HYPOTHETICAL EXERCISE

This dashboard and the Probabilistic Asteroid Impact Risk (PAIR) assessment results it contains are a product of the NASA Asteroid Threat Assessment Project (ATAP) at NASA Ames Research Center. The assessment was performed for hypothetical asteroid 2026 PDC27 in support of the 10th IAA Planetary Defense Conference 2027. The dashboard is meant to be useful to a variety of audiences with big picture information up front and additional details within the tabs. The scope of the dashboard is limited to population damage from immediate hazard sources (blast overpressure, thermal radiation, tsunami inundation, global effects), and does not include details on cascading hazards or damage to infrastructure. All results and statistics presented are based on the 5000 property samples x 5000 orbit samples = 25 million cases modeled for this exercise.

Impacting Earth in about 4 years, hypothetical asteroid 2026 PDC27 is likely to cause blast damage across the Montreal region in southeastern Canada affecting hundreds of thousands to millions of people. James Webb Space Telescope (JWST) observations in 2026 significantly refined diameter estimates from original brightness estimates. A flyby mission constrained the position and further refined volume estimates. The asteroid will be observable again starting in 2038 January, about 7 months before impact.

Date of Assessment

24 July 2034

Date of Potential Impact

10 July 2038

Earth Impact Probability

100%

Next Assessment No Earlier Than

Jan 2038

What is known about the asteroid?
Observation Data: Ground-based brightness estimates; JWST constrained size; Flyby recon mission constrained position and further refined size
Diameter: Modeled range is 78.7 - 87.4 m, most likely in the 81.8 - 84.4 m interval, with a median of 83.0 m and a mean of 83.0 m
Energy: Modeled range is 13.1 - 46.4 Mt, most likely in the 19.4 - 31.5 Mt interval, with a median of 25.7 Mt and a mean of 26.0 Mt

Asteroid Characterization is based on the 5000 property samples x 5000 orbit samples = 25 million cases modeled

Where are potential Earth-impact locations?
What hazards could the impact cause and how likely are they to cause damage (among potential Earth-impacting cases)?
Potential hazards: Blast Overpressure, Thermal Radiation
Most likely hazard to cause damage to populated regions: Blast Overpressure
Other hazards causing serious damage: Thermal Radiation

Chance of no serious damage to populated regions

0.0%

Chance of local (blast/thermal) damage to populated regions

100.0%

Chance of tsunami inundation damage to populated regions

0.0%

How many people could it affect (among potential Earth-impacting cases)?
HYPOTHETICAL EXERCISE

These results show a Probabilistic Asteroid Impact Risk assessment performed for hypothetical asteroid 2026 PDC27 as part of the 10th IAA Planetary Defense Conference 2027.

Results and Dashboard produced by the NASA Asteroid Threat Assessment Project (ATAP) at NASA Ames Research Center.

Ashley Coates1, Lorien Wheeler1, Jessie Dotson1, Rebecca Bennett1,2, Joseph Mirza1,2

1NASA Ames Research Center, 2Analytical Mechanics Associates, Inc.

Local Ground Damage Severity Key
Damage Severity Potential Blast Effects Potential Thermal Effects Fraction of Population Affected
Serious Shattered windows, some structure damage (1-2 psi) 2nd degree burns 10%
Severe Widespread structure damage (2-4 psi) 3rd degree burns 30%
Critical Most residential structures collapse (4-10 psi) Clothing ignition 60%
Unsurvivable Complete devastation (>10 psi) Structure ignition 100%

The lowest damage threshold tracked is 1 psi, however, lesser damaging effects can still occur at lower psi values. Damage levels reflect either blast or thermal effects of the given equivalent severity. Blast and thermal effects do not necessarily both occur within a given damage severity region

Likelihood of Hazard Damaging Population (among potential Earth-impacting cases)

Chance of no serious damage to populated regions

0.0%

Chance of blast damage to populated regions

100.0%

Chance of thermal radiation damage to populated regions

15.2%

Chance of tsunami damage to populated regions

0.0%

Chance of global effects to populated regions

0.0%

A single impact event can cause population damage from multiple hazards (e.g., blast + thermal, tsunami + local near-shore, or global + local or tsunami). Sum of damage occurrence probabilities may exceed 100%. A larger fraction of cases may produce each hazard, but do not affect populated regions.

Blast Overpressure
Thermal Radiation

Probability that blast overpressure will be a given severity or less at each distance bin among Earth-impacting cases. Colors correspond to the severities in the damage key, and grey represents overpressures below the serious threshold

Probability that blast overpressure will be a given severity or worse at each distance bin among Earth-impacting cases. Colors correspond to the severities in the damage key, and grey represents overpressures below the serious threshold

Probability that thermal exposure will be a given severity or less at each distance bin among Earth-impacting cases. Colors correspond to the severities in the damage key, and grey represents exposures below the serious threshold

Probability that thermal exposure will be a given severity or worse at each distance bin among Earth-impacting cases. Colors correspond to the severities in the damage key, and grey represents exposures below the serious threshold

Note that axes are scaled to each plot and differ between hazard types. While a hazard at a given severity level may exist at a certain radius, it does not necessarily occur over a populated region causing damage (compare to Potential Hazards tab).

Blast Overpressure
Thermal Radiation

Probability that the damage radius corresponding to serious blast overpressure is within a given damage radius bin among Earth impacting cases. Leftmost bin is the probability that blast overpressure does not reach the serious damage level

Probability that the damage radius corresponding to severe blast overpressure is within a given damage radius bin among Earth impacting cases. Leftmost bin is the probability that blast overpressure does not reach the severe damage level

Probability that the damage radius corresponding to critical blast overpressure is within a given damage radius bin among Earth impacting cases. Leftmost bin is the probability that blast overpressure does not reach the critical damage level

Probability that the damage radius corresponding to unsurvivable blast overpressure is within a given damage radius bin among Earth impacting cases. Leftmost bin is the probability that blast overpressure does not reach the unsurvivable damage level

Probability that the damage radius corresponding to serious thermal exposure is within a given damage radius bin among Earth impacting cases. Leftmost bin is the probability that thermal exposure does not reach the serious damage level

Probability that the damage radius corresponding to severe thermal exposure is within a given damage radius bin among Earth impacting cases. Leftmost bin is the probability that thermal exposure does not reach the severe damage level

Probability that the damage radius corresponding to critical thermal exposure is within a given damage radius bin among Earth impacting cases. Leftmost bin is the probability that thermal exposure does not reach the critical damage level

Probability that the damage radius corresponding to unsurvivable thermal exposure is within a given damage radius bin among Earth impacting cases. Leftmost bin is the probability that thermal exposure does not reach the unsurvivable damage level

Note that axes are scaled to each plot and differ between hazard types and severities. While a hazard at a given severity level may exist at a certain radius, it does not necessarily occur over a populated region causing damage (compare to Potential Hazards tab).

Stat Serious Damage Radius [km] Severe Damage Radius [km] Critical Damage Radius [km] Unsurvivable Damage Radius [km] Serious Blast Radius [km] Severe Blast Radius [km] Critical Blast Radius [km] Unsurvivable Blast Radius [km] Serious Thermal Radius [km] Severe Thermal Radius [km] Critical Thermal Radius [km] Unsurvivable Thermal Radius [km] Burst Altitude [km]
HPDI 68%, Most Likely Range [36.2 - 49.5] [22.0 - 35.9] [7.3 - 21.3] [0.0 - 0.0] [36.2 - 49.5] [22.0 - 35.9] [7.3 - 21.3] [0.0 - 0.0] [0.0 - 0.0] [0.0 - 0.0] [0.0 - 0.0] [0.0 - 0.0] [11 - 17]
HPDI 99%, Potential Range [30.6 - 89.6] [8.1 - 45.9] [0.0 - 25.1] [0.0 - 9.1] [30.6 - 89.6] [8.1 - 45.9] [0.0 - 25.1] [0.0 - 9.1] [0.0 - 16.6] [0.0 - 10.6] [0.0 - 0.0] [0.0 - 0.0] [9 - 22]
Mean 48.7 28.4 12.1 1.2 48.7 28.4 12.1 1.2 1.4 0.5 0.0 0.0 15
Min Modeled 25.9 0.0 0.0 0.0 25.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 8
1st Percentile 31.1 10.4 0.0 0.0 31.1 10.4 0.0 0.0 0.0 0.0 0.0 0.0 9
5th Percentile 35.3 16.5 0.0 0.0 35.3 16.5 0.0 0.0 0.0 0.0 0.0 0.0 10
50th Percentile 44.8 28.8 12.9 0.0 44.8 28.8 12.9 0.0 0.0 0.0 0.0 0.0 14
95th Percentile 81.9 39.6 22.2 7.5 81.9 39.6 22.2 7.5 11.4 4.4 0.0 0.0 20
99th Percentile 87.7 44.7 25.1 9.1 87.7 44.7 25.1 9.1 16.6 10.6 0.0 0.0 22
Max Modeled 93.2 53.2 34.2 11.7 93.2 53.2 34.2 11.7 21.3 15.2 8.7 5.3 24

Categories labeled (Severity Level) Damage Radius are the local ground damage values calculated as the max of the blast and thermal damage radius values.

Min Modeled and Max Modeled represent the smallest and largest values modeled (5000 property samples x 5000 impact points = 25 million cases modeled), not absolute theoretical limits.

HPDI stands for Highest Probability Density Interval. HPDI 68% represents the most likely range, and HPDI 99% represents the potential range.

HYPOTHETICAL EXERCISE

These results show a Probabilistic Asteroid Impact Risk assessment performed for hypothetical asteroid 2026 PDC27 as part of the 10th IAA Planetary Defense Conference 2027.

Results and Dashboard produced by the NASA Asteroid Threat Assessment Project (ATAP) at NASA Ames Research Center.

Ashley Coates1, Lorien Wheeler1, Jessie Dotson1, Rebecca Bennett1,2, Joseph Mirza1,2

1NASA Ames Research Center, 2Analytical Mechanics Associates, Inc.

If Earth impact occurs, the chance of overall damage exceeding certain affected population thresholds is:

>1 person

100.0%

>1k people

100.0%

>10k people

100.0%

>100k people

93.0%

>1M people

20.0%

>10M people

0.0%

Affected Population Likelihood from All Damage (among potential Earth-impacting cases)

Probabilities of different population ranges being affected
Affected Population Threshold from All Damage (among potential Earth-impacting cases)

Likelihood of a certain number of people or more being affected
Affected Population Likelihood from Local (Blast/Thermal) Damage (among potential Earth-impacting cases)

Probabilities of different population ranges being affected by local damage
Affected Population Threshold from Local (Blast/Thermal) Damage (among potential Earth-impacting cases)

Likelihood of a certain number of people or more being affected by local damage
Affected Population Likelihood from Tsunami Damage (among potential Earth-impacting cases)

Probabilities of different population ranges being affected by tsunami damage
Affected Population Threshold from Tsunami Damage (among potential Earth-impacting cases)

Likelihood of a certain number of people or more being affected by tsunami damage
Stat All Hazard Affected Population Local Affected Population Blast Affected Population Thermal Affected Population Tsunami Affected Population Global Affected Population Local Population, Serious Local Population, Severe Local Population, Critical Local Population, Unsurvivable Tsunami Population
HPDI 68%, Most Likely Range [50.1k - 750k] [50.1k - 750k] [50.1k - 750k] [0 - 0 ] [0 - 0 ] [0 - 0 ] [1.96M - 5.47M] [0 - 1.35M] [0 - 188k] [0 - 0 ] [0 - 0 ]
HPDI 99%, Potential Range [20.5k - 2.16M] [20.5k - 2.16M] [20.5k - 2.16M] [0 - 66.1k] [0 - 0 ] [0 - 0 ] [305k - 5.47M] [0 - 4.04M] [0 - 2.48M] [0 - 249k] [0 - 0 ]
Mean 616k 616k 616k 2.94k 0 0 2.93M 1.2M 263k 9.82k 0
Min Modeled 9.05k 9.05k 9.05k 0 0 0 90.5k 0 0 0 0
1st Percentile 56.0k 56.0k 56.0k 0 0 0 362k 41.1k 0 0 0
5th Percentile 88.0k 88.0k 88.0k 0 0 0 534k 132k 0 0 0
50th Percentile 498k 498k 498k 0 0 0 3.24M 666k 96.8k 0 0
95th Percentile 1.58M 1.58M 1.58M 9.63k 0 0 5.26M 3.52M 1.33M 37.6k 0
99th Percentile 2.16M 2.16M 2.16M 66.1k 0 0 5.44M 4.04M 2.48M 249k 0
Max Modeled 3.42M 3.42M 3.42M 1.26M 0 0 5.68M 4.66M 4.06M 1.81M 0

Min Modeled and Max Modeled represent the smallest and largest values modeled (5000 property samples x 5000 impact points = 25 million cases modeled), not absolute theoretical limits.

HPDI stands for Highest Probability Density Interval. HPDI 68% represents the most likely range, and HPDI 99% represents the potential range.

HYPOTHETICAL EXERCISE

These results show a Probabilistic Asteroid Impact Risk assessment performed for hypothetical asteroid 2026 PDC27 as part of the 10th IAA Planetary Defense Conference 2027.

Results and Dashboard produced by the NASA Asteroid Threat Assessment Project (ATAP) at NASA Ames Research Center.

Ashley Coates1, Lorien Wheeler1, Jessie Dotson1, Rebecca Bennett1,2, Joseph Mirza1,2

1NASA Ames Research Center, 2Analytical Mechanics Associates, Inc.

Top Figure: Average affected population (colormap) for potential entry points along the swath given the range of potential asteroid sizes and properties

Middle Figure: Likelihood of impact occurring within potential impact regions

Bottom Figure (tabs): Average number and ranges of people affected by local (greater of blast overpressure and thermal radiation) or tsunami damage within longitudinal bins along the swath

Average affected population (colormap) and impact probability (bar height) for potential entry points along the swath given the range of potential asteroid sizes and properties

Average affected population for potential entry points along the swath given the range of potential asteroid sizes and properties
HYPOTHETICAL EXERCISE

These results show a Probabilistic Asteroid Impact Risk assessment performed for hypothetical asteroid 2026 PDC27 as part of the 10th IAA Planetary Defense Conference 2027.

Results and Dashboard produced by the NASA Asteroid Threat Assessment Project (ATAP) at NASA Ames Research Center.

Ashley Coates1, Lorien Wheeler1, Jessie Dotson1, Rebecca Bennett1,2, Joseph Mirza1,2

1NASA Ames Research Center, 2Analytical Mechanics Associates, Inc.

Local Ground Damage Severity Key
Damage Severity Potential Blast Effects Potential Thermal Effects Fraction of Population Affected
Serious Shattered windows, some structure damage (1-2 psi) 2nd degree burns 10%
Severe Widespread structure damage (2-4 psi) 3rd degree burns 30%
Critical Most residential structures collapse (4-10 psi) Clothing ignition 60%
Unsurvivable Complete devastation (>10 psi) Structure ignition 100%

The lowest damage threshold tracked is 1 psi, however, lesser damaging effects can still occur at lower psi values. Damage levels reflect either blast or thermal effects of the given equivalent severity. Blast and thermal effects do not necessarily both occur within a given damage severity region

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Examples of potential local ground damage footprints along the swath, given ranges of potential impact locations and damage sizes. Damage severity levels serious, severe, critical, and unsurvivable shown out to the 50th percentile

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Examples of potential local ground damage footprints along the swath, given ranges of potential impact locations and damage sizes. Damage severity levels serious, severe, critical, and unsurvivable shown out to the 95th percentile

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Examples of potential local ground damage footprints along the swath, given ranges of potential impact locations and damage sizes. Damage severity levels serious, severe, critical, and unsurvivable shown out to the 99th percentile

Keep in mind that Mercator projection effects distort the size of the footprints near the poles, causing them to appear larger. Click on the footprints to see the damage radius

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Extent of regions potentially at risk for local ground damage, given ranges of potential impact locations and damage sizes. Damage severity levels serious, severe, critical, and unsurvivable shown out to the 95th percentile

Keep in mind that Mercator projection effects distort the extent of the damage region near the poles, causing it to appear larger

Median (50th percentile) Damage Example
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Large (95th percentile) Damage Example
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Montreal, Canada Region: Highest average affected population from local damage along swath

Median (50th percentile) Damage Example
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Large (95th percentile) Damage Example
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Montreal, Canada Region: Highest impact probability along swath

HYPOTHETICAL EXERCISE

These results show a Probabilistic Asteroid Impact Risk assessment performed for hypothetical asteroid 2026 PDC27 as part of the 10th IAA Planetary Defense Conference 2027.

Results and Dashboard produced by the NASA Asteroid Threat Assessment Project (ATAP) at NASA Ames Research Center.

Ashley Coates1, Lorien Wheeler1, Jessie Dotson1, Rebecca Bennett1,2, Joseph Mirza1,2

1NASA Ames Research Center, 2Analytical Mechanics Associates, Inc.

Asteroid Characterization Highlights
Observation Data: Ground-based brightness estimates; JWST constrained size; Flyby recon mission constrained position and further refined size
Diameter: Modeled range is 78.7 - 87.4 m, most likely in the 81.8 - 84.4 m interval, with a median of 83.0 m and a mean of 83.0 m
Energy: Modeled range is 13.1 - 46.4 Mt, most likely in the 19.4 - 31.5 Mt interval, with a median of 25.7 Mt and a mean of 26.0 Mt

Asteroid Characterization is based on the 5000 property samples x 5000 orbit samples = 25 million cases modeled

Diameter
Bulk Density
Porosity
Aerodynamic Strength
H Magnitude
Albedo
Taxonomy
Entry Velocity
Entry Angle
Ablation Coefficient
Luminous Efficiency
Strength-Scaling Coefficient
Stat Diameter [m] Mass [kg] Impact Energy [Mt TNT] Bulk Density [kg/m³] Porosity [%] Aerodynamic Strength [MPa] H-Magnitude [-] Albedo [-] Entry Velocity [km/s] Entry Latitude [degrees] Entry Longitude [degrees] Entry Angle [degrees] Impact/Airburst Latitude [degrees] Impact/Airburst Longitude [degrees] Ablation Coefficient [kg/J] Luminous Efficiency [-] Strength-Scaling Coefficient [-]
HPDI 68%, Most Likely Range [81.8 - 84.4] [5.02e+08 - 8.17e+08] [19.4 - 31.5] [1630 - 2671] [16 - 46] [0.10 - 2.27] [22.8 - 23.1] [0.13 - 0.19] [17.97 - 17.97] [45.0 - 45.0] [-73.4 - -72.9] [56.1 - 56.2] [45.4 - 45.5] [-73.3 - -72.8] [3.50e-10 - 1.21e-08] [1.00e-04 - 2.33e-03] [0.17 - 0.30]
HPDI 99%, Potential Range [79.6 - 86.1] [3.82e+08 - 1.04e+09] [14.7 - 40.2] [1277 - 3379] [1 - 59] [0.10 - 9.58] [22.5 - 23.5] [0.10 - 0.25] [17.97 - 17.97] [44.9 - 45.0] [-73.7 - -72.5] [56.1 - 56.2] [45.4 - 45.6] [-73.7 - -72.4] [3.50e-10 - 6.66e-08] [1.00e-04 - 9.47e-03] [0.10 - 0.30]
Mean 83.0 6.73e+08 26.0 2247 32 2.17 23.0 0.17 17.97 45.0 -73.1 56.1 45.5 -73.1 1.27e-08 2.16e-03 0.20
Min Modeled 78.7 3.38e+08 13.1 1192 0 0.10 22.3 0.08 17.97 44.9 -74.0 56.0 45.3 -73.9 3.50e-10 1.00e-04 0.10
1st Percentile 80.0 3.94e+08 15.2 1347 2 0.10 22.6 0.11 17.97 44.9 -73.7 56.1 45.4 -73.6 3.70e-10 1.05e-04 0.10
5th Percentile 80.9 4.39e+08 16.9 1484 8 0.13 22.7 0.12 17.97 44.9 -73.5 56.1 45.4 -73.5 4.58e-10 1.27e-04 0.11
50th Percentile 83.0 6.66e+08 25.7 2229 33 1.01 23.0 0.16 17.97 45.0 -73.1 56.1 45.5 -73.1 4.49e-09 1.01e-03 0.20
95th Percentile 85.1 9.31e+08 35.9 3079 55 8.17 23.3 0.22 17.97 45.0 -72.7 56.2 45.5 -72.7 5.23e-08 8.01e-03 0.29
99th Percentile 86.0 1.02e+09 39.5 3339 59 9.58 23.4 0.24 17.97 45.0 -72.6 56.2 45.5 -72.5 6.65e-08 9.46e-03 0.30
Max Modeled 87.4 1.20e+09 46.4 3746 60 10.00 23.7 0.33 17.98 45.0 -72.3 56.3 45.6 -72.2 6.99e-08 1.00e-02 0.30

Property stats are each computed independently. Multiple values from a given percentile cannot necessarily be combined to represent a single physically-plausible asteroid.

Min Modeled and Max Modeled represent the smallest and largest values modeled (5000 property samples x 5000 impact points = 25 million cases modeled), not absolute theoretical limits.

HPDI stands for Highest Probability Density Interval. HPDI 68% represents the most likely range, and HPDI 99% represents the potential range.

HYPOTHETICAL EXERCISE

These results show a Probabilistic Asteroid Impact Risk assessment performed for hypothetical asteroid 2026 PDC27 as part of the 10th IAA Planetary Defense Conference 2027.

Results and Dashboard produced by the NASA Asteroid Threat Assessment Project (ATAP) at NASA Ames Research Center.

Ashley Coates1, Lorien Wheeler1, Jessie Dotson1, Rebecca Bennett1,2, Joseph Mirza1,2

1NASA Ames Research Center, 2Analytical Mechanics Associates, Inc.

Common Terms and Definitions
Term Definition
PAIR Probabilistic Asteroid Impact Risk, fast running Monte Carlo model to assess asteroid impact risk
Hazard Type or category of effect that could cause damage (blast overpressure, thermal radiation, tsunami, etc.)
Damage Result of hazard (Number of people, severity of blast, etc.)
Local Damage Maximum between blast overpressure and thermal radiation damage
Affected Population Scaled population based on damage severity
Most Likely Range HPDI 68%
Potential Range HPDI 99%
HPDI Highest Probability Density Interval, narrowest range that contains a certain percentage of the points
HYPOTHETICAL EXERCISE

These results show a Probabilistic Asteroid Impact Risk assessment performed for hypothetical asteroid 2026 PDC27 as part of the 10th IAA Planetary Defense Conference 2027.

Results and Dashboard produced by the NASA Asteroid Threat Assessment Project (ATAP) at NASA Ames Research Center.

Ashley Coates1, Lorien Wheeler1, Jessie Dotson1, Rebecca Bennett1,2, Joseph Mirza1,2

1NASA Ames Research Center, 2Analytical Mechanics Associates, Inc.