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.

There is a ~19% chance that hypothetical asteroid 2026 PDC27 will impact Earth in 2038 (~12 years). James Webb Space Telescope (JWST) observations significantly refined diameter estimates from original brightness estimates. Large ranges of potential damage sizes, severities, and locations remain possible. The asteroid will be observable again by large telescopes from 2026 December to 2027 August.

Date of Current Assessment

1 Aug 2026

Date of Potential Impact

10 July 2038

Earth Impact Probability

19%

Next Assessment No Earlier Than

2027

What is known about the asteroid?
Observation Data: Ground-based brightness estimates, JWST estimated diameter and determined S taxonomy
Diameter: Potential range is 75 - 88 m, most likely in the 80 - 85 m interval, with a median of 82 m and a mean of 82 m
Energy: Potential range is 13.1 - 40.5 Mt, most likely in the 18.0 - 30.4 Mt interval, with a median of 24.9 Mt and a mean of 25.3 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

50.2%

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

49.8%

Chance of tsunami inundation damage to populated regions

negligible

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

50.2%

Chance of blast damage to populated regions

49.8%

Chance of thermal radiation damage to populated regions

4.4%

Chance of tsunami damage to populated regions

negligible

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

Probability that the damage radius corresponding to severe blast overpressure is within a given damage radius bin among Earth impacting cases

Probability that the damage radius corresponding to critical blast overpressure is within a given damage radius bin among Earth impacting cases

Probability that the damage radius corresponding to unsurvivable blast overpressure is within a given damage radius bin among Earth impacting cases

Probability that the damage radius corresponding to serious thermal exposure is within a given damage radius bin among Earth impacting cases

Probability that the damage radius corresponding to severe thermal exposure is within a given damage radius bin among Earth impacting cases

Probability that the damage radius corresponding to critical thermal exposure is within a given damage radius bin among Earth impacting cases

Probability that the damage radius corresponding to unsurvivable thermal exposure is within a given damage radius bin among Earth impacting cases

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 [36.5 - 48.7] [18.7 - 33.7] [0.0 - 12.6] [0.0 - 0.0] [36.5 - 48.7] [18.7 - 33.7] [0.0 - 12.6] [0.0 - 0.0] [0.0 - 0.0] [0.0 - 0.0] [0.0 - 0.0] [0.0 - 0.0] [12 - 20]
HPDI 99%, Potential Range [23.2 - 82.5] [0.0 - 39.2] [0.0 - 22.0] [0.0 - 7.0] [23.2 - 82.5] [0.0 - 39.2] [0.0 - 22.0] [0.0 - 7.0] [0.0 - 15.2] [0.0 - 8.4] [0.0 - 0.0] [0.0 - 0.0] [10 - 28]
Mean 43.1 24.4 8.3 0.4 43.1 24.4 8.3 0.4 0.9 0.2 0.0 0.0 17
Min Modeled 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 9
1st Percentile 25.9 0.0 0.0 0.0 25.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 10
5th Percentile 31.3 9.3 0.0 0.0 31.3 9.3 0.0 0.0 0.0 0.0 0.0 0.0 12
50th Percentile 42.5 25.2 8.8 0.0 42.5 25.2 8.8 0.0 0.0 0.0 0.0 0.0 16
95th Percentile 56.0 35.8 19.3 3.8 56.0 35.8 19.3 3.8 8.7 0.0 0.0 0.0 24
99th Percentile 79.7 39.2 22.0 7.0 79.7 39.2 22.0 7.0 15.2 8.4 0.0 0.0 28
Max Modeled 94.2 50.1 29.9 10.6 94.2 50.1 29.9 10.6 21.5 15.1 7.8 3.8 37

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

49.8%

>1k people

38.8%

>10k people

25.5%

>100k people

5.2%

>1M people

0.3%

>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 [0 - 4.42k] [0 - 4.42k] [0 - 4.42k] [0 - 0 ] [0 - 0 ] [0 - 0 ] [0 - 30.7k] [0 - 3.78k] [0 - 7] [0 - 0 ] [0 - 0 ]
HPDI 99%, Potential Range [0 - 541k] [0 - 541k] [0 - 541k] [0 - 954] [0 - 0 ] [0 - 0 ] [0 - 2.75M] [0 - 1.08M] [0 - 206k] [0 - 1.76k] [0 - 0 ]
Mean 26.4k 26.4k 26.4k 110 0 0 134k 49.4k 9.97k 207 0
Min Modeled 0 0 0 0 0 0 0 0 0 0 0
1st Percentile 0 0 0 0 0 0 0 0 0 0 0
5th Percentile 0 0 0 0 0 0 0 0 0 0 0
50th Percentile 0 0 0 0 0 0 0 0 0 0 0
95th Percentile 104k 104k 104k 0 0 0 608k 177k 26.0k 0 0
99th Percentile 541k 541k 541k 954 0 0 2.75M 1.08M 206k 1.76k 0
Max Modeled 3.06M 3.06M 3.06M 786k 18 0 7.91M 4.56M 3.62M 1.29M 3.79k

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