11-hour-55-minute orbital period of the moonlet Dimorphos around the asteroid Didymos by 32 minutes [21][22]. The mission validated the principle of kinetic deflection and demonstrated that the technique scales predictably.

But validating a concept and executing an emergency deflection are different problems. DART targeted Dimorphos, a 160-meter object in a binary system, under controlled conditions with years of advance planning [21]. Deflecting Apophis — a 340-meter object roughly eight times more massive — would require substantially more energy, more lead time, or multiple impactors.

NASA's Planetary Defense Coordination Office (PDCO) is the U.S. entity charged with detecting and characterizing potentially hazardous asteroids and coordinating a response [21]. Internationally, two bodies established in 2014 under the UN Committee on the Peaceful Uses of Outer Space (COPUOS) handle threat assessment: the International Asteroid Warning Network (IAWN), which coordinates observations and communicates risks to governments, and the Space Mission Planning Advisory Group (SMPAG), an inter-agency forum that develops deflection recommendations [23][24].

The gap between these structures and an actual deflection mission is significant. SMPAG would convene, prepare scenarios for reconnaissance and deflection, and issue recommendations to national decision-makers [23]. But as a 2024 review in Acta Astronautica noted, "there is a lack of agreement on who is responsible for vetting the science, assessing the risks, and making decisions if Earth were faced with an actual impact threat" [23]. No treaty designates a single authority. No nation has pre-authorized a deflection mission. The lead time required to design, build, launch, and navigate a kinetic impactor to a specific asteroid is measured in years — far longer than the weeks or months that might be available if the 2029 flyby data unexpectedly revealed a future collision trajectory.

In practice, only NASA has demonstrated kinetic impactor technology, and only ESA has a mission designed to characterize a potentially hazardous asteroid up close [12]. China's space agency has announced plans for a kinetic impactor test of its own, but no other country has flown a deflection demonstration.

The Case That the Alarm Is Overblown

Not all planetary scientists are comfortable with the level of public attention Apophis receives. The core argument: the impact probability peaked at 2.7% for a single day in December 2004 and has been effectively zero for over two decades [4][7]. Every headline describing Apophis as the "God of Chaos" that will "skim dangerously close to Earth" relies on a scenario that rigorous observation has firmly ruled out.

Some researchers worry that repeated near-miss framing erodes public trust in scientific risk communication [25]. If every asteroid flyby becomes a news cycle about potential catastrophe — followed by a reassurance that the risk was never real — audiences learn to tune out. The concern is that when a genuinely threatening asteroid is eventually detected, the public may not take the warning seriously.

Others counter that the attention is warranted precisely because it drives funding and institutional preparation. Apophis is the reason OSIRIS-APEX and Ramses exist. The 2029 flyby will provide the first-ever close-range observation of a large asteroid interacting with Earth's gravity — data that cannot be obtained any other way and that directly improves humanity's ability to model and deflect future threats [10][12][25].

The tension is real: scientists who understate the risk may lose funding for missions that are genuinely needed, while scientists who overstate it may be accused of "fear mongering chasing grants, clicks, or prestige" [25]. The Planetary Society has attempted to thread this needle, noting that "the basic calculation remains unchanged: Apophis is highly unlikely to hit Earth during this pass" while emphasizing that the flyby's scientific value is independent of its threat level [9].

A Dress Rehearsal for the Real Thing

Perhaps the most significant aspect of the Apophis encounter is what it reveals about preparation — or the lack of it.

In 2022, NASA ran a planetary defense tabletop exercise using Apophis as a stand-in for a hazardous asteroid [26]. The exercise exposed coordination gaps between agencies, unclear decision-making authority, and a shortage of ready-to-launch reconnaissance spacecraft. The UN General Assembly declared 2029 the International Year of Asteroid Awareness and Planetary Defence [24] — an acknowledgment that the Apophis flyby is as much a political moment as a scientific one.

The asteroid will arrive on a Friday the 13th, visible without telescopes, tracing a bright arc across the sky above Africa and Europe [1][2]. For a few hours, billions of people will be able to see, with their own eyes, an object large enough to destroy a city passing closer than the satellites that carry their television signals.

That it will pass safely is a testament to two decades of precise orbital mechanics. That humanity still lacks a tested, authorized, and funded plan to deflect such an object if it were not passing safely is the less comfortable truth the flyby exposes.